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BEGIN:VEVENT
SUMMARY:Edward Witten (IAS)
DTSTART:20200413T190000Z
DTEND:20200413T200000Z
DTSTAMP:20260404T110830Z
UID:WHCGP/1
DESCRIPTION:Title: Volumes and random matrices\nby Edward Witten (IAS) as part of We
stern Hemisphere colloquium on geometry and physics\n\n\nAbstract\nI will
describe recent results relating two-dimensional gravity and supergravity\
; volumes of moduli spaces of Riemann surfaces and super Riemann surfaces\
; and random matrix ensembles. See arXiv:1907.03363 by Saad\, Shenker\, and Stanford.\n
LOCATION:https://stable.researchseminars.org/talk/WHCGP/1/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Kevin Costello (Perimeter Institute)
DTSTART:20200427T190000Z
DTEND:20200427T200000Z
DTSTAMP:20260404T110830Z
UID:WHCGP/2
DESCRIPTION:Title: Topological strings\, twistors\, and Skyrmions\nby Kevin Costello
(Perimeter Institute) as part of Western Hemisphere colloquium on geometr
y and physics\n\n\nAbstract\nIt has long been known that holomorphic field
theories on twistor space lead to "physical" field theories on Minkowski
space. In this talk I will discuss a type I (unoriented) version of the to
pological B model on twistor space. The corresponding theory on Minkowski
space is a sigma-model with target the group SO(8). This is a variant of t
he Skyrme model that appears as the low-energy effective theory of mesons
in QCD. (The group SO(8) appears because of the Green-Schwarz mechanism in
the topological string). The origin of this model in the topological stri
ng implies many remarkable properties. For one thing\, the model is\, in a
certain sense\, integrable. Further\, although the Lagrangian is power-co
unting non-renormalizable\, counter-terms at all loops can be uniquely fix
ed.\n
LOCATION:https://stable.researchseminars.org/talk/WHCGP/2/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Miranda Cheng (University of Amsterdam)
DTSTART:20200518T190000Z
DTEND:20200518T200000Z
DTSTAMP:20260404T110830Z
UID:WHCGP/3
DESCRIPTION:Title: Quantum modularity from 3-manifolds\nby Miranda Cheng (University
of Amsterdam) as part of Western Hemisphere colloquium on geometry and ph
ysics\n\n\nAbstract\nQuantum modular forms are functions on rational numbe
rs that have rather mysterious weak modular properties. Mock modular forms
and false theta functions are examples of holomorphic functions on the up
per-half plane which lead to quantum modular forms. Inspired by the 3d-3d
correspondence in string theory\, a new topological invariants named homol
ogical blocks for (in particular plumbed) three-manifolds have been propos
ed a few years ago. My talk aims to explain the recent observations on the
quantum modular properties of the homological blocks\, as well as the rel
ation t\n
LOCATION:https://stable.researchseminars.org/talk/WHCGP/3/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Davide Gaiotto (Perimeter Institute)
DTSTART:20200601T190000Z
DTEND:20200601T200000Z
DTSTAMP:20260404T110830Z
UID:WHCGP/4
DESCRIPTION:Title: Integrable Kondo problems and affine geometric Langlands\nby Davi
de Gaiotto (Perimeter Institute) as part of Western Hemisphere colloquium
on geometry and physics\n\n\nAbstract\nI will present some work on integra
ble line defects in WZW models and their relation to 4d CS theory\, the IM
/ODe correspondence and affine generalizations of Geometric Langlands cons
tructions.\n
LOCATION:https://stable.researchseminars.org/talk/WHCGP/4/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Maxim Kontsevich (IHES)
DTSTART:20200615T190000Z
DTEND:20200615T200000Z
DTSTAMP:20260404T110830Z
UID:WHCGP/5
DESCRIPTION:Title: Space-time analyticity in QFT\nby Maxim Kontsevich (IHES) as part
of Western Hemisphere colloquium on geometry and physics\n\n\nAbstract\nI
will talk on a joint work with Graeme Segal. We propose a new axiomatics
for unitary quantum field theory which includes both Lorentzian and Euclid
ean signatures for curved space-time manifolds. The key to the definition
is certain ope\n
LOCATION:https://stable.researchseminars.org/talk/WHCGP/5/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Anton Kapustin (Cal Tech)
DTSTART:20200622T190000Z
DTEND:20200622T200000Z
DTSTAMP:20260404T110830Z
UID:WHCGP/6
DESCRIPTION:Title: From gapped phases of matter to Topological Quantum Field Theory and
back again\nby Anton Kapustin (Cal Tech) as part of Western Hemisphere
colloquium on geometry and physics\n\nAbstract: TBA\n
LOCATION:https://stable.researchseminars.org/talk/WHCGP/6/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Nima Arkani-Hamed (IAS)
DTSTART:20200706T190000Z
DTEND:20200706T200000Z
DTSTAMP:20260404T110830Z
UID:WHCGP/8
DESCRIPTION:Title: Spacetime\, Quantum Mechanics and Clusterhedra at Infinity\nby Ni
ma Arkani-Hamed (IAS) as part of Western Hemisphere colloquium on geometry
and physics\n\nAbstract: TBA\n
LOCATION:https://stable.researchseminars.org/talk/WHCGP/8/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Mina Aganagic (UC Berkeley)
DTSTART:20200713T190000Z
DTEND:20200713T200000Z
DTSTAMP:20260404T110830Z
UID:WHCGP/9
DESCRIPTION:Title: Knot categorification from mirror symmetry\, via string theory\nb
y Mina Aganagic (UC Berkeley) as part of Western Hemisphere colloquium on
geometry and physics\n\nAbstract: TBA\n
LOCATION:https://stable.researchseminars.org/talk/WHCGP/9/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Laura Fredrickson (Stanford / U. Oregon)
DTSTART:20200824T190000Z
DTEND:20200824T200000Z
DTSTAMP:20260404T110830Z
UID:WHCGP/10
DESCRIPTION:Title: The asymptotic geometry of the Hitchin moduli space\nby Laura Fr
edrickson (Stanford / U. Oregon) as part of Western Hemisphere colloquium
on geometry and physics\n\n\nAbstract\nHitchin's equations are a system of
gauge theoretic equations on a Riemann surface that are of interest in ma
ny areas including representation theory\, Teichmuller theory\, and the ge
ometric Langlands correspondence. The Hitchin moduli space carries a natur
al hyperkahler metric. An intricate conjectural description of its asympto
tic structure appears in the work of physicists Gaiotto-Moore-Neitzke and
there has been a lot of progress on this recently. I will discuss some rec
ent results using tools coming out of geometric analysis which are well-su
ited for verifying these extremely delicate conjectures. This strategy oft
en stretches the limits of what can currently be done via geometric analys
is\, and simultaneously leads to new insights into these conjectures.\n
LOCATION:https://stable.researchseminars.org/talk/WHCGP/10/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Greg Moore (Rutgers)
DTSTART:20200720T190000Z
DTEND:20200720T200000Z
DTSTAMP:20260404T110830Z
UID:WHCGP/11
DESCRIPTION:Title: Breaking News About\, Topologically Twisted Rank One N=2* Supersymme
tric Yang-Mills Theory On Four-Manifolds\, Without Spin\nby Greg Moore
(Rutgers) as part of Western Hemisphere colloquium on geometry and physic
s\n\nAbstract: TBA\n
LOCATION:https://stable.researchseminars.org/talk/WHCGP/11/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Sakura Schafer-Nameki (Oxford)
DTSTART:20200803T190000Z
DTEND:20200803T200000Z
DTSTAMP:20260404T110830Z
UID:WHCGP/12
DESCRIPTION:Title: 5d SCFTs: Symmetries and Moduli Spaces\nby Sakura Schafer-Nameki
(Oxford) as part of Western Hemisphere colloquium on geometry and physics
\n\nAbstract: TBA\n
LOCATION:https://stable.researchseminars.org/talk/WHCGP/12/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Marco Gualtieri (Univ. of Toronto)
DTSTART:20200817T190000Z
DTEND:20200817T200000Z
DTSTAMP:20260404T110830Z
UID:WHCGP/13
DESCRIPTION:Title: Branes in symplectic groupoids\nby Marco Gualtieri (Univ. of Tor
onto) as part of Western Hemisphere colloquium on geometry and physics\n\n
\nAbstract\nAfter reviewing coisotropic A-branes in symplectic manifolds a
nd their role in mirror symmetry and geometric quantization\, I will expla
in how the problem of holomorphic quantization of Poisson brackets may be
recast\, and in some cases solved\, as a problem of computing morphisms be
tween coisotropic branes in symplectic groupoids. This is joint work wit
h Francis Bischoff and Joshua Lackman.\n
LOCATION:https://stable.researchseminars.org/talk/WHCGP/13/
END:VEVENT
BEGIN:VEVENT
SUMMARY:David Jordan (Edinburgh)
DTSTART:20200914T190000Z
DTEND:20200914T200000Z
DTSTAMP:20260404T110830Z
UID:WHCGP/14
DESCRIPTION:Title: Quantum geometric Langlands as a fully extended TFT\nby David Jo
rdan (Edinburgh) as part of Western Hemisphere colloquium on geometry and
physics\n\n\nAbstract\nI will survey several recent works realizing Betti
geometric\nLanglands and its quantization as fully extended TFT's. In phys
ics terms\nthis is most closely related to the Kapustin-Witten twist of N=
4 d=4 SYM\nat generic values of \\Psi.\n\nI will outline numerous applicat
ions to quantum topology\, most notably\nto a conjecture of Witten on fini
te-dimensionality of skein modules\, a\nconjecture of Bonahon-Wong concern
ing skein modules at root-of-unity\nparameters\, a proposal of Ben-Zvi con
cerning cluster varieties and\nfactorization homology\, and an appearance
of the type-A spherical DAHA\nfrom a once-marked torus.\n\nFinally\, I wil
l present a novel conjectural appearance of S-duality in\nthe study of ske
in modules of 3-manifolds.\n
LOCATION:https://stable.researchseminars.org/talk/WHCGP/14/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Natalie Paquette (IAS)
DTSTART:20201005T190000Z
DTEND:20201005T200000Z
DTSTAMP:20260404T110830Z
UID:WHCGP/15
DESCRIPTION:Title: Borcherds-Kac-Moody algebras\, 2d strings\, & other curiosities\
nby Natalie Paquette (IAS) as part of Western Hemisphere colloquium on geo
metry and physics\n\n\nAbstract\nIn this talk we will extol the virtues of
compactifying critical string theory down to few noncompact spacetime dim
ensions (particularly two). These string vacua possess rich groups of dual
ities. BPS-saturated quantities\, which mathematically are described by au
tomorphic forms\, are invariant under such duality transformations. Furthe
r\, such BPS states can furnish representations of interesting algebras\,
such as infinite-dimensional Lie algebras. In this talk\, we explore some
particularly nice\, concrete examples\, which employ holomorphic super ver
tex operator algebras in our `compactification' theories. The BPS states i
n these models organize into representations of algebras\, which we prove
are (new) examples of Borcherds-Kac-Moody superalgebras.\n
LOCATION:https://stable.researchseminars.org/talk/WHCGP/15/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Ben Webster (Waterloo)
DTSTART:20200810T190000Z
DTEND:20200810T200000Z
DTSTAMP:20260404T110830Z
UID:WHCGP/16
DESCRIPTION:Title: 3d mirror symmetry and its discontents\nby Ben Webster (Waterloo
) as part of Western Hemisphere colloquium on geometry and physics\n\nAbst
ract: TBA\n
LOCATION:https://stable.researchseminars.org/talk/WHCGP/16/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Lauren Williams (Harvard)
DTSTART:20200921T190000Z
DTEND:20200921T200000Z
DTSTAMP:20260404T110830Z
UID:WHCGP/17
DESCRIPTION:Title: How is the hypersimplex related to the amplituhedron?\nby Lauren
Williams (Harvard) as part of Western Hemisphere colloquium on geometry a
nd physics\n\n\nAbstract\nIn 1987\, Gelfand-Goresky-MacPherson-Serganova m
ade a beautiful\nconnection between the geometry of the Grassmannian and c
onvex polytopes\, via\nthe moment map\; the moment map image of the Grassm
annian Gr(k\,n) is a polytope\nknown as the hypersimplex Delta(k\,n). In
2013\, motivated by the desire to\ngive a geometric basis for the computat
ion of scattering amplitudes in N=4\nSYM\, Arkani-Hamed and Trnka introduc
ed the amplituhedron A(n\,k\,m) as the image\nof the positive Grassmannian
Gr+(k\,n) under a linear map Z from R^n to R^{k+m}\nwhich is totally posi
tive. While the case m=4 is most relevant to physics\,\nthe amplituhedron
makes sense for any m. In my talk I will explain some\nstrange parallels
between the positroidal subdivisions of the hypersimplex\nDelta(k+1\,n) a
nd the m=2 amplituhedron A(n\,k\,2). One link is provided by the\npositiv
e tropical Grassmannian. Attributions: based on joint works with Tomek\nL
ukowski\, Matteo Parisi\, and David Speyer.\n\nDisclaimer: I'm neither a g
eometer nor a physicist.\n
LOCATION:https://stable.researchseminars.org/talk/WHCGP/17/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Mark Gross (Cambridge)
DTSTART:20200511T190000Z
DTEND:20200511T200000Z
DTSTAMP:20260404T110830Z
UID:WHCGP/18
DESCRIPTION:Title: Intrinsic Mirror Symmetry\nby Mark Gross (Cambridge) as part of
Western Hemisphere colloquium on geometry and physics\n\nAbstract: TBA\n
LOCATION:https://stable.researchseminars.org/talk/WHCGP/18/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Harold Williams (USC)
DTSTART:20201214T200000Z
DTEND:20201214T210000Z
DTSTAMP:20260404T110830Z
UID:WHCGP/19
DESCRIPTION:Title: Canonical Bases for Coulomb Branches\nby Harold Williams (USC) a
s part of Western Hemisphere colloquium on geometry and physics\n\n\nAbstr
act\nFollowing work of Kapustin-Saulina and Gaiotto-Moore-Neitzke\, one ex
pects half-BPS line defects in a 4d N=2 field theory to form a monoidal ca
tegory with a rich structure. In general\, a mathematical definition of th
is category is not known. In this talk we discuss an algebro-geometric pro
posal in the case of gauge theories with polarizable matter. The proposed
category is the heart of a nonstandard t-structure on the dg category of c
oherent sheaves on the derived Braverman-Finkelberg-Nakajima space of trip
les. We refer to its objects as Koszul-perverse coherent sheaves\, as this
t-structure interpolates between the perverse coherent t-structure and ce
rtain t-structures appearing in the theory of Koszul duality (specializing
to these in the case of a pure gauge theory and an abelian gauge theory\,
respectively). As a byproduct\, this defines a canonical basis in the ass
ociated quantized Coulomb branch by passing to classes of irreducible obje
cts. This is joint work with Sabin Cautis.\n
LOCATION:https://stable.researchseminars.org/talk/WHCGP/19/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Christopher Beem (Oxford)
DTSTART:20201102T200000Z
DTEND:20201102T210000Z
DTSTAMP:20260404T110830Z
UID:WHCGP/20
DESCRIPTION:Title: Hall-Littlewood chiral rings and derived Higgs branches\nby Chri
stopher Beem (Oxford) as part of Western Hemisphere colloquium on geometry
and physics\n\n\nAbstract\nI will discuss a relatively novel algebraic st
ructure arising in four-dimensional N=2 superconformal field theories: the
Hall-Littlewood Chiral Ring (HLCR). The HLCR is an enhancement of the mor
e familiar Higgs branch chiral ring (which encodes the Higgs branch of the
moduli space of vacua as an algebraic variety). The HLCR in gauge theorie
s is constructed as the cohomology of a kind of BRST complex\, which allow
s it to be identified with the ring of functions on the derived Higgs bran
ch (in the sense of derived algebraic geometry). I will describe the solut
ion of the HLCR cohomology problem for a large class of Lagrangian theorie
s (the class S theories of type A1)\, which illustrate some interesting ph
enomena. This talk is based on work in progress with Diego Berdeja Suárez
.\n
LOCATION:https://stable.researchseminars.org/talk/WHCGP/20/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Sergei Gukov (Cal Tech)
DTSTART:20201116T200000Z
DTEND:20201116T210000Z
DTSTAMP:20260404T110830Z
UID:WHCGP/21
DESCRIPTION:Title: Rokhlin\, quantum groups\, and BPS states\nby Sergei Gukov (Cal
Tech) as part of Western Hemisphere colloquium on geometry and physics\n\n
\nAbstract\nWhat do ADO polynomials\, cobordism invariants\, and affine Gr
assmannians have in common? We will discuss how these seemingly different
objects can be put under one roof of a BPS q-series that\, on the one hand
\, can be thought of as a 3d analogue of the Vafa-Witten partition functio
n and\, on the other hand\, is associated to quantum groups at generic q w
here Verma modules with arbitrary complex weights play an important role.\
n
LOCATION:https://stable.researchseminars.org/talk/WHCGP/21/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Sourav Chatterjee (Stanford)
DTSTART:20201130T200000Z
DTEND:20201130T210000Z
DTSTAMP:20260404T110830Z
UID:WHCGP/22
DESCRIPTION:Title: Strong mass gap implies quark confinement\nby Sourav Chatterjee
(Stanford) as part of Western Hemisphere colloquium on geometry and physic
s\n\n\nAbstract\nI will show that if a lattice gauge theory has exponentia
l decay of correlations under arbitrary boundary conditions (which I call
strong mass gap)\, and the gauge group has a nontrivial center\, then Wils
on's area law holds.\n
LOCATION:https://stable.researchseminars.org/talk/WHCGP/22/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Djordje Radicevic (Brandeis)
DTSTART:20201019T190000Z
DTEND:20201019T200000Z
DTSTAMP:20260404T110830Z
UID:WHCGP/23
DESCRIPTION:Title: The Lattice-Continuum Correspondence in Quantum Mechanics\nby Dj
ordje Radicevic (Brandeis) as part of Western Hemisphere colloquium on geo
metry and physics\n\n\nAbstract\nIt is very well known that long-distance
correlation functions of many lattice systems can be calculated from conti
nuum QFTs. Making this correspondence more precise --- identifying continu
um operators that correspond to individual lattice operators\, or exhibiti
ng the lattice origins of subtler continuum phenomena like operator produc
t expansions --- has proven quite daunting. In this talk\, I will report o
n recent progress in this direction\, using quantum mechanics (QFT in 0+1
dimensions) as an example. I will show how a finite but large quantum syst
em can be systematically reduced to an Ersatz continuum theory\, using bot
h Hamiltonian and path integral formalisms. Along the way I will point out
the lattice origins of several familiar continuum concepts\, including co
ntact terms\, scale invariance\, and the distinction between compact and n
oncompact theories. I will also stress the limitations imposed on the emer
gent continuum theory by its lattice progenitor --- for instance\, any sup
ersymmetric continuum theory emerging from a finite theory must have a van
ishing Witten index.\n
LOCATION:https://stable.researchseminars.org/talk/WHCGP/23/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Mike Freedman (Microsoft Research/ UCSB)
DTSTART:20210111T200000Z
DTEND:20210111T210000Z
DTSTAMP:20260404T110830Z
UID:WHCGP/24
DESCRIPTION:Title: Quantum Codes and Systolic freedom\nby Mike Freedman (Microsoft
Research/ UCSB) as part of Western Hemisphere colloquium on geometry and p
hysics\n\n\nAbstract\nIn work with Hastings we find a two-way street betwe
en quantum\nerror correcting codes and Riemannian manifolds. A recent adva
nce in coding\ntheory allows us to produce the first example of a manifold
s with $Z_2$-power\nlaw-systolic freedom. Specifically we find\, for any$
e>0$\, a sequence of\nappropriately scaled 11D Riemannian manifolds $M_i$\
, so that for any dual 4 and\n7 dimensional $Z_2$-cycles\, $X_i$ and $Y_i$
\, resp.\n\n $ Vol_4(X_i)*Vol_7(Y_i) > (Vol_{11}(M_i))^{(5/4
-e)} $.\n
LOCATION:https://stable.researchseminars.org/talk/WHCGP/24/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Albrecht Klemm (Bonn)
DTSTART:20210125T200000Z
DTEND:20210125T210000Z
DTSTAMP:20260404T110830Z
UID:WHCGP/25
DESCRIPTION:Title: Calabi-Yau modularity and Feynman graphs\nby Albrecht Klemm (Bon
n) as part of Western Hemisphere colloquium on geometry and physics\n\n\nA
bstract\nUsing the GKZ system for the primitive cohomology of an infinite
series of complete intersection Calabi-Yau manifolds\, whose dimension is
the loop order minus one\, we completely clarify the analytic structure of
all banana integrals with arbitrary masses. In particular\, we find that
the leading logarithmic structure in the high energy regime\, which corres
ponds to the point of maximal unipotent monodromy\, is determined by a nov
el \\hat b-class evaluation in the ambient spaces of the mirror\, while th
e imaginary part of the amplitude in this regime is determined by the Î
“b-class of the mirror Calabi-Yau manifold itself. We provide simple clo
sed all loop formulas for the former as well as for the Frobenius κ-con
stants\, which determine the behaviour of the amplitudes\, when the moment
um square equals the sum of the masses squared\, in terms of zeta values.
We find the exact differential equation for the graph integrals with arbit
rary value for the dimensional regularisation (d-\\epsilon) parameter and
extend our previous work from three to four loops by providing for the lat
ter case a complete set of (inhomogenous) Picard-Fuchs differential ideal
for arbitrary masses. Using a recent p-adic analysis of the periods we det
ermine the value of the maximal cut equal mass four-loop amplitude at the
attractor points in terms of periods of modular weight two and four Hecke
eigenforms and the quasiperiods of their meromorphic cousins.\n
LOCATION:https://stable.researchseminars.org/talk/WHCGP/25/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Nikita Nekrasov (SCGP\, Stony Brook)
DTSTART:20210208T200000Z
DTEND:20210208T210000Z
DTSTAMP:20260404T110830Z
UID:WHCGP/26
DESCRIPTION:Title: Beauty of the defects\nby Nikita Nekrasov (SCGP\, Stony Brook) a
s part of Western Hemisphere colloquium on geometry and physics\n\n\nAbstr
act\nSurface and point-like defects in supersymmetric gauge theories in fo
ur dimensions are studied with applications to quantum/classical correspon
dence. In particular\, the GIL formula for the tau-function of Painleve VI
is explained using the blow-up method in the context of the BPS/CFT corre
spondence\, while the spin chain generalisation of Kharchev-Lebedev wavefu
nction of periodic Toda chain is obtained via wallcrossing. \n\nBased on s
everal works\, in particular on papers in collaboration with Saebyeok Jeon
g\; Norton Lee\; Oleksandr Tsymbaliuk\; as well as S. Jeong and N. Lee\n
LOCATION:https://stable.researchseminars.org/talk/WHCGP/26/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Tamas Hausel (IST\, Austria)
DTSTART:20210222T200000Z
DTEND:20210222T210000Z
DTSTAMP:20260404T110830Z
UID:WHCGP/27
DESCRIPTION:Title: Mirror symmetry for Langlands dual Higgs bundles at the tip of the n
ilpotent cone\nby Tamas Hausel (IST\, Austria) as part of Western Hemi
sphere colloquium on geometry and physics\n\n\nAbstract\nI will explain wh
at we can prove and what we conjecture about the mirror of Hecke transform
ed Hitchin section motivated by symmetry ideas of Kapustin-Witten. The tal
k is based on arXiv:2101.08583 joint with Hitchin.\n
LOCATION:https://stable.researchseminars.org/talk/WHCGP/27/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Thomas Dumitrescu (UCLA)
DTSTART:20210308T200000Z
DTEND:20210308T210000Z
DTSTAMP:20260404T110830Z
UID:WHCGP/28
DESCRIPTION:Title: 2-Group Global Symmetry in Quantum Field Theory\nby Thomas Dumit
rescu (UCLA) as part of Western Hemisphere colloquium on geometry and phys
ics\n\n\nAbstract\nHigher-form generalizations of global symmetries play a
n important role in Quantum Field Theory (QFT). In general\, symmetries of
different form degrees need not be independent\; instead\, they can form
a higher group. In this talk I will illustrate this phenomenon by explaini
ng why many simple Lagrangian QFTs in four and six dimensions enjoy 2-grou
p global symmetries. I will then apply this understanding to deduce new ge
neral results about (typically non-Lagrangian) SCFTs in six dimensions.\n
LOCATION:https://stable.researchseminars.org/talk/WHCGP/28/
END:VEVENT
BEGIN:VEVENT
SUMMARY:David Ben-Zvi (UT Austin)
DTSTART:20210322T190000Z
DTEND:20210322T200000Z
DTSTAMP:20260404T110830Z
UID:WHCGP/29
DESCRIPTION:Title: Electric-Magnetic Duality between Periods and L-functions\nby Da
vid Ben-Zvi (UT Austin) as part of Western Hemisphere colloquium on geomet
ry and physics\n\n\nAbstract\nI will describe joint work with Yiannis Sake
llaridis and Akshay Venkatesh\, in\nwhich ideas originating in quantum fie
ld theory are applied to a problem in\nnumber theory.\n\nA fundamental too
l in number theory\, the relative Langlands program\, is\ncentered on the
representation of L-functions of Galois representations as\nintegrals of a
utomorphic forms. However\, the data that naturally index these\nperiod in
tegrals (spherical varieties for a reductive group G) and the\nL-functions
(representations of the Langlands dual group G^) don't seem to line\nup\,
making the search for integral representations somewhat of an art. \n\nWe
present an approach to this problem via the Kapustin-Witten interpretatio
n\nof the [geometric] Langlands correspondence as electric-magnetic dualit
y for\n4-dimensional supersymmetric gauge theory. Namely\, we rewrite the
relative \nLanglands program as duality in the presence of boundary condit
ions. As a\nresult the partial correspondence between periods and L-functi
ons is embedded\nin a natural duality between Hamiltonian actions of the d
ual groups.\n
LOCATION:https://stable.researchseminars.org/talk/WHCGP/29/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Arnav Tripathy (Harvard)
DTSTART:20210405T190000Z
DTEND:20210405T200000Z
DTSTAMP:20260404T110830Z
UID:WHCGP/30
DESCRIPTION:Title: K3 metrics\nby Arnav Tripathy (Harvard) as part of Western Hemis
phere colloquium on geometry and physics\n\n\nAbstract\nIt has long been a
n open problem to explicitly produce a\nRicci-flat metric on a (non-toroid
al) compact manifold. I'll discuss two\napproaches to this problem\, relat
ed by a version of 3d mirror symmetry\,\nfor K3 manifolds. This is joint w
ork with M. Zimet.\n
LOCATION:https://stable.researchseminars.org/talk/WHCGP/30/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Cody Long/Cumrun Vafa (Harvard)
DTSTART:20210419T190000Z
DTEND:20210419T200000Z
DTSTAMP:20260404T110830Z
UID:WHCGP/31
DESCRIPTION:Title: Non-Holomorphic Cycles and Non-BPS Black Branes\nby Cody Long/Cu
mrun Vafa (Harvard) as part of Western Hemisphere colloquium on geometry a
nd physics\n\n\nAbstract\nWe discuss extremal non-BPS black holes and stri
ngs arising in M-theory compactifications on Calabi-Yau threefolds\, obtai
ned by wrapping M2 branes on non-holomorphic 2-cycles and M5 branes on non
-holomorphic 4-cycles. Using the attractor mechanism we compute the black
hole mass and black string tension\, leading to a conjectural formula for
the asymptotic volumes of connected\, locally volume-minimizing representa
tives of non-holomorphic\, even-dimensional homology classes in the threef
old\, without knowledge of an explicit metric. In the case of divisors we
find examples where the volume of the representative corresponding to the
black string is less than the volume of the minimal piecewise-holomorphic
representative\, predicting recombination for those homology classes and l
eading to stable\, non-BPS strings. We also show how to compute the centra
l charges of non-BPS strings in F-theory via a near-horizon AdS3 limit in
6d which\, upon compactification on a circle\, account for the asymptotic
entropy of extremal nonsupersymmetric 5d black holes (i.e.\, the asymptoti
c count of non-holomorphic minimal 2-cycles).\n
LOCATION:https://stable.researchseminars.org/talk/WHCGP/31/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Fei Yan (Rutgers)
DTSTART:20210503T190000Z
DTEND:20210503T200000Z
DTSTAMP:20260404T110830Z
UID:WHCGP/32
DESCRIPTION:Title: Two tales of networks and quantization\nby Fei Yan (Rutgers) as
part of Western Hemisphere colloquium on geometry and physics\n\n\nAbstrac
t\nI will describe two quantization scenarios. The first scenario involves
the construction of a quantum trace map computing a new link "invariant"
(with possible wall-crossing behavior) for links L in a 3-manifold M\, whe
re M is a Riemann surface C times a real line. This construction computes
familiar link invariants in a new way\, moreover it unifies that computati
on with the computation of protected spin characters counting ground state
s with spin for line defects in 4d N=2 theories of class-S. Certain networ
ks on C play an important role in the construction. The second scenario co
ncerns the study of Schroedinger equations and their higher order analogue
s\, which could arise in the quantization of Seiberg-Witten curves in 4d N
=2 theories. Here similarly certain networks play an important part in the
exact WKB analysis for these Schroedinger-like equations. At the end of m
y talk I will also try to sketch a possibility to bridge these two quantiz
ation scenarios. The first part of the talk is based on joint work with A.
Neitzke\; the final sketch is based on discussions with D. Gaiotto\, G. M
oore and A. Neitzke.\n
LOCATION:https://stable.researchseminars.org/talk/WHCGP/32/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Richard Thomas (Imperial College)
DTSTART:20210517T190000Z
DTEND:20210517T200000Z
DTSTAMP:20260404T110830Z
UID:WHCGP/33
DESCRIPTION:Title: Nonabelian DT theory from abelian DT theory\nby Richard Thomas (
Imperial College) as part of Western Hemisphere colloquium on geometry and
physics\n\n\nAbstract\nFix a Calabi-Yau 3-fold X. Its DT invariants count
stable bundles and sheaves on X. Joyce's generalised DT invariants count
semistable sheaves on X.\n\nI will describe ongoing work with Soheyla Feyz
bakhsh with the eventual aim of writing the generalised DT invariants in a
ny rank r in terms of rank 1 invariants. By the MNOP conjecture the latter
are determined by the GW invariants of X.\n\nAlong the way we express ran
k r DT invariants in terms of rank 0 invariants counting D4-D2-D0 branes.
These invariants are predicted by S-duality to be governed by (vector-valu
ed mock) modular forms.\n\nBased partly on arXiv:2007.03037 and arXiv:2103.02915 .\n
LOCATION:https://stable.researchseminars.org/talk/WHCGP/33/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Zohar Komargodski (SCGP\, Stony Brook)
DTSTART:20210607T190000Z
DTEND:20210607T200000Z
DTSTAMP:20260404T110830Z
UID:WHCGP/35
DESCRIPTION:Title: Higher central charges and gapped boundaries\nby Zohar Komargods
ki (SCGP\, Stony Brook) as part of Western Hemisphere colloquium on geomet
ry and physics\n\n\nAbstract\nThe chiral central charge is a famous diagno
stic of edge modes on the boundary of 2+1 dimensional topological phases.
We show that many theories with a vanishing chiral central charge neverthe
less cannot admit a gapped boundary. We define higher chiral central charg
es and investigate their properties.\n
LOCATION:https://stable.researchseminars.org/talk/WHCGP/35/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Sarah Harrison (McGill University)
DTSTART:20210712T190000Z
DTEND:20210712T200000Z
DTSTAMP:20260404T110830Z
UID:WHCGP/36
DESCRIPTION:Title: New BPS algebras from superstring compactifications\nby Sarah Ha
rrison (McGill University) as part of Western Hemisphere colloquium on geo
metry and physics\n\n\nAbstract\nBorcherds Kac-Moody (BKM) algebras are a
generalization of familiar Kac-Moody algebras with imaginary simple roots.
On the one hand\, they were invented by Borcherds in his proof of the mon
strous moonshine conjectures and have many interesting connections to new
moonshines\, number theory and the theory of automorphic forms. On the oth
er hand\, there is an old conjecture of Harvey and Moore that BPS states i
n string theory form an algebra that is in some cases a BKM algebra and wh
ich is based on certain signatures of BKMs observed in 4d threshold correc
tions and black hole physics. I will briefly review the construction of ne
w BKMs superalgebras arising from self-dual vertex operator algebras of ce
ntral charge 12\, and then discuss recent work showing how they arise as a
lgebras of BPS states in physical string theories in 2 dimensions\, as wel
l as their connection with automorphic forms. Based on work with N. Paquet
te\, D. Persson\, and R. Volpato. This can be seen as a follow-up to a tal
k given by N. Paquette at this series this past October.\n
LOCATION:https://stable.researchseminars.org/talk/WHCGP/36/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Theo Johnson-Freyd (Perimeter/Dalhousie)
DTSTART:20210726T190000Z
DTEND:20210726T200000Z
DTSTAMP:20260404T110830Z
UID:WHCGP/38
DESCRIPTION:Title: Semisimple higher categories\nby Theo Johnson-Freyd (Perimeter/D
alhousie) as part of Western Hemisphere colloquium on geometry and physics
\n\n\nAbstract\nSemisimple higher categories are a quantum version of topo
logical spaces (behaving sometimes like homotopy types and sometimes like
manifolds) in which cells are attached along superpositions of other cells
. Many operations from topology make sense for semisimple higher categorie
s: they have homotopy sets (not groups)\, loop spaces\, etc. For example\,
the extended operators in a topological sigma model form a semisimple hig
her category that can be thought of as a type of "cotangent bundle" of the
target space. The "symplectic pairing" on this "cotangent bundle" is meas
ured an S-matrix pairing aka Whitehead bracket defined on the homotopy set
s of any (pointed connected) semisimple higher category\, and the nondegen
eracy of this pairing is a type of Poincare or Atiyah duality. This is joi
nt work in progress with David Reutter.\n
LOCATION:https://stable.researchseminars.org/talk/WHCGP/38/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Nathan Seiberg (IAS)
DTSTART:20210927T190000Z
DTEND:20210927T200000Z
DTSTAMP:20260404T110830Z
UID:WHCGP/39
DESCRIPTION:Title: Comments on Lattice vs. Continuum Quantum Field Theory\nby Natha
n Seiberg (IAS) as part of Western Hemisphere colloquium on geometry and p
hysics\n\n\nAbstract\nThere is an interesting interplay between continuum
quantum field theory (QFT) and lattice systems. First\, as in condensed-ma
tter physics\, we start at short distances (UV) with a lattice model and o
ur goal is to find its long distance (IR) behavior. The lore is that this
behavior is captured by a continuum QFT. Conversely\, as is more common in
high-energy physics and mathematical physics\, the lattice theory is a fi
rst step toward a rigorous definition of the continuum theory. Despite eno
rmous progress over the past decades\, these two directions of the interpl
ay between the lattice and the continuum face interesting challenges. \n\n
Here\, motivated by recently discovered theoretical phases of matter (incl
uding the XY-plaquette model and models of fractons)\, we will address two
aspects of the relation between the lattice in the UV and the continuum i
n the IR. We will present lattice models exhibiting topological properties
of continuum theories\, like winding symmetries\, ‘t Hooft anomalies\,
and duality. We will use this approach to clarify the subsystem global sym
metries of some of the recently discovered exotic models. We will also dis
cuss some more dynamical aspects of these systems and in particular their
enigmatic UV/IR mixing\; i.e.\, some long-distance properties are sensitiv
e to short-distance details.\n
LOCATION:https://stable.researchseminars.org/talk/WHCGP/39/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Ryan Thorngren (Harvard University)
DTSTART:20211011T190000Z
DTEND:20211011T200000Z
DTSTAMP:20260404T110830Z
UID:WHCGP/40
DESCRIPTION:Title: A Tour of Categorical Symmetry\nby Ryan Thorngren (Harvard Unive
rsity) as part of Western Hemisphere colloquium on geometry and physics\n\
n\nAbstract\nA categorical symmetry is a category acting as a symmetry of
a QFT. These symmetries correspond to the topological operators in the QFT
. I'll try to motivate this definition with some simple examples. Then I'l
l discuss a bulk-boundary correspondence which in finite situations allows
us to classify gapped phases with categorical symmetry and define things
like anomalous symmetries and gauging. I'll conclude with some more exampl
es of topological operators in c = 1 CFTs and describe a Noether theorem f
or continuous categorical symmetries.\n
LOCATION:https://stable.researchseminars.org/talk/WHCGP/40/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Ibrahima Bah (Johns Hopkins Univ.)
DTSTART:20211025T190000Z
DTEND:20211025T200000Z
DTSTAMP:20260404T110830Z
UID:WHCGP/41
DESCRIPTION:Title: Non-supersymmetric smooth solitonic solutions in Einstein-Maxwell ty
pe theories\nby Ibrahima Bah (Johns Hopkins Univ.) as part of Western
Hemisphere colloquium on geometry and physics\n\n\nAbstract\nIn this talk
I will present a recent framework to construct and study smooth horizon-le
ss non-supersymmetric solutions in gravity with interesting topologies. Th
ese live in backgrounds that are 4d Minkowski with tori of various dimensi
ons. I will discuss the physical mechanism that allows for their existence
and comment on their classical and thermodynamic stability. I will descri
be a family of these constructions that resolve certain curvature singular
ities.\n
LOCATION:https://stable.researchseminars.org/talk/WHCGP/41/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Tony Pantev (University of Pennsylvania)
DTSTART:20211108T200000Z
DTEND:20211108T210000Z
DTSTAMP:20260404T110830Z
UID:WHCGP/42
DESCRIPTION:Title: Geometry and topology of wild character varieties\nby Tony Pante
v (University of Pennsylvania) as part of Western Hemisphere colloquium on
geometry and physics\n\n\nAbstract\nWild character varieties parametrize
monodromy\nrepresentations of flat meromorphic connections on compact Riem
ann\nsurfaces. They are classical objects with remarkable geometric and\nt
opological properties. \n\nI will recall how intrinsic geometric structure
s resolve singularities\nof wild character varieties and will show that th
eir algebraic\nsymplectic structures extend naturally to the resolutions.
This is\nbased on a new universal method for producing symplectic structu
res\nwhich is a joint work with Arinkin and Toen. I will also describe re
cent joint works with\nChuang\, Diaconescu\, Donagi\, and Nawata in which
we use string dualities \nto extract cohomological invariants of twisted w
ild character\nvarieties from BPS counts on Calabi-Yau threefolds and ref
ined\nChern-Simons invariants of torus knots.\n
LOCATION:https://stable.researchseminars.org/talk/WHCGP/42/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Lotte Hollands (Heriot-Watt University)
DTSTART:20211122T200000Z
DTEND:20211122T210000Z
DTSTAMP:20260404T110830Z
UID:WHCGP/43
DESCRIPTION:Title: Partition functions\, BPS states and abelianization\nby Lotte Ho
llands (Heriot-Watt University) as part of Western Hemisphere colloquium o
n geometry and physics\n\n\nAbstract\nIn this talk I will re-express the N
ekrasov-Shatashvili partition function for a four-dimensional N=2 gauge th
eory as an integral of a ratio of Wronskians of solutions to the relevant
oper equation\, with the AD2 theory and the pure SU(2) theory as two main
examples. This motivates the definition of a generalized Nekrasov-Shatashv
ili partition function for any four-dimensional N=2 theory of class S\, an
d makes a connection with abelianization and exact WKB analysis. We will e
nd with some remarks regarding the five-dimensional generalization and the
relation to similar mathematical structures underlying the topological st
ring partition function. This talk is based on 2109.14699 and work in prog
ress.\n
LOCATION:https://stable.researchseminars.org/talk/WHCGP/43/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Clay Córdova (University of Chicago)
DTSTART:20211206T200000Z
DTEND:20211206T210000Z
DTSTAMP:20260404T110830Z
UID:WHCGP/44
DESCRIPTION:Title: Non-Invertible Duality Defects\nby Clay Córdova (University of
Chicago) as part of Western Hemisphere colloquium on geometry and physics\
n\n\nAbstract\nFor any quantum system invariant under gauging a higher-for
m global symmetry\, we construct a non-invertible topological defect by ga
uging in only half of spacetime. This generalizes the Kramers-Wannier dual
ity line in 1+1 dimensions to higher space- time dimensions. We focus on t
he case of a one-form symmetry in 3+1 dimensions\, and determine the fusio
n rule. From a direct analysis of one-form symmetry protected topological
phases\, we show that the existence of certain kinds of duality defects is
intrinsically incompatible with a trivially gapped phase. We give an expl
icit realization of this duality defect in the free Maxwell theory where i
t is realized by a Chern-Simons coupling between the gauge fields from the
two sides.\n
LOCATION:https://stable.researchseminars.org/talk/WHCGP/44/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Pavel Etingof (MIT)
DTSTART:20210913T190000Z
DTEND:20210913T200000Z
DTSTAMP:20260404T110830Z
UID:WHCGP/45
DESCRIPTION:Title: Hecke operators over local fields and an analytic approach to the ge
ometric Langlands correspondence\nby Pavel Etingof (MIT) as part of We
stern Hemisphere colloquium on geometry and physics\n\n\nAbstract\nI will
review an analytic approach to the geometric Langlands correspondence\, fo
llowing my work with E. Frenkel and D. Kazhdan\, arXiv:1908.09677\, arXiv:
2103.01509\, arXiv:2106.05243. This approach was developed by us in the la
st couple of years and involves ideas from previous and ongoing works of a
number of mathematicians and mathematical physicists\, Kontsevich\, Langl
ands\, Teschner\, and Gaiotto-Witten. One of the goals of this approach is
to understand single-valued real analytic eigenfunctions of the quantum H
itchin integrable system. The main method of studying these functions is r
ealizing them as the eigenbasis for certain compact normal commuting integ
ral operators the Hilbert space of L2 half-densities on the (complex point
s of) the moduli space Bun_G of principal G-bundles on a smooth projective
curve X\, possibly with parabolic points. These operators actually make s
ense over any local field\, and over non-archimedian fields are a replacem
ent for the quantum Hitchin system. We conjecture them to be compact and p
rove this conjecture in the genus zero case (with parabolic points) for G=
PGL(2). I will first discuss the simplest non-trivial example of Hecke ope
rators over local fields\, namely G=PGL(2) and genus 0 curve with 4 parabo
lic points. In this case the moduli space of semistable bundles Bun_G^{ss}
is P^1\, and the situation is relatively well understood\; over C it is t
he theory of single-valued eigenfunctions of the Lame operator with coupli
ng parameter -1/2 (previously studied by Beukers and later in a more funct
ional-analytic sense in our work with Frenkel and Kazhdan). I will conside
r the corresponding spectral theory and then explain its generalization to
N>4 points and conjecturally to higher genus curves.\n
LOCATION:https://stable.researchseminars.org/talk/WHCGP/45/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Hirosi Ooguri (Cal Tech)
DTSTART:20220124T200000Z
DTEND:20220124T210000Z
DTSTAMP:20260404T110830Z
UID:WHCGP/46
DESCRIPTION:Title: Symmetry in QFT and Gravity\nby Hirosi Ooguri (Cal Tech) as part
of Western Hemisphere colloquium on geometry and physics\n\nAbstract: TBA
\n
LOCATION:https://stable.researchseminars.org/talk/WHCGP/46/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Emily Cliff (Université de Sherbrooke)
DTSTART:20220207T200000Z
DTEND:20220207T210000Z
DTSTAMP:20260404T110830Z
UID:WHCGP/47
DESCRIPTION:Title: Moduli spaces of principal 2-group bundles and a categorification of
the Freed--Quinn line bundle\nby Emily Cliff (Université de Sherbroo
ke) as part of Western Hemisphere colloquium on geometry and physics\n\nAb
stract: TBA\n
LOCATION:https://stable.researchseminars.org/talk/WHCGP/47/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Heeyeon Kim (Rutgers University)
DTSTART:20220509T190000Z
DTEND:20220509T200000Z
DTSTAMP:20260404T110830Z
UID:WHCGP/48
DESCRIPTION:Title: Path integral derivations of K-theoretic Donaldson invariants\nb
y Heeyeon Kim (Rutgers University) as part of Western Hemisphere colloquiu
m on geometry and physics\n\n\nAbstract\nWe discuss path integral derivati
ons of topologically twisted partition functions of 5d SU(2) supersymmetri
c Yang-Mills theory on M4 x S1\, where M4 is a smooth closed four-manifold
. Mathematically\, they can be identified with the K-theoretic version of
the Donaldson invariants. In particular\, we provide two different path in
tegral derivations of their wall-crossing formula for b_2^+(M4)=1\, first
in the so-called U-plane integral approach\, and in the perspective of ins
tanton counting. We briefly discuss the generalization to b_2^+(M4)>1.\n
LOCATION:https://stable.researchseminars.org/talk/WHCGP/48/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Constantin Teleman (U. C. Berkeley)
DTSTART:20220425T190000Z
DTEND:20220425T200000Z
DTSTAMP:20260404T110830Z
UID:WHCGP/49
DESCRIPTION:Title: Coulomb branches and Drinfeld centers\nby Constantin Teleman (U.
C. Berkeley) as part of Western Hemisphere colloquium on geometry and phy
sics\n\n\nAbstract\nWe discuss a construction of Coulomb branches of a com
pact Lie group G from the Toda integrable systems and speculate on their o
rigins as Drinfeld centers of modifications of (a variant of) the tensor c
ategory of topological representations of G.\n
LOCATION:https://stable.researchseminars.org/talk/WHCGP/49/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Eric Zaslow (Northwestern University)
DTSTART:20220228T200000Z
DTEND:20220228T210000Z
DTSTAMP:20260404T110830Z
UID:WHCGP/50
DESCRIPTION:Title: Framing Duality\nby Eric Zaslow (Northwestern University) as par
t of Western Hemisphere colloquium on geometry and physics\n\n\nAbstract\n
I will describe joint work in progress with Linhui Shen and Gus Schrader\,
in which we study moduli spaces of Fukaya objects and conjecture about th
eir relationship to BPS and open Gromov-Witten invariants. This unabashedl
y synthesize previous works of many other groups\, whom I will credit in t
he talk. I will try to highlight some new aspects: 1) a definition of phas
es and framings and their combinatorial origins\; 2) conjectures on open G
romov-Witten invariants for Lagrangians bounding certain Legendrian surfac
es\; 3) a “framing duality” relating Dondaldson-Thomas and open Gromov
-Witten invariants.\n
LOCATION:https://stable.researchseminars.org/talk/WHCGP/50/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Joerg Teschner (DESY)
DTSTART:20220314T190000Z
DTEND:20220314T200000Z
DTSTAMP:20260404T110830Z
UID:WHCGP/51
DESCRIPTION:Title: The complex geometry of topological string partition functions\n
by Joerg Teschner (DESY) as part of Western Hemisphere colloquium on geome
try and physics\n\n\nAbstract\nThe goal of this talk will be to review som
e aspects of a program inspired by work of Tom Bridgeland aiming at a non-
perturbative characterisation of topological string partition functions. T
he program is based on two main ingredients: The complex geometry of the u
nderlying moduli spaces on the one hand\, and cluster algebra structures d
efined by BPS- or DT-invariants on the other hand. The general picture is
nicely illustrated by the Borel summation of the conifold partition functi
ons recently studied with M. Alim\, A. Saha and I. Tulli\, with Stokes jum
ps of the partition functions getting related to wall-crossing phenomena i
n the theory of DT-invariants. Based on this and other examples we will pr
opose a conjectural characterisation of the partition functions for local
Calabi-Yau manifolds\, generalising earlier proposals by Marino and collab
orators\, and related to earlier proposals by Alexandrov\, Pioline and col
laborators based on the geometry of hypermultiplet moduli spaces.\n
LOCATION:https://stable.researchseminars.org/talk/WHCGP/51/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Washington Taylor (MIT)
DTSTART:20220328T190000Z
DTEND:20220328T200000Z
DTSTAMP:20260404T110830Z
UID:WHCGP/52
DESCRIPTION:Title: Middle intersection forms on singular elliptic Calabi-Yau fourfolds\
, and applications to the standard model and mirror symmetry\nby Washi
ngton Taylor (MIT) as part of Western Hemisphere colloquium on geometry an
d physics\n\n\nAbstract\nRecent work with Jefferson and Turner indicates t
hat the intersection form on the vertical part of middle cohomology of sin
gular elliptic Calabi-Yau fourfolds is independent of resolution. This sug
gests that the intersection structure should have a natural definition eve
n in these singular geometries. The resulting intersection form has a simp
le block-diagonal structure in terms of Kodaira singularities and the geom
etry of the base of the elliptic fibration\; the talk will describe applic
ations of this intersection form to analysis of chiral matter and standard
model constructions in F-theory as well as new insights into mirror symme
try\, in particular providing in some cases a complete description of the
intersection form on H_4 (X\, Z) for a smooth Calabi-Yau fourfold includin
g both vertical and horizontal parts.\n
LOCATION:https://stable.researchseminars.org/talk/WHCGP/52/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Daniel Halpern-Leistner (Cornell)
DTSTART:20220411T190000Z
DTEND:20220411T200000Z
DTSTAMP:20260404T110830Z
UID:WHCGP/53
DESCRIPTION:Title: Infinite dimensional geometric invariant theory and gauged Gromov-Wi
tten theory\nby Daniel Halpern-Leistner (Cornell) as part of Western H
emisphere colloquium on geometry and physics\n\n\nAbstract\nHarder-Narasim
han (HN) theory gives a structure theorem for holomorphic vector bundles o
n a Riemann surface. A bundle is either semistable\, or it admits a canoni
cal filtration whose associated graded bundle is semistable in a graded se
nse. After reviewing recent advances in extending HN theory to arbitrary m
oduli problems in algebraic geometry I will discuss work in progress with
Andres Fernandez Herrero and Eduardo Gonzalez to apply this general machin
ery to the moduli problem of gauged maps from a curve C to a G-variety X\,
where G is a reductive group. Our main immediate application is to use HN
theory for gauged maps to compute generating functions for K-theoretic ga
uged Gromov-Witten invariants. This problem is interesting more broadly be
cause it can be formulated as an example of an infinite dimensional analog
of the usual set up of geometric invariant theory\, which has application
s to other moduli problems.\n
LOCATION:https://stable.researchseminars.org/talk/WHCGP/53/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Nathan Seiberg (Institute for Advanced Study)
DTSTART:20230911T190000Z
DTEND:20230911T200000Z
DTSTAMP:20260404T110830Z
UID:WHCGP/54
DESCRIPTION:Title: Emanant Symmetries\nby Nathan Seiberg (Institute for Advanced St
udy) as part of Western Hemisphere colloquium on geometry and physics\n\n\
nAbstract\nBased on joint work with Meng Cheng (arXiv:2211.12543)\, with S
hu-Heng Shao (arXiv: 2307.02534)\, and with Shu- Heng Shao and Sahand Seif
nashri (to appear)\, we will discuss some aspects of global symmetries and
their ‘t Hooft anomalies. We will define a notion of an emanant global
symmetry. It is not a symmetry of the UV theory\, but unlike emergent (acc
idental) symmetries\, it is not violated by any relevant or irrelevant ope
rators in the IR theory. It is an exact symmetry of the low-energy theory.
We will demonstrate this notion in several well-known examples. We will d
iscuss in detail the Majorana chain\, the transverse field Ising model\, a
continuum system with a chemical potential\, and the Heisenberg chain. In
all these models\, we will find emanant symmetries. In one case\, it is a
non-invertible emanant symmetry.\n
LOCATION:https://stable.researchseminars.org/talk/WHCGP/54/
END:VEVENT
BEGIN:VEVENT
SUMMARY:John Pardon (Simons Center for Geometry and Physics)
DTSTART:20231016T190000Z
DTEND:20231016T200000Z
DTSTAMP:20260404T110830Z
UID:WHCGP/55
DESCRIPTION:Title: Universally counting curves in Calabi--Yau threefolds\nby John P
ardon (Simons Center for Geometry and Physics) as part of Western Hemisphe
re colloquium on geometry and physics\n\nAbstract: TBA\n
LOCATION:https://stable.researchseminars.org/talk/WHCGP/55/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Sabrina Pasterski (Perimeter Institute)
DTSTART:20231211T200000Z
DTEND:20231211T210000Z
DTSTAMP:20260404T110830Z
UID:WHCGP/56
DESCRIPTION:Title: Celestial holography from bottom-up to top-down\nby Sabrina Past
erski (Perimeter Institute) as part of Western Hemisphere colloquium on ge
ometry and physics\n\n\nAbstract\nThe Celestial Holography program encompa
sses recent efforts to understand the flat space hologram in terms of a CF
T living on the celestial sphere. A key development instigating these effo
rts came from understanding how soft limits of scattering encode infinite
dimensional symmetry enhancements corresponding to the asymptotic symmetry
group of the bulk spacetime. Historically\, the construction of the bulk-
boundary dual pair has followed bottom up approach matching symmetries on
both sides. Recently\, however\, there has been exciting progress in formu
lating top down descriptions using insights from twisted holography. In th
is talk we will cover salient aspects of the celestial construction\, the
status of the dictionary\, and active research directions.\n
LOCATION:https://stable.researchseminars.org/talk/WHCGP/56/
END:VEVENT
END:VCALENDAR