BEGIN:VCALENDAR
VERSION:2.0
PRODID:-//CERN//INDICO//EN
BEGIN:VEVENT
SUMMARY:Horizon strings as microstates
DTSTART;VALUE=DATE-TIME:20221007T153000Z
DTEND;VALUE=DATE-TIME:20221007T163000Z
DTSTAMP;VALUE=DATE-TIME:20221004T161029Z
UID:indico-contribution-23-394@events.perimeterinstitute.ca
DESCRIPTION:Speakers: Daniel Grumiller (Technische Universität Wien)\nWe
combine insights from near horizon symmetries with results from Carrollia
n strings wrapping the horizon to construct BTZ black hole microstates.\n\
nhttps://events.perimeterinstitute.ca/event/23/contributions/394/
LOCATION:Perimeter Institute for Theoretical Physics PI/1-100 - Theatre
URL:https://events.perimeterinstitute.ca/event/23/contributions/394/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Wald-Zoupas vs. improved Noether charge: anomalies as soft terms a
t scri
DTSTART;VALUE=DATE-TIME:20221007T201500Z
DTEND;VALUE=DATE-TIME:20221007T211500Z
DTSTAMP;VALUE=DATE-TIME:20221004T161029Z
UID:indico-contribution-23-397@events.perimeterinstitute.ca
DESCRIPTION:Speakers: Simone Speziale (Centre de Physique Théorique)\nIn
the last few years\, various authors have extended the covariant phase spa
ce to include arbitrary anomalies\, and a notion of improved Noether charg
e. After reviewing this construction and discussing examples of anomalies\
, I will point out that the covariance requirements of the seminal Wald-Zo
upas paper permit the presence of a special class of anomalies. To illustr
ate the meaning of such anomalies\, one can look at the case of future nul
l infinity where they take the form of the soft terms in the flux-balance
laws.\n\nhttps://events.perimeterinstitute.ca/event/23/contributions/397/
LOCATION:Perimeter Institute for Theoretical Physics PI/1-100 - Theatre
URL:https://events.perimeterinstitute.ca/event/23/contributions/397/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Geometric actions for BMS4
DTSTART;VALUE=DATE-TIME:20221007T133000Z
DTEND;VALUE=DATE-TIME:20221007T143000Z
DTSTAMP;VALUE=DATE-TIME:20221004T161029Z
UID:indico-contribution-23-391@events.perimeterinstitute.ca
DESCRIPTION:Speakers: Glenn Barnich (Universite Libre de Bruxelles)\nAfter
reviewing the constrained Hamiltonian analysis of geometric actions\, the
construction is applied to the case of the BMS group in four dimensions\,
where it yields two plus one dimensional BMS4 invariant field theories. (
Based on work done in collaboration with K. Nguyen and R. Ruzziconi)\n\nht
tps://events.perimeterinstitute.ca/event/23/contributions/391/
LOCATION:Perimeter Institute for Theoretical Physics PI/1-100 - Theatre
URL:https://events.perimeterinstitute.ca/event/23/contributions/391/
END:VEVENT
BEGIN:VEVENT
SUMMARY:BMS fluxes from every corner
DTSTART;VALUE=DATE-TIME:20221006T130000Z
DTEND;VALUE=DATE-TIME:20221006T140000Z
DTSTAMP;VALUE=DATE-TIME:20221004T161029Z
UID:indico-contribution-23-384@events.perimeterinstitute.ca
DESCRIPTION:Speakers: Laura Donnay (Technische Universität Wien)\nIn this
talk\, I will present an updated account on the prescription for BMS flux
es in asymptotically flat spacetimes\, including their split into hard and
soft pieces and the associated symplectic structure. Implications for fla
t space holography will be discussed.\n\nhttps://events.perimeterinstitute
.ca/event/23/contributions/384/
LOCATION:Perimeter Institute for Theoretical Physics PI/1-100 - Theatre
URL:https://events.perimeterinstitute.ca/event/23/contributions/384/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Hamiltonian Gauge Theory With Corners I: General Theory
DTSTART;VALUE=DATE-TIME:20221004T181500Z
DTEND;VALUE=DATE-TIME:20221004T184500Z
DTSTAMP;VALUE=DATE-TIME:20221004T161029Z
UID:indico-contribution-23-405@events.perimeterinstitute.ca
DESCRIPTION:Speakers: Michele Schiavina (ETH Zurich)\nI will present an an
alysis of the Hamiltonian formulation of gauge theories on manifolds with
corners in the particular\, yet common\, case in which they admit an equiv
ariant momentum map.\n\nIn the presence of corners\, the momentum map spli
ts into a part encoding “Cauchy data” or constraints\, and a part enco
ding the “flux” across the corner. This decomposition plays an importa
nt role in the construction of the reduced phase space\, which then become
s an application of symplectic reduction in stages for local group actions
.\n\nThe output of this analysis are natural "corner" Poisson structures\,
leading to the concept of (classical) flux superselection sectors as thei
r symplectic leaves.\n\nThis is based on a collaboration with A. Riello. M
y talk will cover the general framework of corner superselection\, while R
iello’s talk will deal with its application to null boundaries and soft
charges.\n\nhttps://events.perimeterinstitute.ca/event/23/contributions/40
5/
LOCATION:Perimeter Institute for Theoretical Physics PI/1-100 - Theatre
URL:https://events.perimeterinstitute.ca/event/23/contributions/405/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Celestial higher spin charges and gravitational multipole moments
DTSTART;VALUE=DATE-TIME:20221006T140000Z
DTEND;VALUE=DATE-TIME:20221006T143000Z
DTSTAMP;VALUE=DATE-TIME:20221004T161029Z
UID:indico-contribution-23-385@events.perimeterinstitute.ca
DESCRIPTION:Speakers: Ali Seraj (Universite Libre de Bruxelles)\nIn this
talk\, I will describe celestial higher spin charges as corner integrals\,
and their relationship with gravitational multipole moments. I will then
explain that these charges uniquely label gravitational vacua and the corr
esponding flux-balance equations describe the transition caused by gravita
tional radiation among different vacua. This tak is based on arXiv:2206.12
597.\n\nhttps://events.perimeterinstitute.ca/event/23/contributions/385/
LOCATION:Perimeter Institute for Theoretical Physics PI/1-100 - Theatre
URL:https://events.perimeterinstitute.ca/event/23/contributions/385/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Carroll symmetry in gravity and string theory
DTSTART;VALUE=DATE-TIME:20221004T153000Z
DTEND;VALUE=DATE-TIME:20221004T163000Z
DTSTAMP;VALUE=DATE-TIME:20221004T161029Z
UID:indico-contribution-23-403@events.perimeterinstitute.ca
DESCRIPTION:Speakers: Niels Obers (NORDITA)\nI will discuss the small spee
d of light expansion of general relativity\, utilizing the modern perspect
ive on non-Lorentzian geometry. The leading order in the expansion leads t
o an action that corresponds to the electric Carroll limit of general rela
tivity\, of which I will highlight some interesting properties. The next-t
o-leading order will also be obtained\, which exhibits a particular subsec
tor that correspond to the magnetic Carroll limit\, which features a solut
ion that describes the Carroll limit of a Schwarzschild black hole. The in
corporation of a cosmological constant in the Carroll (or ultra-local) exp
ansion will also be commented on. Finally\, I will describe how Carroll sy
mmetry and geometry arises on the world-sheet of certain limits of string
theory sigma models.\n\nhttps://events.perimeterinstitute.ca/event/23/cont
ributions/403/
LOCATION:Perimeter Institute for Theoretical Physics PI/1-100 - Theatre
URL:https://events.perimeterinstitute.ca/event/23/contributions/403/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Welcome & Opening Remarks
DTSTART;VALUE=DATE-TIME:20221003T135000Z
DTEND;VALUE=DATE-TIME:20221003T140000Z
DTSTAMP;VALUE=DATE-TIME:20221004T161029Z
UID:indico-contribution-23-367@events.perimeterinstitute.ca
DESCRIPTION:Speakers: Celine Zwikel (Perimeter Institute)\, Luca Ciambelli
(Perimeter Institute)\nhttps://events.perimeterinstitute.ca/event/23/cont
ributions/367/
LOCATION:Perimeter Institute for Theoretical Physics PI/1-100 - Theatre
URL:https://events.perimeterinstitute.ca/event/23/contributions/367/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Review Talk: A primer on the covariant phase space formalism cont.
DTSTART;VALUE=DATE-TIME:20221003T150500Z
DTEND;VALUE=DATE-TIME:20221003T160000Z
DTSTAMP;VALUE=DATE-TIME:20221004T161029Z
UID:indico-contribution-23-369@events.perimeterinstitute.ca
DESCRIPTION:Speakers: Adrien Fiorucci (Technische Universität Wien)\nhttp
s://events.perimeterinstitute.ca/event/23/contributions/369/
LOCATION:Perimeter Institute for Theoretical Physics PI/1-100 - Theatre
URL:https://events.perimeterinstitute.ca/event/23/contributions/369/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Review Talk: An introduction to coadjoint orbits cont.
DTSTART;VALUE=DATE-TIME:20221003T183500Z
DTEND;VALUE=DATE-TIME:20221003T193000Z
DTSTAMP;VALUE=DATE-TIME:20221004T161029Z
UID:indico-contribution-23-410@events.perimeterinstitute.ca
DESCRIPTION:Speakers: Andrea Campoleoni (University Of Mons)\nhttps://even
ts.perimeterinstitute.ca/event/23/contributions/410/
LOCATION:Perimeter Institute for Theoretical Physics PI/1-100 - Theatre
URL:https://events.perimeterinstitute.ca/event/23/contributions/410/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Carrollian spaces at infinity: an embedding space picture
DTSTART;VALUE=DATE-TIME:20221007T191500Z
DTEND;VALUE=DATE-TIME:20221007T194500Z
DTSTAMP;VALUE=DATE-TIME:20221004T161029Z
UID:indico-contribution-23-396@events.perimeterinstitute.ca
DESCRIPTION:Speakers: Jakob Salzer (Université Libre de Bruxelles)\nIn th
is talk\, I will discuss certain homogeneous spaces of the Poincaré group
that correspond to the well-known asymptotic regions of asymptotically fl
at spacetimes: time-\, space-\, and light-like infinity. I will then show
that all of these spaces admit a uniform description as surfaces embedded
in a higher-dimensional space. I will conclude with some comments concerni
ng the computation of correlators of conformal carrollian theories from th
is embedding space picture.\n\nhttps://events.perimeterinstitute.ca/event/
23/contributions/396/
LOCATION:Perimeter Institute for Theoretical Physics PI/1-100 - Theatre
URL:https://events.perimeterinstitute.ca/event/23/contributions/396/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Asymptotic algebra of quantum electrodynamics from the BV-BFV pers
pective
DTSTART;VALUE=DATE-TIME:20221006T201500Z
DTEND;VALUE=DATE-TIME:20221006T211500Z
DTSTAMP;VALUE=DATE-TIME:20221004T161029Z
UID:indico-contribution-23-390@events.perimeterinstitute.ca
DESCRIPTION:Speakers: Kasia Rejzner (University of York)\nThis talk focuse
s on classical features of asymptotic QED\, i.e. the limit of QED at null
and time-like infinity. The BV-BFV formalism allows one to view this as a
boundary theory of bulk QED and carries a natural notion of what it means
to be a symmetry of the model. I will make the connection between this per
spective and the earlier findings of Herdegen (JMP 1996) and Strominger et
.al. (JHEP 2014) concerning large gauge symmetries in QED. This is based o
n a joint paper with Michele Schiavina (CMP 2021).\n\nhttps://events.perim
eterinstitute.ca/event/23/contributions/390/
LOCATION:Perimeter Institute for Theoretical Physics PI/1-100 - Theatre
URL:https://events.perimeterinstitute.ca/event/23/contributions/390/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Hamiltonian Gauge Theory With Corners II: memory as superselection
in null YM theory
DTSTART;VALUE=DATE-TIME:20221007T150000Z
DTEND;VALUE=DATE-TIME:20221007T153000Z
DTSTAMP;VALUE=DATE-TIME:20221004T161029Z
UID:indico-contribution-23-393@events.perimeterinstitute.ca
DESCRIPTION:Speakers: Aldo Riello (Perimeter Institute)\nOn Tuesday\, M. S
chiavina laid out the theoretical framework for the symplectic reduction o
f gauge theories in the presence of corners. In this talk I will apply thi
s theoretical framework to Yang-Mills theory on a null boundary and show h
ow a pair of soft charges controls the residual (corner) gauge symmetry af
ter the first-stage symplectic reduction\, and therefore the superselectio
n structure of the theory after the second-stage symplectic reduction. I w
ill also discuss the subtleties of the gauge A_u = 0\, the interpretation
of electromagnetic memory as superselection\, and how the nonlinear struct
ure of the non-Abelian theory complicates this picture.\n\nhttps://events.
perimeterinstitute.ca/event/23/contributions/393/
LOCATION:Perimeter Institute for Theoretical Physics PI/1-100 - Theatre
URL:https://events.perimeterinstitute.ca/event/23/contributions/393/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Review Talk: An introduction to coadjoint orbits
DTSTART;VALUE=DATE-TIME:20221003T173000Z
DTEND;VALUE=DATE-TIME:20221003T182500Z
DTSTAMP;VALUE=DATE-TIME:20221004T161029Z
UID:indico-contribution-23-409@events.perimeterinstitute.ca
DESCRIPTION:Speakers: Andrea Campoleoni (University Of Mons)\nWe begin by
reviewing the role of coadjoint orbits in the representation theory of ni
lpotents groups and then\, to connect with the recent applications in phy
sics of coadjoint orbits "around the corner" of the mathematical framewor
k developed by Kirillov\, we review the classification of coadjoint orbit
s of the Virasoro group. This will allow us to connect with more recent d
evelopments\, including e.g. the study of coadjoint orbits of BMS algebra
s.\n\nhttps://events.perimeterinstitute.ca/event/23/contributions/409/
LOCATION:Perimeter Institute for Theoretical Physics PI/1-100 - Theatre
URL:https://events.perimeterinstitute.ca/event/23/contributions/409/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Flat asymptotics\, charges and dual charges -- what the Cotton can
do
DTSTART;VALUE=DATE-TIME:20221007T181500Z
DTEND;VALUE=DATE-TIME:20221007T191500Z
DTSTAMP;VALUE=DATE-TIME:20221004T161029Z
UID:indico-contribution-23-395@events.perimeterinstitute.ca
DESCRIPTION:Speakers: Marios Petropoulos (Ecole polytechnique - CNRS)\nIn
this talk I will explore the role of the boundary Cotton tensor in the rec
onstruction of the solution space of four-dimensional asymptotically AdS a
nd mostly asymptotically flat spacetimes. I will discuss charges from a pu
rely boundary perspective\, which emerge in sets of electric and magnetic
towers\, not necessarily conserved and possibly including subleading compo
nents.\n\nhttps://events.perimeterinstitute.ca/event/23/contributions/395/
LOCATION:Perimeter Institute for Theoretical Physics PI/1-100 - Theatre
URL:https://events.perimeterinstitute.ca/event/23/contributions/395/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Gong Show
DTSTART;VALUE=DATE-TIME:20221003T200000Z
DTEND;VALUE=DATE-TIME:20221003T213000Z
DTSTAMP;VALUE=DATE-TIME:20221004T161029Z
UID:indico-contribution-23-411@events.perimeterinstitute.ca
DESCRIPTION:Speakers: Ankit Aggarwal (University of Amsterdam)\, Arnaud De
lfante (University of Mons)\, Florian Ecker (Technische Universität Wien)
\, Giovanni Canepa (Centre de Physique Théorique)\, Gloria Odak (Centre d
e Physique Théorique)\, Monireh Ahmadpour (University of Tehran)\, Roukay
a Dekhil (Ludwig Maximilian University of Munich)\nSpeaker Order:\nAnkit A
ggarwal\, University of Amsterdam\nMonireh Ahmadpour\, University of Tehra
n\nGiovanni Canepa\, Centre de Physique Théorique\nRoukaya Dekhil\, Ludwi
g Maximilian University\nArnaud Delfante\, University of Mons\nFlorian Eck
er\, Technische Universität Wien\nGloria Odak\, Centre de Physique Théor
ique\n\nhttps://events.perimeterinstitute.ca/event/23/contributions/411/
LOCATION:Perimeter Institute for Theoretical Physics PI/1-100 - Theatre
URL:https://events.perimeterinstitute.ca/event/23/contributions/411/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Review Talk: A primer on the covariant phase space formalism
DTSTART;VALUE=DATE-TIME:20221003T140000Z
DTEND;VALUE=DATE-TIME:20221003T145500Z
DTSTAMP;VALUE=DATE-TIME:20221004T161029Z
UID:indico-contribution-23-368@events.perimeterinstitute.ca
DESCRIPTION:Speakers: Adrien Fiorucci (Technische Universität Wien)\nThis
lecture aims at introducing the notion of asymptotic symmetries in gravit
y and the derivation of the related surface charges by means of covariant
phase space techniques. First\, after a short historical introduction\, I
will rigorously define what is meant by “asymptotic symmetry” within t
he so-called gauge-fixing approach. The problem of fixing consistent bound
ary conditions and the formulation of the variational principle will be br
iefly discussed. In the second part of the lecture\, I will introduce the
covariant phase space formalism\, as conceived by Wald and coworkers thirt
y years ago\, which adapts the Hamiltonian formulation of classical mechan
ics to Lagrangian covariant field theories. With the help of this fantasti
c tool\, I will elaborate on the construction of canonical surface charges
associated with asymptotic symmetries and address the crucial questions o
f their conservation and integrability on the phase space. In the third an
d last part\, I will conclude with an analysis of the algebraic properties
of the surface charges\, describing in which sense they represent the asy
mptotic symmetry algebra in full generality\, without assuming conservatio
n or integrability. For pedagogical purposes\, the theoretical concepts wi
ll be illustrated throughout in the crucial and well-known case of radiati
ve asymptotically flat spacetimes in four dimensions\, as described by Ein
stein’s theory of General Relativity\, and where many spectacular and un
expected features appear even in the simplest case of historical asymptoti
cally Minkowskian boundary conditions. In particular\, I will show that th
e surface charge algebra contains the physical information on the flux of
energy and angular momentum at null infinity in the presence of gravitatio
nal radiation.\n\nhttps://events.perimeterinstitute.ca/event/23/contributi
ons/368/
LOCATION:Perimeter Institute for Theoretical Physics PI/1-100 - Theatre
URL:https://events.perimeterinstitute.ca/event/23/contributions/368/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Carrollian Perspective on Celestial Holography
DTSTART;VALUE=DATE-TIME:20221004T150000Z
DTEND;VALUE=DATE-TIME:20221004T153000Z
DTSTAMP;VALUE=DATE-TIME:20221004T161029Z
UID:indico-contribution-23-402@events.perimeterinstitute.ca
DESCRIPTION:Speakers: Romain Ruzziconi (Technische Universität Wien)\nTh
e flat space holography program aims at describing quantum gravity in asym
ptotically flat spacetime in terms of a dual lower-dimensional field theor
y. Two different roads to construct flat space holography have emerged. Th
e first consists of a 4d bulk / 3d boundary duality\, called Carrollian ho
lography\, where 4d gravity is suggested to be dual to a 3d Carrollian CFT
living on the null boundary of the spacetime. The second is a 4d bulk / 2
d boundary duality\, called celestial holography\, where 4d gravity is dua
l to a 2d CFT living on the celestial sphere. I will argue that these two
seemingly contradictory proposals are actually related. The Carrollian ope
rators will be mapped to the celestial operators using an appropriate inte
gral transform. The Ward identities of the sourced Carrollian CFT\, encodi
ng the gravitational flux-balance laws\, will be shown to reproduce those
of the 2d celestial CFT\, encoding the bulk soft theorems.\n\nhttps://even
ts.perimeterinstitute.ca/event/23/contributions/402/
LOCATION:Perimeter Institute for Theoretical Physics PI/1-100 - Theatre
URL:https://events.perimeterinstitute.ca/event/23/contributions/402/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Towers of soft operators and celestial holography
DTSTART;VALUE=DATE-TIME:20221005T140000Z
DTEND;VALUE=DATE-TIME:20221005T143000Z
DTSTAMP;VALUE=DATE-TIME:20221004T161029Z
UID:indico-contribution-23-408@events.perimeterinstitute.ca
DESCRIPTION:Speakers: Ana Maria Raclariu (Perimeter Institute)\nThe tree-l
evel soft theorems were recently shown to arise from the conservation of i
nfinite towers of charges extracted from the asymptotic Einstein equations
. There is evidence this tower promotes the extended BMS algebra to an inf
inite higher-spin symmetry algebra. In this talk I will introduce towers o
f canonically conjugate memory and Goldstone operators\, highlighting thei
r role in parameterizing the gravitational phase space. I will discuss the
conditions under which these towers provide a complete set of scattering
states and demonstrate that they are the building blocks of both soft and
hard charges. I will finally show that the tower of tree level soft symmet
ries can be used to extend the Dirac (Faddeev-Kulish) dressings to include
the infinite towers of Goldstones and comment on their implications for t
he gravitational S-matrix.\n\nhttps://events.perimeterinstitute.ca/event/2
3/contributions/408/
LOCATION:Perimeter Institute for Theoretical Physics PI/1-100 - Theatre
URL:https://events.perimeterinstitute.ca/event/23/contributions/408/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Conformal Carroll Scalar Actions
DTSTART;VALUE=DATE-TIME:20221006T150000Z
DTEND;VALUE=DATE-TIME:20221006T153000Z
DTSTAMP;VALUE=DATE-TIME:20221004T161029Z
UID:indico-contribution-23-386@events.perimeterinstitute.ca
DESCRIPTION:Speakers: Gerben Oling (NORDITA)\nI will construct explicit ac
tions that are invariant under BMS/conformal Carroll symmetries. Over the
last few years\, we have developed a systematic procedure for constructing
non-Lorentzian theories from limits and expansions of Lorentzian theories
. To obtain explicit examples of candidate dual field theories for flat s
pace holography\, I apply this procedure to the conformally coupled scalar
action\, which leads to two classes of actions that are invariant under c
onformal Carroll symmetries. Time permitting\, I will briefly mention ongo
ing work on the computation and classification of Weyl anomalies in such t
heories.\n\nhttps://events.perimeterinstitute.ca/event/23/contributions/38
6/
LOCATION:Perimeter Institute for Theoretical Physics PI/1-100 - Theatre
URL:https://events.perimeterinstitute.ca/event/23/contributions/386/
END:VEVENT
BEGIN:VEVENT
SUMMARY:A Celestial Matrix Model
DTSTART;VALUE=DATE-TIME:20221006T191500Z
DTEND;VALUE=DATE-TIME:20221006T194500Z
DTSTAMP;VALUE=DATE-TIME:20221004T161029Z
UID:indico-contribution-23-430@events.perimeterinstitute.ca
DESCRIPTION:Speakers: Charles Marteau (University of British Columbia)\nWe
construct a Hermitian random matrix model that provides a stable non-pert
urbative completion of Cangemi-Jackiw (CJ) gravity\, a two-dimensional the
ory of black holes in asymptotically flat spacetimes. The matrix model rep
roduces\, to all orders in the topological expansion\, the Euclidean parti
tion function of CJ gravity with an arbitrary number of boundaries. The no
n-perturbative completion enables the exact computation of observables in
flat space quantum gravity which we use to explicitly characterize the Bon
di Hamiltonian spectrum. We discuss the implications of our results for th
e flat space S-matrix and black holes.\n\nhttps://events.perimeterinstitut
e.ca/event/23/contributions/430/
LOCATION:Perimeter Institute for Theoretical Physics PI/1-100 - Theatre
URL:https://events.perimeterinstitute.ca/event/23/contributions/430/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Horizons\, fluid and what non-linearities might await
DTSTART;VALUE=DATE-TIME:20221006T153000Z
DTEND;VALUE=DATE-TIME:20221006T163000Z
DTSTAMP;VALUE=DATE-TIME:20221004T161029Z
UID:indico-contribution-23-387@events.perimeterinstitute.ca
DESCRIPTION:Speakers: Luis Lehner (Perimeter Institute)\nWe analyze\, firs
t from a geometric point of view\, the behavior\nof dynamical horizons. We
then connect with Carrolian fluids and discuss potential phenomena stemmi
ng from non-linearities\nin the resulting equations\n[This is joint work w
ith Jaime Redondo Yuste]\n\nhttps://events.perimeterinstitute.ca/event/23/
contributions/387/
LOCATION:Perimeter Institute for Theoretical Physics PI/1-100 - Theatre
URL:https://events.perimeterinstitute.ca/event/23/contributions/387/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Local Holography and corner symmetry: A paradigm for quantum grav
ity
DTSTART;VALUE=DATE-TIME:20221004T130000Z
DTEND;VALUE=DATE-TIME:20221004T140000Z
DTSTAMP;VALUE=DATE-TIME:20221004T161029Z
UID:indico-contribution-23-400@events.perimeterinstitute.ca
DESCRIPTION:Speakers: Laurent Freidel (Perimeter Institute)\nIn this intro
ductory talk\, I will present a new perspective about quantum gravity whic
h is rooted deeply in a renewed understanding of local symmetries in Gravi
ty that appears when we decompose gravitational systems into subsystems. \
nI will emphasize the central role of the corner symmetry group in capturi
ng all the necessary data needed to glue back seamlessly quantum spacetime
regions. I will present how the charge conservation associated with these
symmetries encoded the dynamics of null surfaces.\nFinally\, I will also
present how the representation theory of the corner symmetry arises and pr
ovides a representation of quantum geometry\, and I will show that deform
ations of this symmetry can be the explanation for a fundamental planckian
cut-off. \nI will also mention how these symmetry groups reduce to asympt
otic symmetry groups and control asymptotic gravitational dynamics when th
e entangling sphere is moved to infinity. If time permits\, I will explain
how these symmetries control asymptotic gravitational dynamics. And I wil
l describe how they provide a new picture of the nature of quantum radiati
on.\nOverall\, this new paradigm allows to connect semi-classical gravitat
ional physics\, S-matrix theory\, and non-perturbative quantum gravity tec
hniques.\nThe talk's goal is to give an overall flavor of how these connec
tions appear from an elementary understanding of symmetries.\n\nhttps://ev
ents.perimeterinstitute.ca/event/23/contributions/400/
LOCATION:Perimeter Institute for Theoretical Physics PI/1-100 - Theatre
URL:https://events.perimeterinstitute.ca/event/23/contributions/400/
END:VEVENT
BEGIN:VEVENT
SUMMARY:The partial Bondi gauge
DTSTART;VALUE=DATE-TIME:20221005T153000Z
DTEND;VALUE=DATE-TIME:20221005T163000Z
DTSTAMP;VALUE=DATE-TIME:20221004T161029Z
UID:indico-contribution-23-383@events.perimeterinstitute.ca
DESCRIPTION:Speakers: Marc Geiller (École Normale Supérieure de Lyon)\n
I will review the recent construction of an extended solution space for gr
avity\, based on a so-called partial Bondi gauge fixing. This aims at inve
stigating the possible relaxations of the boundary conditions\, in order t
o include for example a cosmological constant\, a polyhomogeneous expansio
n\, and an arbitrary time-dependent boundary metric. I will also explain h
ow to properly map these results to the Newman-Penrose formalism. Finally\
, I will discuss the application to three-dimensional gravity\, where a ne
w asymptotic symmetry can be revealed after working out all the subtleties
of the covariant phase space formalism.\n\nhttps://events.perimeterinstit
ute.ca/event/23/contributions/383/
LOCATION:Perimeter Institute for Theoretical Physics PI/1-100 - Theatre
URL:https://events.perimeterinstitute.ca/event/23/contributions/383/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Cutting Corners with Celestial CFT
DTSTART;VALUE=DATE-TIME:20221006T181500Z
DTEND;VALUE=DATE-TIME:20221006T191500Z
DTSTAMP;VALUE=DATE-TIME:20221004T161029Z
UID:indico-contribution-23-388@events.perimeterinstitute.ca
DESCRIPTION:Speakers: Sabrina Pasterski ()\nCelestial Holography proposes
a duality between gravitational scattering in asymptotically flat spacetim
es and a conformal field theory living on the celestial sphere. The main m
otivation for this program comes from the connection between soft theorems
and asymptotic symmetries in asymptotically flat spacetimes\, and our abi
lity to recast soft operators as currents in a codimension 2 CFT. \n\nWe p
resent a streamlined route from asymptotic symmetries in 4D asymptotically
flat spacetimes to currents in a 2D celestial CFT in a manner that makes
their relation to QFT soft theorems manifest. We use this to re-examine th
e bulk picture of radial evolution in the 2D theory and reconcile the cons
truction of charges in CCFT with the more familiar construction from AdS/C
FT\, despite the differing codimension. \n\nIn the process\, we point out
how the Carrollian and Celestial perspectives amount to slicing the bulk a
nd boundary in different ways — our celestial slices cut through the usu
al corner! — and emphasize how these perspectives inform each other. \n
\nBased on 2201.06805\, 2202.11127 and 2205.10901\n\nhttps://events.perime
terinstitute.ca/event/23/contributions/388/
LOCATION:Perimeter Institute for Theoretical Physics PI/1-100 - Theatre
URL:https://events.perimeterinstitute.ca/event/23/contributions/388/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Residual gauge symmetries in the front form
DTSTART;VALUE=DATE-TIME:20221004T140000Z
DTEND;VALUE=DATE-TIME:20221004T143000Z
DTSTAMP;VALUE=DATE-TIME:20221004T161029Z
UID:indico-contribution-23-401@events.perimeterinstitute.ca
DESCRIPTION:Speakers: Sucheta Majumdar (École Normale Supérieure de Lyon
)\nThe goal of this talk is to discuss residual gauge symmetries in electr
omagnetism and gravity in Dirac's front form. Working in the light-cone ga
uge\, I will demonstrate how the large gauge transformations and BMS super
translations may be obtained from residual gauge invariance of the Hamilto
nian action. The residual gauge symmetries in this (2+2) formulation share
some striking similarities with the asymptotic symmetries in the conventi
onal (3+1) Hamiltonian formulation. I will illustrate this fact using the
example of electromagnetism and show how the the zero modes play a crucial
role akin to boundary degrees of freedom in the asymptotic analysis at sp
atial infinity à la Henneaux-Troessaert.\n\nhttps://events.perimeterinsti
tute.ca/event/23/contributions/401/
LOCATION:Perimeter Institute for Theoretical Physics PI/1-100 - Theatre
URL:https://events.perimeterinstitute.ca/event/23/contributions/401/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Orbit Analysis of Corner Symmetries
DTSTART;VALUE=DATE-TIME:20221005T130000Z
DTEND;VALUE=DATE-TIME:20221005T140000Z
DTSTAMP;VALUE=DATE-TIME:20221004T161029Z
UID:indico-contribution-23-407@events.perimeterinstitute.ca
DESCRIPTION:Speakers: Robert Leigh (University of Illinois at Urbana-Champ
aign)\nCorner symmetries are those diffeomorphisms that become physical in
codimension two\, in that they support non-zero Noether charges. Recently
we have shown how to extend phase space so that all such charges are inte
grable and give a representation of the corner symmetry algebra on this ex
tended phase space. More recently we have studied the coadjoint orbits of
what we now call the universal corner symmetry. One finds that certain com
plementary subalgebras\, the extended corner symmetry and the asymptotic c
orner symmetry\, can be associated with finite-distance and asymptotic cor
ners\, respectively. There is a simple geometric interpretation here in te
rms of an Atiyah Lie algebroid over a corner\, whose structure group is th
e universal corner symmetry. The local geometry of a classical spacetime i
s encoded in related geometric structures.\n\nhttps://events.perimeterinst
itute.ca/event/23/contributions/407/
LOCATION:Perimeter Institute for Theoretical Physics PI/1-100 - Theatre
URL:https://events.perimeterinstitute.ca/event/23/contributions/407/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Matrix quantization of gravitational edge modes
DTSTART;VALUE=DATE-TIME:20221005T150000Z
DTEND;VALUE=DATE-TIME:20221005T153000Z
DTSTAMP;VALUE=DATE-TIME:20221004T161029Z
UID:indico-contribution-23-382@events.perimeterinstitute.ca
DESCRIPTION:Speakers: Antony Speranza (University of Illinois at Urbana-Ch
ampaign)\nThe phase space of gravity restricted to a subregion bounded by
a codimension-2 corner possesses an infinite-dimensional symmetry algebra
consisting of diffeomorphisms of the 2-sphere and local SL(2\,R) transform
ations of the normal planes. I will describe a deformation of a subalgebr
a preserving an area form on the sphere\, and show that it leads to the fi
nite dimensional algebra SU(N\,N)\, reminiscent of older results concernin
g the fuzzy sphere\, in which area-preserving diffeomorphisms are deformed
to SU(N). This deformation is conjectured to be relevant to the quantiza
tion of the local gravitational phase space\, and I will further demonstra
te that the representation of SU(N\,N) appearing in the quantization can b
e determined by matching the Casimir operators of the deformed algebra to
classical phase space invariants. Based on 2012.10367 and upcoming work w
ith W. Donnelly\, L. Freidel\, and S.F. Moosavian.\n\nhttps://events.perim
eterinstitute.ca/event/23/contributions/382/
LOCATION:Perimeter Institute for Theoretical Physics PI/1-100 - Theatre
URL:https://events.perimeterinstitute.ca/event/23/contributions/382/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Avoiding the Corners: Partition Functions of Abelian Chern-Simons
Theories on Handlebodies
DTSTART;VALUE=DATE-TIME:20221004T184500Z
DTEND;VALUE=DATE-TIME:20221004T194500Z
DTSTAMP;VALUE=DATE-TIME:20221004T161029Z
UID:indico-contribution-23-404@events.perimeterinstitute.ca
DESCRIPTION:Speakers: Massimo Porrati (New York University)\nThis talk rev
iews the use of radial quantization to compute Chern-Simons partition func
tions on handlebodies of arbitrary genus. The partition function is given
by a particular transition amplitude between two states which are defined
on the Riemann surfaces that define the (singular) foliation of the handle
body. By requiring that the only singularities of the gauge field inside
the handlebody must be compatible with Wilson loop insertions\, we find th
at the Wilson loop shifts the holonomy of the initial state. Together with
an appropriate choice of normalization\, this procedure selects a unique
state in the Hilbert space obtained from a Kähler quantization of the the
ory on the constant-radius Riemann surfaces. Radial quantization allows us
to find the partition functions of Abelian Chern-Simons theories for hand
lebodies of arbitrary genus. For non-Abelian compact gauge groups\, we sho
w that our method reproduces the known partition function and Wilson loop
VEVs at genus one.\n\nhttps://events.perimeterinstitute.ca/event/23/contri
butions/404/
LOCATION:Perimeter Institute for Theoretical Physics PI/1-100 - Theatre
URL:https://events.perimeterinstitute.ca/event/23/contributions/404/
END:VEVENT
END:VCALENDAR