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BEGIN:VEVENT
SUMMARY:Wald-Zoupas vs. improved Noether charge: anomalies as soft terms a
t scri
DTSTART:20221007T184500Z
DTEND:20221007T194500Z
DTSTAMP:20230922T211700Z
UID:indico-contribution-397@events.perimeterinstitute.ca
DESCRIPTION:Speakers: Simone Speziale (Centre de Physique Théorique)\n\nI
n the last few years\, various authors have extended the covariant phase s
pace to include arbitrary anomalies\, and a notion of improved Noether cha
rge. After reviewing this construction and discussing examples of anomalie
s\, I will point out that the covariance requirements of the seminal Wald-
Zoupas paper permit the presence of a special class of anomalies. To illus
trate the meaning of such anomalies\, one can look at the case of future n
ull infinity where they take the form of the soft terms in the flux-balanc
e laws.\n\nhttps://events.perimeterinstitute.ca/event/23/contributions/397
/
LOCATION:PI/1-100 - Theatre (Perimeter Institute for Theoretical Physics)
URL:https://events.perimeterinstitute.ca/event/23/contributions/397/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Geometric actions for BMS4
DTSTART:20221007T133000Z
DTEND:20221007T143000Z
DTSTAMP:20230922T211700Z
UID:indico-contribution-391@events.perimeterinstitute.ca
DESCRIPTION:Speakers: Glenn Barnich (Universite Libre de Bruxelles)\n\nAft
er reviewing the constrained Hamiltonian analysis of geometric actions\, t
he 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\n
https://events.perimeterinstitute.ca/event/23/contributions/391/
LOCATION:PI/1-100 - Theatre (Perimeter Institute for Theoretical Physics)
URL:https://events.perimeterinstitute.ca/event/23/contributions/391/
END:VEVENT
BEGIN:VEVENT
SUMMARY:BMS fluxes from every corner
DTSTART:20221006T130000Z
DTEND:20221006T140000Z
DTSTAMP:20230922T211700Z
UID:indico-contribution-384@events.perimeterinstitute.ca
DESCRIPTION:Speakers: Laura Donnay (Technische Universität Wien)\n\nIn th
is talk\, I will present an updated account on the prescription for BMS fl
uxes in asymptotically flat spacetimes\, including their split into hard a
nd soft pieces and the associated symplectic structure. Implications for f
lat space holography will be discussed.\n\nhttps://events.perimeterinstitu
te.ca/event/23/contributions/384/
LOCATION:PI/1-100 - Theatre (Perimeter Institute for Theoretical Physics)
URL:https://events.perimeterinstitute.ca/event/23/contributions/384/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Hamiltonian Gauge Theory With Corners I: General Theory
DTSTART:20221004T181500Z
DTEND:20221004T184500Z
DTSTAMP:20230922T211700Z
UID:indico-contribution-405@events.perimeterinstitute.ca
DESCRIPTION:Speakers: Michele Schiavina (ETH Zurich)\n\nI will present an
analysis of the Hamiltonian formulation of gauge theories on manifolds wit
h corners in the particular\, yet common\, case in which they admit an equ
ivariant momentum map.\n\nIn the presence of corners\, the momentum map sp
lits into a part encoding “Cauchy data” or constraints\, and a part en
coding the “flux” across the corner. This decomposition plays an impor
tant role in the construction of the reduced phase space\, which then beco
mes an application of symplectic reduction in stages for local group actio
ns.\n\nThe output of this analysis are natural "corner" Poisson structures
\, leading to the concept of (classical) flux superselection sectors as th
eir symplectic leaves.\n\nThis is based on a collaboration with A. Riello.
My talk will cover the general framework of corner superselection\, while
Riello’s talk will deal with its application to null boundaries and sof
t charges.\n\nhttps://events.perimeterinstitute.ca/event/23/contributions/
405/
LOCATION:PI/1-100 - Theatre (Perimeter Institute for Theoretical Physics)
URL:https://events.perimeterinstitute.ca/event/23/contributions/405/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Celestial higher spin charges and gravitational multipole moments
DTSTART:20221006T140000Z
DTEND:20221006T143000Z
DTSTAMP:20230922T211700Z
UID:indico-contribution-385@events.perimeterinstitute.ca
DESCRIPTION:Speakers: Ali Seraj (Universite Libre de Bruxelles)\n\nIn thi
s talk\, I will describe celestial higher spin charges as corner integrals
\, and their relationship with gravitational multipole moments. I will the
n explain that these charges uniquely label gravitational vacua and the co
rresponding flux-balance equations describe the transition caused by gravi
tational radiation among different vacua. This tak is based on arXiv:2206.
12597.\n\nhttps://events.perimeterinstitute.ca/event/23/contributions/385/
LOCATION:PI/1-100 - Theatre (Perimeter Institute for Theoretical Physics)
URL:https://events.perimeterinstitute.ca/event/23/contributions/385/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Carroll symmetry in gravity and string theory
DTSTART:20221004T153000Z
DTEND:20221004T163000Z
DTSTAMP:20230922T211700Z
UID:indico-contribution-403@events.perimeterinstitute.ca
DESCRIPTION:Speakers: Niels Obers (NORDITA)\n\nI will discuss the small sp
eed of light expansion of general relativity\, utilizing the modern perspe
ctive on non-Lorentzian geometry. The leading order in the expansion leads
to an action that corresponds to the electric Carroll limit of general re
lativity\, of which I will highlight some interesting properties. The next
-to-leading order will also be obtained\, which exhibits a particular subs
ector that correspond to the magnetic Carroll limit\, which features a sol
ution that describes the Carroll limit of a Schwarzschild black hole. The
incorporation of a cosmological constant in the Carroll (or ultra-local) e
xpansion will also be commented on. Finally\, I will describe how Carroll
symmetry and geometry arises on the world-sheet of certain limits of strin
g theory sigma models.\n\nhttps://events.perimeterinstitute.ca/event/23/co
ntributions/403/
LOCATION:PI/1-100 - Theatre (Perimeter Institute for Theoretical Physics)
URL:https://events.perimeterinstitute.ca/event/23/contributions/403/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Conclusive Remarks
DTSTART:20221007T194500Z
DTEND:20221007T200000Z
DTSTAMP:20230922T211700Z
UID:indico-contribution-459@events.perimeterinstitute.ca
DESCRIPTION:Speakers: Celine Zwikel (Perimeter Institute)\, Luca Ciambelli
(Perimeter Institute)\n\nhttps://events.perimeterinstitute.ca/event/23/co
ntributions/459/
LOCATION:PI/1-100 - Theatre (Perimeter Institute for Theoretical Physics)
URL:https://events.perimeterinstitute.ca/event/23/contributions/459/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Welcome & Opening Remarks
DTSTART:20221003T135000Z
DTEND:20221003T140000Z
DTSTAMP:20230922T211700Z
UID:indico-contribution-367@events.perimeterinstitute.ca
DESCRIPTION:Speakers: Celine Zwikel (Perimeter Institute)\, Luca Ciambelli
(Perimeter Institute)\n\nhttps://events.perimeterinstitute.ca/event/23/co
ntributions/367/
LOCATION:PI/1-100 - Theatre (Perimeter Institute for Theoretical Physics)
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:20221003T150500Z
DTEND:20221003T160000Z
DTSTAMP:20230922T211700Z
UID:indico-contribution-369@events.perimeterinstitute.ca
DESCRIPTION:Speakers: Adrien Fiorucci (Technische Universität Wien)\n\nht
tps://events.perimeterinstitute.ca/event/23/contributions/369/
LOCATION:PI/1-100 - Theatre (Perimeter Institute for Theoretical Physics)
URL:https://events.perimeterinstitute.ca/event/23/contributions/369/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Review Talk: An introduction to coadjoint orbits cont.
DTSTART:20221003T183500Z
DTEND:20221003T193000Z
DTSTAMP:20230922T211700Z
UID:indico-contribution-410@events.perimeterinstitute.ca
DESCRIPTION:Speakers: Andrea Campoleoni (University Of Mons)\n\nhttps://ev
ents.perimeterinstitute.ca/event/23/contributions/410/
LOCATION:PI/1-100 - Theatre (Perimeter Institute for Theoretical Physics)
URL:https://events.perimeterinstitute.ca/event/23/contributions/410/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Carrollian spaces at infinity: an embedding space picture
DTSTART:20221007T181500Z
DTEND:20221007T184500Z
DTSTAMP:20230922T211700Z
UID:indico-contribution-396@events.perimeterinstitute.ca
DESCRIPTION:Speakers: Jakob Salzer (Université Libre de Bruxelles)\n\nIn
this talk\, I will discuss certain homogeneous spaces of the Poincaré gro
up that correspond to the well-known asymptotic regions of asymptotically
flat spacetimes: time-\, space-\, and light-like infinity. I will then sho
w that all of these spaces admit a uniform description as surfaces embedde
d in a higher-dimensional space. I will conclude with some comments concer
ning the computation of correlators of conformal carrollian theories from
this embedding space picture.\n\nhttps://events.perimeterinstitute.ca/even
t/23/contributions/396/
LOCATION:PI/1-100 - Theatre (Perimeter Institute for Theoretical Physics)
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:20221006T201500Z
DTEND:20221006T211500Z
DTSTAMP:20230922T211700Z
UID:indico-contribution-390@events.perimeterinstitute.ca
DESCRIPTION:Speakers: Kasia Rejzner (University of York)\n\nThis talk focu
ses on classical features of asymptotic QED\, i.e. the limit of QED at nul
l 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 mean
s to be a symmetry of the model. I will make the connection between this p
erspective and the earlier findings of Herdegen (JMP 1996) and Strominger
et.al. (JHEP 2014) concerning large gauge symmetries in QED. This is based
on a joint paper with Michele Schiavina (CMP 2021).\n\nhttps://events.per
imeterinstitute.ca/event/23/contributions/390/
LOCATION:PI/1-100 - Theatre (Perimeter Institute for Theoretical Physics)
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:20221007T150000Z
DTEND:20221007T153000Z
DTSTAMP:20230922T211700Z
UID:indico-contribution-393@events.perimeterinstitute.ca
DESCRIPTION:Speakers: Aldo Riello (Perimeter Institute)\n\nOn Tuesday\, M.
Schiavina laid out the theoretical framework for the symplectic reduction
of gauge theories in the presence of corners. In this talk I will apply t
his theoretical framework to Yang-Mills theory on a null boundary and show
how a pair of soft charges controls the residual (corner) gauge symmetry
after the first-stage symplectic reduction\, and therefore the superselect
ion structure of the theory after the second-stage symplectic reduction. I
will also discuss the subtleties of the gauge A_u = 0\, the interpretatio
n of electromagnetic memory as superselection\, and how the nonlinear stru
cture of the non-Abelian theory complicates this picture.\n\nhttps://event
s.perimeterinstitute.ca/event/23/contributions/393/
LOCATION:PI/1-100 - Theatre (Perimeter Institute for Theoretical Physics)
URL:https://events.perimeterinstitute.ca/event/23/contributions/393/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Review Talk: An introduction to coadjoint orbits
DTSTART:20221003T173000Z
DTEND:20221003T182500Z
DTSTAMP:20230922T211700Z
UID:indico-contribution-409@events.perimeterinstitute.ca
DESCRIPTION:Speakers: Andrea Campoleoni (University Of Mons)\n\nWe begin b
y reviewing the role of coadjoint orbits in the representation theory of
nilpotents groups and then\, to connect with the recent applications in p
hysics of coadjoint orbits "around the corner" of the mathematical framew
ork developed by Kirillov\, we review the classification of coadjoint orb
its of the Virasoro group. This will allow us to connect with more recent
developments\, including e.g. the study of coadjoint orbits of BMS algeb
ras.\n\nhttps://events.perimeterinstitute.ca/event/23/contributions/409/
LOCATION:PI/1-100 - Theatre (Perimeter Institute for Theoretical Physics)
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:20221007T153000Z
DTEND:20221007T163000Z
DTSTAMP:20230922T211700Z
UID:indico-contribution-395@events.perimeterinstitute.ca
DESCRIPTION:Speakers: Marios Petropoulos (Ecole polytechnique - CNRS)\n\nI
n this talk I will explore the role of the boundary Cotton tensor in the r
econstruction of the solution space of four-dimensional asymptotically AdS
and mostly asymptotically flat spacetimes. I will discuss charges from a
purely boundary perspective\, which emerge in sets of electric and magneti
c towers\, not necessarily conserved and possibly including subleading com
ponents.\n\nhttps://events.perimeterinstitute.ca/event/23/contributions/39
5/
LOCATION:PI/1-100 - Theatre (Perimeter Institute for Theoretical Physics)
URL:https://events.perimeterinstitute.ca/event/23/contributions/395/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Gong Show
DTSTART:20221003T200000Z
DTEND:20221003T213000Z
DTSTAMP:20230922T211700Z
UID:indico-contribution-411@events.perimeterinstitute.ca
DESCRIPTION:Speakers: Florian Ecker (Technische Universität Wien)\, Rouka
ya Dekhil (Ludwig Maximilian University of Munich)\, Arnaud Delfante (Univ
ersity of Mons)\, Gloria Odak (Centre de Physique Théorique)\, Ankit Agga
rwal (University of Amsterdam)\, Monireh Ahmadpour (University of Tehran)\
, Giovanni Canepa (Centre de Physique Théorique)\n\nSpeaker Order:\nAnkit
Aggarwal\, University of Amsterdam\nMonireh Ahmadpour\, University of Teh
ran\nGiovanni Canepa\, Centre de Physique Théorique\nRoukaya Dekhil\, Lud
wig Maximilian University\nArnaud Delfante\, University of Mons\nFlorian E
cker\, Technische Universität Wien\nGloria Odak\, Centre de Physique Thé
orique\n\nhttps://events.perimeterinstitute.ca/event/23/contributions/411/
LOCATION:PI/1-100 - Theatre (Perimeter Institute for Theoretical Physics)
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:20221003T140000Z
DTEND:20221003T145500Z
DTSTAMP:20230922T211700Z
UID:indico-contribution-368@events.perimeterinstitute.ca
DESCRIPTION:Speakers: Adrien Fiorucci (Technische Universität Wien)\n\nTh
is lecture aims at introducing the notion of asymptotic symmetries in grav
ity and the derivation of the related surface charges by means of covarian
t phase space techniques. First\, after a short historical introduction\,
I will rigorously define what is meant by “asymptotic symmetry” within
the so-called gauge-fixing approach. The problem of fixing consistent bou
ndary conditions and the formulation of the variational principle will be
briefly discussed. In the second part of the lecture\, I will introduce th
e covariant phase space formalism\, as conceived by Wald and coworkers thi
rty years ago\, which adapts the Hamiltonian formulation of classical mech
anics to Lagrangian covariant field theories. With the help of this fantas
tic tool\, I will elaborate on the construction of canonical surface charg
es associated with asymptotic symmetries and address the crucial questions
of their conservation and integrability on the phase space. In the third
and last part\, I will conclude with an analysis of the algebraic properti
es of the surface charges\, describing in which sense they represent the a
symptotic symmetry algebra in full generality\, without assuming conservat
ion or integrability. For pedagogical purposes\, the theoretical concepts
will be illustrated throughout in the crucial and well-known case of radia
tive asymptotically flat spacetimes in four dimensions\, as described by E
instein’s theory of General Relativity\, and where many spectacular and
unexpected features appear even in the simplest case of historical asympto
tically Minkowskian boundary conditions. In particular\, I will show that
the surface charge algebra contains the physical information on the flux o
f energy and angular momentum at null infinity in the presence of gravitat
ional radiation.\n\nhttps://events.perimeterinstitute.ca/event/23/contribu
tions/368/
LOCATION:PI/1-100 - Theatre (Perimeter Institute for Theoretical Physics)
URL:https://events.perimeterinstitute.ca/event/23/contributions/368/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Carrollian Perspective on Celestial Holography
DTSTART:20221004T150000Z
DTEND:20221004T153000Z
DTSTAMP:20230922T211700Z
UID:indico-contribution-402@events.perimeterinstitute.ca
DESCRIPTION:Speakers: Romain Ruzziconi (Technische Universität Wien)\n\n
The flat space holography program aims at describing quantum gravity in as
ymptotically flat spacetime in terms of a dual lower-dimensional field the
ory. Two different roads to construct flat space holography have emerged.
The first consists of a 4d bulk / 3d boundary duality\, called Carrollian
holography\, where 4d gravity is suggested to be dual to a 3d Carrollian C
FT living on the null boundary of the spacetime. The second is a 4d bulk /
2d boundary duality\, called celestial holography\, where 4d gravity is d
ual to a 2d CFT living on the celestial sphere. I will argue that these tw
o seemingly contradictory proposals are actually related. The Carrollian o
perators will be mapped to the celestial operators using an appropriate in
tegral transform. The Ward identities of the sourced Carrollian CFT\, enco
ding the gravitational flux-balance laws\, will be shown to reproduce thos
e of the 2d celestial CFT\, encoding the bulk soft theorems.\n\nhttps://ev
ents.perimeterinstitute.ca/event/23/contributions/402/
LOCATION:PI/1-100 - Theatre (Perimeter Institute for Theoretical Physics)
URL:https://events.perimeterinstitute.ca/event/23/contributions/402/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Towers of soft operators and celestial holography
DTSTART:20221005T140000Z
DTEND:20221005T143000Z
DTSTAMP:20230922T211700Z
UID:indico-contribution-408@events.perimeterinstitute.ca
DESCRIPTION:Speakers: Ana Maria Raclariu (Perimeter Institute)\n\nThe tree
-level soft theorems were recently shown to arise from the conservation of
infinite towers of charges extracted from the asymptotic Einstein equatio
ns. There is evidence this tower promotes the extended BMS algebra to an i
nfinite higher-spin symmetry algebra. In this talk I will introduce towers
of canonically conjugate memory and Goldstone operators\, highlighting th
eir role in parameterizing the gravitational phase space. I will discuss t
he conditions under which these towers provide a complete set of scatterin
g states and demonstrate that they are the building blocks of both soft an
d hard charges. I will finally show that the tower of tree level soft symm
etries can be used to extend the Dirac (Faddeev-Kulish) dressings to inclu
de the infinite towers of Goldstones and comment on their implications for
the gravitational S-matrix.\n\nhttps://events.perimeterinstitute.ca/event
/23/contributions/408/
LOCATION:PI/1-100 - Theatre (Perimeter Institute for Theoretical Physics)
URL:https://events.perimeterinstitute.ca/event/23/contributions/408/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Conformal Carroll Scalar Actions
DTSTART:20221006T150000Z
DTEND:20221006T153000Z
DTSTAMP:20230922T211700Z
UID:indico-contribution-386@events.perimeterinstitute.ca
DESCRIPTION:Speakers: Gerben Oling (NORDITA)\n\nI will construct explicit
actions that are invariant under BMS/conformal Carroll symmetries. Over th
e last few years\, we have developed a systematic procedure for constructi
ng non-Lorentzian theories from limits and expansions of Lorentzian theori
es. To obtain explicit examples of candidate dual field theories for flat
space holography\, I apply this procedure to the conformally coupled scal
ar action\, which leads to two classes of actions that are invariant under
conformal Carroll symmetries. Time permitting\, I will briefly mention on
going work on the computation and classification of Weyl anomalies in such
theories.\n\nhttps://events.perimeterinstitute.ca/event/23/contributions/
386/
LOCATION:PI/1-100 - Theatre (Perimeter Institute for Theoretical Physics)
URL:https://events.perimeterinstitute.ca/event/23/contributions/386/
END:VEVENT
BEGIN:VEVENT
SUMMARY:A Celestial Matrix Model
DTSTART:20221006T191500Z
DTEND:20221006T194500Z
DTSTAMP:20230922T211700Z
UID:indico-contribution-430@events.perimeterinstitute.ca
DESCRIPTION:Speakers: Charles Marteau (University of British Columbia)\n\n
We construct a Hermitian random matrix model that provides a stable non-pe
rturbative completion of Cangemi-Jackiw (CJ) gravity\, a two-dimensional t
heory of black holes in asymptotically flat spacetimes. The matrix model r
eproduces\, to all orders in the topological expansion\, the Euclidean par
tition function of CJ gravity with an arbitrary number of boundaries. The
non-perturbative completion enables the exact computation of observables i
n flat space quantum gravity which we use to explicitly characterize the B
ondi Hamiltonian spectrum. We discuss the implications of our results for
the flat space S-matrix and black holes.\n\nhttps://events.perimeterinstit
ute.ca/event/23/contributions/430/
LOCATION:PI/1-100 - Theatre (Perimeter Institute for Theoretical Physics)
URL:https://events.perimeterinstitute.ca/event/23/contributions/430/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Horizons\, fluid and what non-linearities might await
DTSTART:20221006T153000Z
DTEND:20221006T163000Z
DTSTAMP:20230922T211700Z
UID:indico-contribution-387@events.perimeterinstitute.ca
DESCRIPTION:Speakers: Luis Lehner (Perimeter Institute)\n\nWe analyze\, fi
rst from a geometric point of view\, the behavior\nof dynamical horizons.
We then connect with Carrolian fluids and discuss potential phenomena stem
ming from non-linearities\nin the resulting equations\n[This is joint work
with Jaime Redondo Yuste]\n\nhttps://events.perimeterinstitute.ca/event/2
3/contributions/387/
LOCATION:PI/1-100 - Theatre (Perimeter Institute for Theoretical Physics)
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:20221004T130000Z
DTEND:20221004T140000Z
DTSTAMP:20230922T211700Z
UID:indico-contribution-400@events.perimeterinstitute.ca
DESCRIPTION:Speakers: Laurent Freidel (Perimeter Institute)\n\nIn this int
roductory talk\, I will present a new perspective about quantum gravity wh
ich is rooted deeply in a renewed understanding of local symmetries in Gra
vity that appears when we decompose gravitational systems into subsystems.
\nI will emphasize the central role of the corner symmetry group in captu
ring all the necessary data needed to glue back seamlessly quantum spaceti
me regions. I will present how the charge conservation associated with the
se symmetries encoded the dynamics of null surfaces.\nFinally\, I will als
o present how the representation theory of the corner symmetry arises and
provides a representation of quantum geometry\, and I will show that defo
rmations of this symmetry can be the explanation for a fundamental plancki
an cut-off. \nI will also mention how these symmetry groups reduce to asym
ptotic symmetry groups and control asymptotic gravitational dynamics when
the entangling sphere is moved to infinity. If time permits\, I will expla
in how these symmetries control asymptotic gravitational dynamics. And I w
ill describe how they provide a new picture of the nature of quantum radia
tion.\nOverall\, this new paradigm allows to connect semi-classical gravit
ational physics\, S-matrix theory\, and non-perturbative quantum gravity t
echniques.\nThe talk's goal is to give an overall flavor of how these conn
ections appear from an elementary understanding of symmetries.\n\nhttps://
events.perimeterinstitute.ca/event/23/contributions/400/
LOCATION:PI/1-100 - Theatre (Perimeter Institute for Theoretical Physics)
URL:https://events.perimeterinstitute.ca/event/23/contributions/400/
END:VEVENT
BEGIN:VEVENT
SUMMARY:The partial Bondi gauge
DTSTART:20221005T153000Z
DTEND:20221005T163000Z
DTSTAMP:20230922T211700Z
UID:indico-contribution-383@events.perimeterinstitute.ca
DESCRIPTION:Speakers: Marc Geiller (École Normale Supérieure de Lyon)\n
\nI will review the recent construction of an extended solution space for
gravity\, based on a so-called partial Bondi gauge fixing. This aims at in
vestigating the possible relaxations of the boundary conditions\, in order
to include for example a cosmological constant\, a polyhomogeneous expans
ion\, and an arbitrary time-dependent boundary metric. I will also explain
how to properly map these results to the Newman-Penrose formalism. Finall
y\, I will discuss the application to three-dimensional gravity\, where a
new asymptotic symmetry can be revealed after working out all the subtleti
es of the covariant phase space formalism.\n\nhttps://events.perimeterinst
itute.ca/event/23/contributions/383/
LOCATION:PI/1-100 - Theatre (Perimeter Institute for Theoretical Physics)
URL:https://events.perimeterinstitute.ca/event/23/contributions/383/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Cutting Corners with Celestial CFT
DTSTART:20221006T181500Z
DTEND:20221006T191500Z
DTSTAMP:20230922T211700Z
UID:indico-contribution-388@events.perimeterinstitute.ca
DESCRIPTION:Speakers: Sabrina Pasterski\n\nCelestial Holography proposes a
duality between gravitational scattering in asymptotically flat spacetime
s and a conformal field theory living on the celestial sphere. The main mo
tivation for this program comes from the connection between soft theorems
and asymptotic symmetries in asymptotically flat spacetimes\, and our abil
ity to recast soft operators as currents in a codimension 2 CFT. \n\nWe pr
esent a streamlined route from asymptotic symmetries in 4D asymptotically
flat spacetimes to currents in a 2D celestial CFT in a manner that makes t
heir relation to QFT soft theorems manifest. We use this to re-examine the
bulk picture of radial evolution in the 2D theory and reconcile the const
ruction of charges in CCFT with the more familiar construction from AdS/CF
T\, despite the differing codimension. \n\nIn the process\, we point out h
ow the Carrollian and Celestial perspectives amount to slicing the bulk an
d boundary in different ways — our celestial slices cut through the usua
l corner! — and emphasize how these perspectives inform each other. \n\
nBased on 2201.06805\, 2202.11127 and 2205.10901\n\nhttps://events.perimet
erinstitute.ca/event/23/contributions/388/
LOCATION:PI/1-100 - Theatre (Perimeter Institute for Theoretical Physics)
URL:https://events.perimeterinstitute.ca/event/23/contributions/388/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Residual gauge symmetries in the front form
DTSTART:20221004T140000Z
DTEND:20221004T143000Z
DTSTAMP:20230922T211700Z
UID:indico-contribution-401@events.perimeterinstitute.ca
DESCRIPTION:Speakers: Sucheta Majumdar (École Normale Supérieure de Lyon
)\n\nThe goal of this talk is to discuss residual gauge symmetries in elec
tromagnetism and gravity in Dirac's front form. Working in the light-cone
gauge\, I will demonstrate how the large gauge transformations and BMS sup
ertranslations may be obtained from residual gauge invariance of the Hamil
tonian action. The residual gauge symmetries in this (2+2) formulation sha
re some striking similarities with the asymptotic symmetries in the conven
tional (3+1) Hamiltonian formulation. I will illustrate this fact using th
e example of electromagnetism and show how the the zero modes play a cruci
al role akin to boundary degrees of freedom in the asymptotic analysis at
spatial infinity à la Henneaux-Troessaert.\n\nhttps://events.perimeterins
titute.ca/event/23/contributions/401/
LOCATION:PI/1-100 - Theatre (Perimeter Institute for Theoretical Physics)
URL:https://events.perimeterinstitute.ca/event/23/contributions/401/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Orbit Analysis of Corner Symmetries
DTSTART:20221005T130000Z
DTEND:20221005T140000Z
DTSTAMP:20230922T211700Z
UID:indico-contribution-407@events.perimeterinstitute.ca
DESCRIPTION:Speakers: Robert Leigh (University of Illinois at Urbana-Champ
aign)\n\nCorner symmetries are those diffeomorphisms that become physical
in codimension two\, in that they support non-zero Noether charges. Recent
ly we have shown how to extend phase space so that all such charges are in
tegrable and give a representation of the corner symmetry algebra on this
extended phase space. More recently we have studied the coadjoint orbits o
f what we now call the universal corner symmetry. One finds that certain c
omplementary subalgebras\, the extended corner symmetry and the asymptotic
corner symmetry\, can be associated with finite-distance and asymptotic c
orners\, respectively. There is a simple geometric interpretation here in
terms of an Atiyah Lie algebroid over a corner\, whose structure group is
the universal corner symmetry. The local geometry of a classical spacetime
is encoded in related geometric structures.\n\nhttps://events.perimeterin
stitute.ca/event/23/contributions/407/
LOCATION:PI/1-100 - Theatre (Perimeter Institute for Theoretical Physics)
URL:https://events.perimeterinstitute.ca/event/23/contributions/407/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Matrix quantization of gravitational edge modes
DTSTART:20221005T150000Z
DTEND:20221005T153000Z
DTSTAMP:20230922T211700Z
UID:indico-contribution-382@events.perimeterinstitute.ca
DESCRIPTION:Speakers: Antony Speranza (University of Illinois at Urbana-Ch
ampaign)\n\nThe phase space of gravity restricted to a subregion bounded b
y a codimension-2 corner possesses an infinite-dimensional symmetry algebr
a consisting of diffeomorphisms of the 2-sphere and local SL(2\,R) transfo
rmations of the normal planes. I will describe a deformation of a subalge
bra preserving an area form on the sphere\, and show that it leads to the
finite dimensional algebra SU(N\,N)\, reminiscent of older results concern
ing the fuzzy sphere\, in which area-preserving diffeomorphisms are deform
ed to SU(N). This deformation is conjectured to be relevant to the quanti
zation of the local gravitational phase space\, and I will further demonst
rate that the representation of SU(N\,N) appearing in the quantization can
be determined by matching the Casimir operators of the deformed algebra t
o classical phase space invariants. Based on 2012.10367 and upcoming work
with W. Donnelly\, L. Freidel\, and S.F. Moosavian.\n\nhttps://events.per
imeterinstitute.ca/event/23/contributions/382/
LOCATION:PI/1-100 - Theatre (Perimeter Institute for Theoretical Physics)
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:20221004T184500Z
DTEND:20221004T194500Z
DTSTAMP:20230922T211700Z
UID:indico-contribution-404@events.perimeterinstitute.ca
DESCRIPTION:Speakers: Massimo Porrati (New York University)\n\nThis talk r
eviews the use of radial quantization to compute Chern-Simons partition fu
nctions on handlebodies of arbitrary genus. The partition function is give
n by a particular transition amplitude between two states which are define
d on the Riemann surfaces that define the (singular) foliation of the hand
lebody. By requiring that the only singularities of the gauge field insid
e the handlebody must be compatible with Wilson loop insertions\, we find
that the Wilson loop shifts the holonomy of the initial state. Together wi
th an appropriate choice of normalization\, this procedure selects a uniqu
e state in the Hilbert space obtained from a Kähler quantization of the t
heory on the constant-radius Riemann surfaces. Radial quantization allows
us to find the partition functions of Abelian Chern-Simons theories for ha
ndlebodies of arbitrary genus. For non-Abelian compact gauge groups\, we s
how that our method reproduces the known partition function and Wilson loo
p VEVs at genus one.\n\nhttps://events.perimeterinstitute.ca/event/23/cont
ributions/404/
LOCATION:PI/1-100 - Theatre (Perimeter Institute for Theoretical Physics)
URL:https://events.perimeterinstitute.ca/event/23/contributions/404/
END:VEVENT
END:VCALENDAR