BEGIN:VCALENDAR
VERSION:2.0
PRODID:researchseminars.org
CALSCALE:GREGORIAN
X-WR-CALNAME:researchseminars.org
BEGIN:VEVENT
SUMMARY:Suvrat Raju (ICTS\, Bengaluru)
DTSTART;VALUE=DATE-TIME:20200504T093000Z
DTEND;VALUE=DATE-TIME:20200504T103000Z
DTSTAMP;VALUE=DATE-TIME:20220528T192937Z
UID:ictsvirtual/1
DESCRIPTION:Title: The holographic nature of null infinity\nby Suvrat Raju (ICTS\, Be
ngaluru) as part of ICTS String Seminars\n\n\nAbstract\nI will argue that
a careful examination of the low energy properties of quantum gravity\, to
gether with reasonable assumptions about the UV theory\, leads to insights
into the origin of holography in anti-de Sitter space. The same technique
s also lead to a clear conjecture about how quantum information is localiz
ed in asymptotically flat spacetimes. The conjecture is that\, in quantum
gravity\, all information about massless excitations can be obtained from
an infinitesimal neighbourhood of the past boundary of future null infini
ty and does not require observations over all of future null infinity. In
the context of the information paradox\, this suggests that the fine-grain
ed von Neumann entropy of the state defined on a segment (-\\infty\,u) of
future null infinity is independent of u. This conjecture also implies tha
t the oft-discussed "Page curve" may be a misleading target to aim for in
analyses of black hole evaporation.\n
LOCATION:https://researchseminars.org/talk/ictsvirtual/1/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Matteo Baggioli (IFT UAM-CSIC)
DTSTART;VALUE=DATE-TIME:20200506T093000Z
DTEND;VALUE=DATE-TIME:20200506T103000Z
DTSTAMP;VALUE=DATE-TIME:20220528T192937Z
UID:ictsvirtual/2
DESCRIPTION:Title: From Hydrodynamics to Viscoelasticity in Holography and beyond ...
\nby Matteo Baggioli (IFT UAM-CSIC) as part of ICTS String Seminars\n\n\nA
bstract\nHow to construct a holographic model for viscoelastic materials ?
\n\nWhy can that be useful and for what purpose ?\nWhich is the hydrodynam
ics behind these models ?\nWhat do these models have in common with quasic
rystals ?\nWhat is a diffusive Goldstone mode and when does it appear ?\nH
ow and in which sense are solids different from fluids ?\nWhat do theory a
nd experiments in confined fluids tell us ?\nHow do glasses and Weyl semim
etals sound ?\n\nThese are the questions that I will discuss with you dur
ing my talk!\n
LOCATION:https://researchseminars.org/talk/ictsvirtual/2/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Gautam Mandal (TIFR\, Mumbai)
DTSTART;VALUE=DATE-TIME:20200513T093000Z
DTEND;VALUE=DATE-TIME:20200513T103000Z
DTSTAMP;VALUE=DATE-TIME:20220528T192937Z
UID:ictsvirtual/3
DESCRIPTION:Title: Holographic interpretation of Bulk entanglement entropy\nby Gautam
Mandal (TIFR\, Mumbai) as part of ICTS String Seminars\n\n\nAbstract\nWe
propose a holographic interpretation of entanglement entropy (EE) of a spa
tial subregion A in the bulk\, in terms of the reduced density matrix for
an appropriate sub algebra of observables\nin the boundary field theory/bo
undary quantum mechanics. The construct in the boundary theory corresponds
to partitioning of the target space and is called a target space EE. We
discuss this in the context of supergravity dual of Dp brane field theori
es\, in particular for D0 brane quantum mechanics. We find qualitative agr
eement between the bulk and boundary calculations.\n
LOCATION:https://researchseminars.org/talk/ictsvirtual/3/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Juan Maldacena (IAS\, Princeton)
DTSTART;VALUE=DATE-TIME:20200522T113000Z
DTEND;VALUE=DATE-TIME:20200522T123000Z
DTSTAMP;VALUE=DATE-TIME:20220528T192937Z
UID:ictsvirtual/4
DESCRIPTION:Title: Magnetic black holes\nby Juan Maldacena (IAS\, Princeton) as part
of ICTS String Seminars\n\n\nAbstract\nWe discuss properties of magnetical
ly charged black holes in the\nStandard Model. We will discuss how the ele
ctroweak symmetry is restored\naround the black hole. In addition\, the Ha
wking evaporation rate is\ngreatly enhanced by a factor of the charge of t
he black hole.\n
LOCATION:https://researchseminars.org/talk/ictsvirtual/4/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Leopoldo Pando Zayas (University of Michigan)
DTSTART;VALUE=DATE-TIME:20200527T103000Z
DTEND;VALUE=DATE-TIME:20200527T113000Z
DTSTAMP;VALUE=DATE-TIME:20220528T192937Z
UID:ictsvirtual/5
DESCRIPTION:Title: Precision microstate counting of AdS black hole entropy\nby Leopol
do Pando Zayas (University of Michigan) as part of ICTS String Seminars\n\
n\nAbstract\nI will describe how within eleven dimensional supergravity on
e can compute the logarithmic correction to the Bekenstein-Hawking entropy
of certain magnetically charged asymptotically AdS$_4$ black holes with a
rbitrary horizon topology. The result perfectly agrees with the dual fiel
d theory computation of the topologically twisted index in ABJM theory an
d in certain theories obtained from M5 wrapping a hyperbolic 3-manifold. T
he extension to rotating\, electrically charged AdS$_4$ black holes and th
e dual superconformal index will also be discussed.\n
LOCATION:https://researchseminars.org/talk/ictsvirtual/5/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Per Kraus (UCLA)
DTSTART;VALUE=DATE-TIME:20200604T160000Z
DTEND;VALUE=DATE-TIME:20200604T170000Z
DTSTAMP;VALUE=DATE-TIME:20220528T192937Z
UID:ictsvirtual/6
DESCRIPTION:Title: Anomalous Dimensions from Thermal AdS Partition Functions\nby Per
Kraus (UCLA) as part of ICTS String Seminars\n\n\nAbstract\nI will present
an efficient method for computing thermal partition functions of weakly c
oupled scalar fields in AdS. We consider quartic contact interactions and
show how to evaluate the relevant two-loop vacuum diagrams without perform
ing any explicit AdS integration\, the key step being the use of Kallen-Le
hmann type identities. This leads to a simple method for extracting double
-trace anomalous dimensions in any spacetime dimension\, recovering known
first-order results in a streamlined fashion.\n
LOCATION:https://researchseminars.org/talk/ictsvirtual/6/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Larus Thorlacius (University of Iceland)
DTSTART;VALUE=DATE-TIME:20200608T093000Z
DTEND;VALUE=DATE-TIME:20200608T103000Z
DTSTAMP;VALUE=DATE-TIME:20220528T192937Z
UID:ictsvirtual/7
DESCRIPTION:Title: Page curves in asymptotically flat spacetime\nby Larus Thorlacius
(University of Iceland) as part of ICTS String Seminars\n\n\nAbstract\nIf
black hole evaporation is a unitary process\, the entanglement entropy bet
ween the \noutgoing Hawking radiation and the quantum state describing the
remaining black hole \nis expected to follow a so-called Page curve as a
function of time. A Page curve for an \nevaporating black hole in asymptot
ically flat spacetime can be computed analytically by\nadapting the Quantu
m Ryu-Takayanagi (QRT) proposal to a solvable two-dimensional \ndilaton gr
avity theory. The associated Page time is found to be one third of the bla
ck \nhole lifetime\, at leading order in semi-classical corrections. A Pag
e curve can also be \nobtained for a semi-classical eternal black hole\, w
here energy loss due to Hawking \nevaporation is balanced by an incoming e
nergy flux.\n
LOCATION:https://researchseminars.org/talk/ictsvirtual/7/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Zhenbin Yang (Stanford)
DTSTART;VALUE=DATE-TIME:20200610T033000Z
DTEND;VALUE=DATE-TIME:20200610T043000Z
DTSTAMP;VALUE=DATE-TIME:20220528T192937Z
UID:ictsvirtual/8
DESCRIPTION:Title: Finite-cutoff JT gravity and self-avoiding loops\nby Zhenbin Yang
(Stanford) as part of ICTS String Seminars\n\n\nAbstract\nWe study quantum
JT gravity at finite cutoff using a mapping to the statistical mechanics
of a self-avoiding loop in hyperbolic space\, with positive pressure and f
ixed length. The semiclassical limit (small $G_{N}$) corresponds to large
pressure\, and we solve the problem in that limit in three overlapping reg
imes that apply for different loop sizes. For intermediate loop sizes\, a
semiclassical effective description is valid\, but for very large or very
small loops\, fluctuations dominate. For large loops\, this quantum regime
is controlled by the Schwarzian theory. For small loops\, the effective d
escription fails altogether\, but the problem is controlled using a conjec
ture from the theory of self-avoiding walks.\n
LOCATION:https://researchseminars.org/talk/ictsvirtual/8/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Geoff Penington (Stanford University)
DTSTART;VALUE=DATE-TIME:20200624T033000Z
DTEND;VALUE=DATE-TIME:20200624T043000Z
DTSTAMP;VALUE=DATE-TIME:20220528T192937Z
UID:ictsvirtual/9
DESCRIPTION:Title: Replica Wormholes\, Entanglement Wedges and the Black Hole Information
Paradox\nby Geoff Penington (Stanford University) as part of ICTS Str
ing Seminars\n\n\nAbstract\nHawking famously argued\, based on semiclassic
al calculations\, that the radiation from evaporating black holes is alway
s perfectly thermal and contains no information about the matter that fell
in. Such a result is inconsistent with the unitarity of quantum mechanics
. In this talk\, I will argue that a more careful replica trick calculatio
n shows that the gravitational path integral becomes dominated at late tim
es by saddles containing spacetime wormholes. These wormholes cause the en
tropy to decrease after the Page time\, consistent with unitarity\, and al
low information to escape from the interior of the black hole. In very sim
ple toy models\, we can evaluate the path integral exactly\, and see the i
nformation emerge. In more realistic black holes\, the full wormhole solut
ions cannot be found explicitly. However\, their existence\, and their mos
t important consequences\, can be derived by studying the location and pro
perties of a non-trivial ‘quantum extremal surface’ in the original Ha
wking solution.\n
LOCATION:https://researchseminars.org/talk/ictsvirtual/9/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Nabamita Banerjee (IISER\, Bhopal)
DTSTART;VALUE=DATE-TIME:20200626T093000Z
DTEND;VALUE=DATE-TIME:20200626T103000Z
DTSTAMP;VALUE=DATE-TIME:20220528T192937Z
UID:ictsvirtual/10
DESCRIPTION:Title: A 3D flat-space holography inspired by AdS3/CFT2 duality\nby Naba
mita Banerjee (IISER\, Bhopal) as part of ICTS String Seminars\n\n\nAbstra
ct\nI shall mostly talk about the status of flat-space holography in three
space time dimensions. The works are in parallel to AdS3/CFT2 duality. I
shall end with the open ends in the field.\n
LOCATION:https://researchseminars.org/talk/ictsvirtual/10/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Sean Hartnoll (Stanford University)
DTSTART;VALUE=DATE-TIME:20200723T123000Z
DTEND;VALUE=DATE-TIME:20200723T133000Z
DTSTAMP;VALUE=DATE-TIME:20220528T192937Z
UID:ictsvirtual/11
DESCRIPTION:Title: Bootstrapping Matrix Quantum Mechanics\nby Sean Hartnoll (Stanfor
d University) as part of ICTS String Seminars\n\n\nAbstract\nMatrix quantu
m mechanics theories are at the heart of holography\, but only the simple
case of a single matrix has been tractable. We have developed a new method
to calculate the spectrum and expectation values of operators in matrix q
uantum mechanics\, including with multiple matrices. Firstly\, we relate t
he expectation values of simple operators to those of more complicated ope
rators. We then impose certain positivity constraints on the longer operat
ors. This is seen to strongly constrain the simple expectation values. Usi
ng this method\, we easily reproduce the known solution of single-matrix q
uantum mechanics\, and then go on to obtain new results on the ground stat
e of two-matrix quantum mechanics. This talk is based on 2004.10212.\n
LOCATION:https://researchseminars.org/talk/ictsvirtual/11/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Arnab Priya Saha (HRI)
DTSTART;VALUE=DATE-TIME:20200617T093000Z
DTEND;VALUE=DATE-TIME:20200617T103000Z
DTSTAMP;VALUE=DATE-TIME:20220528T192937Z
UID:ictsvirtual/12
DESCRIPTION:Title: Double soft theorem in generalized bi-adjoint scalars\nby Arnab P
riya Saha (HRI) as part of ICTS String Seminars\n\n\nAbstract\nIn CHY form
alism\, scattering equations map the kinematic space of Mandelstam invaria
nts to the points on $\\mathbb{CP}^{1}$. Recently Cachazo\, Early\, Gueva
ra and Mizera have introduced generalization to the scattering equations o
n higher dimensional projective spaces\, $\\mathbb{CP}^{k-1}$. Bi-adjoint
scalar amplitude is a well studied example of this generalisation. We stu
dy double soft limits of the generalised bi-adjoint scalar amplitudes for
$k=3$. \n \nThis talk is based on the work in progress with Md. Abhishek\,
Subramanya Hegde and Dileep P. Jatkar\n
LOCATION:https://researchseminars.org/talk/ictsvirtual/12/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Geoffrey Compere (Université libre de Bruxelles)
DTSTART;VALUE=DATE-TIME:20200619T093000Z
DTEND;VALUE=DATE-TIME:20200619T103000Z
DTSTAMP;VALUE=DATE-TIME:20220528T192937Z
UID:ictsvirtual/13
DESCRIPTION:Title: The BMS group in (A)dS\nby Geoffrey Compere (Université libre de
Bruxelles) as part of ICTS String Seminars\n\n\nAbstract\nRecent work has
uncovered interesting connections between memory effects\, soft theorems
and BMS asymptotic symmetries in the infrared structure of asymptotically
flat gravity. In this talk\, I will present the AdS/dS generalization of t
he BMS symmetries. I will discuss the realization of these “Lambda-BMS
” symmetries as a surface charge algebra. I will also show that the asym
ptotically flat BMS surface charge algebra is recovered in the asymptotica
lly flat limit only after adding corner terms in the variational principle
in addition to the standard holographic counterterms.\n
LOCATION:https://researchseminars.org/talk/ictsvirtual/13/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Douglas Stanford (Stanford)
DTSTART;VALUE=DATE-TIME:20200708T033000Z
DTEND;VALUE=DATE-TIME:20200708T043000Z
DTSTAMP;VALUE=DATE-TIME:20220528T192937Z
UID:ictsvirtual/14
DESCRIPTION:Title: On the density matrix of the Hawking radiation\nby Douglas Stanfo
rd (Stanford) as part of ICTS String Seminars\n\n\nAbstract\nWe set up the
computation of the density matrix of the Hawking radiation by computing i
nner products of black hole states projected onto different histories of H
awking radiation. A simple computation of these inner products suggests th
at an ensemble average is implicit in the simple gravity description.\n
LOCATION:https://researchseminars.org/talk/ictsvirtual/14/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Tom Hartman (Cornell)
DTSTART;VALUE=DATE-TIME:20200715T120000Z
DTEND;VALUE=DATE-TIME:20200715T130000Z
DTSTAMP;VALUE=DATE-TIME:20220528T192937Z
UID:ictsvirtual/15
DESCRIPTION:Title: Holographic duality for averaged free CFTs\nby Tom Hartman (Corne
ll) as part of ICTS String Seminars\n\n\nAbstract\nI will describe recent
progress on the connections among the conformal bootstrap\, the sphere pac
king problem\, and quantum gravity in three dimensions. This leads us towa
rd a holographic duality between Narain CFTs averaged over moduli and a Ch
ern-Simons-like theory of "U(1) gravity"\n
LOCATION:https://researchseminars.org/talk/ictsvirtual/15/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Subhroneel Chakrabarti (The Institute of Mathematical Sciences (IM
Sc)\, Chennai)
DTSTART;VALUE=DATE-TIME:20200821T093000Z
DTEND;VALUE=DATE-TIME:20200821T103000Z
DTSTAMP;VALUE=DATE-TIME:20220528T192937Z
UID:ictsvirtual/16
DESCRIPTION:Title: Pure Spinor Superstrings: Massive States\nby Subhroneel Chakrabar
ti (The Institute of Mathematical Sciences (IMSc)\, Chennai) as part of IC
TS String Seminars\n\n\nAbstract\nPure Spinor formulation\, introduced by
Nathan Berkovits 20 years ago\, is the only known Super-Poincare covariant
worldsheet formulation of superstring theory. The last two decades saw pu
re spinor formulation emerge as the most efficient way to compute string a
mplitudes\, especially at higher loop levels. However\, most of these succ
esses revolved around external massless states and the massive states rema
ined largely unexplored. In this talk\, I will describe the recent develop
ment in understanding the massive states of superstrings in pure spinor fo
rmalism\, as carried out in a series of works by me and my collaborators.
We will present the first proposal for systematic covariant construction o
f massive vertex operators and discuss how that proposal lead to the const
ruction of integrated massive vertex for the first time\, as well as its f
ully covariant theta expansion. With these new results\, we will also expl
ain how for the first time an explicit equivalence of pure spinor and the
well-known RNS formalism for massive states was achieved. I will assume no
prior knowledge of pure spinor formulation from the audience and spend so
me time introducing this formalism to make the talk more accessible to a c
omparatively larger audience.\n
LOCATION:https://researchseminars.org/talk/ictsvirtual/16/
END:VEVENT
BEGIN:VEVENT
SUMMARY:R Loganayagam (ICTS\, Bengaluru)
DTSTART;VALUE=DATE-TIME:20200422T093000Z
DTEND;VALUE=DATE-TIME:20200422T103000Z
DTSTAMP;VALUE=DATE-TIME:20220528T192937Z
UID:ictsvirtual/17
DESCRIPTION:Title: Open QFTs from holography\nby R Loganayagam (ICTS\, Bengaluru) as
part of ICTS String Seminars\n\n\nAbstract\nIn this talk\, I will outline
a formalism to study open quantum field theories using holographic method
s. More precisely\, I will consider a quantum field theory (the system) co
upled to a holographic field theory at finite temperature (the environment
). The aim here is to integrate out the holographic environment with an ai
m of obtaining an effective dynamics for the resulting open quantum field
theory. This is done using semiclassical gravitational Schwinger-Keldysh s
addle geometries obtained by complexifying black hole spacetimes. In add
ition to shedding light on open quantum systems coupled to strongly correl
ated thermal environments\, these results also provide a principled comput
ation of Schwinger-Keldysh observables in gravity and holography. In parti
cular\, these influence functionals capture both the dissipative physics o
f black hole quasinormal modes\, as well as that of the fluctuations encod
ed in outgoing Hawking quanta\, and interactions between them.\n\n\nThis t
alk will be based on https://arxiv.org/abs/2004.02888\n
LOCATION:https://researchseminars.org/talk/ictsvirtual/17/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Shamik Banerjee (IOP\, Bhubaneswar)
DTSTART;VALUE=DATE-TIME:20200429T093000Z
DTEND;VALUE=DATE-TIME:20200429T103000Z
DTSTAMP;VALUE=DATE-TIME:20220528T192937Z
UID:ictsvirtual/18
DESCRIPTION:Title: BMS symmetry of celestial OPE\nby Shamik Banerjee (IOP\, Bhubanes
war) as part of ICTS String Seminars\n\n\nAbstract\nIn this talk\, we stud
y the BMS symmetry of the celestial\nOPE of two positive helicity graviton
s in Einstein theory in four\ndimensions. The celestial OPE is obtained by
Mellin transforming the\nscattering amplitude in the (holomorphic) collin
ear limit. The collinear\nlimit at leading order gives the singular term o
f the celestial OPE. We\ncompute the first subleading correction to the OP
E by analysing the four\ngraviton scattering amplitude directly in Mellin
space. The subleading\nterm can be written as a linear combination of BMS
descendants with the\nOPE coefficients determined by BMS algebra and the c
oefficient of the\nleading term in the OPE. This can be done by defining a
suitable BMS\nprimary state. We find that among the descendants\, which a
ppear at the\nfirst subleading order\, there is one which is created by ho
lomorphic\nsupertranslation with a simple pole on the celestial sphere.\n\
n This talk is based on https://arxiv.org/abs/2002.00975\n (htt
ps://doi.org/10.1007/JHEP04(2020)130 )\n
LOCATION:https://researchseminars.org/talk/ictsvirtual/18/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Mark Van Raamsdonk (UBC)
DTSTART;VALUE=DATE-TIME:20200729T033000Z
DTEND;VALUE=DATE-TIME:20200729T043000Z
DTSTAMP;VALUE=DATE-TIME:20220528T192937Z
UID:ictsvirtual/19
DESCRIPTION:Title: Holo-ween\nby Mark Van Raamsdonk (UBC) as part of ICTS String Sem
inars\n\n\nAbstract\nWe argue that given holographic $CFT_1$ in some state
with a dual spacetime geometry $M$\, and given some other holographic $C
FT_2$\, we can find states of $CFT_2$ whose dual geometries closely approx
imate arbitrarily large causal patches of M\, provided that $CFT_1$ and $C
FT_2$ can be non-trivially coupled at an interface. Our $CFT_2$ states are
"dressed up as" states of CFT1: they are obtained from the original $CFT_
1$ state by a regularized quench operator defined using a Euclidean path-i
ntegral with an interface between $CFT_2$ and $CFT_1$. Our results are con
sistent with the idea that the precise microscopic degrees of freedom and
Hamiltonian of a holographic $CFT$ are only important in fixing the asympt
otic behavior of a dual spacetime\, while the interior spacetime of a regi
on spacelike separated from a boundary time slice is determined by more un
iversal properties (such as entanglement structure) of the quantum state a
t this time slice. Our picture requires that low-energy gravitational theo
ries related to $CFTs$ that can be non-trivially coupled at an interface a
re part of the same non-perturbative theory of quantum gravity.\n
LOCATION:https://researchseminars.org/talk/ictsvirtual/19/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Derek Teaney (SUNY)
DTSTART;VALUE=DATE-TIME:20200805T113000Z
DTEND;VALUE=DATE-TIME:20200805T123000Z
DTSTAMP;VALUE=DATE-TIME:20220528T192937Z
UID:ictsvirtual/20
DESCRIPTION:Title: Transport and hydrodynamics in almost the chiral limit.\nby Derek
Teaney (SUNY) as part of ICTS String Seminars\n\n\nAbstract\nFirst I will
briefly review lattice data on the QCD phase transition\, which shows tha
t real world QCD at the physical pion mass is close enough to the chiral l
imit that the $O_4$ phase transition describes several features of the QCD
crossover. Next I describe the appropriate hydrodynamic theory in the sp
ontaneously broken chiral limit\, where the pions must be included in the
list of hydrodynamic fields\, and the theory is a prototype for non-abelia
n superfluids more generally. In the real world the mass of the pion is fi
nite\, and thus theory is superfluid like at short distances\, but normal
fluid like at long distances. The superfluid modes can be integrated out b
y evaluating the appropriate hydrodynamic loop\, leaving calculable correc
tions to the transport parameters of the normal fluid. Alternatively\, on
e can develop a kinetic equation for the soft pion modes\, which can be us
ed to evaluate these corrections. I discuss how these corrections scale
near the chiral critical point. Finally\, I point out a few problems tha
t normal-fluid hydro simulations have in describing the observed soft pio
n yields in heavy ion collisions. I suggest that the superfluid theory ca
n help to resolve these residual discrepancies with the otherwise remarkab
ly successful hydro model.\n
LOCATION:https://researchseminars.org/talk/ictsvirtual/20/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Raghu Mahajan (IAS\, Princeton)
DTSTART;VALUE=DATE-TIME:20200826T043000Z
DTEND;VALUE=DATE-TIME:20200826T053000Z
DTSTAMP;VALUE=DATE-TIME:20220528T192937Z
UID:ictsvirtual/21
DESCRIPTION:Title: A Tutorial on Entanglement Island Computations\nby Raghu Mahajan
(IAS\, Princeton) as part of ICTS String Seminars\n\n\nAbstract\nIn this t
alk we will present details of quantum extremal surface computations in a
simple setup\, demonstrating the role of entanglement islands in resolving
entropy paradoxes in gravity. The setup involves eternal AdS2 black holes
in thermal equilibrium with auxiliary bath systems. We will also describ
e the extension of this setup to higher dimensions using Randall-Sundrum b
ranes.\n
LOCATION:https://researchseminars.org/talk/ictsvirtual/21/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Atish Dabholkar (ICTP)
DTSTART;VALUE=DATE-TIME:20200812T093000Z
DTEND;VALUE=DATE-TIME:20200812T103000Z
DTSTAMP;VALUE=DATE-TIME:20220528T192937Z
UID:ictsvirtual/22
DESCRIPTION:Title: Three Avatars of Mock Modularity\nby Atish Dabholkar (ICTP) as pa
rt of ICTS String Seminars\n\n\nAbstract\nMock theta functions were introd
uced by Ramanujan in his famous last letter to Hardy in 1920 but were prop
erly understood only recently with the work of Zwegers in 2002. I will des
cribe three manifestations of this apparently exotic mathematics in thre
e important physical contexts of holography\, topology and duality where
mock modularity is essential to exhibit modular symmetries expected fr
om the $AdS_3/CFT_2$ holographic equivalence in quantum gravity and
the S-duality symmetry of four-dimensional quantum gauge theories. \nI
n particular\, I will show that the completion of mock modular forms occur
ring in these contexts satisfy a holomorphic anomaly equation. This p
henomenon can be related to the holomorphic anomaly of the elliptic genu
s of a two-dimensional noncompact supersymmetric sigma model\, and in a si
mpler context of quantum mechanics to the Atiyah-Patodi-Singer eta invar
iant.\n
LOCATION:https://researchseminars.org/talk/ictsvirtual/22/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Pavel Putrov (ICTP)
DTSTART;VALUE=DATE-TIME:20200819T093000Z
DTEND;VALUE=DATE-TIME:20200819T103000Z
DTSTAMP;VALUE=DATE-TIME:20220528T192937Z
UID:ictsvirtual/23
DESCRIPTION:Title: Holomorphic anomaly in Vafa-Witten theory\nby Pavel Putrov (ICTP)
as part of ICTS String Seminars\n\n\nAbstract\nVafa-Witten theory is a to
pologically twisted version of 4d N=4 super Yang-Mills theory. In my talk
I will tell how to derive a holomorphic anomaly equation for its partition
function on a Kaehler 4-manifold with b_2^+=1 and b_1=0 from the path int
egral of the effective theory on the Coulomb branch. I will also briefly m
ention an alternative but somewhat similar computation of the same holomor
phic anomaly in the effective 2d theory obtained by compactification of th
e corresponding 6d (2\,0) theory on the 4-manifold. The talk is based on a
joint work with A. Dabholkar and E. Witten.\n
LOCATION:https://researchseminars.org/talk/ictsvirtual/23/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Netta Englehardt (MIT)
DTSTART;VALUE=DATE-TIME:20200902T133000Z
DTEND;VALUE=DATE-TIME:20200902T143000Z
DTSTAMP;VALUE=DATE-TIME:20220528T192937Z
UID:ictsvirtual/24
DESCRIPTION:Title: Free Energy from Replica Wormholes\nby Netta Englehardt (MIT) as
part of ICTS String Seminars\n\n\nAbstract\nRecent developments on the bla
ck hole information paradox have shown that Euclidean wormholes — so cal
led “replica wormholes’’ can dominate the von Neumann entropy as com
puted by a gravitational path integral\, and that inclusion of these wormh
oles results in a unitary Page curve. This development raises some puzzles
from the perspective of factorization\, and has raised questions regardin
g what the gravitational path integral is computing. In this talk\, I will
focus on understanding the relationship between the gravitational path in
tegral and the partition function via the gravitational free energy (more
generally the generating functional). A proper computation of the free ene
rgy requires a replica trick distinct from the usual one used to compute t
he entropy. I will show that in JT gravity there is a regime where the fre
e energy computed without replica wormholes is pathological. Interestingly
\, the inclusion of replica wormholes is not quite sufficient to resolve t
he pathology: an alternative analytic continuation is required. I will dis
cuss the implications of this for various interpretations of the gravitati
onal path integral (e.g. as computing an ensemble average) and also mentio
n some parallels with spin glasses.\n
LOCATION:https://researchseminars.org/talk/ictsvirtual/24/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Sujay Ashok (IMSc\, Chennai)
DTSTART;VALUE=DATE-TIME:20200916T093000Z
DTEND;VALUE=DATE-TIME:20200916T103000Z
DTSTAMP;VALUE=DATE-TIME:20220528T192937Z
UID:ictsvirtual/25
DESCRIPTION:Title: Surface Defects from Fractional Branes\nby Sujay Ashok (IMSc\, Ch
ennai) as part of ICTS String Seminars\n\n\nAbstract\nWe show that the Guk
ov-Witten defects of supersymmetric Yang-Mills theory can be realized in p
erturbative string theory. This is done by considering an orbifold backgro
und of the Kanno-Tachikawa type and placing stacks of fractional D3-branes
whose world-volume partially extends along the orbifold directions. In pa
rticular\, we show that turning on a constant background value for some sc
alar fields in the closed string twisted sectors induces a non-trivial pro
file for the gauge field and one of the complex scalars of the world-volum
e theory. This profile exactly matches the singular behavior that one expe
cts for a Gukov-Witten surface defect in the N=4 supersymmetric gauge theo
ry.\n
LOCATION:https://researchseminars.org/talk/ictsvirtual/25/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Abhijit Gadde (TIFR)
DTSTART;VALUE=DATE-TIME:20200923T093000Z
DTEND;VALUE=DATE-TIME:20200923T103000Z
DTSTAMP;VALUE=DATE-TIME:20220528T192937Z
UID:ictsvirtual/26
DESCRIPTION:Title: Modularity of supersymmetric partition functions\nby Abhijit Gadd
e (TIFR) as part of ICTS String Seminars\n\n\nAbstract\nIn this talk\, I w
ill present a novel modular property of 4d N=1 supersymmetric partition fu
nctions of supersymmetric theories with R-symmetry. It is a generalization
of the modular invariance of the supersymmetric partition function of two
-dimensional supersymmetric theories on a torus i.e. of the elliptic genus
. It comes from requiring consistency of partition functions under gluing
and\, among other things\, can be used to rederive the supersymmetric Card
y formula for four-dimensional gauge theories that has played a key role i
n computing the entropy of supersymmetric black holes.\n
LOCATION:https://researchseminars.org/talk/ictsvirtual/26/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Nima Arkani-Hamed (IAS\, Princeton)
DTSTART;VALUE=DATE-TIME:20200710T130000Z
DTEND;VALUE=DATE-TIME:20200710T140000Z
DTSTAMP;VALUE=DATE-TIME:20220528T192937Z
UID:ictsvirtual/27
DESCRIPTION:Title: Spacetime\, quantum mechanics and clusterhedra at Infinity\nby Ni
ma Arkani-Hamed (IAS\, Princeton) as part of ICTS String Seminars\n\n\nAbs
tract\nElementary particle scattering is perhaps the most basic physical p
rocess in Nature. The data specifying the scattering process defines a "ki
nematic space"\, associated with the on-shell propagation of particles ou
t to infinity. By contrast the usual approach to computing scattering ampl
itudes\, involving path integrals and Feynman diagrams\, invokes auxilliar
y structures beyond this kinematic space--local interactions in the interi
or of spacetime\, and unitary evolution in Hilbert space. This description
makes space-time locality and quantum-mechanical unitarity manifest\, but
hides the extraordinary simplicity and infinite hidden symmetries of the
amplitudes\,g that have been uncovered over the past thirty years. The pas
t decade has seen the emergence of a new picture\, where scattering amplit
udes are seen as the answer to an entirely different sort of mathematical
question involving "positive geometries" directly in the kinematic space\,
making surprising connections to total positivity\, combinatorics and geo
metry of the grassmannian\, and cluster algebras. The hidden symmetries of
amplitudes are made manifest in this way\, while locality and unitarity
are seen as derivative notions\, arising from the "factorizing" boundary
structure of the positive geometries. This was first see in the story of
"amplituhedra" and scattering amplitudes in planar N=4 SYM theory. In the
past few years\, a similar structure has been seen for non-superysmmetric
"bi-adjoint" scalar theories with cubic interactions\, in any number of d
imensions. The positive geometries through to one-loop order are given by
"cluster polytopes"--generalized associahedra for finite-type cluster alge
bras--with a simple description involving "dynamical evolution" in the kin
ematic space. Extending these ideas involves understanding cluster algebra
s associated with triangulations of general Riemann surfaces. These cluste
r algebras are infinite\, reflecting the infinite action of mapping class
group. One of the manifestations of this infinity is that the "g-vector fa
n" of the cluster algebra is not space-filling\, making it impossible to d
efine cluster polytopes\, and obstructing the connection with positive geo
metries and scattering amplitudes. Remarkably\, incorporating non-cluster
variables\, associated with closed loops in the Riemann surfaces\, suggest
s a natural way of modding out by the mapping class group\, canonically co
mpactifying the cluster complex\, and associating it with "clusterhedron"
polytopes. Clusterhedra are conjectured to exist for all surfaces\, provid
ing the positive geometry in kinematic space for scattering amplitudes in
the bi-adjoint scalar theory to all loop orders and all orders in the 1/N
expansion. In this talk I will give an overview of this set of ideas\, ass
uming no prior knowledge of scattering amplitudes or cluster algebras. M
y lectures at the ICTS workshop on scattering amplitudes later this month\
, will give a systematic\, self-contained exposition of all the physical a
nd mathematical ideas involved\n
LOCATION:https://researchseminars.org/talk/ictsvirtual/27/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Vijay Balasubramanian (University of Pennsylvania)
DTSTART;VALUE=DATE-TIME:20200909T130000Z
DTEND;VALUE=DATE-TIME:20200909T140000Z
DTSTAMP;VALUE=DATE-TIME:20220528T192937Z
UID:ictsvirtual/28
DESCRIPTION:Title: Euclidean wormholes\, baby universes\, and unitarity in quantum gravi
ty\nby Vijay Balasubramanian (University of Pennsylvania) as part of I
CTS String Seminars\n\n\nAbstract\nSpacetime wormholes in the Euclidean pa
th integral for gravity represent the nucleation and annihilation of baby
universes. In the first part of the seminar I show how their inclusion in
the replica method preserves monogamy of entanglement and semiclassical u
nitarity. I apply the results to universes that have a positive cosmologi
cal constant. In the second part of the talk I extend a recently introdu
ced topological model of gravity with baby universes to include a sum over
spin structures. The results suggest that the gravitational path integra
l with wormholes should be interpreted in terms of an ensemble of dual th
eories. I conclude by discussing the apparent tension between these eff
ects of spacetime wormholes\, namely\, the restoration of unitarity in man
ifestations of quantum entanglement in semiclassical gravity vs. the appar
ent need to describe gravitating systems in terms of a statistical ensembl
e.\n
LOCATION:https://researchseminars.org/talk/ictsvirtual/28/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Luca Delacretaz (University of Chicago)
DTSTART;VALUE=DATE-TIME:20200930T140000Z
DTEND;VALUE=DATE-TIME:20200930T150000Z
DTSTAMP;VALUE=DATE-TIME:20220528T192937Z
UID:ictsvirtual/29
DESCRIPTION:Title: Heavy Operators and Hydrodynamic Tails\nby Luca Delacretaz (Unive
rsity of Chicago) as part of ICTS String Seminars\n\n\nAbstract\nThe late
time physics of interacting QFTs at finite temperature is controlled by hy
drodynamics. For CFTs this implies that heavy operators -- which are gener
ically expected to create thermal states -- can be studied semiclassically
. We show that hydrodynamics universally fixes the OPE coefficients C_{HH'
L}\, on average\, of all neutral light operators with two non-identical he
avy ones\, as a function of the scaling dimension and spin of the operator
s. These methods can be straightforwardly extended to CFTs with global sym
metries\, and generalize recent EFT results on large charge operators away
from the case of minimal dimension at fixed charge. We also revisit certa
in aspects of late time thermal correlators in QFT and other diffusive sys
tems.\n
LOCATION:https://researchseminars.org/talk/ictsvirtual/29/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Seok Kim (Seoul National University)
DTSTART;VALUE=DATE-TIME:20201007T093000Z
DTEND;VALUE=DATE-TIME:20201007T103000Z
DTSTAMP;VALUE=DATE-TIME:20220528T192937Z
UID:ictsvirtual/30
DESCRIPTION:Title: Black hole microstates and the index\nby Seok Kim (Seoul National
University) as part of ICTS String Seminars\n\n\nAbstract\nI will explain
the simple idea which allowed the recent microstate countings of BPS AdS
black holes.\n
LOCATION:https://researchseminars.org/talk/ictsvirtual/30/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Upamanyu Moitra (TIFR)
DTSTART;VALUE=DATE-TIME:20201014T093000Z
DTEND;VALUE=DATE-TIME:20201014T103000Z
DTSTAMP;VALUE=DATE-TIME:20220528T192937Z
UID:ictsvirtual/31
DESCRIPTION:Title: Near-Extremal Fluid Mechanics\nby Upamanyu Moitra (TIFR) as part
of ICTS String Seminars\n\n\nAbstract\nThis talk concerns fluid mechanics
corresponding to near-extremal black branes in anti-de Sitter spacetime\,
in an unconventional regime. In this regime\, in contrast with the convent
ional one\, the temperature of the fluid is much smaller than the spatial
and temporal rates of variation of the various fluid parameters. It turns
out that Einstein-Maxwell equations admit a systematic perturbative expans
ion even in the new regime. There are interesting new features for fluid d
ynamics at low temperatures – non-localities in the constitutive relatio
ns beyond first order in derivatives\, for example. My talk will focus on
a simple model which will illustrate the essential features of the near-ex
tremal fluid-gravity correspondence. I will also describe some key results
for the actual fluid system dual to the gravitational theory.\n
LOCATION:https://researchseminars.org/talk/ictsvirtual/31/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Edward Witten (IAS\, Princeton)
DTSTART;VALUE=DATE-TIME:20200717T120000Z
DTEND;VALUE=DATE-TIME:20200717T130000Z
DTSTAMP;VALUE=DATE-TIME:20220528T192937Z
UID:ictsvirtual/32
DESCRIPTION:Title: Deformations of JT gravity and matrix models\nby Edward Witten (I
AS\, Princeton) as part of ICTS String Seminars\n\n\nAbstract\nRecently it
was shown by Saad\, Shenker\, and Stanford that JT gravity in two dimensi
ons is dual not to any particular quantum system but to a random ensemble
of quantum systems. I will explain that if one deforms JT gravity by add
ing a self-coupling of the scalar field\, the resulting model is still dua
l to a random ensemble of quantum systems\, with a different density of en
ergy levels. I will also briefly describe work of Maxfield and Turiaci\
, who made a similar analysis in two dimensions and related it to issues i
n three-dimensional gravity.\n
LOCATION:https://researchseminars.org/talk/ictsvirtual/32/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Cumrun Vafa and Miguel Montero (Harvard University)
DTSTART;VALUE=DATE-TIME:20200904T120000Z
DTEND;VALUE=DATE-TIME:20200904T130000Z
DTSTAMP;VALUE=DATE-TIME:20220528T192937Z
UID:ictsvirtual/33
DESCRIPTION:Title: The Swampland in d>6\nby Cumrun Vafa and Miguel Montero (Harvard
University) as part of ICTS String Seminars\n\nAbstract: TBA\n
LOCATION:https://researchseminars.org/talk/ictsvirtual/33/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Mithat Unsal (NCSU)
DTSTART;VALUE=DATE-TIME:20201021T093000Z
DTEND;VALUE=DATE-TIME:20201021T103000Z
DTSTAMP;VALUE=DATE-TIME:20220528T192937Z
UID:ictsvirtual/34
DESCRIPTION:Title: Strongly coupled QFT dynamics via TQFT coupling\nby Mithat Unsal
(NCSU) as part of ICTS String Seminars\n\n\nAbstract\nWe consider a class
of quantum field theories and quantum\nmechanics\, which we couple to topo
logical QFTs\, in order to classify\nnon-perturbative effects in the origi
nal theory. The TQFT structure\narises naturally from turning on a classic
al background field for a\ndiscrete global symmetry. In SU(N) Yang-Mills t
heory coupled to\nTQFT\, the non-perturbative expansion parameter is\nexp[
-S_I/N] both in the semi-classical weak coupling domain and\nstrong coupli
ng domain\, corresponding to a\nfractional topological charge and action c
onfigurations. To classify\nthe non-perturbative effects in original SU(N)
theory\, we must use\nPSU(N) bundle and lift configurations (critical poi
nts at infinity)\nfor which there is no obstruction back to SU(N). These p
rovide a\nrefinement of instanton sums: integer topological charge\, but\n
crucially fractional action configurations contribute\, providing a\nTQFT
protected generalization of resurgent semiclassical expansion to\nstrong c
oupling.\n
LOCATION:https://researchseminars.org/talk/ictsvirtual/34/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Noppadol Mekareeya (INFN Milano-Bicocca)
DTSTART;VALUE=DATE-TIME:20201028T093000Z
DTEND;VALUE=DATE-TIME:20201028T103000Z
DTSTAMP;VALUE=DATE-TIME:20220528T192937Z
UID:ictsvirtual/35
DESCRIPTION:Title: Supersymmetry enhancement in 3d S-fold SCFTs\nby Noppadol Mekaree
ya (INFN Milano-Bicocca) as part of ICTS String Seminars\n\n\nAbstract\nA
local SL(2\,Z) transformation on the Type IIB brane configuration gives ri
se to an interesting class of 3d superconformal field theories\, known as
the S-fold SCFTs. One of the interesting features of such a theory is that
\, in general\, it does not admit a conventional Lagrangian description. N
evertheless\, it can be described by a quiver diagram with a building bloc
k being an SCFT known as the T(U(N)) theory. In this talk\, we discuss var
ious interesting properties of the S-fold theories\, including supersymmet
ry enhancement in the infrared as well as several interesting dualities.
This talk will have a different emphasis than previous talks with the sim
ilar title and abstract.\n
LOCATION:https://researchseminars.org/talk/ictsvirtual/35/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Soumyadeep Chaudhuri (Hebrew University)
DTSTART;VALUE=DATE-TIME:20201104T093000Z
DTEND;VALUE=DATE-TIME:20201104T103000Z
DTSTAMP;VALUE=DATE-TIME:20220528T192937Z
UID:ictsvirtual/36
DESCRIPTION:Title: Thermal order in large N conformal gauge theories\nby Soumyadeep
Chaudhuri (Hebrew University) as part of ICTS String Seminars\n\n\nAbstrac
t\nOur experience with many physical systems (eg. magnets) tells us that u
sually when a symmetry is spontaneously broken at low temperatures\, it is
restored upon increasing the temperature sufficiently. The abundance of
such systems raises the question of whether this is a universal feature of
all quantum systems. In this talk\, I will present examples of (3+1)-dime
nsional non-supersymmetric large N gauge theories which demonstrate violat
ions of the above feature. I will argue that in the N tending to infinity
limit\, these theories have conformal manifolds which survive under all lo
op corrections to the beta functions of the couplings. I will show that un
der certain conditions\, a subset of points on such a conformal manifold d
emonstrates the spontaneous breaking of a global symmetry at all nonzero t
emperatures. Furthermore\, I will demonstrate that this symmetry breaking
is accompanied by the Higgsing of a subset of gauge bosons leading the sys
tem to be in a persistent Brout-Englert-Higgs phase.\n
LOCATION:https://researchseminars.org/talk/ictsvirtual/36/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Julian Sonner (University of Geneva)
DTSTART;VALUE=DATE-TIME:20201111T093000Z
DTEND;VALUE=DATE-TIME:20201111T103000Z
DTSTAMP;VALUE=DATE-TIME:20220528T192937Z
UID:ictsvirtual/37
DESCRIPTION:Title: Causal symmetry breaking: late time physics of holographic quantum ch
aos\nby Julian Sonner (University of Geneva) as part of ICTS String Se
minars\n\n\nAbstract\nQuantum chaotic systems are often defined via the as
sertion that their spectral\nstatistics coincides with\, or is well approx
imated by\, random matrix theory. In this\ntalk I will explain how the uni
versal content of random matrix theory emerges as the\nconsequence of a si
mple symmetry-breaking principle and its associated Goldstone\nmodes. This
approach naturally leads to wormhole-like correlations in holography\, ev
en for individual theories. \nFinally I will comment on very recent result
s that allow us to extend the Goldstone effective-field-theory approach to
operator correlation functions\n
LOCATION:https://researchseminars.org/talk/ictsvirtual/37/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Rob Myers (Perimeter Institute)
DTSTART;VALUE=DATE-TIME:20201125T093000Z
DTEND;VALUE=DATE-TIME:20201125T103000Z
DTSTAMP;VALUE=DATE-TIME:20220528T192937Z
UID:ictsvirtual/39
DESCRIPTION:Title: Quantum Extremal Islands Made Easy\nby Rob Myers (Perimeter Insti
tute) as part of ICTS String Seminars\n\n\nAbstract\nWe illustrate the app
earance of quantum extremal islands in holographic setups in higher dimens
ions. We emphasize the close parallel with the behaviour of holographic en
tanglement entropy in more familiar settings.\n
LOCATION:https://researchseminars.org/talk/ictsvirtual/39/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Chandramouli Chowdhury (ICTS-TIFR)
DTSTART;VALUE=DATE-TIME:20200925T093000Z
DTEND;VALUE=DATE-TIME:20200925T103000Z
DTSTAMP;VALUE=DATE-TIME:20220528T192937Z
UID:ictsvirtual/40
DESCRIPTION:Title: A physical protocol for observers near the boundary to obtain bulk in
formation in quantum gravity\nby Chandramouli Chowdhury (ICTS-TIFR) as
part of ICTS String Seminars\n\n\nAbstract\nWe consider a set of observer
s who live near the boundary of global AdS\, and are allowed to act only w
ith simple low-energy unitaries and make measurements in a small interval
of time. The observers are not allowed to leave the near-boundary region.
We describe a physical protocol that nevertheless allows these observers t
o obtain detailed information about the bulk state. This protocol utilizes
the leading gravitational back-reaction of a bulk excitation on the metri
c\, and also relies on the entanglement-structure of the vacuum. For low-e
nergy states\, we show how the near-boundary observers can use this protoc
ol to completely identify the bulk state. We explain why the protocol fail
s completely in theories without gravity\, including non-gravitational gau
ge theories. This provides perturbative evidence for the claim that one of
the signatures of holography -- the fact that information about the bulk
is also available near the boundary -- is already visible in semiclassical
gravity.\n\nThis is work done in collaboration with Olga Papadoulaki and
Suvrat Raju and the reference is: https://arxiv.org/abs/2008.01740.\n
LOCATION:https://researchseminars.org/talk/ictsvirtual/40/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Justin David (IISc)
DTSTART;VALUE=DATE-TIME:20201202T093000Z
DTEND;VALUE=DATE-TIME:20201202T103000Z
DTSTAMP;VALUE=DATE-TIME:20220528T192937Z
UID:ictsvirtual/41
DESCRIPTION:Title: Information theoretic measures in 2d CFT and their universal propert
ies\nby Justin David (IISc) as part of ICTS String Seminars\n\n\nAbstr
act\nWe begin with a brief review of measures such as entanglement entropy
\, \nrelative entropy and techniques to evaluate them in 2d CFT. \nWe the
n study the properties of these measures when the theory \nor the state on
which these measures are evaluated are deformed by \nthe symmetries of th
e theory. The symmetries we focus are the \nVirasoro symmetries and highe
r spin symmetries. \nWe present 2 situations for which the deformations re
sult in universal \ncorrections to the information theoretic measures.\n
LOCATION:https://researchseminars.org/talk/ictsvirtual/41/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Soeren Schlichting (Bielefeld University)
DTSTART;VALUE=DATE-TIME:20201216T093000Z
DTEND;VALUE=DATE-TIME:20201216T103000Z
DTSTAMP;VALUE=DATE-TIME:20220528T192937Z
UID:ictsvirtual/43
DESCRIPTION:Title: Non-equilibrium QCD in heavy ion collisions\nby Soeren Schlichtin
g (Bielefeld University) as part of ICTS String Seminars\n\n\nAbstract\nOv
er the past decades\, experiments at the Relativistic Heavy-Ion Collider (
RHIC) and the Large Hadron Collider (LHC) have collected an overwhelming a
mount of evidence of the formation of a de-confined Quark-Gluon Plasma (QG
P) \, and established a standard picture of the space-time evolution of th
e QGP based on relativistic viscous hydrodynamics. While high-energy Heavy
-Ion Collisions thus provide a unique laboratory to study strong-interacti
on matter under extreme conditions\, it has proven challenging to understa
nd how the far-from equilibrium initial state eventually turns into a near
ly equilibrated plasma of quarks and gluons. In this talk I will highlight
recent theoretical progress in understanding different thermalization mec
hanisms in QCD plasmas and address the question how an almost equilibrated
Quark-Gluon plasma is created during the early stages of high-energy coll
isions. I will also discuss how these studies provide new insights into th
e range of applicability of dissipative fluid dynamics and the emergence o
f universal properties in out-of-equilibrium systems\, and if time remains
address some phenomenological consequences of the early time non-equilibr
ium dynamics.\n
LOCATION:https://researchseminars.org/talk/ictsvirtual/43/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Akhil Sivakumar (ICTS-TIFR)
DTSTART;VALUE=DATE-TIME:20201118T053000Z
DTEND;VALUE=DATE-TIME:20201118T063000Z
DTSTAMP;VALUE=DATE-TIME:20220528T192937Z
UID:ictsvirtual/44
DESCRIPTION:Title: Gravitational probes with memory\nby Akhil Sivakumar (ICTS-TIFR)
as part of ICTS String Seminars\n\n\nAbstract\nBlackholes are interesting
mainly due to two reasons. The first is that they give rise to irreversibl
e dynamics - event horizons mark a region of no return. Secondly they prod
uce Hawking radiation. While the first dissipative behaviour is well studi
ed\, the physics of fluctuations or Hawking radiation is not. In this talk
I will present preliminary results on understanding the real-time Hawking
fluctuations around an AdS blackbrane. The techniques we develop give a c
lean separation of short lived and long lived dynamics of the blackbrane.\
n
LOCATION:https://researchseminars.org/talk/ictsvirtual/44/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Pavel Kovtun (University of Victoria)
DTSTART;VALUE=DATE-TIME:20210120T093000Z
DTEND;VALUE=DATE-TIME:20210120T103000Z
DTSTAMP;VALUE=DATE-TIME:20220528T192937Z
UID:ictsvirtual/45
DESCRIPTION:Title: Hydrodynamics beyond hydrodynamics\nby Pavel Kovtun (University o
f Victoria) as part of ICTS String Seminars\n\n\nAbstract\nHydrodynamics i
s a well-established field with a venerable history. In\nthis talk\, I wil
l focus on two foundational aspects of hydrodynamics\nwhich have received
renewed attention in recent years. 1) Do the\nequations of hydrodynamics e
ven make sense? and 2) How do we describe\nlong-wavelength phenomena that
hydrodynamics is supposed to describe but\nfails to?\n
LOCATION:https://researchseminars.org/talk/ictsvirtual/45/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Sudarshan Ananth (IISER\, Pune)
DTSTART;VALUE=DATE-TIME:20210127T093000Z
DTEND;VALUE=DATE-TIME:20210127T103000Z
DTSTAMP;VALUE=DATE-TIME:20220528T192937Z
UID:ictsvirtual/46
DESCRIPTION:Title: An intricate path to gravity\nby Sudarshan Ananth (IISER\, Pune)
as part of ICTS String Seminars\n\n\nAbstract\nSymmetry enhancements in su
pergravity are presented and the resulting consequences for pure gravity d
iscussed.\n
LOCATION:https://researchseminars.org/talk/ictsvirtual/46/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Rajesh Gopakumar (ICTS)
DTSTART;VALUE=DATE-TIME:20210106T093000Z
DTEND;VALUE=DATE-TIME:20210106T103000Z
DTSTAMP;VALUE=DATE-TIME:20220528T192937Z
UID:ictsvirtual/47
DESCRIPTION:Title: From Symmetric Product CFTs to AdS_3\nby Rajesh Gopakumar (ICTS)
as part of ICTS String Seminars\n\n\nAbstract\nHow exactly do large N QFTs
reassemble themselves into perturbative string theories? This talk will f
ocus on an example which explicitly illustrates a general program of how t
his can happen around a free field fixed point. Specifically\, we consider
n-point correlators in the symmetric product orbifold theory\, dual to te
nsionless strings on AdS_3\, in a Gross-Mende like limit of large conforma
l dimensions. These correlators are given in terms of branched covering ma
ps which we can exactly solve for in this limit\, via a map to a matrix mo
del with a logarithmic potential. The spectral curve encoding the matrix m
odel solution then naturally gives rise to an integral over the dual strin
g moduli space through a special (Strebel) parameterization of the latter.
This is a precise realisation of what was proposed as the underlying mech
anism for gauge-string duality in weakly coupled QFTS. Finally\, the integ
rand on the moduli space can be cast in a number of striking forms includi
ng an action given by (the modulus of) the Schwarzian of the covering map\
n
LOCATION:https://researchseminars.org/talk/ictsvirtual/47/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Christopher Mogni (UC Berkeley)
DTSTART;VALUE=DATE-TIME:20210113T043000Z
DTEND;VALUE=DATE-TIME:20210113T063000Z
DTSTAMP;VALUE=DATE-TIME:20220528T192937Z
UID:ictsvirtual/48
DESCRIPTION:Title: Large-N Expansion and String Theory Out of Equilibrium\nby Christ
opher Mogni (UC Berkeley) as part of ICTS String Seminars\n\n\nAbstract\nS
tring theory has been incredibly successful at describing both gauge and g
ravity systems in equilibrium\, whereby the vacuum state is assumed to be
eternal and static. While progress has been made in applying string theory
to non-equilibrium scenarios\, such as the fate of non-extremal black hol
es and early universe cosmology\, there is no framework for describing str
ing theory out of equilibrium. In this talk\, I will describe how the larg
e-N expansion of field theories with matrix degrees of freedom put on a cl
osed time contour implies a refined topological worldsheet expansion for s
trings out of equilibrium.\n
LOCATION:https://researchseminars.org/talk/ictsvirtual/48/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Amirhossein Tajdini (UCSB)
DTSTART;VALUE=DATE-TIME:20210205T133000Z
DTEND;VALUE=DATE-TIME:20210205T143000Z
DTSTAMP;VALUE=DATE-TIME:20220528T192937Z
UID:ictsvirtual/49
DESCRIPTION:Title: Replica wormholes for an evaporating black hole\nby Amirhossein T
ajdini (UCSB) as part of ICTS String Seminars\n\n\nAbstract\nQuantum extre
mal islands reproduce the unitary Page curve of an evaporating black hole
in JT gravity. In previous work\, this result was formally derived by incl
uding replica wormholes in the gravitational path integral\, but the wormh
oles were not found explicitly\, or even fully defined\, for the time-depe
ndent geometries relevant to Hawking’s paradox. A technical challenge is
that replica wormholes rely on a Euclidean path integral while the quantu
m extremal islands of an evaporating black hole exist only in Lorentzian s
ignature. In this talk\, I will discuss how to construct these wormholes f
or n ∼ 1 replicas and confirm that they lead to the island rule for the
entropy.\n
LOCATION:https://researchseminars.org/talk/ictsvirtual/49/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Ashoke Sen (HRI)
DTSTART;VALUE=DATE-TIME:20210210T093000Z
DTEND;VALUE=DATE-TIME:20210210T103000Z
DTSTAMP;VALUE=DATE-TIME:20220528T192937Z
UID:ictsvirtual/50
DESCRIPTION:Title: D-instanton amplitudes\nby Ashoke Sen (HRI) as part of ICTS Strin
g Seminars\n\n\nAbstract\nD-instantons give non-perturbative contribution
to string theory\namplitudes which can be computed using world-sheet techn
iques. However the\nintegrals that appear in this computation often have d
ivergences from\ncorners of the moduli spaces which cannot be tamed by the
usual procedure\nof analytic continuation. We show how using insights fro
m string field\ntheory we can extract finite unambiguous results from thes
e apparently\ndivergent integrals.\n
LOCATION:https://researchseminars.org/talk/ictsvirtual/50/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Michal P. Heller (AEI)
DTSTART;VALUE=DATE-TIME:20210310T093000Z
DTEND;VALUE=DATE-TIME:20210310T103000Z
DTSTAMP;VALUE=DATE-TIME:20220528T192937Z
UID:ictsvirtual/51
DESCRIPTION:Title: Spacetime as a quantum circuit\nby Michal P. Heller (AEI) as part
of ICTS String Seminars\n\n\nAbstract\nWe propose that finite cutoff regi
ons of holographic spacetimes represent quantum circuits that map between
boundary states at different times and Wilsonian cutoffs\, and that the co
mplexity of those quantum circuits is given by the gravitational action. T
he optimal circuit minimizes the gravitational action. This is a generaliz
ation of both the "complexity equals volume" conjecture to unoptimized cir
cuits\, and path integral optimization to finite cutoffs. Using tools from
holographic $T\\bar{T}$\, we find that surfaces of constant scalar curvat
ure play a special role in optimizing quantum circuits. We also find an in
teresting connection of our proposal to kinematic space\, and discuss poss
ible circuit representations and gate counting interpretations of the grav
itational action.\n
LOCATION:https://researchseminars.org/talk/ictsvirtual/51/
END:VEVENT
BEGIN:VEVENT
SUMMARY:David Tong (DAMTP)
DTSTART;VALUE=DATE-TIME:20210317T093000Z
DTEND;VALUE=DATE-TIME:20210317T103000Z
DTSTAMP;VALUE=DATE-TIME:20220528T192937Z
UID:ictsvirtual/52
DESCRIPTION:Title: How to Give Chiral Fermions a Mass\nby David Tong (DAMTP) as part
of ICTS String Seminars\n\n\nAbstract\nChiral fermions have the property
that their left-handed and right-handed components transform differently u
nder some symmetry. Folklore suggests that it is impossible to give such f
ermions a mass \nwithout breaking this symmetry. I'll show\, through a num
ber of examples\, why this folklore is wrong. In particular\, I'll show ho
w one generation of fermions in the Standard Model can get a mass without
the need for a Higgs boson that breaks electroweak symmetry.\n
LOCATION:https://researchseminars.org/talk/ictsvirtual/52/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Jorge Santos (DAMTP)
DTSTART;VALUE=DATE-TIME:20210414T093000Z
DTEND;VALUE=DATE-TIME:20210414T103000Z
DTSTAMP;VALUE=DATE-TIME:20220528T192937Z
UID:ictsvirtual/53
DESCRIPTION:Title: AdS Euclidean wormholes\nby Jorge Santos (DAMTP) as part of ICTS
String Seminars\n\n\nAbstract\nWe explore the construction and stability o
f asymptotically anti-de Sitter Euclidean wormholes in a variety of models
. In simple ad hoc low-energy models\, it is not hard to construct two-bou
ndary Euclidean wormholes that dominate over disconnected solutions and wh
ich are stable (lacking negative modes) in the usual sense of Euclidean qu
antum gravity. Indeed\, the structure of such solutions turns out to stron
gly resemble that of the Hawking-Page phase transition for AdS-Schwarzschi
ld black holes\, in that for boundary sources above some threshold we find
both a `large' and a `small' branch of wormhole solutions with the latter
being stable and dominating over the disconnected solution for large enou
gh sources. We are also able to construct two-boundary Euclidean wormholes
in a variety of string compactifications that dominate over the disconnec
ted solutions we find and that are stable with respect to field-theoretic
perturbations. However\, as in classic examples investigated by Maldacena
and Maoz\, the wormholes in these UV-complete settings always suffer from
brane-nucleation instabilities (even when sources that one might hope woul
d stabilize such instabilities are tuned to large values). This indicates
the existence of additional disconnected solutions with lower action. We d
iscuss the significance of such results for the factorization problem of A
dS/CFT.\n
LOCATION:https://researchseminars.org/talk/ictsvirtual/53/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Andreas Karch (UT Austin)
DTSTART;VALUE=DATE-TIME:20210217T043000Z
DTEND;VALUE=DATE-TIME:20210217T053000Z
DTSTAMP;VALUE=DATE-TIME:20220528T192937Z
UID:ictsvirtual/54
DESCRIPTION:Title: Information Transfer with a Gravitating Bath\nby Andreas Karch (U
T Austin) as part of ICTS String Seminars\n\n\nAbstract\nRecent progress i
n our understanding of black hole evaporation\nhas mostly occurred in the
context of black holes coupled to an\nexternal\, non-gravitating bath. In
order to compare and contrast to what\nhappens to black holes in asymptoti
cally flat space it is imperative to\nunderstand whether the non-gravitati
ng bath is just some external\nspectator or actively changes the physics i
n this system. Equivalently\,\none can wonder to what extent the results g
eneralize to the case of a\ngravitating bath. We use Randall-Sundrum brane
worlds\, and their\nholographic interpretation\, to answer this important
question.\n
LOCATION:https://researchseminars.org/talk/ictsvirtual/54/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Shiraz Minwalla (TIFR)
DTSTART;VALUE=DATE-TIME:20210224T093000Z
DTEND;VALUE=DATE-TIME:20210224T103000Z
DTSTAMP;VALUE=DATE-TIME:20220528T192937Z
UID:ictsvirtual/55
DESCRIPTION:Title: Bounds on Regge growth of flat space scattering from bounds on chaos<
/a>\nby Shiraz Minwalla (TIFR) as part of ICTS String Seminars\n\n\nAbstra
ct\nWe study four-point functions of scalars\, conserved currents\, and st
ress tensors in a conformal field theory\, generated by a local contact te
rm in the bulk dual description\, in two different causal configurations.
The first of these is the standard Regge configuration in which the chaos
bound applies. The second is the `causally scattering configuration' in wh
ich the correlator develops a bulk point singularity. We find an expressio
n for the coefficient of the bulk point singularity in terms of the bulk S
matrix of the bulk dual metric\, gauge fields and scalars\, and use it to
determine the Regge scaling of the correlator on the causally scattering
sheet in terms of the Regge growth of this S matrix. We then demonstrate t
hat the scaling on this this sheet is governed by the same power as in the
standard Regge configuration\, and so is constrained by the chaos bound\,
which turns out to be violated unless the bulk flat space S matrix grows
no faster than s^2\nin the Regge limit. It follows that in the context of
the AdS/CFT correspondence and local bulk interactions that the chaos bou
nd applied to the boundary field theory implies that the S matrices of the
dual bulk scalars\, gauge fields\, and gravitons obey the Classical Regge
Growth (CRG) conjecture.\n
LOCATION:https://researchseminars.org/talk/ictsvirtual/55/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Nava Gaddam (University of Utrecht)
DTSTART;VALUE=DATE-TIME:20210303T093000Z
DTEND;VALUE=DATE-TIME:20210303T103000Z
DTSTAMP;VALUE=DATE-TIME:20220528T192937Z
UID:ictsvirtual/56
DESCRIPTION:Title: The black hole eikonal and the information paradox\nby Nava Gadda
m (University of Utrecht) as part of ICTS String Seminars\n\n\nAbstract\nI
n this talk\, I will show that there is a remarkable phase of quantum grav
ity (which we will call the 'black hole eikonal' phase in contrast to the
flat space eikonal phase). It is defined by gravitational collisions near
the horizon\, and dominated by centre of mass energies $E >> \\gamma M_Pl$
\, with $\\gamma = M_Pl/M_B H$. This regime captures gravitational scatter
ing with impact parameters smaller than the Schwarzschild radius. Scatteri
ng amplitudes are unitary suggesting a resolution of the information parad
ox\; I will sketch the explicit derivation of the 2-2 amplitude for massle
ss scalars\, non-perturbatively in $\\gamma$. Owing to the low energies of
collisions\, there are no firewalls experienced by infalling observers. A
consequence of these results is that the information paradox is an emerge
nt one at low energies and does not require detailed ultra-violet physics
for a resolution.\n
LOCATION:https://researchseminars.org/talk/ictsvirtual/56/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Jaume Gomis (Perimeter Institute)
DTSTART;VALUE=DATE-TIME:20210326T130000Z
DTEND;VALUE=DATE-TIME:20210326T140000Z
DTSTAMP;VALUE=DATE-TIME:20220528T192937Z
UID:ictsvirtual/57
DESCRIPTION:Title: Global Anomalies on the Hilbert Space\nby Jaume Gomis (Perimeter
Institute) as part of ICTS String Seminars\n\n\nAbstract\nWe will discuss
an elementary way of detecting some global anomalies\nfrom the way the sym
metry algebra is realized on the torus Hilbert\nspace of the anomalous the
ory\, give a physical description of the\nimprint of the “layers”that
enter in the cobordism classification of\nanomalies and discuss applicatio
ns\, including how anomalies can imply\na supersymmetric spectrum in stron
gly coupled (nonsupersymmetric)\ngauge theories.\n
LOCATION:https://researchseminars.org/talk/ictsvirtual/57/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Masanori Hanada (University of Surrey)
DTSTART;VALUE=DATE-TIME:20210331T093000Z
DTEND;VALUE=DATE-TIME:20210331T103000Z
DTSTAMP;VALUE=DATE-TIME:20220528T192937Z
UID:ictsvirtual/58
DESCRIPTION:Title: Color confinement\, Bose-Einstein condensation\, and emergent geometr
y in gauge/gravity duality\nby Masanori Hanada (University of Surrey)
as part of ICTS String Seminars\n\n\nAbstract\nIn gauge/gravity duality\,
the information regarding the gravitational geometry (e.g.\, black hole an
d smooth exterior geometry) has to be encoded in gauge theory. The color d
egrees of freedom (matrix degrees of freedom) have to play the key role\,
because the duality can hold even when the gauge theory side is a matrix m
odel. In this talk\, I will provide a very simple way of encoding the geom
etry to matrices\, along the line of Witten's work on the effective action
of D-branes and strings\, and the Matrix Theory conjecture by Banks\, Fis
chler\, Shenker and Susskind. Roughly speaking\, eigenvalues of matrices c
an be identified with the location of the D-brane probe or extended object
s such as black hole. \n\nActually there is a famous argument against such
simple interpretation advocated by Polchinski in 1998. His argument used
generic properties of large-N gauge theory to show that the ground-state w
ave function delocalizes at large N\, leading to a conflict with the local
ity in the bulk geometry. We show that this argument is not correct: the g
round-state wave function does not delocalize\, and there is no conflict w
ith the locality of the bulk geometry. In order to understand how Polchins
ki's argument fails\, recently-discovered connection between color confine
ment at large N and Bose-Einstein condensation is useful. This confinement
-BEC connection has a striking consequence: in the SU(N) gauge theory\, th
ere is a partially-deconfined phase in which an SU(M)-subgroup is deconfin
ed. Partial deconfinement gives a natural realization of the idea in BFSS
Matrix Theory conjecture --- extended objects\, such as black hole\, are r
ealized as bound states of D-branes and strings\, that look like non-commu
tative blocks in big matrices --- in the Maldacena-type gauge/gravity dual
ity.\n
LOCATION:https://researchseminars.org/talk/ictsvirtual/58/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Nikhil Kalyanapuram (Pennsylvania State University)
DTSTART;VALUE=DATE-TIME:20210428T093000Z
DTEND;VALUE=DATE-TIME:20210428T103000Z
DTSTAMP;VALUE=DATE-TIME:20220528T192937Z
UID:ictsvirtual/59
DESCRIPTION:Title: The Tensionless Limit of Chiral Superstring Integrands\nby Nikhil
Kalyanapuram (Pennsylvania State University) as part of ICTS String Semin
ars\n\n\nAbstract\nChiral splitting is the superholomorphic factorisation
of integrands in superstring theory\, derived several decades ago by D'Hok
er and Phong. I will place this phenomenon in a modern context by expandin
g the chiral integrand of external graviton states in terms of the string
tension. In doing so\, the half integrand of the ambitwistor string will b
e shown to arise as a tensionless limit thereof. The possible implications
for the duality between colour and kinematics will be discussed.\n
LOCATION:https://researchseminars.org/talk/ictsvirtual/59/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Aninda Sinha (IISc)
DTSTART;VALUE=DATE-TIME:20210421T093000Z
DTEND;VALUE=DATE-TIME:20210421T103000Z
DTSTAMP;VALUE=DATE-TIME:20220528T192937Z
UID:ictsvirtual/60
DESCRIPTION:Title: Crossing symmetric dispersion relations in QFTs and CFTs\nby Anin
da Sinha (IISc) as part of ICTS String Seminars\n\n\nAbstract\nI will disc
uss crossing symmetric dispersion relations and its applications. 1) In QF
T I will derive two sided bounds on Wilson coefficients in a low energy ef
fective expansion of 2-2 scattering. I will also show an intriguing connec
tion with the Bieberbach conjecture in mathematics. 2) In CFT\, I will sho
w a rigorous derivation of the Polyakov bootstrap which will enable us to
fix the contact terms in the Witten diagram basis expansion.\n
LOCATION:https://researchseminars.org/talk/ictsvirtual/60/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Congkao Wen (Queen Mary University)
DTSTART;VALUE=DATE-TIME:20210407T093000Z
DTEND;VALUE=DATE-TIME:20210407T103000Z
DTSTAMP;VALUE=DATE-TIME:20220528T192937Z
UID:ictsvirtual/61
DESCRIPTION:Title: Integrated four-point correlators in N=4 SYM\nby Congkao Wen (Que
en Mary University) as part of ICTS String Seminars\n\n\nAbstract\nIn this
talk\, we will discuss integrated correlators of four superconformal prim
aries in N=4 super Yang-Mills\, that are defined by integrating over space
time coordinates of the four-point correlator with certain integration mea
sures. The integrated correlators can be computed using supersymmetric loc
alisation\, which are expressed as N-dimensional matrix-model integrals. W
e will mostly focus on one of the integrated correlators. We find that thi
s integrated correlator can be presented as a lattice sum\, which makes ma
nifest the SL(2\, Z) modular invariance of N=4 SYM. Furthermore\, the int
egrated correlator obeys a remarkable Laplace-difference equation\, which
relates the correlator of SU(N) theory with those of SU(N-1) and SU(N+1) t
heories. The expression allows us to obtain exact results of the integrat
ed correlator in various limits. For instance\, in perturbation\, the expr
ession is checked to be consistent with known results in the literature\;
in the large-N limit\, it is shown to match with the expected results from
string theory due to AdS/CFT duality.\n
LOCATION:https://researchseminars.org/talk/ictsvirtual/61/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Chethan Krishnan (IISc)
DTSTART;VALUE=DATE-TIME:20210505T093000Z
DTEND;VALUE=DATE-TIME:20210505T103000Z
DTSTAMP;VALUE=DATE-TIME:20220528T192937Z
UID:ictsvirtual/62
DESCRIPTION:Title: Comments on the Information Paradox\nby Chethan Krishnan (IISc) a
s part of ICTS String Seminars\n\n\nAbstract\nI will discuss some calculat
ions that shed light on some of the conceptual questions regarding (recent
developments on) the information paradox.\n
LOCATION:https://researchseminars.org/talk/ictsvirtual/62/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Biswajit Sahoo (EPFL)
DTSTART;VALUE=DATE-TIME:20210602T093000Z
DTEND;VALUE=DATE-TIME:20210602T103000Z
DTSTAMP;VALUE=DATE-TIME:20220528T192937Z
UID:ictsvirtual/63
DESCRIPTION:Title: Classical Soft Graviton Theorem and Gravitational Memory\nby Bisw
ajit Sahoo (EPFL) as part of ICTS String Seminars\n\n\nAbstract\nFirst I s
hall briefly review the results of the quantum soft graviton theorem deriv
ed from scattering amplitudes. Then I briefly discuss the classical limit
of the soft graviton theorem to show how it is related to the long-wavelen
gth gravitational waveform. Finally\, I shall talk about the derivation of
the classical soft graviton theorem in detail and how it is related to gr
avitational memory. I shall also address the following questions along wit
h some observational signature:\n\nHow to derive all order soft theorem an
d gravitational memory systematically\, and how much have we succeeded?\n\
nIn which order of soft expansion spin and structure of the scattered obje
cts start contributing?\n
LOCATION:https://researchseminars.org/talk/ictsvirtual/63/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Subir Sachdev (Harvard)
DTSTART;VALUE=DATE-TIME:20210609T130000Z
DTEND;VALUE=DATE-TIME:20210609T140000Z
DTSTAMP;VALUE=DATE-TIME:20220528T192937Z
UID:ictsvirtual/64
DESCRIPTION:Title: Random t-J model theory of the cuprate phase diagram\nby Subir Sa
chdev (Harvard) as part of ICTS String Seminars\n\n\nAbstract\nThe cuprate
high temperature superconductors display three distinct metallic phases a
round the superconducting dome: a pseudogap metal at low doping\, an inter
mediate Planckian metal\, and a Fermi liquid at large doping. I will prese
nt numerical and analytical results showing that all three phases are pres
ent in the t-J model with random and all-to-all hopping and exchange. The
Planckian metal is realized in a SYK-type theory of fractionalized holons
and spinons: it exhibits linear-in-temperature resistivity at low temperat
ures (in a closely-related large-dimension model) arising from a time repa
rameterization soft mode. This soft mode has a holographic interpretation
as a boundary graviton of charged black holes.\n
LOCATION:https://researchseminars.org/talk/ictsvirtual/64/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Kristan Jensen (Victoria)
DTSTART;VALUE=DATE-TIME:20210512T050000Z
DTEND;VALUE=DATE-TIME:20210512T060000Z
DTSTAMP;VALUE=DATE-TIME:20220528T192937Z
UID:ictsvirtual/65
DESCRIPTION:Title: Wormholes and black hole microstates in AdS/CFT\nby Kristan Jense
n (Victoria) as part of ICTS String Seminars\n\n\nAbstract\nIt has long be
en known that the coarse-grained approximation to the black hole density o
f states can be computed using classical Euclidean gravity. In this talk I
will argue for another entry in the dictionary between Euclidean gravity
and black hole physics\, namely that Euclidean wormholes describe a coarse
-grained approximation to the energy level statistics of black hole micros
tates. We obtain an integral representation of wormhole amplitudes in Eins
tein gravity and in full-fledged AdS/CFT. These amplitudes are non-perturb
ative corrections to the two-boundary problem in AdS quantum gravity. The
full amplitude is likely UV sensitive\, dominated by small wormholes\, but
it admits an integral transformation with a macroscopic\, weakly curved s
addle-point approximation. The saddle is the "double cone" geometry of Saa
d\, Shenker\, and Stanford\, with fixed moduli. In the boundary descriptio
n this saddle appears to dominate a smeared version of the connected two-p
oint function of the black hole density of states\, and suggests level rep
ulsion in the microstate spectrum. I will also discuss the stability of th
ese wormholes to small fluctuations and to brane nucleation. Our results i
ndicate a factorization paradox in AdS/CFT.\n
LOCATION:https://researchseminars.org/talk/ictsvirtual/65/
END:VEVENT
BEGIN:VEVENT
SUMMARY:David Poland (Yale)
DTSTART;VALUE=DATE-TIME:20210520T130000Z
DTEND;VALUE=DATE-TIME:20210520T140000Z
DTSTAMP;VALUE=DATE-TIME:20220528T192937Z
UID:ictsvirtual/66
DESCRIPTION:Title: Charting the Landscape of 3d CFTs\nby David Poland (Yale) as part
of ICTS String Seminars\n\n\nAbstract\nI will summarize progress at using
the conformal bootstrap to solve 3d CFTs. These include the critical 3d I
sing model\, the O(N) vector models\, and the minimal 3d SCFT. Recent resu
lts for the O(2) model resolve a longstanding discrepancy between experime
nt and Monte Carlo simulations\, while results for the O(3) model prove th
e instability of Heisenberg magnets to cubic anisotropy.\n
LOCATION:https://researchseminars.org/talk/ictsvirtual/66/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Matthew Reece (Harvard)
DTSTART;VALUE=DATE-TIME:20210527T130000Z
DTEND;VALUE=DATE-TIME:20210527T140000Z
DTSTAMP;VALUE=DATE-TIME:20220528T192937Z
UID:ictsvirtual/67
DESCRIPTION:Title: No Global Symmetries\, with Applications to Axions and Cosmic Strings
\nby Matthew Reece (Harvard) as part of ICTS String Seminars\n\n\nAbst
ract\nThere are reasons to believe that consistent quantum gravity theorie
s do not admit exact global symmetries. This claim has surprisingly strong
implications\, some of which are relevant for particle physics and cosmol
ogy. I will discuss some recent variations on this theme\, including the a
bsence of Chern-Weil symmetries (with applications to axion physics) and t
he absence of higher-form symmetries (with implications for the existence
of cosmic strings).\n
LOCATION:https://researchseminars.org/talk/ictsvirtual/67/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Stephane Detournay (Brussels U.)
DTSTART;VALUE=DATE-TIME:20210616T093000Z
DTEND;VALUE=DATE-TIME:20210616T103000Z
DTSTAMP;VALUE=DATE-TIME:20220528T192937Z
UID:ictsvirtual/68
DESCRIPTION:Title: The 3d black string and its dual\nby Stephane Detournay (Brussels
U.) as part of ICTS String Seminars\n\n\nAbstract\nAbout 30 years ago\, H
orne and Horowitz described a three-dimensional black string solution shar
ing many qualitative features of the Reissner-Nordstrom black hole.\nViewi
ng the black string as a certain deformation of the BTZ black hole\, we wi
ll give evidence that its field theory dual consists in an irrelevant defo
rmation of a 2d CFT of the TTbar form.\nBased on 1911.12359 with Luis Apo
lo and Wei Song.\n
LOCATION:https://researchseminars.org/talk/ictsvirtual/68/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Soumangsu Chakraborty (TIFR)
DTSTART;VALUE=DATE-TIME:20210707T093000Z
DTEND;VALUE=DATE-TIME:20210707T103000Z
DTSTAMP;VALUE=DATE-TIME:20220528T192937Z
UID:ictsvirtual/69
DESCRIPTION:Title: (SL(2\,R) X U(1))/U(1) CFT\, NS5+F1 system & single trace TTbar\n
by Soumangsu Chakraborty (TIFR) as part of ICTS String Seminars\n\n\nAbstr
act\nIn this talk\, I'm going to talk about the equivalence among (i) the
weakly coupled worldsheet string theory described by the coset sigma model
$\\frac{SL(2\,\\mathbb{R})_k\\times U(1)}{U(1)}\\times S^3 \\times T^4$ w
ith $SL(2\,\\mathbb{R})$ WZW level $k\\geq 2$\, (ii) the full near horizon
theory of the NS5 branes with $k$ NS5 branes wrapping $T^4\\times S^1$\,
$p\\gg1$ F1 strings wrapping $S^1$ and $n$ units of momentum along the $S^
1$ and (iii) the single trace $T\\bar{T}$ deformation of string theory in
$AdS_3\\times S^3\\times T^4$. As a check\, I'll compute the spectrum of
the spacetime theory by performing BRST quantization of the coset descript
ion of the worldsheet theory and show that it matches exactly with the one
derived in the case of single trace $T\\bar{T}$ deformed string theory in
$AdS_3$. If time permits\, I'll talk about the two-point function of the
spacetime theory.\n
LOCATION:https://researchseminars.org/talk/ictsvirtual/69/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Felix Haehl (IAS)
DTSTART;VALUE=DATE-TIME:20210714T130000Z
DTEND;VALUE=DATE-TIME:20210714T140000Z
DTSTAMP;VALUE=DATE-TIME:20220528T192937Z
UID:ictsvirtual/71
DESCRIPTION:Title: The p-spin glass model: a holographer's point of view\nby Felix H
aehl (IAS) as part of ICTS String Seminars\n\n\nAbstract\nI will discuss a
large-N bosonic quantum mechanical sigma-model with a spherical target sp
ace subject to disordered interactions\, more colloquially known as the p-
spin spherical model. Replica symmetry is broken at low temperatures and f
or sufficiently weak quantum fluctuations\, which drives the system into a
spin glass phase. This spin glass phase exhibits an emergent conformal sy
mmetry in the strong coupling regime\, which dictates its thermodynamic pr
operties. I will discuss an approximate analytical solution to the spin gl
ass equations\, which interpolates between the conformal regime and a cons
istent short-distance solution. I will also discuss the real-time dynamics
of the model with emphasis on quantum chaos as measured by out-of-time-or
der four-point functions. We find exponential Lyapunov growth\, which intr
icately depends on the model's couplings. The spin glass phase also exhibi
ts quantum chaos\, albeit with parametrically smaller Lyapunov exponent th
an in the replica symmetric phase. An analytical calculation in the spin g
lass phase suggests that this Lyapunov exponent vanishes in a particular i
nfinite coupling limit. I will comment on the potential meaning of these o
bservations from the perspective of holography.\n
LOCATION:https://researchseminars.org/talk/ictsvirtual/71/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Anindya Dey (Johns Hopkins)
DTSTART;VALUE=DATE-TIME:20210804T130000Z
DTEND;VALUE=DATE-TIME:20210804T140000Z
DTSTAMP;VALUE=DATE-TIME:20220528T192937Z
UID:ictsvirtual/73
DESCRIPTION:Title: S-type Operations\, Line Defects and 3D Mirror Symmetry beyond ADE qu
ivers\nby Anindya Dey (Johns Hopkins) as part of ICTS String Seminars\
n\n\nAbstract\nI will present a systematic field theory prescription for c
onstructing 3D N=4 mirror pairs involving quiver gauge theories beyond the
well-known ADE examples. The construction involves a certain generalizati
on of the S operation\, which arises in the context of the 3d SL(2\,Z) act
ion on a CFT with a U(1) 0-form symmetry. I will show how this constructio
n can be used to determine 3d Lagrangians for a large class of Argyres-Dou
glas theories compactified on a circle. I will also discuss how the prescr
iption can be extended to include half-BPS line defects and determine the
associated mirror maps\, which were only known earlier for A-type theories
.\n
LOCATION:https://researchseminars.org/talk/ictsvirtual/73/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Suresh Govindarajan (IIT Madras)
DTSTART;VALUE=DATE-TIME:20210728T093000Z
DTEND;VALUE=DATE-TIME:20210728T103000Z
DTSTAMP;VALUE=DATE-TIME:20220528T192937Z
UID:ictsvirtual/74
DESCRIPTION:Title: Looking for a new kind of Lie algebra using a clue from counting dyon
degeneracies\nby Suresh Govindarajan (IIT Madras) as part of ICTS Str
ing Seminars\n\n\nAbstract\nThe refined counting of BPS states in four-dim
ensional string\ntheories with $N=4$ supersymmetry has brought interesting
connections with\nmodular forms\, mock modular forms\, Lie algebras and t
he surprising\nappearance of the sporadic simple group\, $M_24$\, is calle
d Mathieu\nmoonshine. The (inverse of the) generating function of dyon deg
eneracies\nis a Siegel modular form.\n\nIn this talk\, we focus on the app
earance of families of Lie Algebras\nthat are obtained by interpreting the
square-root of the generating\nfunction of dyons degeneracies as the deno
minator formulae of the Lie\nalgebras. In most of the examples\, the Lie a
lgebras are generalized\nKac-Moody Lie superalgebras or Borcherds-Kac-Mood
y Lie superalgebras.\nThere are examples that are not BKM Lie superalgebra
s. In these cases\nthe square-root provides us a tool to look for an exten
sion of BKM Lie\nsuperalgebras. With this in mind\, we discuss the decompo
sition of this\nsquare-root in terms of an affine Lie algebra. This leads
to the\nappearance of vector valued modular forms that encode the multipli
cities\nof simple roots of the (potential) Lie superalgebra.\n\nBased on a
rXiv:2106.01605\n
LOCATION:https://researchseminars.org/talk/ictsvirtual/74/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Gui Pimentel (University of Amsterdam)
DTSTART;VALUE=DATE-TIME:20210929T093000Z
DTEND;VALUE=DATE-TIME:20210929T103000Z
DTSTAMP;VALUE=DATE-TIME:20220528T192937Z
UID:ictsvirtual/75
DESCRIPTION:Title: Decoding and bootstrapping cosmological fluctuations\nby Gui Pime
ntel (University of Amsterdam) as part of ICTS String Seminars\n\n\nAbstra
ct\nI will review our current understanding of the initial conditions of t
he universe\, and describe what information is available from current and
future measurements of cosmological correlation functions. Then I will des
cribe a new method to compute and constrain the possible shapes of those c
orrelation functions\, assuming they were generated during inflation. This
``cosmological bootstrap” draws inspiration from the modern scattering
amplitudes program in flat space\, as well as the conformal bootstrap of p
hase transitions. After discussing primordial scalar fluctuations\, I will
also explain how the consistent propagation of gravitational waves impose
s further constraints on the structure of spinning primordial correlators.
Finally if there’s time I’ll discuss some work in progress trying to
understand the general structure of tree level correlators in FLRW cosmolo
gy.\n
LOCATION:https://researchseminars.org/talk/ictsvirtual/75/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Alok Laddha (Chennai Mathematical Institute)
DTSTART;VALUE=DATE-TIME:20211006T093000Z
DTEND;VALUE=DATE-TIME:20211006T103000Z
DTSTAMP;VALUE=DATE-TIME:20220528T192937Z
UID:ictsvirtual/76
DESCRIPTION:Title: Towards a Positive Geometry for the massive S-matrix\nby Alok Lad
dha (Chennai Mathematical Institute) as part of ICTS String Seminars\n\n\n
Abstract\nS-matrix of Quantum field theory has an intricate Analytic struc
ture. In the last few years\, there has been a striking development in def
ining the S-matrix of scalar quantum field theories as volume of certain
polytopes known as Accordiohedra. These polytopes live in the kinematic sp
ace parametrized by Mandelstam invariants and many of the fundamental pro
perties of the S-matrix such as locality and unitarity emerge from simp
le combinatorial properties of such polytopes. \n\nIn this talk\, we will
review some recent ideas to extend the positive geometry program to multi-
scalar field amplitudes with scalar fields having distinct masses. In part
icular\, we will analyze scattering involving two scalars with unequal mas
ses and find the class of polytopes whose volume generates S-matrix for su
ch theories. We will also argue that ``integrating out the heavier field"
induces a map between different accordiohedra\, thus giving some prelimin
ary insight into geometrisation of effective field theory.\n
LOCATION:https://researchseminars.org/talk/ictsvirtual/76/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Evita Verheijden (University of Amsterdam)
DTSTART;VALUE=DATE-TIME:20211013T093000Z
DTEND;VALUE=DATE-TIME:20211013T103000Z
DTSTAMP;VALUE=DATE-TIME:20220528T192937Z
UID:ictsvirtual/77
DESCRIPTION:Title: No Page curves for the de Sitter horizon\nby Evita Verheijden (Un
iversity of Amsterdam) as part of ICTS String Seminars\n\n\nAbstract\nOne
of the greatest puzzles in our universe\, which can -- to good approximati
on -- be described by de Sitter space\, is a proper understanding of the c
osmological horizon that surrounds any observer. Over the past few years\,
a semi-classical approach involving quantum extremal surfaces and so-call
ed ‘islands’ has been very successful to increase our understanding of
the black hole information problem\; in light of these advancements\, it
could prove fruitful to undertake a similar approach to investigate an eva
porating de Sitter horizon. In this talk I will consider such an approach
for two-dimensional de Sitter space. Starting from three-dimensional de Si
tter space\, I will show how a partial dimensional reduction supplies 2D J
T de Sitter with an auxiliary system acting as a heat bath. I will then co
ntrast the time-dependent entropy of radiation collected by an observer at
future infinity with that collected by an observer inside the static patc
h. Central to the analysis in the static patch is the identification of a
weakly-coupled region close to the cosmological horizon. I will highlight
how backreaction considerations crucially obstruct both observers from wit
nessing unitary evaporation.\n
LOCATION:https://researchseminars.org/talk/ictsvirtual/77/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Miranda Cheng (University of Amsterdam)
DTSTART;VALUE=DATE-TIME:20211027T093000Z
DTEND;VALUE=DATE-TIME:20211027T103000Z
DTSTAMP;VALUE=DATE-TIME:20220528T192937Z
UID:ictsvirtual/78
DESCRIPTION:Title: Machine learning and theoretical physics: some applications\nby M
iranda Cheng (University of Amsterdam) as part of ICTS String Seminars\n\n
\nAbstract\nIn this talk I will briefly summarise my two recent papers on
the interactions between physics and machine learning. In the paper with V
Anagiannis\, we exploit the analogy between quantum many-body systems and
certain neural networks to analyse the learning process using quantum ent
anglement. In the second paper with de Haan\, Rainone\, and Bondesan\, we
use a continuous flow model to help ameliorate the numerical difficulties
in sampling in lattice field theories\, which for instance hampers high-p
recision computations in LQCD.\n
LOCATION:https://researchseminars.org/talk/ictsvirtual/78/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Eran Palti (Ben Gurion University)
DTSTART;VALUE=DATE-TIME:20210922T093000Z
DTEND;VALUE=DATE-TIME:20210922T103000Z
DTSTAMP;VALUE=DATE-TIME:20220528T192937Z
UID:ictsvirtual/79
DESCRIPTION:Title: Convexity of Charged Operators in CFTs and the Weak Gravity Conjectur
e\nby Eran Palti (Ben Gurion University) as part of ICTS String Semina
rs\n\n\nAbstract\nIn this talk I will introduce a particular formulation o
f the Weak Gravity Conjecture in AdS space in terms of the self-binding en
ergy of a particle. The holographic CFT dual of this formulation correspon
ds to a certain convex-like structure for operators charged under continuo
us global symmetries. Motivated by this\, we propose a conjecture that thi
s convexity is a general property of all CFTs\, not just those with weakly
-curved gravitational duals. It is possible to test this in simple CFTs\,
the conjecture passes all the tests performed so far.\n
LOCATION:https://researchseminars.org/talk/ictsvirtual/79/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Ofer Aharony (Weizmann Institute)
DTSTART;VALUE=DATE-TIME:20211019T083000Z
DTEND;VALUE=DATE-TIME:20211019T093000Z
DTSTAMP;VALUE=DATE-TIME:20220528T192937Z
UID:ictsvirtual/80
DESCRIPTION:Title: A derivation of AdS/CFT for vector models\nby Ofer Aharony (Weizm
ann Institute) as part of ICTS String Seminars\n\n\nAbstract\nAfter discus
sing what it means to derive the AdS/CFT correspondence\, I will describe
our attempts (in collaboration with Shai Chester and Erez Urbach\, 2011.06
328+2109.05512) to make this correspondence explicit in the simplest case
of the U(N) vector model\, conjectured to be dual to high-spin gravity in
Anti-de Sitter space. We explicitly rewrite the path integral for the free
or critical U(N) (or O(N)) bosonic vector models in d space-time dimensio
ns as a path integral over fields (including massless high-spin fields) li
ving on (d+1)-dimensional anti-de Sitter space. Inspired by de Mello Koch\
, Jevicki\, Suzuki and Yoon and earlier work\, we first rewrite the vector
models in terms of bi-local fields\, then expand these fields in eigenmod
es of the conformal group\, and finally map these eigenmodes to those of f
ields on anti-de Sitter space. Our results provide an explicit (non-local)
action for a high-spin theory on anti-de Sitter space\, which is presumab
ly equivalent in the large N limit to Vasiliev's classical high-spin gravi
ty theory (with some specific gauge-fixing to a fixed background)\, but wh
ich can be used also for loop computations. Our mapping is explicit within
the 1/N expansion\, but in principle can be extended also to finite N the
ories\, where extra constraints on products of bulk fields need to be take
n into account.\n
LOCATION:https://researchseminars.org/talk/ictsvirtual/80/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Lorenz Eberhardt (IAS)
DTSTART;VALUE=DATE-TIME:20211103T120000Z
DTEND;VALUE=DATE-TIME:20211103T130000Z
DTSTAMP;VALUE=DATE-TIME:20220528T192937Z
UID:ictsvirtual/81
DESCRIPTION:Title: A perturbative CFT dual for pure NS-NS AdS3 strings\nby Lorenz Eb
erhardt (IAS) as part of ICTS String Seminars\n\n\nAbstract\nI will discus
s perturbative string theory on AdS3 with pure NS-NS flux and propose a du
al spacetime CFT. It is given by a symmetric orbifold of a linear dilaton
theory deformed by a marginal operator from the twist-2 sector. I explain
the computation of two- and three-point functions on the CFT side to 4th o
rder in conformal perturbation theory at large N. They agree with the stri
ng computation at genus 0\, thus providing ample evidence for a duality. I
also explain how to match the full spectra of both short and long strings
.\n
LOCATION:https://researchseminars.org/talk/ictsvirtual/81/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Alexandre Belin (CERN)
DTSTART;VALUE=DATE-TIME:20211110T093000Z
DTEND;VALUE=DATE-TIME:20211110T103000Z
DTSTAMP;VALUE=DATE-TIME:20220528T192937Z
UID:ictsvirtual/82
DESCRIPTION:Title: Quantum Gravity meets Statistical Physics\nby Alexandre Belin (CE
RN) as part of ICTS String Seminars\n\n\nAbstract\nIn this talk\, I will d
iscuss the statistical distribution of OPE coefficients in chaotic conform
al field theories. I will present the OPE Randomness Hypothesis (ORH)\, a
generalization of ETH to CFTs which treats any OPE coefficient involving a
heavy operator as a pseudo-random variable with an approximate Gaussian d
istribution. I will then present some evidence for this conjecture\, based
on the size of the non-Gaussianities and on insights from random matrix t
heory. Turning to the bulk\, I will argue that semi-classical gravity geom
etrizes these statistical correlations by wormhole geometries. I will show
that the non-Gaussianities of the OPE coefficients predict a new connecte
d wormhole geometry that dominates over the genus-2 wormhole.\n
LOCATION:https://researchseminars.org/talk/ictsvirtual/82/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Monica Guica (IPhT)
DTSTART;VALUE=DATE-TIME:20211124T093000Z
DTEND;VALUE=DATE-TIME:20211124T103000Z
DTSTAMP;VALUE=DATE-TIME:20220528T192937Z
UID:ictsvirtual/83
DESCRIPTION:Title: JTbar-deformed CFTs as non-local CFTs\nby Monica Guica (IPhT) as
part of ICTS String Seminars\n\n\nAbstract\nVarious holographic set-ups in
string theory suggest the existence of non-local\, UV complete two-dimens
ional QFTs that possess Virasoro symmetry\, in spite of their non-locality
. We argue that JTbar-deformed CFTs are the first concrete realisation of
such "non-local CFTs"\, through a detailed analysis of their classical and
quantum symmetry algebra. Concretely\, we show that JTbar-deformed CFTs p
ossess an infinite set of symmetries\, which in a certain basis organise
into two commuting copies of the Virasoro-Kac-Moody algebra\, with the sam
e central extension as that of the undeformed CFT. A peculiarity of these
Virasoro generators is that their zero mode does not equal the Hamiltonian
\, but is a quadratic function of it\; this helps reconcile the Virasoro s
ymmetry with the non-locality of the model. We argue that TTbar-deformed
CFTs also possess Virasoro symmetries of this type.\n
LOCATION:https://researchseminars.org/talk/ictsvirtual/83/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Nissan Itzhaki (Tel Aviv University)
DTSTART;VALUE=DATE-TIME:20211201T093000Z
DTEND;VALUE=DATE-TIME:20211201T103000Z
DTSTAMP;VALUE=DATE-TIME:20220528T192937Z
UID:ictsvirtual/84
DESCRIPTION:Title: A Puncture in the Euclidean Black Hole\nby Nissan Itzhaki (Tel Av
iv University) as part of ICTS String Seminars\n\n\nAbstract\nWe consider
the backreaction of the winding zero mode on the cigar geometry. We focus
on the case of the $SL(2\,R)_k/U(1)$ cigar associated with e.g. the near-h
orizon limit of $k$ NS5 black-branes. We solve the equations of motion num
erically in the large $k$ limit as a function of the amplitude of the wind
ing mode at infinity. We find that there is a critical amplitude $C_c=\\ex
p(-\\gamma/2)$ that admits a critical solution. The exact CFT description
of the $SL(2\,R)_k/U(1)$ cigar\, in particular the FZZ duality\, fixes com
pletely the winding amplitude. We find that in the large $k$ limit there i
s an exact agreement $C_c=C_{FZZ}$. The critical solution is a cigar with
a puncture at its tip\; consequently\, the BH entropy is carried entirely
by the winding condensate. We argue that\, in the Lorentzian case\, the in
formation is ejected from the black hole through this puncture.\n
LOCATION:https://researchseminars.org/talk/ictsvirtual/84/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Juan Maldacena (IAS)
DTSTART;VALUE=DATE-TIME:20211117T120000Z
DTEND;VALUE=DATE-TIME:20211117T130000Z
DTSTAMP;VALUE=DATE-TIME:20220528T192937Z
UID:ictsvirtual/85
DESCRIPTION:Title: On the black hole/string transition\nby Juan Maldacena (IAS) as p
art of ICTS String Seminars\n\n\nAbstract\nWe discuss aspects of the possi
ble transition between small black holes and highly excited fundamental st
rings. We focus on the connection between black holes and the self gravita
ting string solution of Horowitz and Polchinski. This solution is interest
ing because it has non-zero entropy at the classical level and it is natur
al to suspect that it might be continuously connected to the black hole. S
urprisingly\, we find a different behavior for heterotic and type II cases
. For the type II case we find an obstruction to the idea that the two are
connected as classical solutions of string theory\, while no such obstruc
tion exists for the heterotic case. We further provide a linear sigma mode
l analysis that suggests a continuous connection for the heterotic case. W
e also describe a solution generating transformation that produces a charg
ed version of the self gravitating string. This provides a fuzzball-like c
onstruction of near extremal configurations carrying fundamental string mo
mentum and winding charges. We provide formulas which are exact in α′ r
elating the thermodynamic properties of the charged and the uncharged solu
tions.\n
LOCATION:https://researchseminars.org/talk/ictsvirtual/85/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Shamik Banerjee (IOP Bhubaneswar)
DTSTART;VALUE=DATE-TIME:20211208T093000Z
DTEND;VALUE=DATE-TIME:20211208T103000Z
DTSTAMP;VALUE=DATE-TIME:20220528T192937Z
UID:ictsvirtual/86
DESCRIPTION:Title: MHV graviton scattering amplitudes from celestial current algebras\nby Shamik Banerjee (IOP Bhubaneswar) as part of ICTS String Seminars\n\
n\nAbstract\nIn this talk I will describe how one can determine the MHV gr
aviton scattering amplitudes from celestial current algebras. I will also
discuss recent developments in our understanding of the symmetries of gene
ral tree level graviton scattering amplitudes in Einstein gravity.\n
LOCATION:https://researchseminars.org/talk/ictsvirtual/86/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Sourav Roychowdhury (CMI Chennai)
DTSTART;VALUE=DATE-TIME:20211222T093000Z
DTEND;VALUE=DATE-TIME:20211222T103000Z
DTSTAMP;VALUE=DATE-TIME:20220528T192937Z
UID:ictsvirtual/89
DESCRIPTION:Title: Non-Abelian T-dual of Klebanov-Tseytlin background and its Penrose li
mits\nby Sourav Roychowdhury (CMI Chennai) as part of ICTS String Semi
nars\n\n\nAbstract\nIn this talk I will discuss Klebanov-Tseytlin backgrou
nd and it’s non-Abelian T-dual geometry. In particular I will show that
the T-dual background admits pp-wave geometry in the neighbourhood of appr
opriate null geodesic. I will make comments on possible dual gauge theory\
nfor our pp-wave background.\n
LOCATION:https://researchseminars.org/talk/ictsvirtual/89/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Dalimil Mazac (IAS)
DTSTART;VALUE=DATE-TIME:20220202T050000Z
DTEND;VALUE=DATE-TIME:20220202T060000Z
DTSTAMP;VALUE=DATE-TIME:20220528T192937Z
UID:ictsvirtual/90
DESCRIPTION:Title: Automorphic Spectra and the Conformal Bootstrap\nby Dalimil Mazac
(IAS) as part of ICTS String Seminars\n\n\nAbstract\nI will explain that
the spectral geometry of hyperbolic manifolds provides a remarkably faithf
ul model of the modern conformal bootstrap. In particular\, to each hyperb
olic D-manifold\, one can associate a Hilbert space of local operators\, w
hich is a unitary representation of a conformal group. The local operators
live in an emergent (D-1)-dimensional spacetime. The scaling dimensions o
f the operators are related to the eigenvalues of the Laplacian on the man
ifold. The operators satisfy an operator product expansion. Finally\, one
can define their correlation functions and derive bootstrap equations cons
training the spectrum. As an application\, I will use conformal bootstrap
techniques to derive upper bounds on the lowest positive eigenvalue of the
Laplacian on closed hyperbolic surfaces and 2-orbifolds. In a number of n
otable cases\, the bounds are nearly saturated by known surfaces and orbif
olds. For instance\, the bound on all genus-2 surfaces is λ1≤3.83889764
81\, while the Bolza surface has λ1≈3.838887258. The talk will be based
on https://arxiv.org/abs/2111.12716\, which is joint work with P. Kravchu
k and S. Pal.\n
LOCATION:https://researchseminars.org/talk/ictsvirtual/90/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Arjun Bagchi (IIT Kanpur)
DTSTART;VALUE=DATE-TIME:20220216T093000Z
DTEND;VALUE=DATE-TIME:20220216T103000Z
DTSTAMP;VALUE=DATE-TIME:20220528T192937Z
UID:ictsvirtual/91
DESCRIPTION:Title: Tensionless Tales\nby Arjun Bagchi (IIT Kanpur) as part of ICTS S
tring Seminars\n\n\nAbstract\nThe tensionless limit of string theory has l
ong been an enigmatic regime of the theory. In this talk\, I give an overv
iew of the recent developments in understanding tensionless bosonic closed
strings in flat space based on the symmetries on the worldsheet which tur
n out to be the Bondi-Metzner-Sachs (BMS) algebra. After a broad introduct
ion\, I will touch upon various new developments\, including a closed-to-o
pen string transition\, different tensionless vacua\, and Rindler physics
appearing on the worldsheet.\n
LOCATION:https://researchseminars.org/talk/ictsvirtual/91/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Shahin Sheikh-Jabbari (IPM Tehran)
DTSTART;VALUE=DATE-TIME:20220105T093000Z
DTEND;VALUE=DATE-TIME:20220105T103000Z
DTSTAMP;VALUE=DATE-TIME:20220528T192937Z
UID:ictsvirtual/92
DESCRIPTION:Title: Null Surface Thermodynamics\nby Shahin Sheikh-Jabbari (IPM Tehran
) as part of ICTS String Seminars\n\n\nAbstract\nWe study D dimensional pu
re Einstein gravity theory in a region of spacetime bounded by a generic n
ull boundary. We show besides the graviton modes propagating in the bulk\,
the system is described by boundary degrees of freedom labeled by D surfa
ce charges associated with nontrivial diffeomorphisms at the boundary. We
establish that the system admits a natural thermodynamical description. Us
ing standard surface charge analysis and covariant phase space method\, we
formulate laws of null surface thermodynamics which are local equations o
ver an arbitrary null surface. This thermodynamical system is generally an
open system and can be closed only when there is no flux of gravitons thr
ough the null surface. Our analysis extends the usual black hole thermodyn
amics to a universal feature of any area element on a generic null surface
.\n
LOCATION:https://researchseminars.org/talk/ictsvirtual/92/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Shreya Vardhan (MIT)
DTSTART;VALUE=DATE-TIME:20220209T130000Z
DTEND;VALUE=DATE-TIME:20220209T140000Z
DTSTAMP;VALUE=DATE-TIME:20220528T192937Z
UID:ictsvirtual/93
DESCRIPTION:Title: Mixed-state entanglement and information recovery in evaporating blac
k holes\nby Shreya Vardhan (MIT) as part of ICTS String Seminars\n\n\n
Abstract\nIt is generally expected that during the black hole evaporation
process\, correlations within the Hawking radiation first start to grow at
a time scale called the Page time. The information of a diary thrown into
the black hole is also expected to become accessible from the radiation a
t the Page time. These expectations are based on averages over Haar-random
pure states\, which assume that the evaporating black hole resembles an e
quilibrated pure state at infinite temperature. Using a method called the
equilibrium approximation\, we study the universal behavior of quantities
such as logarithmic negativity and Petz map fidelity in equilibrated pure
states at finite temperature. This reveals surprising new features of the
entanglement structure of the black hole and its radiation in the presence
of energy constraints. In particular\, we find that both the entanglement
within the radiation and the likelihood of information recovery first sta
rt to grow at a new time scale\, which is earlier than the Page time by a
finite fraction of the total evaporation time.\n
LOCATION:https://researchseminars.org/talk/ictsvirtual/93/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Hong Liu (MIT)
DTSTART;VALUE=DATE-TIME:20220223T033000Z
DTEND;VALUE=DATE-TIME:20220223T043000Z
DTSTAMP;VALUE=DATE-TIME:20220528T192937Z
UID:ictsvirtual/94
DESCRIPTION:Title: Emergent times in holography\nby Hong Liu (MIT) as part of ICTS S
tring Seminars\n\n\nAbstract\nIn holographic duality an eternal AdS black
hole is described by two copies of the boundary CFT in the thermal field d
ouble state. We provide explicit constructions in the boundary theory of i
nfalling time evolutions which can take bulk observers behind the horizon.
The constructions also help to illuminate the boundary emergence of the b
lack hole horizons\, the interiors\, and the associated causal structure.
A key element is the emergence\, in the large N limit of the boundary theo
ry\, of a type III1 von Neumann algebraic structure and the half-sided mod
ular translation structure associated with it.\n
LOCATION:https://researchseminars.org/talk/ictsvirtual/94/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Eric Sharpe (Virginia Tech)
DTSTART;VALUE=DATE-TIME:20220302T133000Z
DTEND;VALUE=DATE-TIME:20220302T143000Z
DTSTAMP;VALUE=DATE-TIME:20220528T192937Z
UID:ictsvirtual/95
DESCRIPTION:Title: An introduction to decomposition\nby Eric Sharpe (Virginia Tech)
as part of ICTS String Seminars\n\n\nAbstract\nIn this talk I will review
work on `decomposition\,' a property of 2d theories with 1-form symmetries
and\, more generally\, d-dim'l theories with (d-1)-form symmetries. Dec
omposition is the observation that such quantum field theories are equival
ent to ('decompose into’) disjoint unions of other QFTs\, known in this
context as "universes.” Examples include two-dimensional gauge theories
and orbifolds with matter invariant under a subgroup of the gauge group. D
ecomposition explains and relates several physical properties of these the
ories -- for example\, restrictions on allowed instantons arise as a "mult
iverse interference effect" between contributions from constituent univers
es. First worked out in 2006 as part of efforts to understand string propa
gation on stacks\, decomposition has been the driver of a number of develo
pments since. In the first half of this talk\, I will review decomposition
\; in the second half\, I will focus on the recent application to anomaly
resolution of Wang-Wen-Witten in two-dimensional orbifolds.\n\nTalk joint
with the Math-Pays seminar series (https://researchseminars.org/seminar/ic
tsmathphys).\n
LOCATION:https://researchseminars.org/talk/ictsvirtual/95/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Eric Perlmutter (IPhT (Saclay))
DTSTART;VALUE=DATE-TIME:20220316T093000Z
DTEND;VALUE=DATE-TIME:20220316T103000Z
DTSTAMP;VALUE=DATE-TIME:20220528T192937Z
UID:ictsvirtual/96
DESCRIPTION:Title: Harnessing S-Duality in N=4 SYM & Supergravity as SL(2\,Z)-Averaged S
trings\nby Eric Perlmutter (IPhT (Saclay)) as part of ICTS String Semi
nars\n\n\nAbstract\nI will talk about this paper\, written with Scott Coll
ier: https://arxiv.org/abs/2201.05093\n
LOCATION:https://researchseminars.org/talk/ictsvirtual/96/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Tim Adamo (University of Edinburgh)
DTSTART;VALUE=DATE-TIME:20220309T093000Z
DTEND;VALUE=DATE-TIME:20220309T103000Z
DTSTAMP;VALUE=DATE-TIME:20220528T192937Z
UID:ictsvirtual/97
DESCRIPTION:Title: Twistor theory and infinite-dimensional soft symmetries\nby Tim A
damo (University of Edinburgh) as part of ICTS String Seminars\n\n\nAbstra
ct\nRecently\, certain infinite towers of soft theorems associated with th
e self-dual sector of gravity were discovered by recasting scattering ampl
itudes in a conformal primary basis. The generators of the soft theorems m
iraculously organize themselves into a certain infinite-dimensional algebr
a which arises in 2d CFTs. I will discuss how this miracle is almost tauto
logical from the perspective of twistor theory\, which enables a first-pri
nciples derivation of many of recent results in celestial holography.\n
LOCATION:https://researchseminars.org/talk/ictsvirtual/97/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Edward Witten (IAS\, Princeton)
DTSTART;VALUE=DATE-TIME:20220301T130000Z
DTEND;VALUE=DATE-TIME:20220301T140000Z
DTSTAMP;VALUE=DATE-TIME:20220528T192937Z
UID:ictsvirtual/98
DESCRIPTION:Title: No Ensemble Averaging Below the Black Hole Threshold\nby Edward W
itten (IAS\, Princeton) as part of ICTS String Seminars\n\nAbstract: TBA\n
LOCATION:https://researchseminars.org/talk/ictsvirtual/98/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Chris Akers (MIT)
DTSTART;VALUE=DATE-TIME:20220323T130000Z
DTEND;VALUE=DATE-TIME:20220323T140000Z
DTSTAMP;VALUE=DATE-TIME:20220528T192937Z
UID:ictsvirtual/99
DESCRIPTION:Title: Black holes as non-isometric codes\nby Chris Akers (MIT) as part
of ICTS String Seminars\n\n\nAbstract\nThe interior of an old black hole i
s encoded in the Hawking radiation. This seems to be the implication of re
cent computations of the Page curve. We take this idea to its logical conc
lusion\, modeling old black holes as quantum codes embedding a large numbe
r of degrees of freedom (the interior and semiclassical radiation) into a
smaller number (the stretched horizon and physical radiation). I will prov
e that such codes exist\, and explain their novel properties and what they
can tell us about black holes. \n
LOCATION:https://researchseminars.org/talk/ictsvirtual/99/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Shu-Heng Shao (Stony Brook)
DTSTART;VALUE=DATE-TIME:20220401T133000Z
DTEND;VALUE=DATE-TIME:20220401T143000Z
DTSTAMP;VALUE=DATE-TIME:20220528T192937Z
UID:ictsvirtual/100
DESCRIPTION:Title: Non-invertible symmetries from higher gauging\nby Shu-Heng Shao
(Stony Brook) as part of ICTS String Seminars\n\n\nAbstract\nWe discuss in
vertible and non-invertible topological defects arising from gauging a dis
crete higher-form symmetry on a higher codimensional manifold in spacetime
\, which we define as higher gauging. A higher-form symmetry is called p-g
augeable if it can be gauged on a codimension-p manifold in spacetime. We
focus on 1-gaugeable 1-form symmetries in general 2+1d QFT\, and gauge the
m on a surface in spacetime. The universal fusion rules of the resulting i
nvertible and non-invertible condensation surfaces are determined. In the
special case of 2+1d TQFT\, every ordinary global symmetry is realized fro
m higher gauging. We further determine the fusion rules be- tween the surf
aces\, lines\, and lines that only live on the surfaces\, making the first
step towards building a fusion 2-category. We emphasize that the fusion
“coefficients” in these non-invertible fusion rules are generally not
numbers\, but 1+1d TQFTs. Finally\, we discuss examples of non-invertible
symmetries in non-topological QFT such as the free compact scalar theory a
nd QED.\n
LOCATION:https://researchseminars.org/talk/ictsvirtual/100/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Sabrina Pasterski (Perimeter Institute)
DTSTART;VALUE=DATE-TIME:20220420T123000Z
DTEND;VALUE=DATE-TIME:20220420T133000Z
DTSTAMP;VALUE=DATE-TIME:20220528T192937Z
UID:ictsvirtual/102
DESCRIPTION:Title: Revisiting the Flat Space Hologram\nby Sabrina Pasterski (Perime
ter Institute) as part of ICTS String Seminars\n\n\nAbstract\nWe start by
revisiting the task of constructing a holographic dual to quantum gravity
in asymptotically flat spacetimes. Upon recasting the S-matrix in terms of
data at the conformal boundary\, we see that the two standard approaches
(Carrollian and Celestial) amount to slicing up the bulk and boundary in d
ifferent ways. In particular\, the Celestial Hologram organizes scattering
from the point of view of Rindler evolution. \n\nNow the main motivation
for Celestial Holography comes from the connection between soft theorems a
nd asymptotic symmetries in asymptotically flat spacetimes\, and our abili
ty to recast soft operators as currents in a codimension 2 CFT. Taking rad
ial = Rindler evolution provides a streamlined route from asymptotic symm
etries in 4D asymptotically flat spacetimes to currents in a 2D celestial
CFT in a manner that makes their relation to QFT soft theorems manifest. W
e use this to reconcile the construction of charges in CCFT with the more
familiar construction from AdS/CFT\, despite the differing codimension\, a
nd discuss the advantages of the celestial basis.\n\nBased on 2201.06805 a
nd 2202.11127\n
LOCATION:https://researchseminars.org/talk/ictsvirtual/102/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Kevin Costello (Perimeter Institute)
DTSTART;VALUE=DATE-TIME:20220427T130000Z
DTEND;VALUE=DATE-TIME:20220427T140000Z
DTSTAMP;VALUE=DATE-TIME:20220528T192937Z
UID:ictsvirtual/103
DESCRIPTION:Title: On the associativity of one loop corrections to the celestial OPE\nby Kevin Costello (Perimeter Institute) as part of ICTS String Seminars
\n\n\nAbstract\nThe celestial holography program suggests that collinear s
ingularities in gauge theory and gravity can form the OPE coefficients of
a two-dimensional CFT. We investigate whether known one-loop corrections t
o QCD collinear singularities satisfy the associativity conditions of an O
PE. We find they do not\, but that associativity can be restored for cert
ain gauge groups by a certain Green-Schwarz mechanism. This is joint work
with Natalie Paquette.\n
LOCATION:https://researchseminars.org/talk/ictsvirtual/103/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Yuji Tachikawa (IPMU)
DTSTART;VALUE=DATE-TIME:20220525T060000Z
DTEND;VALUE=DATE-TIME:20220525T070000Z
DTSTAMP;VALUE=DATE-TIME:20220528T192937Z
UID:ictsvirtual/104
DESCRIPTION:Title: Undecidable problems in quantum field theory\nby Yuji Tachikawa
(IPMU) as part of ICTS String Seminars\n\n\nAbstract\nWe point out that so
me questions in quantum field theory are undecidable in a precise mathemat
ical sense. More concretely\, it will be demonstrated that there is no alg
orithm answering whether a given 2d supersymmetric Lagrangian theory break
s supersymmetry or not. It will also be shown that there is a specific 2d
supersymmetric Lagrangian theory which breaks supersymmetry if and only if
the standard Zermelo-Fraenkel set theory with the axiom of choice is cons
istent\, which can never be proved or disproved as the consequence of Göd
el's second incompleteness theorem. The article includes a brief and infor
mal introduction to the phenomenon of undecidability and its previous appe
arances in theoretical physics. This talk is based on 2203.16689 .\n
LOCATION:https://researchseminars.org/talk/ictsvirtual/104/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Sunil Sake (TIFR)
DTSTART;VALUE=DATE-TIME:20220413T093000Z
DTEND;VALUE=DATE-TIME:20220413T103000Z
DTSTAMP;VALUE=DATE-TIME:20220528T192937Z
UID:ictsvirtual/105
DESCRIPTION:by Sunil Sake (TIFR) as part of ICTS String Seminars\n\nAbstra
ct: TBA\n
LOCATION:https://researchseminars.org/talk/ictsvirtual/105/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Edgar Shaghoulian (University of Pennsylvania)
DTSTART;VALUE=DATE-TIME:20220511T133000Z
DTEND;VALUE=DATE-TIME:20220511T143000Z
DTSTAMP;VALUE=DATE-TIME:20220528T192937Z
UID:ictsvirtual/106
DESCRIPTION:Title: The central dogma and entanglement in de Sitter space\nby Edgar
Shaghoulian (University of Pennsylvania) as part of ICTS String Seminars\n
\n\nAbstract\nThe central dogma of black hole physics – which says that
from the outside a black hole can be described in terms of a quantum syste
m with exp(Area/4G) states evolving unitarily – has recently been suppor
ted by computations indicating that the interior of the black hole is enco
ded in the Hawking radiation of the exterior. In this paper\, we probe whe
ther such a dogma for cosmological horizons has any support from similar c
omputations.The fact that the de Sitter bifurcation surface is a minimax s
urface (instead of a maximin surface in the case of black holes) causes pr
oblems with this interpretation when trying to import calculations analogo
us to the AdS case. This suggests placing the holographic dual on the de S
itter horizon itself\, where we formulate a two-sided extremization prescr
iption for computing entanglement entropy in the holographic dual. We find
answers consistent with general expectations for a quantum theory of de S
itter space\, including a vanishing total entropy and an entropy of A/4G w
hen restricting to a single static patch. We will also explore some of its
more exotic predictions.\n
LOCATION:https://researchseminars.org/talk/ictsvirtual/106/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Dam Thanh Son (University of Chicago)
DTSTART;VALUE=DATE-TIME:20220504T130000Z
DTEND;VALUE=DATE-TIME:20220504T140000Z
DTSTAMP;VALUE=DATE-TIME:20220528T192937Z
UID:ictsvirtual/107
DESCRIPTION:Title: Bosonization of Fermi Surfaces and Coadjoint Orbits\nby Dam Than
h Son (University of Chicago) as part of ICTS String Seminars\n\n\nAbstrac
t\nFermi liquid theory is a cornerstone of condensed matter physics. Howev
er\, Landau's formulation of Fermi liquid theory does not fit into the par
adigm of effective field theory. We describe a new method that leads to a
field-theoretical reformulation of Landau Fermi liquid theory. In this app
roach\, a system with a Fermi surface is described as a coadjoint orbit of
the group of canonical transformations. The method naturally leads to a n
onlinear bosonization of the Fermi surface. The Berry phase that the Fermi
surface acquires when changing shape is shown to be given by the Kirillov
-Kostant-Souriau symplectic form on the coadjoint orbit. We show that the
resulting local effective field theory captures both linear and nonlinear
effects in Landau’s Fermi liquid theory. Possible extensions and applica
tions of the theory are described. (Reference: Luca Delacrétaz\, Umang Me
hta\, Yi-Hsien Du\, DTS arXiv:2203.05004.)\n
LOCATION:https://researchseminars.org/talk/ictsvirtual/107/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Shailesh Lal (U. Porto)
DTSTART;VALUE=DATE-TIME:20220601T093000Z
DTEND;VALUE=DATE-TIME:20220601T103000Z
DTSTAMP;VALUE=DATE-TIME:20220528T192937Z
UID:ictsvirtual/108
DESCRIPTION:Title: The World in a Grain of Sand\nby Shailesh Lal (U. Porto) as part
of ICTS String Seminars\n\n\nAbstract\nThe proliferation of vacuum soluti
ons to string theory highly deter the search for the Standard Model within
the string landscape.\nWe propose a novel approach to this problem by usi
ng machine learning to find a measure of similarity of vacua. Using comple
te intersection Calabi Yau manifolds as\na concrete example\, our approach
represents these manifolds as points in Euclidean three-space with simila
r points clustered together.\nOur analysis provides an explicit method for
machine-learning the landscape even with minuscule data.\n
LOCATION:https://researchseminars.org/talk/ictsvirtual/108/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Semanti Dutta (IMSc Chennai)
DTSTART;VALUE=DATE-TIME:20220608T093000Z
DTEND;VALUE=DATE-TIME:20220608T103000Z
DTSTAMP;VALUE=DATE-TIME:20220528T192937Z
UID:ictsvirtual/109
DESCRIPTION:by Semanti Dutta (IMSc Chennai) as part of ICTS String Seminar
s\n\nAbstract: TBA\n
LOCATION:https://researchseminars.org/talk/ictsvirtual/109/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Sayantani Bhattacharya (NISER Bhubaneswar)
DTSTART;VALUE=DATE-TIME:20220615T093000Z
DTEND;VALUE=DATE-TIME:20220615T103000Z
DTSTAMP;VALUE=DATE-TIME:20220528T192937Z
UID:ictsvirtual/110
DESCRIPTION:by Sayantani Bhattacharya (NISER Bhubaneswar) as part of ICTS
String Seminars\n\nAbstract: TBA\n
LOCATION:https://researchseminars.org/talk/ictsvirtual/110/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Cumrun Vafa (Harvard University)
DTSTART;VALUE=DATE-TIME:20220622T093000Z
DTEND;VALUE=DATE-TIME:20220622T103000Z
DTSTAMP;VALUE=DATE-TIME:20220528T192937Z
UID:ictsvirtual/111
DESCRIPTION:by Cumrun Vafa (Harvard University) as part of ICTS String Sem
inars\n\nAbstract: TBA\n
LOCATION:https://researchseminars.org/talk/ictsvirtual/111/
END:VEVENT
END:VCALENDAR