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BEGIN:VEVENT
SUMMARY:Jose Figueroa-O'Farrill (University of Edinburgh)
DTSTART:20200505T114500Z
DTEND:20200505T124500Z
DTSTAMP:20260422T225847Z
UID:JointTheorySeminar/1
DESCRIPTION:Title: A cohomological approach to rigid supersymmetry in curved space
\nby Jose Figueroa-O'Farrill (University of Edinburgh) as part of Join
t Theory Seminar between Vienna University of Technology and University of
Vienna\n\n\nAbstract\nApart from any intrinsic interest one might have in
supersymmetry\, supersymmetric field theories in curved space are the sub
ject of study because of their utility in computing exact quantities in (n
on-supersymmetric) quantum field theory via supersymmetric localisation te
chniques. I will review the usual methods by which we may construct such
theories and motivate the central question I will answer in the talk: how
to define a suitable notion of “Killing spinor”. The approach I wil
l present is based on the observation that Killing spinors generate a Lie
superalgebra with a very particular algebraic structure\, which is amenabl
e to cohomological calculation. I will explain how the cohomology calcul
ation gives rise to the Killing spinor equation and summarise some of the
calculations that we have done in a number of different dimensions. (Thi
s is based on ongoing collaborations with my student Andrew Beckett (Edinb
urgh) and my long-term collaborators Paul de Medeiros (Stavanger) and Andr
ea Santi (Padova).)\n
LOCATION:https://researchseminars.org/talk/JointTheorySeminar/1/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Gaston Giribet (Buenos Aires University)
DTSTART:20200512T114500Z
DTEND:20200512T124500Z
DTSTAMP:20260422T225847Z
UID:JointTheorySeminar/2
DESCRIPTION:Title: On string theory on AdS3 x M7 in the tensionless limit\nby
Gaston Giribet (Buenos Aires University) as part of Joint Theory Seminar b
etween Vienna University of Technology and University of Vienna\n\n\nAbstr
act\nIn this talk I will review old and recent results on a special limit
of string theory on AdS3 x M7 with pure NS-NS fluxes: the limit in which t
he string length (l_s) equals the AdS3 radius (R). At this point of the mo
duli space\, the theory exhibits special properties\, which I will discuss
. Special attention will be focused on features of correlation functions t
hat are related to the non-compactness of the boundary CFT target space\,
and on how these features change when the point l_s=R is approached. Also\
, we briefly review recent proposals for exact realizations of AdS/CFT cor
respondence at this special point.\n
LOCATION:https://researchseminars.org/talk/JointTheorySeminar/2/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Evgeny Skvortsov (Albert Einstein Institute)
DTSTART:20200519T114500Z
DTEND:20200519T124500Z
DTSTAMP:20260422T225847Z
UID:JointTheorySeminar/3
DESCRIPTION:Title: (Quantum) Higher spin gravity and applications to physics\n
by Evgeny Skvortsov (Albert Einstein Institute) as part of Joint Theory Se
minar between Vienna University of Technology and University of Vienna\n\n
\nAbstract\nI will give a general overview of Higher Spin Gravities and al
so discuss the recent developments\nthat give a class of models where UV-d
ivergences of Einstein gravity cancel out thanks to the higher spin symmet
ry. \nAt the end I will discuss the relation between Higher Spin Gravities
and a class of conformal field theories in three dimensions\nthat describ
e the physics of many second order phase transitions in the real world and
have been recently conjectured to exhibit a number\nof remarkable dualiti
es\, in particular the three-dimensional bosonization duality. I will show
how Higher Spin Gravity can help to prove the dualities\nand how it makes
new predictions. The relation to QCD and self-dual Yang-Mills will also b
e discussed.\n
LOCATION:https://researchseminars.org/talk/JointTheorySeminar/3/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Eran Palti (MPI Munich)
DTSTART:20200514T140000Z
DTEND:20200514T150000Z
DTSTAMP:20260422T225847Z
UID:JointTheorySeminar/4
DESCRIPTION:Title: Scale separation\, Swampland\, and type IIA orientifold vacua\nby Eran Palti (MPI Munich) as part of Joint Theory Seminar between Vie
nna University of Technology and University of Vienna\n\n\nAbstract\nI wil
l introduce the Swampland program which aims to capture constraints on whi
ch effective theories can be completed into quantum gravity in the UV. I w
ill then discuss such a proposed constraint which states that effective th
eories in anti-de Sitter space must have an infinite tower of states whose
mass is related to the cosmological constant. I will describe how this is
satisfied in almost all fully understood vacua of string theory. I will t
hen focus on a proposed counter example to the conjecture based on four-di
mensional effective theories from compactifications of type IIA string the
ory. I will present recent results on testing such counter examples by stu
dying whether they can be uplifted to full ten-dimensional solutions or no
t. In particular\, presenting a ten-dimensional solution which holds at th
e two-derivative level and at first order in a certain perturbative expans
ion.\n
LOCATION:https://researchseminars.org/talk/JointTheorySeminar/4/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Tom Rudelius (IAS)
DTSTART:20200526T140000Z
DTEND:20200526T150000Z
DTSTAMP:20260422T225847Z
UID:JointTheorySeminar/5
DESCRIPTION:Title: Conditions for (no) eternal inflation\nby Tom Rudelius (IAS
) as part of Joint Theory Seminar between Vienna University of Technology
and University of Vienna\n\n\nAbstract\nIn the first half of this talk\, I
will present a pedagogical introduction to eternal inflation\, featuring
necessary and sufficient conditions on scalar field potentials for eternal
inflation. In the second half\, I will speculate on possible connections
between a "No Eternal Inflation" conjecture and recently-proposed de Sitte
r Swampland conjectures.\n
LOCATION:https://researchseminars.org/talk/JointTheorySeminar/5/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Kevin Grosvenor (University of Wuerzburg)
DTSTART:20200616T114500Z
DTEND:20200616T124500Z
DTSTAMP:20260422T225847Z
UID:JointTheorySeminar/7
DESCRIPTION:Title: Entanglement entropy and subregion complexity in thermal pertur
bations around pure-AdS\nby Kevin Grosvenor (University of Wuerzburg)
as part of Joint Theory Seminar between Vienna University of Technology an
d University of Vienna\n\n\nAbstract\nI will discuss the computation of th
e entanglement entropy \nand subregion complexity for spherical entangling
regions in the AdS \nblack hole background up to third order in the black
hole mass using \nthe "complexity equals volume" conjecture. I will show
that a \nreinterpretation of the conjectured relationship between Fisher \
ninformation and subregion complexity in 1701.02319 suggests an \nextensio
n of the "first law of entanglement thermodynamics" to second \norder. By
analogy to standard thermodynamics\, entanglement and \ncomplexity play th
e roles of heat and work\, respectively.\n
LOCATION:https://researchseminars.org/talk/JointTheorySeminar/7/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Ilka Brunner (LMU Munich)
DTSTART:20200623T114500Z
DTEND:20200623T124500Z
DTSTAMP:20260422T225847Z
UID:JointTheorySeminar/8
DESCRIPTION:Title: Flows\, defects\, and transport of D-branes\nby Ilka Brunne
r (LMU Munich) as part of Joint Theory Seminar between Vienna University o
f Technology and University of Vienna\n\n\nAbstract\nI will discuss RG flo
ws of two dimensional supersymmetric field theories using defects.\nIn par
ticular\, defects provide a tool to transport D-branes between UV and IR.\
nThe main example will be linear sigma models with different Landau-Ginzbu
rg phases.\n\nThe seminar will be held via BigBlueButton. Please contact t
he organizers for the link.\n
LOCATION:https://researchseminars.org/talk/JointTheorySeminar/8/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Henning Samtleben (Ecole Normale Supérieure de Lyon)
DTSTART:20200630T090000Z
DTEND:20200630T100000Z
DTSTAMP:20260422T225847Z
UID:JointTheorySeminar/9
DESCRIPTION:Title: Kaluza-Klein spectrometer from exceptional field theory\nby
Henning Samtleben (Ecole Normale Supérieure de Lyon) as part of Joint Th
eory Seminar between Vienna University of Technology and University of Vie
nna\n\n\nAbstract\nI present new tools for the computation of Kaluza-Klei
n mass spectra associated with compactifications around various background
geometries relevant for string theory. This includes geometries with litt
le to no remaining symmetries\, hardly accessible to standard methods. The
new tools build on exceptional field theory\, the duality covariant formu
lation of supergravity. Among the applications I discuss the tachyonic Kal
uza-Klein modes arising at higher levels in the spectrum of the non-supers
ymmetric SO(3) × SO(3)-invariant AdS4 vacuum of 11-dimensional supergravi
ty.\n
LOCATION:https://researchseminars.org/talk/JointTheorySeminar/9/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Jarkko Peuron (ECT\, Trento)
DTSTART:20200721T110000Z
DTEND:20200721T120000Z
DTSTAMP:20260422T225847Z
UID:JointTheorySeminar/10
DESCRIPTION:Title: Heavy quark diffusion in an overoccupied gluon plasma\nby
Jarkko Peuron (ECT\, Trento) as part of Joint Theory Seminar between Vienn
a University of Technology and University of Vienna\n\n\nAbstract\nWe extr
act the heavy-quark diffusion coefficient \\kappa and the resulting moment
um broadening in a far-from-equilibrium non-Abelian plasma. We find severa
l features in the time dependence of the momentum broadening: a short init
ial rapid growth of \, followed by linear growth with time due to Langevin
-type dynamics and damped oscillations around this growth at the plasmon f
requency. We show that these novel oscillations are not easily explained u
sing perturbative techniques but result from an excess of gluons at low mo
menta. These oscillation are therefore a gauge invariant confirmation of t
he infrared enhancement we had previously observed in gauge-fixed correlat
ion functions. We argue that the kinetic theory description of such system
s becomes less reliable in the presence of this IR enhancement.\n
LOCATION:https://researchseminars.org/talk/JointTheorySeminar/10/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Edgar Shaghoulian (Cornell)
DTSTART:20201006T120000Z
DTEND:20201006T130000Z
DTSTAMP:20260422T225847Z
UID:JointTheorySeminar/11
DESCRIPTION:Title: Looking for islands\nby Edgar Shaghoulian (Cornell) as par
t of Joint Theory Seminar between Vienna University of Technology and Univ
ersity of Vienna\n\n\nAbstract\nI will review the role of replica wormhole
s in deriving a unitary Page curve for Hawking radiation and discuss exten
sions to flat spacetime and cosmology. I will also discuss general consist
ency conditions that guide the search for such nontrivial saddles in the g
ravitational path integral.\n
LOCATION:https://researchseminars.org/talk/JointTheorySeminar/11/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Yuhma Asano (Universität Wien)
DTSTART:20201103T130000Z
DTEND:20201103T140000Z
DTSTAMP:20260422T225847Z
UID:JointTheorySeminar/12
DESCRIPTION:Title: M-brane Realisation in Matrix Model\nby Yuhma Asano (Unive
rsität Wien) as part of Joint Theory Seminar between Vienna University of
Technology and University of Vienna\n\n\nAbstract\nIn this talk\, we cons
ider a one-dimensional matrix model\, called the BMN matrix model\, which
is considered as a non-perturbative formulation of M-theory. In the BMN ma
trix model\, there are some evidences that spherical M2- and M5-branes cor
respond to vacua of the matrix model. While it is easy to understand reali
sation of M2-brane geometries because the vacua form fuzzy 2-spheres\, it
requires non-perturbative computation in a strongly coupled regime to obta
in realisation of M5-brane geometries. We solve this notorious problem by
using the supersymmetric localisation method and see how the M-brane geome
tries are successfully obtained. Intriguingly\, this result gives us a con
sistent picture of how the gravity-side spacetime in the gauge/gravity cor
respondence emerges from the matrix model.\n
LOCATION:https://researchseminars.org/talk/JointTheorySeminar/12/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Adrien Fiorucci (Université Libre de Bruxelles (ULB))
DTSTART:20201110T130000Z
DTEND:20201110T140000Z
DTSTAMP:20260422T225847Z
UID:JointTheorySeminar/13
DESCRIPTION:Title: The Λ-BMS Charge Algebra in n dimensions\nby Adrien Fioru
cci (Université Libre de Bruxelles (ULB)) as part of Joint Theory Seminar
between Vienna University of Technology and University of Vienna\n\n\nAbs
tract\nThe aim of my talk is to discuss brand-new results about the phase
space of Einstein’s gravity in arbitrary dimensions with non-vanishing c
osmological constant Λ. I will start by reviewing the solution space of a
symptotically locally (A)dS spacetimes in the Starobinsky/Fefferman-Graham
gauge and the renormalization of the presymplectic current needed when th
e boundary structure is allowed to fluctuate. Next\, I will discuss the gr
avitational charge algebra for generic Al(A)dSnspacetimes\, without assumi
ng any further boundary condition than the minimal falloffs allowing for c
onformal compactification. Then I will introduce the Λ-BMSnalgebroid aris
ing from some boundary gauge fixing and reducing to the Generalized BMSnal
gebra in the flat limit Λ→0. The associated boundary conditions\, equiv
alent to fix a foliation and a measure as universal structure on the bound
ary\, do not freeze completely the transverse metric\, leading to some sym
plectic flux through the conformal boundary. Finally\, I will particulariz
e the framework to the n=4 case and show that one can give sense to the fl
at limit of the phase space thanks to the incorporation of kinetic corner
terms in the variational principle. The result of this process is exactly
the phase space for Generalized BMS4 symmetries in asymptotically locally
flat spacetimes.\n\nBased on:\n\nA. FIORUCCI\, R. RUZZICONI\,Charge Algebr
a in Al(A)dSnspacetimes (Nov 2020). e-Print: 2011.02002[hep-th]\n\nG. COMP
ÈRE\, A. FIORUCCI\, R. RUZZICONI\,The Λ-BMS4Charge Algebra (Apr 2020). e
-Print: 2004.10769[hep-th]\n\nG. COMPÈRE\, A. FIORUCCI\, R. RUZZICONI\,Su
perboost transitions\, refraction memory and super-Lorentz charge algebra
(Sep 2018). e-Print: 1810.00377[hep-th]\n
LOCATION:https://researchseminars.org/talk/JointTheorySeminar/13/
END:VEVENT
BEGIN:VEVENT
SUMMARY:David Andriot (TU Wien)
DTSTART:20201117T130000Z
DTEND:20201117T140000Z
DTSTAMP:20260422T225847Z
UID:JointTheorySeminar/14
DESCRIPTION:Title: Do classical de Sitter string backgrounds exist?\nby David
Andriot (TU Wien) as part of Joint Theory Seminar between Vienna Universi
ty of Technology and University of Vienna\n\n\nAbstract\nA classical solut
ion of string theory with a 4d de Sitter space-time could provide a simple
and well-controlled setting to establish a connection to cosmological mod
els. So far however\, it has proven very difficult to find any example of
such a solution. As will be recalled\, attempts in this direction are plag
ued by many no-go theorems\, or by the difficulty for concrete 10d supergr
avity solutions to fit in the classical stringy regime. This situation agr
ees with the recent claims of de Sitter swampland conjectures. These conje
ctures can actually be verified quantitatively\, with a surprisingly good
agreement\, as will be shown. This may hint at a deep reason against class
ical de Sitter background\, possibly to be found within the web of swampla
nd conjectures\, and the relation to the distance conjecture will be comme
nted on.\n
LOCATION:https://researchseminars.org/talk/JointTheorySeminar/14/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Flavio Tonioni (Liverpool U.)
DTSTART:20201124T130000Z
DTEND:20201124T140000Z
DTSTAMP:20260422T225847Z
UID:JointTheorySeminar/15
DESCRIPTION:Title: Misaligned Supersymmetry and Anti-D-branes\nby Flavio Toni
oni (Liverpool U.) as part of Joint Theory Seminar between Vienna Universi
ty of Technology and University of Vienna\n\n\nAbstract\nIn this talk\, I
will review the concept of misaligned supersymmetry and discuss its relati
onship with anti-D-branes in type II string theories. Misaligned supersymm
etry characterises a variety of non-supersymmetric string models: even if
the particle spectrum lacks a one-by-one matching between particles with a
different spin\, there exist theories in which an infinite oscillation be
tween fermionic and bosonic surpluses at each mass level results in a net
cancellation that allows for a finite one-loop cosmological constant. Such
a scenario is often discussed with regard to closed-string theories\, but
I will show that the spectrum of an anti-D-brane on top of an orientifold
plane presents essentially the same properties. Anti-D-branes are crucial
tools in many phenomenological string-theory realisations of features suc
h as supersymmetry breaking and de Sitter uplifting\, and I will comment o
n how an understanding of the effects of their infinite tower of states is
related to their low-energy descriptions.\n
LOCATION:https://researchseminars.org/talk/JointTheorySeminar/15/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Laurent Freidel
DTSTART:20201208T130000Z
DTEND:20201208T140000Z
DTSTAMP:20260422T225847Z
UID:JointTheorySeminar/16
DESCRIPTION:Title: Quantum gravity at the corner\nby Laurent Freidel as part
of Joint Theory Seminar between Vienna University of Technology and Univer
sity of Vienna\n\n\nAbstract\nIn this talk\, I will present a new perspect
ive on the non-perturbative\nquantization of gravity based on the concept
of corner symmetries associated with local subregions.\nAfter introducing
the corner algebra for various formulations of general relativity\, I will
illustrate its physical content in 4d metric and tetrad gravity. I will
also present the formalism of edge modes\, whose role is to restore gauge-
invariance at boundaries while preserving non-trivial charges. If time per
mits\, I'll show our recent progress on the representation theory of these
algebras. I will also describe the relationship that these results entert
ain with standard loop gravity\, asymptotic quantization\, and the concept
of holography.\n
LOCATION:https://researchseminars.org/talk/JointTheorySeminar/16/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Severin Lüst (Harvard)
DTSTART:20201215T130000Z
DTEND:20201215T140000Z
DTSTAMP:20260422T225847Z
UID:JointTheorySeminar/17
DESCRIPTION:Title: The Tadpole Problem\nby Severin Lüst (Harvard) as part of
Joint Theory Seminar between Vienna University of Technology and Universi
ty of Vienna\n\n\nAbstract\nI will discuss string theory compactifications
where a large number of moduli is stabilized by fluxes. I will present a
conjecture which rules out the stabilization of all complex-structure modu
li in F-theory at a generic point in moduli space by fluxes that satisfy t
he tadpole cancellation condition. Evidence for this conjecture comes from
K3xK3 compactifications. Using evolutionary algorithms we found that modu
li stabilization needs fluxes whose charge is slightly smaller than 1/2 of
the number of moduli and larger than what is allowed by tadpole cancellat
ion. I will furthermore comment on possible implications on de Sitter vacu
a obtained by antibrane uplift in long warped throats.\n
LOCATION:https://researchseminars.org/talk/JointTheorySeminar/17/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Joshua Kames-King (University of Bonn)
DTSTART:20210119T130000Z
DTEND:20210119T140000Z
DTSTAMP:20260422T225847Z
UID:JointTheorySeminar/21
DESCRIPTION:Title: Deformations of JT Gravity and KdV Equations\nby Joshua Ka
mes-King (University of Bonn) as part of Joint Theory Seminar between Vien
na University of Technology and University of Vienna\n\n\nAbstract\nRecent
ly\, it was shown that the duality of double-scaled matrix models and JT g
ravity can be extended to include surfaces with conical defects.\nWe show
that the thermal partition function of this deformed theory may be written
as the free energy of topological gravity around a shifted expansion poin
t.\nBy use of the KdV equation we furnish an off-shell de- scription for b
oth the single and multi-boundary cases of the partition function.\nWe als
o rewrite the deformed partition function as a low temperature expansion\,
which allows for a convenient calculation of contributions up to a desire
d order.\nWe use this approach to demonstrate the existence of a Hawking-P
age phase transition between connected and disconnected surfaces for this
instance of JT gravity.\nFurthermore\, we calculate the spectral form fact
or and compare with the standard JT case.\nWe conclude by commenting on th
e dS2 case.\n
LOCATION:https://researchseminars.org/talk/JointTheorySeminar/21/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Prateek Agrawal (Oxford U.)
DTSTART:20210126T130000Z
DTEND:20210126T140000Z
DTSTAMP:20260422T225847Z
UID:JointTheorySeminar/22
DESCRIPTION:Title: Topological Gravity as the Early Phase of our Universe\nby
Prateek Agrawal (Oxford U.) as part of Joint Theory Seminar between Vienn
a University of Technology and University of Vienna\n\n\nAbstract\nI will
present a scenario motivated by string dualities and the swampland where t
he early universe is described by a topological phase of gravity. Many cos
mological puzzles can be explained in terms of the topological nature of t
his phase. To obtain phenomenological predictions\, a concrete realization
of this scenario using Witten's four dimensional topological gravity will
be presented. In this model\, the CMB power spectrum is controlled by co
nformal anomaly coefficients. The model predicts the absence of tensor mod
es in the CMB fluctuations and significant non-Gaussianities in 4- and hig
her point functions.\n
LOCATION:https://researchseminars.org/talk/JointTheorySeminar/22/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Shahin Sheikh Jabbari (IPM)
DTSTART:20210112T100000Z
DTEND:20210112T110000Z
DTSTAMP:20260422T225847Z
UID:JointTheorySeminar/24
DESCRIPTION:Title: Temperature of Black Holes in Horndeski Gravity Theories\n
by Shahin Sheikh Jabbari (IPM) as part of Joint Theory Seminar between Vie
nna University of Technology and University of Vienna\n\n\nAbstract\nHornd
eski theories are the most general family of scalar-tensor gravity with se
cond order equations of motion. In these theories speeds of propagation o
f gravitons and photons are in general different and gravitons move on an
effective metric different than the one seen by photons. These theories a
dmit black hole solutions with the peculiar feature that they do not satis
fy the first law with the entropy given by the Wald formula. We argue that
the issue with the first law stems from the fact that black hole temperat
ure is not given by the surface gravity of the black hole metric\, but wit
h the surface gravity of the effective metric seen by gravitons. The modif
ied temperature\, with the entropy unambiguously computed by the solution
phase space method\, yields the correct first law. We discuss far-reaching
implications of our results for black hole thermodynamics beyond the Horn
deski theories.\n
LOCATION:https://researchseminars.org/talk/JointTheorySeminar/24/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Marc Geiller (ENS Lyon)
DTSTART:20210216T130000Z
DTEND:20210216T140000Z
DTSTAMP:20260422T225847Z
UID:JointTheorySeminar/25
DESCRIPTION:Title: A new look at symmetries of 3d gravity\nby Marc Geiller (E
NS Lyon) as part of Joint Theory Seminar between Vienna University of Tech
nology and University of Vienna\n\n\nAbstract\nI will review the analysis
of boundary symmetries in first order 3d gravity\, and explain how the stu
dy of the boundary current algebra and the Sugawara construction actually
leads to two dual notions of diffeomorphism charges. This provides a new u
nderstanding of the relationship between the second order and first order
formulations\, and of the existence of finite distance asymptotic (or symp
lectic) symmetries in topological theories. This analysis is performed on
the most general theory of first order 3d gravity\, which also enables to
understand the duality between curvature and torsion\, as well as the rela
tionship with chiral and massive gravity.\n
LOCATION:https://researchseminars.org/talk/JointTheorySeminar/25/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Christoph Nega (University of Bonn)
DTSTART:20210209T130000Z
DTEND:20210209T140000Z
DTSTAMP:20260422T225847Z
UID:JointTheorySeminar/26
DESCRIPTION:Title: Analytic Structure of Banana Feynman Integrals\nby Christo
ph Nega (University of Bonn) as part of Joint Theory Seminar between Vienn
a University of Technology and University of Vienna\n\n\nAbstract\nIn this
talk I will introduce the so called banana Feynman integrals and explain
their analytic properties in dimensional regularization.\nThese Feynman in
tegrals have a natural interpretation as relative periods of a complete in
tersection Calabi-Yau manifold\, whose dimension is the loop order minus o
ne of the banana integral.\nIn particular\, we find that the leading logar
ithmic structure in the high energy regime\, which corresponds to the poin
t of maximal unipotent monodromy\, is determined by a novel Gamma-class ev
aluation in the ambient space of the mirror CY and the mirror CY itself.\n
Moreover\, we provide simple closed all loop formulas for the Frobenius ka
ppa-constants at the physical threshold in terms of zeta values.\nI will a
lso give a short outlook how the above structures evolve in the expansion
in the dimensional regularization parameter.\nFinally\, I comment on the s
ituation in the non-equal mass case.\n
LOCATION:https://researchseminars.org/talk/JointTheorySeminar/26/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Klaus Sibold
DTSTART:20210323T130000Z
DTEND:20210323T140000Z
DTSTAMP:20260422T225847Z
UID:JointTheorySeminar/27
DESCRIPTION:Title: Perturbative Quantization of Einstein-Hilbert Gravity\nby
Klaus Sibold as part of Joint Theory Seminar between Vienna University of
Technology and University of Vienna\n\n\nAbstract\nIn a perturbative appr
oach Einstein-Hilbert gravity is quantized about a \nflat background. In o
rder to render the model power counting \nrenormalizable\, higher order cu
rvature terms are added to the action.\nThey serve as Pauli-Villars type r
egulators and require an expansion in \nthe number of fields in addition t
o the standard expansion in the number \nof loops.\nRenormalization is the
n performed within the BPHZL scheme\, which \nprovides the action principl
e to construct the Slavnov-Taylor identity \nand invariant differential op
erators.\nAfter removal of the regulators\, the final physical state space
of the \nEinstein-Hilbert theory is realized via the quartet mechanism of
Kugo \nand Ojima.\nRenormalization group and Callan-Symanzik equation are
derived for the \nGreen functions and\, formally\, also for the S-matrix.
\n
LOCATION:https://researchseminars.org/talk/JointTheorySeminar/27/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Roberto Emparan (Barcelona U.)
DTSTART:20210427T120000Z
DTEND:20210427T130000Z
DTSTAMP:20260422T225847Z
UID:JointTheorySeminar/30
DESCRIPTION:Title: Digging traversable wormholes\nby Roberto Emparan (Barcelo
na U.) as part of Joint Theory Seminar between Vienna University of Techno
logy and University of Vienna\n\n\nAbstract\nIn recent years there have ap
peared several constructions of traversable wormholes\, in four and other
dimensions\, which only involve physically acceptable\, controllable ingre
dients. They connect in deep ways many aspects of gravity\, quantum field
theory\, and quantum information. I will discuss several features of these
constructions\, with a focus on traversability\, connectivity between mul
tiple mouths\, and the (im)possibility of time travel.\n
LOCATION:https://researchseminars.org/talk/JointTheorySeminar/30/
END:VEVENT
BEGIN:VEVENT
SUMMARY:James Gray (Virginia Tech)
DTSTART:20210302T130000Z
DTEND:20210302T140000Z
DTSTAMP:20260422T225847Z
UID:JointTheorySeminar/31
DESCRIPTION:Title: Machine learning and SU(3) structures on six manifolds\nby
James Gray (Virginia Tech) as part of Joint Theory Seminar between Vienna
University of Technology and University of Vienna\n\n\nAbstract\nIn this
talk we will discuss the application of Machine Learning techniques to obt
ain numerical approximations to various metrics of SU(3) structure on Cala
bi-Yau manifolds. More precisely\, we will be interested in SU(3) structur
es whose torsion classes make them suitable backgrounds for various string
compactifications. A variety of aspects of this topic will be covered. Th
ese will include learning moduli dependent Ricci-Flat metrics on Calabi-Ya
u threefolds and obtaining numerical approximations to torsional SU(3) str
uctures.\n
LOCATION:https://researchseminars.org/talk/JointTheorySeminar/31/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Lukas Müller
DTSTART:20210309T130000Z
DTEND:20210309T140000Z
DTSTAMP:20260422T225847Z
UID:JointTheorySeminar/32
DESCRIPTION:Title: Anomalous field theories as boundaries\nby Lukas Müller a
s part of Joint Theory Seminar between Vienna University of Technology and
University of Vienna\n\n\nAbstract\nThis talk will be about the descripti
on of anomalies in quantum field theory through boundary states of certain
field theories in one dimensions higher.\nI will give a gentle introducti
on to the mathematical formulation of this approach developed by Freed and
Monnier and explain its relation to more classical approaches.\nI will di
scuss two concrete examples in detail\, namely the parity anomaly of fermi
onic gauge theories in odd spacetime dimensions and 't Hooft anomalies of
discrete gauge theories.\nTime permitting I will mention some open questio
ns related to smooth families of field theories. The talk is based on join
t work with R. J. Szabo.\n
LOCATION:https://researchseminars.org/talk/JointTheorySeminar/32/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Mahdi Godazgar (Queen Mary University)
DTSTART:20210316T130000Z
DTEND:20210316T140000Z
DTSTAMP:20260422T225847Z
UID:JointTheorySeminar/33
DESCRIPTION:Title: Asymptotic charges in gravity\nby Mahdi Godazgar (Queen
Mary University) as part of Joint Theory Seminar between Vienna Universit
y of Technology and University of Vienna\n\n\nAbstract\nI will discuss the
Hamiltonian derivation of dual BMS charges at null infinity using the fir
st order formalism. More generally\, I will discuss how this idea can be
used to classify asymptotic charges in gravity.\n
LOCATION:https://researchseminars.org/talk/JointTheorySeminar/33/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Linus Wulff (Masaryk University)
DTSTART:20210413T120000Z
DTEND:20210413T130000Z
DTSTAMP:20260422T225847Z
UID:JointTheorySeminar/34
DESCRIPTION:Title: O(D\,D) and string alpha'-corrections\nby Linus Wulff (Mas
aryk University) as part of Joint Theory Seminar between Vienna University
of Technology and University of Vienna\n\n\nAbstract\nString theory on a
d-dimensional torus features an O(d\,d) duality \nsymmetry. It has been su
ggested that the low-energy effective action can \nbe formulated with a la
rger O(D\,D) symmetry (D=10 or 26)\, even before \nputting the theory on a
torus. This approach\, which goes by the name of \nDouble Field Theory (D
FT)\, has proven very useful. I will address the\nproblem of constructing
higher derivative invariants in this formalism. \nIn agreement with the li
terature we find that a quadratic Riemann \ninvariant can be constructed\,
which can account for the first \nalpha'-correction to the bosonic and he
terotic string. However\, we find \nthat no cubic or quartic Riemann invar
iants can be constructed. This \nsuggests that the quartic Riemann terms a
rising at order alpha'^3 in \nstring theory do not have a DFT embedding.\n
LOCATION:https://researchseminars.org/talk/JointTheorySeminar/34/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Jie Gu
DTSTART:20210420T120000Z
DTEND:20210420T130000Z
DTSTAMP:20260422T225847Z
UID:JointTheorySeminar/35
DESCRIPTION:Title: Resurgence and BPS invariants\nby Jie Gu as part of Joint
Theory Seminar between Vienna University of Technology and University of V
ienna\n\n\nAbstract\nAsymptotic series abound in physics. Borel resummatio
n and resurgence theory are among the powerful tools to deal with them. Th
e former provides a way to convert asymptotic series to numbers\, \nthe la
tter reveals that different asymptotic series at different saddle points a
re related to each other by Stokes automorphism characterised by Stokes co
nstants. We argue that the Stokes constants can be treated \nas new invari
ants of the system\, and in many cases can be interpreted as counting BPS
states. We support this statement with examples in Seiberg-Witten theory\,
complex Chern-Simons theory\, and topological string theory.\n
LOCATION:https://researchseminars.org/talk/JointTheorySeminar/35/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Johannes Thürigen
DTSTART:20210518T120000Z
DTEND:20210518T130000Z
DTSTAMP:20260422T225847Z
UID:JointTheorySeminar/36
DESCRIPTION:Title: BPHZ renormalization in combinatorially non-local field theory
\nby Johannes Thürigen as part of Joint Theory Seminar between Vienna
University of Technology and University of Vienna\n\n\nAbstract\nCombinat
orial non-locality occurs in various field theories such as non-commutativ
e field theory\, matrix and tensor theories or the group field theory appr
oach to quantum gravity. Though interactions in such theories are not poin
t-like\, they are still local in the sense that for any divergent Feynman
diagram there is a unique counter term vertex\, described in general by a
graph. This allows to generalize the renormalization Hopf algebra of Feynm
an graphs to a Hopf algebra of 2-graphs which gives a concise algorithm fo
r applying Zimmermann’s forest formula to amplitudes in any renormalizab
le non-local field theory.\n
LOCATION:https://researchseminars.org/talk/JointTheorySeminar/36/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Jun Nishimura
DTSTART:20210615T120000Z
DTEND:20210615T130000Z
DTSTAMP:20260422T225847Z
UID:JointTheorySeminar/37
DESCRIPTION:by Jun Nishimura as part of Joint Theory Seminar between Vien
na University of Technology and University of Vienna\n\nAbstract: TBA\n
LOCATION:https://researchseminars.org/talk/JointTheorySeminar/37/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Claudia de Rham (Imperial)
DTSTART:20210525T140000Z
DTEND:20210525T150000Z
DTSTAMP:20260422T225847Z
UID:JointTheorySeminar/38
DESCRIPTION:Title: Positivity with Gravity\nby Claudia de Rham (Imperial) as
part of Joint Theory Seminar between Vienna University of Technology and U
niversity of Vienna\n\n\nAbstract\nIn standard effective field theories\,
the notion of causality is intrinsically linked with that of subluminality
and with a set of positivity constraints to be imposed on the low-energy
scattering amplitudes. I will highlight how the presence of gravity leads
to a more subtle relation between causality\, (sub)luminality and positivi
ty bounds. These considerations are relevant for putting constraints on co
smological and gravitational effective field theories and I will provide e
xplicit criteria to be satisfied so as to ensure causality and a standard
high energy completion in gravitational effective field theories.\n
LOCATION:https://researchseminars.org/talk/JointTheorySeminar/38/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Petr Kravchuk (IAS Princeton)
DTSTART:20210504T120000Z
DTEND:20210504T130000Z
DTSTAMP:20260422T225847Z
UID:JointTheorySeminar/39
DESCRIPTION:Title: CFTs and Wightman axioms in general dimensions\nby Petr Kr
avchuk (IAS Princeton) as part of Joint Theory Seminar between Vienna Univ
ersity of Technology and University of Vienna\n\n\nAbstract\nIn Conformal
Field Theory\, one is often concerned with computing local correlation fun
ctions from the spectrum of local operators and their OPE coefficients.\nI
n general quantum field theories\, we expect these correlation functions t
o satisfy Wightman and Osterwalder-Schrader axioms.\nIn this talk\, I will
explain that Wightman axioms are not obvious for CFT correlation function
s and then present a proof for correlators up to four points.\nIn the proc
ess I will also briefly review the classic results relating Wightman and O
-S axioms\, which have caveats that are important in the CFT setup.\n
LOCATION:https://researchseminars.org/talk/JointTheorySeminar/39/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Charles Marteau (British Columbia U.)
DTSTART:20210511T120000Z
DTEND:20210511T130000Z
DTSTAMP:20260422T225847Z
UID:JointTheorySeminar/40
DESCRIPTION:Title: From baby universes to black holes in 2d flat space gravity\nby Charles Marteau (British Columbia U.) as part of Joint Theory Semina
r between Vienna University of Technology and University of Vienna\n\n\nAb
stract\nIn this talk I will discuss a simple model of 2d flat gravity that
derives from the CGHS model. Its simplicity allows one to compute exactly
the Euclidean gravitational path integral. When one allows for more than
one thermal boundary\, the model is dual to an ensemble of theories\, I wi
ll discuss this ensemble in detail. The ensemble description is equivalent
to a description in terms of baby universe Hilbert space in which one can
build the so-called alpha-states\, states in which the theory is now dual
to only one theory. I will end the presentation by describing how this 2d
model appears as a universal sector in the near-horizon dynamics of non-e
xtremal black holes.\n
LOCATION:https://researchseminars.org/talk/JointTheorySeminar/40/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Dieter Lüst (LMU Munich)
DTSTART:20210608T120000Z
DTEND:20210608T130000Z
DTSTAMP:20260422T225847Z
UID:JointTheorySeminar/41
DESCRIPTION:Title: The swampland at a large number of space-time dimensions\n
by Dieter Lüst (LMU Munich) as part of Joint Theory Seminar between Vienn
a University of Technology and University of Vienna\n\n\nAbstract\nIn this
talk we discuss some aspects of swampland constraints - \nespecially the
swampland distance conjecture - in a large number of space-time dimension
s D.\nWe analyze Kaluza-Klein (KK) states at large D and find that some KK
spectra possess an interesting dependence on D.\nOn the basis of these ob
servations we propose a new large dimension conjecture.\nWe apply it to K
K states of compactifications to anti-de Sitter backgrounds where it predi
cts an upper bound on the dimension of space-time as a function of its cha
racteristic radius.\n
LOCATION:https://researchseminars.org/talk/JointTheorySeminar/41/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Abhiram Kidambi (Kavli IPMU\, University of Tokyo)
DTSTART:20210629T110000Z
DTEND:20210629T120000Z
DTSTAMP:20260422T225847Z
UID:JointTheorySeminar/42
DESCRIPTION:Title: Generalized Siegel-Weil formula\, Chern-Simons invariants and
3d gravity\nby Abhiram Kidambi (Kavli IPMU\, University of Tokyo) as p
art of Joint Theory Seminar between Vienna University of Technology and Un
iversity of Vienna\n\n\nAbstract\nA recent discovery in holography is the
idea of a dual not of a particular CFT but rather of an ensemble of CFT's
and its gravitational interpretation. In this talk\, I will explain the ca
se of the generalization of the recent work of Maloney-Witten and Afkhami-
Jeddi et.al. Following a pedagogical introduction to the number theory req
uirements\, I will talk about the holographic duality that follows from co
nsidering the average over toroidal CFTs with unequal left and right movin
g central charges.\n
LOCATION:https://researchseminars.org/talk/JointTheorySeminar/42/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Elias Kiritsis
DTSTART:20210713T120000Z
DTEND:20210713T130000Z
DTSTAMP:20260422T225847Z
UID:JointTheorySeminar/43
DESCRIPTION:Title: Emergent gravity from hidden sectors and TT deformations\n
by Elias Kiritsis as part of Joint Theory Seminar between Vienna Universit
y of Technology and University of Vienna\n\n\nAbstract\nWe investigate eme
rgent gravity extending the paradigm of the AdS/CFT correspondence.\nThe e
mergent graviton is associated to the (dynamical) expectation value of the
energy-momentum tensor.\nWe derive the general effective description of s
uch dynamics\, and apply it to the case where a hidden theory generates gr
avity that is coupled to the Standard Model.\nIn the linearized descriptio
n\, generically\, such gravity is massive with the presence of an extra sc
alar degree of freedom.\nThe propagators of both the spin-two and spin-zer
o modes are positive and well defined.\nThe associated emergent gravitatio
nal theory is a bi-gravity theory\, as is (secretly) the case in holograph
y.\nThe background metric on which the QFTs are defined\, plays the role o
f dark energy and the emergent theory has always as a solution the origina
l background metric.\nIn the case where the hidden theory is holographic\,
the overall description yields a higher-dimensional bulk theory coupled t
o a brane.\nThe effective graviton on the brane has four-dimensional chara
cteristics both in the UV and IR and is always massive.\n
LOCATION:https://researchseminars.org/talk/JointTheorySeminar/43/
END:VEVENT
END:VCALENDAR