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BEGIN:VEVENT
SUMMARY:Henry Lin (Princeton University)
DTSTART;VALUE=DATE-TIME:20200429T160000Z
DTEND;VALUE=DATE-TIME:20200429T170000Z
DTSTAMP;VALUE=DATE-TIME:20210514T190855Z
UID:SimonsBootstrapSeries/1
DESCRIPTION:Title: Bootstrapping Random Matrix Models\nby Henry Lin (Prince
ton University) as part of Simons Bootstrap Collaboration Seminar Series\n
\nAbstract: TBA\n
LOCATION:https://researchseminars.org/talk/SimonsBootstrapSeries/1/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Damon Binder (Princeton University)
DTSTART;VALUE=DATE-TIME:20200506T140000Z
DTEND;VALUE=DATE-TIME:20200506T150000Z
DTSTAMP;VALUE=DATE-TIME:20210514T190855Z
UID:SimonsBootstrapSeries/2
DESCRIPTION:Title: Deligne categories in QFT\nby Damon Binder (Princeton Un
iversity) as part of Simons Bootstrap Collaboration Seminar Series\n\n\nAb
stract\nIn QFT\, we often analytically continue the number of fields\, or
the number of spatial dimensions\, from the integers to real numbers. Desp
ite its usefulness\, the exact mathematical meaning of this procedure is o
bscure. In recent work with Slava Rychkov\, arXiv:1911.07895\, we show tha
t the appropriate language is provided by symmetric tensor categories\, wi
th specific constructions by Pierre Deligne describing O(n)\, U(n) and S_n
symmetries for any real value of n. This language allows us to describe t
heories with both integer and non-integer numbers of fields in a unified f
ramework\, shedding light on previously puzzling aspects of analytically c
ontinued theories.\n
LOCATION:https://researchseminars.org/talk/SimonsBootstrapSeries/2/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Baurzhan Mukhametzhanov (IAS)
DTSTART;VALUE=DATE-TIME:20200513T160000Z
DTEND;VALUE=DATE-TIME:20200513T170000Z
DTSTAMP;VALUE=DATE-TIME:20210514T190855Z
UID:SimonsBootstrapSeries/3
DESCRIPTION:Title: Beurling-Selberg extremization and modular bootstrap at high
energies\nby Baurzhan Mukhametzhanov (IAS) as part of Simons Bootstra
p Collaboration Seminar Series\n\n\nAbstract\nWe consider modular invarian
ce of 2d CFTs. Combining the high-temperature limit of the partition funct
ion with ideas of tauberian theory we derive upper/lower bounds on the num
ber of operators in a given window of scaling dimensions at high energies.
This gives precise meaning to Cardy formula. The bounds depend on a choic
e of functions that majorize/minorize the characteristic function of an in
terval and have Fourier of finite support. Optimization of the bounds over
this choice turns out to be the Beurling-Selberg problem. We review solut
ion of this optimization problem and present corresponding bounds. For int
ervals of integer size the bounds are saturated by known modular invariant
partition functions.\n
LOCATION:https://researchseminars.org/talk/SimonsBootstrapSeries/3/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Abhijit Gadde (TIFR)
DTSTART;VALUE=DATE-TIME:20200527T160000Z
DTEND;VALUE=DATE-TIME:20200527T170000Z
DTSTAMP;VALUE=DATE-TIME:20210514T190855Z
UID:SimonsBootstrapSeries/4
DESCRIPTION:Title: Modularity of supersymmetric partition functions\nby Abh
ijit Gadde (TIFR) as part of Simons Bootstrap Collaboration Seminar Series
\n\n\nAbstract\nIn this talk\, I will present a novel modular property of
4d N=1 supersymmetric partition functions of supersymmetric theories with
R-symmetry. It is a generalization of the modular invariance of the\nsuper
symmetric partition function of two-dimensional supersymmetric theories on
a torus i.e. of the elliptic genus. It comes from requiring consistency o
f partition functions under gluing and\, among\nother things\, can be used
to rederive the supersymmetric Cardy formula for four-dimensional gauge t
heories that has played a key role in computing the entropy of supersymmet
ric black holes.\n
LOCATION:https://researchseminars.org/talk/SimonsBootstrapSeries/4/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Yin-Chen He (Perimeter Institute)
DTSTART;VALUE=DATE-TIME:20200603T160000Z
DTEND;VALUE=DATE-TIME:20200603T170000Z
DTSTAMP;VALUE=DATE-TIME:20210514T190855Z
UID:SimonsBootstrapSeries/5
DESCRIPTION:Title: O(N) Non-Wilson-Fisher Kinks: Deconfined Phase Transition an
d Beyond\nby Yin-Chen He (Perimeter Institute) as part of Simons Boots
trap Collaboration Seminar Series\n\n\nAbstract\nIn this talk I will discu
ss a family of kinks of the O(N) numerical bootstrap bounds\, which are sh
arply different from the well-known kinks of O(N) Wilson-Fisher CFTs. The
nature of these new kinks remains mysterious\, but we managed to understan
d few special cases\, hinting interesting physics. In 2D\, the O(4) non-Wi
lson-Fisher kink turns out to be the familiar SU(2)_1 Wess-Zumino-Witten m
odel. We further consider its dimensional continuation towards the 3D SO(5
) deconfined phase transition\, and we find the kink disappears at fractio
nal dimension (around D=2.7)\, suggesting the 3D SO(5) deconfined phase tr
ansition is pseudo-critical (also called complex CFT). I will also talk ab
out the infinite-N limit\, where we have obtained the analytical four poin
t correlation function for arbitrary space-time dimensions. The infinite-N
solution contains a full tower of higher spin conserved current\, opening
the possibility of a new family of CFTs for finite N.\n
LOCATION:https://researchseminars.org/talk/SimonsBootstrapSeries/5/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Tom Hartman (Cornell)
DTSTART;VALUE=DATE-TIME:20200617T160000Z
DTEND;VALUE=DATE-TIME:20200617T170000Z
DTSTAMP;VALUE=DATE-TIME:20210514T190855Z
UID:SimonsBootstrapSeries/6
DESCRIPTION:Title: Applications of the modular bootstrap\nby Tom Hartman (C
ornell) as part of Simons Bootstrap Collaboration Seminar Series\n\n\nAbst
ract\nI will describe recent progress on the connections among the modular
bootstrap\, the sphere packing problem\, and quantum gravity in three dim
ensions. This leads us toward a holographic duality between Narain CFTs av
eraged over moduli and a Chern-Simons-like theory of "U(1) gravity."\n
LOCATION:https://researchseminars.org/talk/SimonsBootstrapSeries/6/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Sasha Zhiboedov (CERN)
DTSTART;VALUE=DATE-TIME:20200624T160000Z
DTEND;VALUE=DATE-TIME:20200624T170000Z
DTSTAMP;VALUE=DATE-TIME:20210514T190855Z
UID:SimonsBootstrapSeries/7
DESCRIPTION:Title: An Analytic Toolkit for the S-matrix Bootstrap\nby Sasha
Zhiboedov (CERN) as part of Simons Bootstrap Collaboration Seminar Series
\n\n\nAbstract\nWe revisit analytical methods for constraining the nonpert
urbative S-matrix of unitary\, relativistic\, gapped theories in d≥3 spa
cetime dimensions. We assume extended analyticity of the two-to-two scatte
ring amplitude and use it together with elastic unitarity to develop two n
atural expansions of the amplitude. One is the threshold (non-relativistic
) expansion and the other is the large spin expansion. The two are related
by the Froissart-Gribov inversion formula. When combined with crossing an
d a local bound on the discontinuity of the amplitude\, this allows us to
constrain scattering at finite energy and spin in terms of the low-energy
parameters measured in the experiment. Finally\, we discuss the modern num
erical approach to the S-matrix bootstrap and how it can be improved based
on the results of our analysis.\n
LOCATION:https://researchseminars.org/talk/SimonsBootstrapSeries/7/
END:VEVENT
BEGIN:VEVENT
SUMMARY:NO SEMINAR
DTSTART;VALUE=DATE-TIME:20200701T160000Z
DTEND;VALUE=DATE-TIME:20200701T170000Z
DTSTAMP;VALUE=DATE-TIME:20210514T190855Z
UID:SimonsBootstrapSeries/8
DESCRIPTION:by NO SEMINAR as part of Simons Bootstrap Collaboration Semina
r Series\n\nAbstract: TBA\n
LOCATION:https://researchseminars.org/talk/SimonsBootstrapSeries/8/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Parijat Dey (Uppsala University)
DTSTART;VALUE=DATE-TIME:20200708T160000Z
DTEND;VALUE=DATE-TIME:20200708T170000Z
DTSTAMP;VALUE=DATE-TIME:20210514T190855Z
UID:SimonsBootstrapSeries/9
DESCRIPTION:Title: Operator expansions and layer susceptibility in BCFT\nby
Parijat Dey (Uppsala University) as part of Simons Bootstrap Collaboratio
n Seminar Series\n\n\nAbstract\nWe show that in boundary CFTs (BCFTs)\, th
ere exists a one-to-one correspondence between the boundary operator expan
sion of the two point correlation function and a power series expansion of
the layer susceptibility. This allows the direct identification of the bo
undary spectrum and expansion coefficients from the layer susceptibility w
hich is easier to compute. To show how it works we compute the two point f
unction < phi_i phi^i > of the O(N) model at the extraordinary transition
in 4-\\epsilon dimensions to order \\epsilon. Via the bulk operator produc
t expansion\, this fixes a part of the spectrum of the bulk CFT to order \
\epsilon^2.\n
LOCATION:https://researchseminars.org/talk/SimonsBootstrapSeries/9/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Xinan Zhou (Princeton University)
DTSTART;VALUE=DATE-TIME:20200715T160000Z
DTEND;VALUE=DATE-TIME:20200715T170000Z
DTSTAMP;VALUE=DATE-TIME:20210514T190855Z
UID:SimonsBootstrapSeries/10
DESCRIPTION:Title: All holographic four-point correlators in maximally supersy
mmetric CFTs\nby Xinan Zhou (Princeton University) as part of Simons B
ootstrap Collaboration Seminar Series\n\n\nAbstract\nIn this talk\, I will
introduce a powerful new method to constructively derive all tree-level f
our-point functions in holographic CFTs with maximal supersymmetry. I will
introduce the notion of maximally R-symmetry violating (MRV) limit\, whic
h is key to our construction. In this limit\, the correlators simplify dra
stically and become easy to compute. I will then show that the full correl
ators can be reconstructed from the MRV limit by using symmetries. A remar
kable feature is that the four-point functions do not have intrinsic conta
ct interactions\, and can be expressed as sums of exchanges alone. Using t
his method we reproduce the known results for AdS5xS5 dual to 4d N=4 SYM\,
and also compute all four-point functions from AdS4xS7 and AdS7xS4\, dual
respectively to 3d N=8 ABJM and the 6d (2\,0) theory. Along the way\, I w
ill review the relation with the previous developments including the boots
trap methods\, and point out various intriguing similarities with the flat
space scattering amplitudes. I will also make brief comments on various f
uture extensions of this program.\n
LOCATION:https://researchseminars.org/talk/SimonsBootstrapSeries/10/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Henry Maxfield (UCSB)
DTSTART;VALUE=DATE-TIME:20200722T160000Z
DTEND;VALUE=DATE-TIME:20200722T170000Z
DTSTAMP;VALUE=DATE-TIME:20210514T190855Z
UID:SimonsBootstrapSeries/11
DESCRIPTION:Title: 3D gravity near extremality and JT gravity with defects
\nby Henry Maxfield (UCSB) as part of Simons Bootstrap Collaboration Semin
ar Series\n\n\nAbstract\nA potential inconsistency of 3D pure gravity was
recently observed in the form of a negative density of states for near-ext
remal black holes. I will argue that this pathology is cured by including
additional topologies in the path integral\, for which no classical soluti
on exists. Along the way\, I introduce a closely-related two-dimensional t
heory generalising JT gravity by including dynamical defects\, which is du
al to a matrix integral. Finally\, I will discuss the problem from the per
spective of the modular bootstrap.\n
LOCATION:https://researchseminars.org/talk/SimonsBootstrapSeries/11/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Kurt Hinterbichler (Case Western)
DTSTART;VALUE=DATE-TIME:20200729T160000Z
DTEND;VALUE=DATE-TIME:20200729T170000Z
DTSTAMP;VALUE=DATE-TIME:20210514T190855Z
UID:SimonsBootstrapSeries/12
DESCRIPTION:Title: Unitarization in Kaluza Klein theory and a bootstrap for ge
ometry\nby Kurt Hinterbichler (Case Western) as part of Simons Bootstr
ap Collaboration Seminar Series\n\n\nAbstract\nThe infinite towers of mass
ive particles present in Kaluza Klein reductions of Einstein gravity consp
ire to soften the high-energy behavior of the scattering of massive spin-2
states. The mechanism by which this occurs leads to a bootstrap procedur
e\, analogous to the conformal bootstrap\, that yields new non-trivial con
straints on the eigenvalue spectra of closed Einstein manifolds.\n
LOCATION:https://researchseminars.org/talk/SimonsBootstrapSeries/12/
END:VEVENT
BEGIN:VEVENT
SUMMARY:David Meltzer (Caltech)
DTSTART;VALUE=DATE-TIME:20200805T160000Z
DTEND;VALUE=DATE-TIME:20200805T170000Z
DTSTAMP;VALUE=DATE-TIME:20210514T190855Z
UID:SimonsBootstrapSeries/13
DESCRIPTION:Title: The Inversion Formula and the Spectrum of the O(2) Model\nby David Meltzer (Caltech) as part of Simons Bootstrap Collaboration Se
minar Series\n\n\nAbstract\nThe Lorentzian inversion formula proves that C
FT data is analytic in spin and that operators can be organized on Regge t
rajectories. In this talk we investigate the leading Regge trajectories of
the O(2) model using a combination of numerical and analytical techniques
. We show that the predictions of the inversion formula for spinning opera
tors agrees with the numerical predictions. Furthermore\, we give more evi
dence that scalar operators lie on Regge trajectories and also compute the
Regge intercept of the O(2) model. Using this data\, we are able to make
predictions for the four-point function of the fundamental\, charge 1 scal
ar in both Euclidean and Lorentzian regimes.\n
LOCATION:https://researchseminars.org/talk/SimonsBootstrapSeries/13/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Lorenz Eberhardt (IAS)
DTSTART;VALUE=DATE-TIME:20200819T160000Z
DTEND;VALUE=DATE-TIME:20200819T170000Z
DTSTAMP;VALUE=DATE-TIME:20210514T190855Z
UID:SimonsBootstrapSeries/14
DESCRIPTION:Title: Scattering equations in AdS\nby Lorenz Eberhardt (IAS)
as part of Simons Bootstrap Collaboration Seminar Series\n\n\nAbstract\nI
will discuss an analogue of the CHY formalism in AdS. Considering the biad
joint scalar theory on AdS\, I will explain how to rewrite all the tree-le
vel amplitudes as an integral over the moduli space of punctured Riemann s
pheres. Contrary to the flat space\, the scattering equations are operator
-valued. The resulting formula is motivated via a bosonic ambitwistor stri
ng on AdS and can be proven to be equivalent to the corresponding Witten d
iagram computation by applying a series of contour deformations. (NOTE NEW
ZOOM LINK)\n\nhttps://cornell.zoom.us/j/92760097069?pwd=YmdpOVMweGp1RklkT
k5wNFhlRFN6UT09\n\nNOTE NEW ZOOM LINK\n
LOCATION:https://researchseminars.org/talk/SimonsBootstrapSeries/14/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Zahra Zahraee (McGill)
DTSTART;VALUE=DATE-TIME:20200902T160000Z
DTEND;VALUE=DATE-TIME:20200902T170000Z
DTSTAMP;VALUE=DATE-TIME:20210514T190855Z
UID:SimonsBootstrapSeries/15
DESCRIPTION:Title: The leading trajectory in the 2+1D Ising CFT\nby Zahra
Zahraee (McGill) as part of Simons Bootstrap Collaboration Seminar Series\
n\n\nAbstract\nIn this talk we will discuss the low-spin analyticity of th
e leading Regge trajectories in 3D Ising CFT. The analysis is performed by
using the Lorentzian inversion formula and the precise spectrum (obtained
from the numerical conformal bootstrap) as an input. Specifically\, we wi
ll answer two questions\; first\, can the leading Regge trajectories be ex
tended to J<2 and include spin 0 operators? We will provide evidence that
the answer to this question is affirmative. Second\, what is the value of
the intercept for the leading Regge trajectory? We will argue that the int
ercept of the model is below unity: j∗ ≈ 0.8\, indicating regularity o
f the spectrum. Lastly\, we will indicate how our observation is supported
by analytics in the large-N O(N) model.\n
LOCATION:https://researchseminars.org/talk/SimonsBootstrapSeries/15/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Slava Rychkov (IHES and ENS)
DTSTART;VALUE=DATE-TIME:20200909T160000Z
DTEND;VALUE=DATE-TIME:20200909T170000Z
DTSTAMP;VALUE=DATE-TIME:20210514T190855Z
UID:SimonsBootstrapSeries/16
DESCRIPTION:Title: Musings and some results about non-perturbative RG\nby
Slava Rychkov (IHES and ENS) as part of Simons Bootstrap Collaboration Sem
inar Series\n\n\nAbstract\nI will motivate why non-perturbative RG is an u
nfinished business\, and what kind of developments are needed in this area
. I will then describe recent rigorous work about RG fixed points in a mod
el of symplectic fermions with a long-range kinetic term and a local quart
ic interaction. This may be the simplest field theory in which a non-gauss
ian fixed point can be shown to exist without any truncation or approximat
ion. It is a perfect toy model where various folklore properties of RG fix
ed points (universality of critical exponents\, conformal invariance\, etc
) could be examined explicitly. It also offers some hints for better numer
ical implementations of non-perturbative RG. Based on 2008.04361 with Ales
sandro Giuliani and Vieri Mastropietro.\n
LOCATION:https://researchseminars.org/talk/SimonsBootstrapSeries/16/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Balt van Rees (Ecole Polytechnique)
DTSTART;VALUE=DATE-TIME:20200923T160000Z
DTEND;VALUE=DATE-TIME:20200923T170000Z
DTSTAMP;VALUE=DATE-TIME:20210514T190855Z
UID:SimonsBootstrapSeries/17
DESCRIPTION:Title: Bootstrapping defects and boundaries for the free scalar fi
eld\nby Balt van Rees (Ecole Polytechnique) as part of Simons Bootstra
p Collaboration Seminar Series\n\n\nAbstract\nIs there any room for non-tr
ivial unitary and conformal defects in the theory of a single free massles
s scalar field? And what about boundaries? We use the free scalar equation
of motion and the structure of the bulk-to-defect operator expansion to r
ule out the existence of such defects in several (co-)dimensions. For boun
daries we are led to a non-trivial system of crossing equations that we an
alyze numerically in four bulk dimensions. We show that large regions of p
arameter spaces are excluded\, but a 'kink' in the numerical bounds obeys
all our consistency checks and might be an indication of a new conformal b
oundary condition.\n
LOCATION:https://researchseminars.org/talk/SimonsBootstrapSeries/17/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Dalimil Mazac (IAS)
DTSTART;VALUE=DATE-TIME:20200930T160000Z
DTEND;VALUE=DATE-TIME:20200930T170000Z
DTSTAMP;VALUE=DATE-TIME:20210514T190855Z
UID:SimonsBootstrapSeries/18
DESCRIPTION:Title: Dispersive CFT sum rules\nby Dalimil Mazac (IAS) as par
t of Simons Bootstrap Collaboration Seminar Series\n\n\nAbstract\nI will m
otivate and discuss the notion of dispersive sum rules in conformal field
theory. The defining property of these sum rules is that they suppress dou
ble-twist operators. This makes them very useful for various analytic boot
strap applications. Physically\, they arise from consistency in the Lorent
zian signature. Dispersive sum rules can be derived through several equiva
lent approaches: 1) as analytic functionals applied to the crossing equati
on\, 2) by expanding the conformal dispersion relation\, 3) as the Polyako
v condition in Mellin space and 4) as superconvergence sum rules. I will d
iscuss how these approaches are unified through the Polyakov-Regge expansi
on of the correlator. I will mention some applications\, including an extr
emal functional for spin-2 gap maximization. Based on https://arxiv.org/pd
f/2008.04931.pdf.\n
LOCATION:https://researchseminars.org/talk/SimonsBootstrapSeries/18/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Andrea Guerrieri (Tel Aviv University)
DTSTART;VALUE=DATE-TIME:20201007T160000Z
DTEND;VALUE=DATE-TIME:20201007T170000Z
DTSTAMP;VALUE=DATE-TIME:20210514T190855Z
UID:SimonsBootstrapSeries/19
DESCRIPTION:Title: Exploring the Dual S-matrix Bootstrap\nby Andrea Guerri
eri (Tel Aviv University) as part of Simons Bootstrap Collaboration Semina
r Series\n\n\nAbstract\nObtaining numerical rigorous bounds on QFT observa
bles using the S-matrix Bootstrap is often a difficult task. In this talk
I will discuss how duality in optimization theory provides an alternative
and efficient formulation of the problem. In particular\, I will focus on
2D gapped systems with stable particles of different masses and bound sta
tes. I will explain how their rich analytic and crossing structure is inhe
rited by the dual variables and how the unitarity constraints are automati
cally saturated. This will serve as a toy model to bootstrap some popular
physical systems.\n
LOCATION:https://researchseminars.org/talk/SimonsBootstrapSeries/19/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Max Metliski (MIT)
DTSTART;VALUE=DATE-TIME:20201014T160000Z
DTEND;VALUE=DATE-TIME:20201014T170000Z
DTSTAMP;VALUE=DATE-TIME:20210514T190855Z
UID:SimonsBootstrapSeries/20
DESCRIPTION:Title: Boundary criticality of the O(N) model in d = 3 critically
revisited.\nby Max Metliski (MIT) as part of Simons Bootstrap Collabor
ation Seminar Series\n\n\nAbstract\nIt is known that the classical O(N) mo
del in dimension d > 3 at its bulk critical point admits three boundary un
iversality classes: the ordinary\, the extra-ordinary and the special. The
extraordinary fixed point corresponds to the bulk transition occurring in
the presence of an ordered boundary\, while the special fixed point corre
sponds to a boundary phase transition between the ordinary and the extra-o
rdinary classes. While the ordinary fixed point survives in d = 3\, it is
less clear what happens to the extra-ordinary and special fixed points whe
n d = 3 and N is greater or equal to 2. I'll show that formally treating N
as a continuous parameter\, there exists a critical value Nc > 2 separati
ng two distinct regimes. For N < Nc the extra-ordinary fixed point survive
s in d = 3\, albeit in a modified form: the long-range boundary order is l
ost\, instead\, the order parameter correlation function decays as a power
of log r. For N > Nc there is no fixed point with order parameter correla
tions decaying slower than power law. I'll discuss several scenarios for t
he evolution of the system with N through Nc. One of these scenarios might
explain recent numerical results on boundary criticality in 2+1D quantum
spin systems with SO(3) symmetry.\n
LOCATION:https://researchseminars.org/talk/SimonsBootstrapSeries/20/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Ami Katz (Boston University)
DTSTART;VALUE=DATE-TIME:20201104T170000Z
DTEND;VALUE=DATE-TIME:20201104T180000Z
DTSTAMP;VALUE=DATE-TIME:20210514T190855Z
UID:SimonsBootstrapSeries/21
DESCRIPTION:Title: Nonperturbative dynamics in (2+1)d from Hamiltonian truncat
ion\nby Ami Katz (Boston University) as part of Simons Bootstrap Colla
boration Seminar Series\n\n\nAbstract\nWe use Lightcone Conformal Truncati
on to study phi^4 theory in (2+1)d.\nThis theory contains divergences. In
Hamiltonian truncation methods these cannot be dealt with via a simple lo
cal counter-term\, requiring a different approach.\nWe implement a state-d
ependent renormalization procedure\, which we find to be \nessential to ha
ving the mass gap close at a scheme dependent critical coupling.\nWe then
calculate real time correlation functions of local operators\nboth at gene
ric strong coupling and near the critical point . Near the critical point
\nwe find evidence for IR universality and the vanishing of the trace of
the stress tensor.\n
LOCATION:https://researchseminars.org/talk/SimonsBootstrapSeries/21/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Marco Serone (SISSA)
DTSTART;VALUE=DATE-TIME:20201111T170000Z
DTEND;VALUE=DATE-TIME:20201111T180000Z
DTSTAMP;VALUE=DATE-TIME:20210514T190855Z
UID:SimonsBootstrapSeries/22
DESCRIPTION:Title: elf-Dualities and Renormalization Dependence of the Phase D
iagram in 3d O(N) Vector Models\nby Marco Serone (SISSA) as part of Si
mons Bootstrap Collaboration Seminar Series\n\n\nAbstract\nIn the classica
lly unbroken phase\, 3d $O(N)$ symmetric $\\phi^4$ vector models admit two
equivalent descriptions connected by a strong-weak duality closely relate
d to the one found by Chang and Magruder long ago. We determine the exact
analytic renormalization dependence of the critical couplings in the weak
and strong branches as a function of the renormalization scheme (parametri
zed by $\\kappa$) and for any $N$. It is shown that for $\\kappa=\\kappa_*
$ the two fixed points merge and then\, for $\\kappa<\\kappa_*$\, they mov
e into the complex plane in complex conjugate pairs\, making the phase tra
nsition no longer visible from the classically unbroken phase. We verify t
hese considerations by computing the perturbative series of the 3d $O(N)$
models for the vacuum energy and for the mass gap up to order eight\, and
Borel resumming the series. In particular\, we provide numerical evidence
for the self-duality and verify that in renormalization schemes where the
critical couplings are complex the theory is gapped.\n
LOCATION:https://researchseminars.org/talk/SimonsBootstrapSeries/22/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Aditya Hebbar (EPFL)
DTSTART;VALUE=DATE-TIME:20201202T170000Z
DTEND;VALUE=DATE-TIME:20201202T180000Z
DTSTAMP;VALUE=DATE-TIME:20210514T190855Z
UID:SimonsBootstrapSeries/23
DESCRIPTION:Title: Spinning S-matrix Bootstrap in 4d\nby Aditya Hebbar (EP
FL) as part of Simons Bootstrap Collaboration Seminar Series\n\n\nAbstract
\nWe review unitarity and crossing constraints on scattering amplitudes fo
r particles with spin in four dimensional quantum field theories. As an ap
plication we study two to two scattering of neutral spin 1/2 fermions in d
etail. Assuming Mandelstam analyticity of its scattering amplitude\, we us
e the numerical S-matrix bootstrap method to estimate various non-perturba
tive bounds on quartic and cubic (Yukawa) couplings.\n
LOCATION:https://researchseminars.org/talk/SimonsBootstrapSeries/23/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Sourav Sarkar (Porto University)
DTSTART;VALUE=DATE-TIME:20201209T170000Z
DTEND;VALUE=DATE-TIME:20201209T180000Z
DTSTAMP;VALUE=DATE-TIME:20210514T190855Z
UID:SimonsBootstrapSeries/24
DESCRIPTION:Title: A perturbative optical theorem for CFT and conformal Regge
theory.\nby Sourav Sarkar (Porto University) as part of Simons Bootstr
ap Collaboration Seminar Series\n\n\nAbstract\nWe shall discuss a new pert
urbative optical theorem for CFTs which computes the double discontinuity
of conformal correlators from the single discontinuities of lower order co
rrelators. We shall then use it to study the Regge limit of a four point c
orrelator at one loop and finite t'Hooft coupling. This incorporates contr
ibutions from tidal excitations that are packaged into am AdS vertex funct
ion. We shall then discuss the flat space limit of these results and const
rain the AdS vertex function for type IIB strings in AdS using the corresp
onding flat space vertex function that is known.\n
LOCATION:https://researchseminars.org/talk/SimonsBootstrapSeries/24/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Alessandro Vichi (Universita' di Pisa)
DTSTART;VALUE=DATE-TIME:20210120T170000Z
DTEND;VALUE=DATE-TIME:20210120T180000Z
DTSTAMP;VALUE=DATE-TIME:20210514T190855Z
UID:SimonsBootstrapSeries/25
DESCRIPTION:Title: The Good\, the Bad and the Unstable: a bootstrap study of O
(3) and related models\nby Alessandro Vichi (Universita' di Pisa) as p
art of Simons Bootstrap Collaboration Seminar Series\n\n\nAbstract\nI will
present the results of a numerical bootstrap study of the critical O(3) v
ector model.\nUsing a two recently developed new algorithms\, it is possib
le to put an upper bound on the dimension of the leading rank-4 symmetric
tensor. This operators is found to be relevant\, thus providing a numerica
l proof that systems described by the critical O(3) model\, such as class
ical Heisenberg ferromagnets at the Curie transition\, are unstable to cub
ic anisotropy. I will briefly discuss the steps leading to this determinat
ion and analyze the physical consequences. Based on arXiv:2011.14647\n
LOCATION:https://researchseminars.org/talk/SimonsBootstrapSeries/25/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Piotr Tourkine (LPTHE\, Sorbonne)
DTSTART;VALUE=DATE-TIME:20210127T170000Z
DTEND;VALUE=DATE-TIME:20210127T180000Z
DTSTAMP;VALUE=DATE-TIME:20210514T190855Z
UID:SimonsBootstrapSeries/26
DESCRIPTION:Title: Scattering from production in 2d\nby Piotr Tourkine (LP
THE\, Sorbonne) as part of Simons Bootstrap Collaboration Seminar Series\n
\n\nAbstract\nn this seminar\, I will talk about recent results about a nu
merical method to find unitary S-matrices. The method\, based on works of
Atkinson\, was invented in the late 60s and was used as a proof of existen
ce of functions that satisfy all of the S-matrix axioms in 4d. However\, i
t was not put in practical use.\nOur recent results concern the implementa
tion of those methods for S-matrices in two dimensions\, using two differe
nt iterative schemes: a fixed-point iteration and Newton’s method. Those
schemes iterate the unitarity and dispersion relations\, and converge to
solutions to the S-matrix axioms. This numerical strategy provides a solut
ion to the problem of reconstructing the scattering amplitude starting fro
m a given particle production probability. After a general introduction\,
the talk will be focused on how we implemented the algorithms\, what they
converge to\, and the conditions under which they converge. We will see t
hat the question of convergence naturally connects to the recent study of
the coupling maximization in the two-dimensional S-matrix bootstrap. If ti
me allows\, I’ll also comment on a fractal structure which we observed t
o be related to the so-called CDD-ambiguities. I’ll conclude with possib
le future directions. [In collaboration with Alexander Zhiboedov\, based o
n http://arxiv.org/abs/2101.05211]\n
LOCATION:https://researchseminars.org/talk/SimonsBootstrapSeries/26/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Ashley Milsted (Caltech)
DTSTART;VALUE=DATE-TIME:20210203T170000Z
DTEND;VALUE=DATE-TIME:20210203T180000Z
DTSTAMP;VALUE=DATE-TIME:20210514T190855Z
UID:SimonsBootstrapSeries/27
DESCRIPTION:Title: Collisions of false-vacuum bubble walls in a quantum spin c
hain\nby Ashley Milsted (Caltech) as part of Simons Bootstrap Collabor
ation Seminar Series\n\n\nAbstract\nWe study the real-time dynamics of a s
mall bubble of “false vacuum’’ in a quantum spin chain near critical
ity\, where the low-energy physics is described by a relativistic (1+1)-di
mensional quantum field theory. Such a bubble can be thought of as a confi
ned kink-antikink pair (a meson). We carefully construct bubbles so that p
article production does not occur until the walls collide. To achieve this
in the presence of strong correlations\, we extend a Matrix Product State
(MPS) ansatz for quasiparticle wavepackets [Van Damme et al.\, arXiv:1907
.02474 (2019)] to the case of confined\, topological quasiparticles. By ch
oosing the wavepacket width and the bubble size appropriately\, we avoid s
trong lattice effects and observe relativistic kink-antikink collisions. W
e use the MPS quasiparticle ansatz to identify scattering outcomes: In the
Ising model\, with transverse and longitudinal fields\, we do not observe
particle production despite nonintegrability (supporting recent numerical
observations of nonthermalizing mesonic states). With additional interact
ions\, we see production of confined and unconfined particle pairs. Althou
gh we simulated these low-energy\, few-particle events with moderate resou
rces\, we observe significant growth of entanglement with energy and with
the number of collisions\, suggesting that increasing either will ultimate
ly exhaust our methods. Quantum devices\, in contrast\, are not limited by
entanglement production\, and promise to allow us to go far beyond classi
cal methods. We anticipate that kink-antikink scattering in 1+1 dimensions
will be an instructive benchmark problem for relatively near-term quantum
devices.\n
LOCATION:https://researchseminars.org/talk/SimonsBootstrapSeries/27/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Aninda Sinha (IIS)
DTSTART;VALUE=DATE-TIME:20210210T170000Z
DTEND;VALUE=DATE-TIME:20210210T180000Z
DTSTAMP;VALUE=DATE-TIME:20210514T190855Z
UID:SimonsBootstrapSeries/28
DESCRIPTION:Title: Crossing symmetric dispersion relations in QFTs and CFTs\nby Aninda Sinha (IIS) as part of Simons Bootstrap Collaboration Seminar
Series\n\n\nAbstract\nI will discuss crossing symmetric dispersion relati
ons in QFTs and CFTs. I will talk about connections with Polyakov’s 1974
work\, the crossing symmetric Polyakov-Mellin bootstrap\, and connections
with fixed-t dispersion relations.\n
LOCATION:https://researchseminars.org/talk/SimonsBootstrapSeries/28/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Adam Nahum (Oxford)
DTSTART;VALUE=DATE-TIME:20210217T170000Z
DTEND;VALUE=DATE-TIME:20210217T180000Z
DTSTAMP;VALUE=DATE-TIME:20210514T190855Z
UID:SimonsBootstrapSeries/29
DESCRIPTION:Title: Self-dual criticality in the Z2 gauge-Higgs model in three
dimensions\nby Adam Nahum (Oxford) as part of Simons Bootstrap Collabo
ration Seminar Series\n\n\nAbstract\nThe simplest topologically ordered ph
ase in 2+1D is the deconfined phase of Z2 gauge theory. This phase permits
a duality that exchanges electric and magnetic excitations (“e” and
“m” particles). In the simplest lattice gauge theory formulation\, the
re is a self-dual line in the space of gauge and matter couplings. Away fr
om the self-dual line\, there are phase transitions out of the deconfined
phase (the Higgs and confinement transitions) that are well understood. Bu
t the phase transition onthe self dual line is still mysterious\, and -- i
f continuous -- may be the simplest critical point for which we still lack
a useful continuum field theory description. After reviewing applications
of this model to quantum and classical statistical mechanics\, I will des
cribe Monte Carlo results for a wide range of observables at the self-dual
transition. The results indicate that it is a novel continuous transition
. If time permits I will briefly mention a connection between ``geometrica
l’’ (percolation) observables in the gauge-Higgs model and its emergen
t one-form symmetries\, as well as some extensions of the model. Work with
Andres Somoza and Pablo Serna (https://arxiv.org/abs/2012.15845).\n
LOCATION:https://researchseminars.org/talk/SimonsBootstrapSeries/29/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Simon Caron-Huot (McGill)
DTSTART;VALUE=DATE-TIME:20210303T170000Z
DTEND;VALUE=DATE-TIME:20210303T180000Z
DTSTAMP;VALUE=DATE-TIME:20210514T190855Z
UID:SimonsBootstrapSeries/30
DESCRIPTION:Title: Sharp Boundaries for the Swampland\nby Simon Caron-Huot
(McGill) as part of Simons Bootstrap Collaboration Seminar Series\n\n\nAb
stract\nWe reconsider the problem of bounding higher derivative couplings
in consistent weakly coupled gravitational theories\, starting from genera
l assumptions about analyticity and Regge growth of the S-matrix. Higher d
erivative couplings are expected to be of order one in the units of the UV
cutoff. Our approach justifies this expectation and allows to prove preci
se bounds on the order one coefficients. Our main tool are dispersive sum
rules for the S-matrix. We overcome the difficulties presented by the grav
iton pole by measuring couplings at small impact parameter\, rather than i
n the forward limit. We illustrate the method in theories containing a mas
sless scalar coupled to gravity\, and in theories with maximal supersymmet
ry.\n
LOCATION:https://researchseminars.org/talk/SimonsBootstrapSeries/30/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Yifei He (ENS)
DTSTART;VALUE=DATE-TIME:20210407T160000Z
DTEND;VALUE=DATE-TIME:20210407T170000Z
DTSTAMP;VALUE=DATE-TIME:20210514T190855Z
UID:SimonsBootstrapSeries/31
DESCRIPTION:Title: S-matrix bootstrap in 3+1 dimensions: regularization and du
al problem\nby Yifei He (ENS) as part of Simons Bootstrap Collaboratio
n Seminar Series\n\n\nAbstract\nThe S-matrix bootstrap maps out the space
of S-matrices allowed by analyticity\, crossing and unitarity. For 2-to-2
scattering\, such space is an infinite dimensional convex space whose boun
dary can be approached by maximizing a linear functional. I will describe
S-matrix bootstrap in 3+1 dimensions with focus on the equivalent dual pro
blem which provides strict upper bounds for the regularized primal problem
. The dual problem has interesting practical and physical advantages over
the primal problem\, and its variables are the dual partial waves who are
free from constraints yet directly related to the physical partial waves.
The formulation is done in the context of scalar fields related to pion ph
ysics. This talk is based on joint work https://arxiv.org/abs/2103.11484 w
ith Martin Kruczenski.\n
LOCATION:https://researchseminars.org/talk/SimonsBootstrapSeries/31/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Sasha Zhiboedov (CERN)
DTSTART;VALUE=DATE-TIME:20210414T160000Z
DTEND;VALUE=DATE-TIME:20210414T170000Z
DTSTAMP;VALUE=DATE-TIME:20210514T190855Z
UID:SimonsBootstrapSeries/32
DESCRIPTION:Title: Probing gravitational EFTs with the four-graviton amplitude
\nby Sasha Zhiboedov (CERN) as part of Simons Bootstrap Collaboration
Seminar Series\n\n\nAbstract\nWe discuss constraints from perturbative uni
tarity and crossing on the leading contributions of the higher-dimension o
perators to the four-graviton amplitude in four spacetime dimensions. We f
ocus on the leading order effect due to exchange by massive degrees of fre
edom which makes the amplitudes of interest IR finite. To test the constra
ints we obtain nontrivial effective field theory data by computing and tak
ing the large mass expansion of the one-loop minimally-coupled four-gravit
on amplitude with massive particles up to spin 2 circulating in the loop.
Remarkably\, the leading EFT corrections to Einstein gravity of physical t
heories\, both string theory and QFT coupled to gravity\, end up in island
s which are much smaller than what is suggested by the generic bounds obta
ined from consistency of the 2-2 graviton scattering amplitude. We discuss
the underlying mechanism for this phenomenon.\n
LOCATION:https://researchseminars.org/talk/SimonsBootstrapSeries/32/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Valentina Prilepina (Laval University\, Quebec\, and Lomonosov Uni
versity\, Moscow)
DTSTART;VALUE=DATE-TIME:20210428T160000Z
DTEND;VALUE=DATE-TIME:20210428T170000Z
DTSTAMP;VALUE=DATE-TIME:20210514T190855Z
UID:SimonsBootstrapSeries/33
DESCRIPTION:Title: Recursion Relations for Five-Point Conformal Blocks: A Prac
tical Approach\nby Valentina Prilepina (Laval University\, Quebec\, an
d Lomonosov University\, Moscow) as part of Simons Bootstrap Collaboration
Seminar Series\n\n\nAbstract\nIn this talk\, I will consider five-point f
unctions in conformal field theories (CFTs) in d > 2 spacetime dimensions.
I will put forward a concrete and practical ap- proach to computing globa
l conformal blocks that appear in 5-point functions of arbitrary scalar op
erators in general CFTs. By exploiting the weight-shifting operator formal
ism\, I will construct a simple set of recursion relations for gener- atin
g five-point blocks for arbitrary symmetric traceless exchange\, which may
be utilized to reduce such blocks to linear combinations of scalar exchan
ge blocks with shifted external dimensions. Throughout\, I will restrict a
ttention to parity- even five-point functions in parity-preserving CFTs. O
ur results may be seen as a natural generalization of the work of Dolan an
d Osborn to the 5-point case. Moving beyond the external scalar case\, I w
ill consider how to promote one of the external scalars to a spin-1 or a s
pin-2 operator. I will show a way to derive additional recursion relations
which encode these blocks in terms of combinations of weight shifting ope
rators acting on the seed blocks for external scalars. Lastly\, I will dis
cuss one possible application of these results. (Joint work with David Pol
and http://arxiv.org/abs/2103.12092).\n
LOCATION:https://researchseminars.org/talk/SimonsBootstrapSeries/33/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Kamran Salehi Vaziri (EPFL)
DTSTART;VALUE=DATE-TIME:20210505T160000Z
DTEND;VALUE=DATE-TIME:20210505T170000Z
DTSTAMP;VALUE=DATE-TIME:20210514T190855Z
UID:SimonsBootstrapSeries/34
DESCRIPTION:Title: Hamiltonian truncation in Anti-de Sitter spacetime\nby
Kamran Salehi Vaziri (EPFL) as part of Simons Bootstrap Collaboration Semi
nar Series\n\n\nAbstract\nQuantum Field Theories in Anti-de Sitter spaceti
me are often strongly coupled when the radius of AdS is large\, and few me
thods are available to study them. In this work\, we develop a Hamiltonian
truncation method to compute the energy spectrum of QFTs in two-dimension
al AdS. The infinite volume of constant timeslices of AdS leads to diverge
nces in the energy levels. We propose a simple prescription to obtain fini
te physical energies and test it with numerical diagonalization in several
models: the free massive scalar field\, φ4 theory\, Lee-Yang and Ising f
ield theory. Along the way\, we discuss spontaneous symmetry breaking in A
dS and derive a compact formula for perturbation theory in quantum mechani
cs at arbitrary order. Our results suggest that all conformal boundary con
ditions for a given theory are connected via bulk renormalization group fl
ows in AdS\n
LOCATION:https://researchseminars.org/talk/SimonsBootstrapSeries/34/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Balt van Rees (Ecole Polytechnique)
DTSTART;VALUE=DATE-TIME:20210512T160000Z
DTEND;VALUE=DATE-TIME:20210512T170000Z
DTSTAMP;VALUE=DATE-TIME:20210514T190855Z
UID:SimonsBootstrapSeries/35
DESCRIPTION:Title: Navigator Function for the Conformal Bootstrap\nby Balt
van Rees (Ecole Polytechnique) as part of Simons Bootstrap Collaboration
Seminar Series\n\n\nAbstract\nCurrent numerical conformal bootstrap techni
ques carve out islands in theory space by repeatedly checking whether poin
ts are allowed or excluded. We propose a new method for searching theory s
pace that replaces the binary information “allowed”/“excluded” wit
h a continuous “navigator” function that is negative in the allowed re
gion and positive in the excluded region. Such a navigator function allows
one to efficiently explore high-dimensional parameter spaces and smoothly
sail towards any islands they may contain. The specific functions we intr
oduce have several attractive features: they are everywhere well-defined\,
can be computed with standard methods\, and evaluation of their gradient
is immediate due to an SDP gradient formula that we provide. The latter pr
operty allows for the use of efficient quasi-Newton optimization methods\,
which we illustrate by navigating towards the 3d Ising island.\n
LOCATION:https://researchseminars.org/talk/SimonsBootstrapSeries/35/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Sebastian Mizera (IAS)
DTSTART;VALUE=DATE-TIME:20210519T160000Z
DTEND;VALUE=DATE-TIME:20210519T170000Z
DTSTAMP;VALUE=DATE-TIME:20210514T190855Z
UID:SimonsBootstrapSeries/36
DESCRIPTION:Title: Recent Progress on Crossing Symmetry\nby Sebastian Mize
ra (IAS) as part of Simons Bootstrap Collaboration Seminar Series\n\nInter
active livestream: https://stonybrook.zoom.us/j/91261039763?pwd=QjJ1SWxWcD
kwY2JOa1dRVDVob0xLdz09\n\nAbstract\nWe will review recent progress in revi
siting the problem of crossing symmetry in perturbative quantum field theo
ries. The new approach is based on analyzing saddle points of the worldlin
e action\, using which we show that analytic continuation between pairs of
physical regions can be obstructed only by a special class of anomalous t
hresholds. For planar scattering processes with consecutive in/out states\
, there is a concise explanation for the absence of such singularities\, t
hus proving crossing symmetry to all loops and multiplicities.\n
LOCATION:https://researchseminars.org/talk/SimonsBootstrapSeries/36/
URL:https://stonybrook.zoom.us/j/91261039763?pwd=QjJ1SWxWcDkwY2JOa1dRVDVob
0xLdz09
END:VEVENT
END:VCALENDAR