BEGIN:VCALENDAR
VERSION:2.0
PRODID:researchseminars.org
CALSCALE:GREGORIAN
X-WR-CALNAME:researchseminars.org
BEGIN:VEVENT
SUMMARY:Edward Witten (IAS)
DTSTART;VALUE=DATE-TIME:20200413T190000Z
DTEND;VALUE=DATE-TIME:20200413T200000Z
DTSTAMP;VALUE=DATE-TIME:20230208T060818Z
UID:WHCGP/1
DESCRIPTION:Title: Vo
lumes and random matrices\nby Edward Witten (IAS) as part of Western H
emisphere colloquium on geometry and physics\n\n\nAbstract\nI will describ
e recent results relating two-dimensional gravity and supergravity\; volum
es of moduli spaces of Riemann surfaces and super Riemann surfaces\; and r
andom matrix ensembles. See arX
iv:1907.03363 by Saad\, Shenker\, and Stanford.\n
LOCATION:https://researchseminars.org/talk/WHCGP/1/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Kevin Costello (Perimeter Institute)
DTSTART;VALUE=DATE-TIME:20200427T190000Z
DTEND;VALUE=DATE-TIME:20200427T200000Z
DTSTAMP;VALUE=DATE-TIME:20230208T060818Z
UID:WHCGP/2
DESCRIPTION:Title: To
pological strings\, twistors\, and Skyrmions\nby Kevin Costello (Perim
eter Institute) as part of Western Hemisphere colloquium on geometry and p
hysics\n\n\nAbstract\nIt has long been known that holomorphic field theori
es on twistor space lead to "physical" field theories on Minkowski space.
In this talk I will discuss a type I (unoriented) version of the topologic
al B model on twistor space. The corresponding theory on Minkowski space i
s a sigma-model with target the group SO(8). This is a variant of the Skyr
me 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 to
pological string). The origin of this model in the topological string impl
ies many remarkable properties. For one thing\, the model is\, in a certai
n sense\, integrable. Further\, although the Lagrangian is power-counting
non-renormalizable\, counter-terms at all loops can be uniquely fixed.\n
LOCATION:https://researchseminars.org/talk/WHCGP/2/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Miranda Cheng (University of Amsterdam)
DTSTART;VALUE=DATE-TIME:20200518T190000Z
DTEND;VALUE=DATE-TIME:20200518T200000Z
DTSTAMP;VALUE=DATE-TIME:20230208T060818Z
UID:WHCGP/3
DESCRIPTION:Title: Qu
antum modularity from 3-manifolds\nby Miranda Cheng (University of Ams
terdam) as part of Western Hemisphere colloquium on geometry and physics\n
\n\nAbstract\nQuantum modular forms are functions on rational numbers that
have rather mysterious weak modular properties. Mock modular forms and fa
lse theta functions are examples of holomorphic functions on the upper-hal
f plane which lead to quantum modular forms. Inspired by the 3d-3d corresp
ondence in string theory\, a new topological invariants named homological
blocks for (in particular plumbed) three-manifolds have been proposed a fe
w years ago. My talk aims to explain the recent observations on the quantu
m modular properties of the homological blocks\, as well as the relation t
\n
LOCATION:https://researchseminars.org/talk/WHCGP/3/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Davide Gaiotto (Perimeter Institute)
DTSTART;VALUE=DATE-TIME:20200601T190000Z
DTEND;VALUE=DATE-TIME:20200601T200000Z
DTSTAMP;VALUE=DATE-TIME:20230208T060818Z
UID:WHCGP/4
DESCRIPTION:Title: In
tegrable Kondo problems and affine geometric Langlands\nby Davide Gaio
tto (Perimeter Institute) as part of Western Hemisphere colloquium on geom
etry and physics\n\n\nAbstract\nI will present some work on integrable lin
e defects in WZW models and their relation to 4d CS theory\, the IM/ODe co
rrespondence and affine generalizations of Geometric Langlands constructio
ns.\n
LOCATION:https://researchseminars.org/talk/WHCGP/4/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Maxim Kontsevich (IHES)
DTSTART;VALUE=DATE-TIME:20200615T190000Z
DTEND;VALUE=DATE-TIME:20200615T200000Z
DTSTAMP;VALUE=DATE-TIME:20230208T060818Z
UID:WHCGP/5
DESCRIPTION:Title: Sp
ace-time analyticity in QFT\nby Maxim Kontsevich (IHES) as part of Wes
tern Hemisphere colloquium on geometry and physics\n\n\nAbstract\nI will t
alk on a joint work with Graeme Segal. We propose a new axiomatics for uni
tary quantum field theory which includes both Lorentzian and Euclidean sig
natures for curved space-time manifolds. The key to the definition is cert
ain ope\n
LOCATION:https://researchseminars.org/talk/WHCGP/5/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Anton Kapustin (Cal Tech)
DTSTART;VALUE=DATE-TIME:20200622T190000Z
DTEND;VALUE=DATE-TIME:20200622T200000Z
DTSTAMP;VALUE=DATE-TIME:20230208T060818Z
UID:WHCGP/6
DESCRIPTION:Title: Fr
om gapped phases of matter to Topological Quantum Field Theory and back ag
ain\nby Anton Kapustin (Cal Tech) as part of Western Hemisphere colloq
uium on geometry and physics\n\nAbstract: TBA\n
LOCATION:https://researchseminars.org/talk/WHCGP/6/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Nima Arkani-Hamed (IAS)
DTSTART;VALUE=DATE-TIME:20200706T190000Z
DTEND;VALUE=DATE-TIME:20200706T200000Z
DTSTAMP;VALUE=DATE-TIME:20230208T060818Z
UID:WHCGP/8
DESCRIPTION:Title: Sp
acetime\, Quantum Mechanics and Clusterhedra at Infinity\nby Nima Arka
ni-Hamed (IAS) as part of Western Hemisphere colloquium on geometry and ph
ysics\n\nAbstract: TBA\n
LOCATION:https://researchseminars.org/talk/WHCGP/8/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Mina Aganagic (UC Berkeley)
DTSTART;VALUE=DATE-TIME:20200713T190000Z
DTEND;VALUE=DATE-TIME:20200713T200000Z
DTSTAMP;VALUE=DATE-TIME:20230208T060818Z
UID:WHCGP/9
DESCRIPTION:Title: Kn
ot categorification from mirror symmetry\, via string theory\nby Mina
Aganagic (UC Berkeley) as part of Western Hemisphere colloquium on geometr
y and physics\n\nAbstract: TBA\n
LOCATION:https://researchseminars.org/talk/WHCGP/9/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Laura Fredrickson (Stanford / U. Oregon)
DTSTART;VALUE=DATE-TIME:20200824T190000Z
DTEND;VALUE=DATE-TIME:20200824T200000Z
DTSTAMP;VALUE=DATE-TIME:20230208T060818Z
UID:WHCGP/10
DESCRIPTION:Title: T
he asymptotic geometry of the Hitchin moduli space\nby Laura Fredricks
on (Stanford / U. Oregon) as part of Western Hemisphere colloquium on geom
etry and physics\n\n\nAbstract\nHitchin's equations are a system of gauge
theoretic equations on a Riemann surface that are of interest in many area
s including representation theory\, Teichmuller theory\, and the geometric
Langlands correspondence. The Hitchin moduli space carries a natural hype
rkahler metric. An intricate conjectural description of its asymptotic str
ucture appears in the work of physicists Gaiotto-Moore-Neitzke and there h
as been a lot of progress on this recently. I will discuss some recent res
ults using tools coming out of geometric analysis which are well-suited fo
r verifying these extremely delicate conjectures. This strategy often stre
tches the limits of what can currently be done via geometric analysis\, an
d simultaneously leads to new insights into these conjectures.\n
LOCATION:https://researchseminars.org/talk/WHCGP/10/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Greg Moore (Rutgers)
DTSTART;VALUE=DATE-TIME:20200720T190000Z
DTEND;VALUE=DATE-TIME:20200720T200000Z
DTSTAMP;VALUE=DATE-TIME:20230208T060818Z
UID:WHCGP/11
DESCRIPTION:Title: B
reaking News About\, Topologically Twisted Rank One N=2* Supersymmetric Ya
ng-Mills Theory On Four-Manifolds\, Without Spin\nby Greg Moore (Rutge
rs) as part of Western Hemisphere colloquium on geometry and physics\n\nAb
stract: TBA\n
LOCATION:https://researchseminars.org/talk/WHCGP/11/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Sakura Schafer-Nameki (Oxford)
DTSTART;VALUE=DATE-TIME:20200803T190000Z
DTEND;VALUE=DATE-TIME:20200803T200000Z
DTSTAMP;VALUE=DATE-TIME:20230208T060818Z
UID:WHCGP/12
DESCRIPTION:Title: 5
d SCFTs: Symmetries and Moduli Spaces\nby Sakura Schafer-Nameki (Oxfor
d) as part of Western Hemisphere colloquium on geometry and physics\n\nAbs
tract: TBA\n
LOCATION:https://researchseminars.org/talk/WHCGP/12/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Marco Gualtieri (Univ. of Toronto)
DTSTART;VALUE=DATE-TIME:20200817T190000Z
DTEND;VALUE=DATE-TIME:20200817T200000Z
DTSTAMP;VALUE=DATE-TIME:20230208T060818Z
UID:WHCGP/13
DESCRIPTION:Title: B
ranes in symplectic groupoids\nby Marco Gualtieri (Univ. of Toronto) a
s part of Western Hemisphere colloquium on geometry and physics\n\n\nAbstr
act\nAfter reviewing coisotropic A-branes in symplectic manifolds and thei
r role in mirror symmetry and geometric quantization\, I will explain how
the problem of holomorphic quantization of Poisson brackets may be recast\
, and in some cases solved\, as a problem of computing morphisms between c
oisotropic branes in symplectic groupoids. This is joint work with Franc
is Bischoff and Joshua Lackman.\n
LOCATION:https://researchseminars.org/talk/WHCGP/13/
END:VEVENT
BEGIN:VEVENT
SUMMARY:David Jordan (Edinburgh)
DTSTART;VALUE=DATE-TIME:20200914T190000Z
DTEND;VALUE=DATE-TIME:20200914T200000Z
DTSTAMP;VALUE=DATE-TIME:20230208T060818Z
UID:WHCGP/14
DESCRIPTION:Title: Q
uantum geometric Langlands as a fully extended TFT\nby David Jordan (E
dinburgh) as part of Western Hemisphere colloquium on geometry and physics
\n\n\nAbstract\nI will survey several recent works realizing Betti geometr
ic\nLanglands and its quantization as fully extended TFT's. In physics ter
ms\nthis is most closely related to the Kapustin-Witten twist of N=4 d=4 S
YM\nat generic values of \\Psi.\n\nI will outline numerous applications to
quantum topology\, most notably\nto a conjecture of Witten on finite-dime
nsionality of skein modules\, a\nconjecture of Bonahon-Wong concerning ske
in modules at root-of-unity\nparameters\, a proposal of Ben-Zvi concerning
cluster varieties and\nfactorization homology\, and an appearance of the
type-A spherical DAHA\nfrom a once-marked torus.\n\nFinally\, I will prese
nt a novel conjectural appearance of S-duality in\nthe study of skein modu
les of 3-manifolds.\n
LOCATION:https://researchseminars.org/talk/WHCGP/14/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Natalie Paquette (IAS)
DTSTART;VALUE=DATE-TIME:20201005T190000Z
DTEND;VALUE=DATE-TIME:20201005T200000Z
DTSTAMP;VALUE=DATE-TIME:20230208T060818Z
UID:WHCGP/15
DESCRIPTION:Title: B
orcherds-Kac-Moody algebras\, 2d strings\, & other curiosities\nby Nat
alie Paquette (IAS) as part of Western Hemisphere colloquium on geometry a
nd physics\n\n\nAbstract\nIn this talk we will extol the virtues of compac
tifying critical string theory down to few noncompact spacetime dimensions
(particularly two). These string vacua possess rich groups of dualities.
BPS-saturated quantities\, which mathematically are described by automorph
ic forms\, are invariant under such duality transformations. Further\, suc
h BPS states can furnish representations of interesting algebras\, such as
infinite-dimensional Lie algebras. In this talk\, we explore some particu
larly nice\, concrete examples\, which employ holomorphic super vertex ope
rator algebras in our `compactification' theories. The BPS states in these
models organize into representations of algebras\, which we prove are (ne
w) examples of Borcherds-Kac-Moody superalgebras.\n
LOCATION:https://researchseminars.org/talk/WHCGP/15/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Ben Webster (Waterloo)
DTSTART;VALUE=DATE-TIME:20200810T190000Z
DTEND;VALUE=DATE-TIME:20200810T200000Z
DTSTAMP;VALUE=DATE-TIME:20230208T060818Z
UID:WHCGP/16
DESCRIPTION:Title: 3
d mirror symmetry and its discontents\nby Ben Webster (Waterloo) as pa
rt of Western Hemisphere colloquium on geometry and physics\n\nAbstract: T
BA\n
LOCATION:https://researchseminars.org/talk/WHCGP/16/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Lauren Williams (Harvard)
DTSTART;VALUE=DATE-TIME:20200921T190000Z
DTEND;VALUE=DATE-TIME:20200921T200000Z
DTSTAMP;VALUE=DATE-TIME:20230208T060818Z
UID:WHCGP/17
DESCRIPTION:Title: H
ow is the hypersimplex related to the amplituhedron?\nby Lauren Willia
ms (Harvard) as part of Western Hemisphere colloquium on geometry and phys
ics\n\n\nAbstract\nIn 1987\, Gelfand-Goresky-MacPherson-Serganova made a b
eautiful\nconnection between the geometry of the Grassmannian and convex p
olytopes\, via\nthe moment map\; the moment map image of the Grassmannian
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 computation of
scattering amplitudes in N=4\nSYM\, Arkani-Hamed and Trnka introduced 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 positive.
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 betwee
n the positroidal subdivisions of the hypersimplex\nDelta(k+1\,n) and the
m=2 amplituhedron A(n\,k\,2). One link is provided by the\npositive tropi
cal Grassmannian. Attributions: based on joint works with Tomek\nLukowski
\, Matteo Parisi\, and David Speyer.\n\nDisclaimer: I'm neither a geometer
nor a physicist.\n
LOCATION:https://researchseminars.org/talk/WHCGP/17/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Mark Gross (Cambridge)
DTSTART;VALUE=DATE-TIME:20200511T190000Z
DTEND;VALUE=DATE-TIME:20200511T200000Z
DTSTAMP;VALUE=DATE-TIME:20230208T060818Z
UID:WHCGP/18
DESCRIPTION:Title: I
ntrinsic Mirror Symmetry\nby Mark Gross (Cambridge) as part of Western
Hemisphere colloquium on geometry and physics\n\nAbstract: TBA\n
LOCATION:https://researchseminars.org/talk/WHCGP/18/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Harold Williams (USC)
DTSTART;VALUE=DATE-TIME:20201214T200000Z
DTEND;VALUE=DATE-TIME:20201214T210000Z
DTSTAMP;VALUE=DATE-TIME:20230208T060818Z
UID:WHCGP/19
DESCRIPTION:Title: C
anonical Bases for Coulomb Branches\nby Harold Williams (USC) as part
of Western Hemisphere colloquium on geometry and physics\n\n\nAbstract\nFo
llowing work of Kapustin-Saulina and Gaiotto-Moore-Neitzke\, one expects h
alf-BPS line defects in a 4d N=2 field theory to form a monoidal category
with a rich structure. In general\, a mathematical definition of this cate
gory is not known. In this talk we discuss an algebro-geometric proposal i
n the case of gauge theories with polarizable matter. The proposed categor
y is the heart of a nonstandard t-structure on the dg category of coherent
sheaves on the derived Braverman-Finkelberg-Nakajima space of triples. We
refer to its objects as Koszul-perverse coherent sheaves\, as this t-stru
cture interpolates between the perverse coherent t-structure and certain t
-structures appearing in the theory of Koszul duality (specializing to the
se in the case of a pure gauge theory and an abelian gauge theory\, respec
tively). As a byproduct\, this defines a canonical basis in the associated
quantized Coulomb branch by passing to classes of irreducible objects. Th
is is joint work with Sabin Cautis.\n
LOCATION:https://researchseminars.org/talk/WHCGP/19/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Christopher Beem (Oxford)
DTSTART;VALUE=DATE-TIME:20201102T200000Z
DTEND;VALUE=DATE-TIME:20201102T210000Z
DTSTAMP;VALUE=DATE-TIME:20230208T060818Z
UID:WHCGP/20
DESCRIPTION:Title: H
all-Littlewood chiral rings and derived Higgs branches\nby Christopher
Beem (Oxford) as part of Western Hemisphere colloquium on geometry and ph
ysics\n\n\nAbstract\nI will discuss a relatively novel algebraic structure
arising in four-dimensional N=2 superconformal field theories: the Hall-L
ittlewood Chiral Ring (HLCR). The HLCR is an enhancement of the more famil
iar Higgs branch chiral ring (which encodes the Higgs branch of the moduli
space of vacua as an algebraic variety). The HLCR in gauge theories is co
nstructed as the cohomology of a kind of BRST complex\, which allows it to
be identified with the ring of functions on the derived Higgs branch (in
the sense of derived algebraic geometry). I will describe the solution of
the HLCR cohomology problem for a large class of Lagrangian theories (the
class S theories of type A1)\, which illustrate some interesting phenomena
. This talk is based on work in progress with Diego Berdeja Suárez.\n
LOCATION:https://researchseminars.org/talk/WHCGP/20/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Sergei Gukov (Cal Tech)
DTSTART;VALUE=DATE-TIME:20201116T200000Z
DTEND;VALUE=DATE-TIME:20201116T210000Z
DTSTAMP;VALUE=DATE-TIME:20230208T060818Z
UID:WHCGP/21
DESCRIPTION:Title: R
okhlin\, quantum groups\, and BPS states\nby Sergei Gukov (Cal Tech) a
s part of Western Hemisphere colloquium on geometry and physics\n\n\nAbstr
act\nWhat do ADO polynomials\, cobordism invariants\, and affine Grassmann
ians 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 function and\,
on the other hand\, is associated to quantum groups at generic q where Ve
rma modules with arbitrary complex weights play an important role.\n
LOCATION:https://researchseminars.org/talk/WHCGP/21/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Sourav Chatterjee (Stanford)
DTSTART;VALUE=DATE-TIME:20201130T200000Z
DTEND;VALUE=DATE-TIME:20201130T210000Z
DTSTAMP;VALUE=DATE-TIME:20230208T060818Z
UID:WHCGP/22
DESCRIPTION:Title: S
trong mass gap implies quark confinement\nby Sourav Chatterjee (Stanfo
rd) as part of Western Hemisphere colloquium on geometry and physics\n\n\n
Abstract\nI will show that if a lattice gauge theory has exponential decay
of correlations under arbitrary boundary conditions (which I call strong
mass gap)\, and the gauge group has a nontrivial center\, then Wilson's ar
ea law holds.\n
LOCATION:https://researchseminars.org/talk/WHCGP/22/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Djordje Radicevic (Brandeis)
DTSTART;VALUE=DATE-TIME:20201019T190000Z
DTEND;VALUE=DATE-TIME:20201019T200000Z
DTSTAMP;VALUE=DATE-TIME:20230208T060818Z
UID:WHCGP/23
DESCRIPTION:Title: T
he Lattice-Continuum Correspondence in Quantum Mechanics\nby Djordje R
adicevic (Brandeis) as part of Western Hemisphere colloquium on geometry a
nd physics\n\n\nAbstract\nIt is very well known that long-distance correla
tion functions of many lattice systems can be calculated from continuum QF
Ts. Making this correspondence more precise --- identifying continuum oper
ators that correspond to individual lattice operators\, or exhibiting the
lattice origins of subtler continuum phenomena like operator product expan
sions --- has proven quite daunting. In this talk\, I will report on recen
t progress in this direction\, using quantum mechanics (QFT in 0+1 dimensi
ons) as an example. I will show how a finite but large quantum system can
be systematically reduced to an Ersatz continuum theory\, using both Hamil
tonian and path integral formalisms. Along the way I will point out the la
ttice origins of several familiar continuum concepts\, including contact t
erms\, scale invariance\, and the distinction between compact and noncompa
ct theories. I will also stress the limitations imposed on the emergent co
ntinuum theory by its lattice progenitor --- for instance\, any supersymme
tric continuum theory emerging from a finite theory must have a vanishing
Witten index.\n
LOCATION:https://researchseminars.org/talk/WHCGP/23/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Mike Freedman (Microsoft Research/ UCSB)
DTSTART;VALUE=DATE-TIME:20210111T200000Z
DTEND;VALUE=DATE-TIME:20210111T210000Z
DTSTAMP;VALUE=DATE-TIME:20230208T060818Z
UID:WHCGP/24
DESCRIPTION:Title: Q
uantum Codes and Systolic freedom\nby Mike Freedman (Microsoft Researc
h/ UCSB) as part of Western Hemisphere colloquium on geometry and physics\
n\n\nAbstract\nIn work with Hastings we find a two-way street between quan
tum\nerror correcting codes and Riemannian manifolds. A recent advance in
coding\ntheory allows us to produce the first example of a manifolds 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 th
at 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://researchseminars.org/talk/WHCGP/24/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Albrecht Klemm (Bonn)
DTSTART;VALUE=DATE-TIME:20210125T200000Z
DTEND;VALUE=DATE-TIME:20210125T210000Z
DTSTAMP;VALUE=DATE-TIME:20230208T060818Z
UID:WHCGP/25
DESCRIPTION:Title: C
alabi-Yau modularity and Feynman graphs\nby Albrecht Klemm (Bonn) as p
art of Western Hemisphere colloquium on geometry and physics\n\n\nAbstract
\nUsing the GKZ system for the primitive cohomology of an infinite series
of complete intersection Calabi-Yau manifolds\, whose dimension is the loo
p order minus one\, we completely clarify the analytic structure of all ba
nana integrals with arbitrary masses. In particular\, we find that the lea
ding logarithmic structure in the high energy regime\, which corresponds t
o the point of maximal unipotent monodromy\, is determined by a novel \\ha
t b-class evaluation in the ambient spaces of the mirror\, while the imagi
nary part of the amplitude in this regime is determined by the Î“b-clas
s of the mirror Calabi-Yau manifold itself. We provide simple closed all l
oop formulas for the former as well as for the Frobenius Îº-constants\,
which determine the behaviour of the amplitudes\, when the momentum square
equals the sum of the masses squared\, in terms of zeta values. We find t
he exact differential equation for the graph integrals with arbitrary valu
e for the dimensional regularisation (d-\\epsilon) parameter and extend ou
r previous work from three to four loops by providing for the latter case
a complete set of (inhomogenous) Picard-Fuchs differential ideal for arbit
rary masses. Using a recent p-adic analysis of the periods we determine th
e 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 eigenform
s and the quasiperiods of their meromorphic cousins.\n
LOCATION:https://researchseminars.org/talk/WHCGP/25/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Nikita Nekrasov (SCGP\, Stony Brook)
DTSTART;VALUE=DATE-TIME:20210208T200000Z
DTEND;VALUE=DATE-TIME:20210208T210000Z
DTSTAMP;VALUE=DATE-TIME:20230208T060818Z
UID:WHCGP/26
DESCRIPTION:Title: B
eauty of the defects\nby Nikita Nekrasov (SCGP\, Stony Brook) as part
of Western Hemisphere colloquium on geometry and physics\n\n\nAbstract\nSu
rface and point-like defects in supersymmetric gauge theories in four dime
nsions are studied with applications to quantum/classical correspondence.
In particular\, the GIL formula for the tau-function of Painleve VI is exp
lained using the blow-up method in the context of the BPS/CFT corresponden
ce\, while the spin chain generalisation of Kharchev-Lebedev wavefunction
of periodic Toda chain is obtained via wallcrossing. \n\nBased on several
works\, in particular on papers in collaboration with Saebyeok Jeong\; Nor
ton Lee\; Oleksandr Tsymbaliuk\; as well as S. Jeong and N. Lee\n
LOCATION:https://researchseminars.org/talk/WHCGP/26/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Tamas Hausel (IST\, Austria)
DTSTART;VALUE=DATE-TIME:20210222T200000Z
DTEND;VALUE=DATE-TIME:20210222T210000Z
DTSTAMP;VALUE=DATE-TIME:20230208T060818Z
UID:WHCGP/27
DESCRIPTION:Title: M
irror symmetry for Langlands dual Higgs bundles at the tip of the nilpoten
t cone\nby Tamas Hausel (IST\, Austria) as part of Western Hemisphere
colloquium on geometry and physics\n\n\nAbstract\nI will explain what we c
an prove and what we conjecture about the mirror of Hecke transformed Hitc
hin section motivated by symmetry ideas of Kapustin-Witten. The talk is ba
sed on arXiv:2101.08583 joint with Hitchin.\n
LOCATION:https://researchseminars.org/talk/WHCGP/27/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Thomas Dumitrescu (UCLA)
DTSTART;VALUE=DATE-TIME:20210308T200000Z
DTEND;VALUE=DATE-TIME:20210308T210000Z
DTSTAMP;VALUE=DATE-TIME:20230208T060818Z
UID:WHCGP/28
DESCRIPTION:Title: 2
-Group Global Symmetry in Quantum Field Theory\nby Thomas Dumitrescu (
UCLA) as part of Western Hemisphere colloquium on geometry and physics\n\n
\nAbstract\nHigher-form generalizations of global symmetries play an impor
tant role in Quantum Field Theory (QFT). In general\, symmetries of differ
ent form degrees need not be independent\; instead\, they can form a highe
r group. In this talk I will illustrate this phenomenon by explaining why
many simple Lagrangian QFTs in four and six dimensions enjoy 2-group globa
l symmetries. I will then apply this understanding to deduce new general r
esults about (typically non-Lagrangian) SCFTs in six dimensions.\n
LOCATION:https://researchseminars.org/talk/WHCGP/28/
END:VEVENT
BEGIN:VEVENT
SUMMARY:David Ben-Zvi (UT Austin)
DTSTART;VALUE=DATE-TIME:20210322T190000Z
DTEND;VALUE=DATE-TIME:20210322T200000Z
DTSTAMP;VALUE=DATE-TIME:20230208T060818Z
UID:WHCGP/29
DESCRIPTION:Title: E
lectric-Magnetic Duality between Periods and L-functions\nby David Ben
-Zvi (UT Austin) as part of Western Hemisphere colloquium on geometry and
physics\n\n\nAbstract\nI will describe joint work with Yiannis Sakellaridi
s and Akshay Venkatesh\, in\nwhich ideas originating in quantum field theo
ry are applied to a problem in\nnumber theory.\n\nA fundamental tool in nu
mber theory\, the relative Langlands program\, is\ncentered on the represe
ntation of L-functions of Galois representations as\nintegrals of automorp
hic forms. However\, the data that naturally index these\nperiod integrals
(spherical varieties for a reductive group G) and the\nL-functions (repre
sentations of the Langlands dual group G^) don't seem to line\nup\, making
the search for integral representations somewhat of an art. \n\nWe presen
t an approach to this problem via the Kapustin-Witten interpretation\nof t
he [geometric] Langlands correspondence as electric-magnetic duality for\n
4-dimensional supersymmetric gauge theory. Namely\, we rewrite the relativ
e \nLanglands program as duality in the presence of boundary conditions. A
s a\nresult the partial correspondence between periods and L-functions is
embedded\nin a natural duality between Hamiltonian actions of the dual gro
ups.\n
LOCATION:https://researchseminars.org/talk/WHCGP/29/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Arnav Tripathy (Harvard)
DTSTART;VALUE=DATE-TIME:20210405T190000Z
DTEND;VALUE=DATE-TIME:20210405T200000Z
DTSTAMP;VALUE=DATE-TIME:20230208T060818Z
UID:WHCGP/30
DESCRIPTION:Title: K
3 metrics\nby Arnav Tripathy (Harvard) as part of Western Hemisphere c
olloquium on geometry and physics\n\n\nAbstract\nIt has long been an open
problem to explicitly produce a\nRicci-flat metric on a (non-toroidal) com
pact manifold. I'll discuss two\napproaches to this problem\, related by a
version of 3d mirror symmetry\,\nfor K3 manifolds. This is joint work wit
h M. Zimet.\n
LOCATION:https://researchseminars.org/talk/WHCGP/30/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Cody Long/Cumrun Vafa (Harvard)
DTSTART;VALUE=DATE-TIME:20210419T190000Z
DTEND;VALUE=DATE-TIME:20210419T200000Z
DTSTAMP;VALUE=DATE-TIME:20230208T060818Z
UID:WHCGP/31
DESCRIPTION:Title: N
on-Holomorphic Cycles and Non-BPS Black Branes\nby Cody Long/Cumrun Va
fa (Harvard) as part of Western Hemisphere colloquium on geometry and phys
ics\n\n\nAbstract\nWe discuss extremal non-BPS black holes and strings ari
sing in M-theory compactifications on Calabi-Yau threefolds\, obtained by
wrapping M2 branes on non-holomorphic 2-cycles and M5 branes on non-holomo
rphic 4-cycles. Using the attractor mechanism we compute the black hole ma
ss and black string tension\, leading to a conjectural formula for the asy
mptotic volumes of connected\, locally volume-minimizing representatives o
f non-holomorphic\, even-dimensional homology classes in the threefold\, w
ithout knowledge of an explicit metric. In the case of divisors we find ex
amples where the volume of the representative corresponding to the black s
tring is less than the volume of the minimal piecewise-holomorphic represe
ntative\, predicting recombination for those homology classes and leading
to stable\, non-BPS strings. We also show how to compute the central charg
es of non-BPS strings in F-theory via a near-horizon AdS3 limit in 6d whic
h\, upon compactification on a circle\, account for the asymptotic entropy
of extremal nonsupersymmetric 5d black holes (i.e.\, the asymptotic count
of non-holomorphic minimal 2-cycles).\n
LOCATION:https://researchseminars.org/talk/WHCGP/31/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Fei Yan (Rutgers)
DTSTART;VALUE=DATE-TIME:20210503T190000Z
DTEND;VALUE=DATE-TIME:20210503T200000Z
DTSTAMP;VALUE=DATE-TIME:20230208T060818Z
UID:WHCGP/32
DESCRIPTION:Title: T
wo tales of networks and quantization\nby Fei Yan (Rutgers) as part of
Western Hemisphere colloquium on geometry and physics\n\n\nAbstract\nI wi
ll describe two quantization scenarios. The first scenario involves the co
nstruction of a quantum trace map computing a new link "invariant" (with p
ossible wall-crossing behavior) for links L in a 3-manifold M\, where M is
a Riemann surface C times a real line. This construction computes familia
r link invariants in a new way\, moreover it unifies that computation with
the computation of protected spin characters counting ground states with
spin for line defects in 4d N=2 theories of class-S. Certain networks on C
play an important role in the construction. The second scenario concerns
the study of Schroedinger equations and their higher order analogues\, whi
ch could arise in the quantization of Seiberg-Witten curves in 4d N=2 theo
ries. Here similarly certain networks play an important part in the exact
WKB analysis for these Schroedinger-like equations. At the end of my talk
I will also try to sketch a possibility to bridge these two quantization s
cenarios. The first part of the talk is based on joint work with A. Neitzk
e\; the final sketch is based on discussions with D. Gaiotto\, G. Moore an
d A. Neitzke.\n
LOCATION:https://researchseminars.org/talk/WHCGP/32/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Richard Thomas (Imperial College)
DTSTART;VALUE=DATE-TIME:20210517T190000Z
DTEND;VALUE=DATE-TIME:20210517T200000Z
DTSTAMP;VALUE=DATE-TIME:20230208T060818Z
UID:WHCGP/33
DESCRIPTION:Title: N
onabelian DT theory from abelian DT theory\nby Richard Thomas (Imperia
l College) as part of Western Hemisphere colloquium on geometry and physic
s\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 semista
ble sheaves on X.\n\nI will describe ongoing work with Soheyla Feyzbakhsh
with the eventual aim of writing the generalised DT invariants in any rank
r in terms of rank 1 invariants. By the MNOP conjecture the latter are de
termined by the GW invariants of X.\n\nAlong the way we express rank r DT
invariants in terms of rank 0 invariants counting D4-D2-D0 branes. These i
nvariants are predicted by S-duality to be governed by (vector-valued mock
) modular forms.\n\nBased partly on arXiv:2007.03037 and
arXiv:2103.02915 .\n
LOCATION:https://researchseminars.org/talk/WHCGP/33/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Zohar Komargodski (SCGP\, Stony Brook)
DTSTART;VALUE=DATE-TIME:20210607T190000Z
DTEND;VALUE=DATE-TIME:20210607T200000Z
DTSTAMP;VALUE=DATE-TIME:20230208T060818Z
UID:WHCGP/35
DESCRIPTION:Title: H
igher central charges and gapped boundaries\nby Zohar Komargodski (SCG
P\, Stony Brook) as part of Western Hemisphere colloquium on geometry and
physics\n\n\nAbstract\nThe chiral central charge is a famous diagnostic of
edge modes on the boundary of 2+1 dimensional topological phases. We show
that many theories with a vanishing chiral central charge nevertheless ca
nnot admit a gapped boundary. We define higher chiral central charges and
investigate their properties.\n
LOCATION:https://researchseminars.org/talk/WHCGP/35/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Sarah Harrison (McGill University)
DTSTART;VALUE=DATE-TIME:20210712T190000Z
DTEND;VALUE=DATE-TIME:20210712T200000Z
DTSTAMP;VALUE=DATE-TIME:20230208T060818Z
UID:WHCGP/36
DESCRIPTION:Title: N
ew BPS algebras from superstring compactifications\nby Sarah Harrison
(McGill University) as part of Western Hemisphere colloquium on geometry a
nd physics\n\n\nAbstract\nBorcherds Kac-Moody (BKM) algebras are a general
ization of familiar Kac-Moody algebras with imaginary simple roots. On the
one hand\, they were invented by Borcherds in his proof of the monstrous
moonshine conjectures and have many interesting connections to new moonshi
nes\, number theory and the theory of automorphic forms. On the other hand
\, there is an old conjecture of Harvey and Moore that BPS states in strin
g theory form an algebra that is in some cases a BKM algebra and which is
based on certain signatures of BKMs observed in 4d threshold corrections a
nd black hole physics. I will briefly review the construction of new BKMs
superalgebras arising from self-dual vertex operator algebras of central c
harge 12\, and then discuss recent work showing how they arise as algebras
of BPS states in physical string theories in 2 dimensions\, as well as th
eir connection with automorphic forms. Based on work with N. Paquette\, D.
Persson\, and R. Volpato. This can be seen as a follow-up to a talk given
by N. Paquette at this series this past October.\n
LOCATION:https://researchseminars.org/talk/WHCGP/36/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Theo Johnson-Freyd (Perimeter/Dalhousie)
DTSTART;VALUE=DATE-TIME:20210726T190000Z
DTEND;VALUE=DATE-TIME:20210726T200000Z
DTSTAMP;VALUE=DATE-TIME:20230208T060818Z
UID:WHCGP/38
DESCRIPTION:Title: S
emisimple higher categories\nby Theo Johnson-Freyd (Perimeter/Dalhousi
e) as part of Western Hemisphere colloquium on geometry and physics\n\n\nA
bstract\nSemisimple higher categories are a quantum version of topological
spaces (behaving sometimes like homotopy types and sometimes like manifol
ds) in which cells are attached along superpositions of other cells. Many
operations from topology make sense for semisimple higher categories: they
have homotopy sets (not groups)\, loop spaces\, etc. For example\, the ex
tended operators in a topological sigma model form a semisimple higher cat
egory that can be thought of as a type of "cotangent bundle" of the target
space. The "symplectic pairing" on this "cotangent bundle" is measured an
S-matrix pairing aka Whitehead bracket defined on the homotopy sets of an
y (pointed connected) semisimple higher category\, and the nondegeneracy o
f this pairing is a type of Poincare or Atiyah duality. This is joint work
in progress with David Reutter.\n
LOCATION:https://researchseminars.org/talk/WHCGP/38/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Nathan Seiberg (IAS)
DTSTART;VALUE=DATE-TIME:20210927T190000Z
DTEND;VALUE=DATE-TIME:20210927T200000Z
DTSTAMP;VALUE=DATE-TIME:20230208T060818Z
UID:WHCGP/39
DESCRIPTION:Title: C
omments on Lattice vs. Continuum Quantum Field Theory\nby Nathan Seibe
rg (IAS) as part of Western Hemisphere colloquium on geometry and physics\
n\n\nAbstract\nThere is an interesting interplay between continuum quantum
field theory (QFT) and lattice systems. First\, as in condensed-matter ph
ysics\, we start at short distances (UV) with a lattice model and our goal
is to find its long distance (IR) behavior. The lore is that this behavio
r is captured by a continuum QFT. Conversely\, as is more common in high-e
nergy physics and mathematical physics\, the lattice theory is a first ste
p toward a rigorous definition of the continuum theory. Despite enormous p
rogress over the past decades\, these two directions of the interplay betw
een the lattice and the continuum face interesting challenges. \n\nHere\,
motivated by recently discovered theoretical phases of matter (including t
he XY-plaquette model and models of fractons)\, we will address two aspect
s of the relation between the lattice in the UV and the continuum in the I
R. We will present lattice models exhibiting topological properties of con
tinuum theories\, like winding symmetries\, ‘t Hooft anomalies\, and dua
lity. We will use this approach to clarify the subsystem global symmetries
of some of the recently discovered exotic models. We will also discuss so
me more dynamical aspects of these systems and in particular their enigmat
ic UV/IR mixing\; i.e.\, some long-distance properties are sensitive to sh
ort-distance details.\n
LOCATION:https://researchseminars.org/talk/WHCGP/39/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Ryan Thorngren (Harvard University)
DTSTART;VALUE=DATE-TIME:20211011T190000Z
DTEND;VALUE=DATE-TIME:20211011T200000Z
DTSTAMP;VALUE=DATE-TIME:20230208T060818Z
UID:WHCGP/40
DESCRIPTION:Title: A
Tour of Categorical Symmetry\nby Ryan Thorngren (Harvard University)
as part of Western Hemisphere colloquium on geometry and physics\n\n\nAbst
ract\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'll discu
ss a bulk-boundary correspondence which in finite situations allows us to
classify gapped phases with categorical symmetry and define things like an
omalous symmetries and gauging. I'll conclude with some more examples of t
opological operators in c = 1 CFTs and describe a Noether theorem for cont
inuous categorical symmetries.\n
LOCATION:https://researchseminars.org/talk/WHCGP/40/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Ibrahima Bah (Johns Hopkins Univ.)
DTSTART;VALUE=DATE-TIME:20211025T190000Z
DTEND;VALUE=DATE-TIME:20211025T200000Z
DTSTAMP;VALUE=DATE-TIME:20230208T060818Z
UID:WHCGP/41
DESCRIPTION:Title: N
on-supersymmetric smooth solitonic solutions in Einstein-Maxwell type theo
ries\nby Ibrahima Bah (Johns Hopkins Univ.) as part of Western Hemisph
ere colloquium on geometry and physics\n\n\nAbstract\nIn this talk I will
present a recent framework to construct and study smooth horizon-less non-
supersymmetric solutions in gravity with interesting topologies. These liv
e in backgrounds that are 4d Minkowski with tori of various dimensions. I
will discuss the physical mechanism that allows for their existence and co
mment on their classical and thermodynamic stability. I will describe a fa
mily of these constructions that resolve certain curvature singularities.\
n
LOCATION:https://researchseminars.org/talk/WHCGP/41/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Tony Pantev (University of Pennsylvania)
DTSTART;VALUE=DATE-TIME:20211108T200000Z
DTEND;VALUE=DATE-TIME:20211108T210000Z
DTSTAMP;VALUE=DATE-TIME:20230208T060818Z
UID:WHCGP/42
DESCRIPTION:Title: G
eometry and topology of wild character varieties\nby Tony Pantev (Univ
ersity of Pennsylvania) as part of Western Hemisphere colloquium on geomet
ry and physics\n\n\nAbstract\nWild character varieties parametrize monodro
my\nrepresentations of flat meromorphic connections on compact Riemann\nsu
rfaces. They are classical objects with remarkable geometric and\ntopologi
cal properties. \n\nI will recall how intrinsic geometric structures resol
ve singularities\nof wild character varieties and will show that their al
gebraic\nsymplectic structures extend naturally to the resolutions. This i
s\nbased on a new universal method for producing symplectic structures\nwh
ich is a joint work with Arinkin and Toen. I will also describe recent jo
int works with\nChuang\, Diaconescu\, Donagi\, and Nawata in which we use
string dualities \nto extract cohomological invariants of twisted wild cha
racter\nvarieties from BPS counts on Calabi-Yau threefolds and refined\nC
hern-Simons invariants of torus knots.\n
LOCATION:https://researchseminars.org/talk/WHCGP/42/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Lotte Hollands (Heriot-Watt University)
DTSTART;VALUE=DATE-TIME:20211122T200000Z
DTEND;VALUE=DATE-TIME:20211122T210000Z
DTSTAMP;VALUE=DATE-TIME:20230208T060818Z
UID:WHCGP/43
DESCRIPTION:Title: P
artition functions\, BPS states and abelianization\nby Lotte Hollands
(Heriot-Watt University) as part of Western Hemisphere colloquium on geome
try and physics\n\n\nAbstract\nIn this talk I will re-express the Nekrasov
-Shatashvili partition function for a four-dimensional N=2 gauge theory as
an integral of a ratio of Wronskians of solutions to the relevant oper eq
uation\, with the AD2 theory and the pure SU(2) theory as two main example
s. This motivates the definition of a generalized Nekrasov-Shatashvili par
tition function for any four-dimensional N=2 theory of class S\, and makes
a connection with abelianization and exact WKB analysis. We will end with
some remarks regarding the five-dimensional generalization and the relati
on to similar mathematical structures underlying the topological string pa
rtition function. This talk is based on 2109.14699 and work in progress.\n
LOCATION:https://researchseminars.org/talk/WHCGP/43/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Clay Córdova (University of Chicago)
DTSTART;VALUE=DATE-TIME:20211206T200000Z
DTEND;VALUE=DATE-TIME:20211206T210000Z
DTSTAMP;VALUE=DATE-TIME:20230208T060818Z
UID:WHCGP/44
DESCRIPTION:Title: N
on-Invertible Duality Defects\nby Clay Córdova (University of Chicago
) as part of Western Hemisphere colloquium on geometry and physics\n\n\nAb
stract\nFor any quantum system invariant under gauging a higher-form globa
l symmetry\, we construct a non-invertible topological defect by gauging i
n only half of spacetime. This generalizes the Kramers-Wannier duality lin
e in 1+1 dimensions to higher space- time dimensions. We focus on the case
of a one-form symmetry in 3+1 dimensions\, and determine the fusion rule.
From a direct analysis of one-form symmetry protected topological phases\
, we show that the existence of certain kinds of duality defects is intrin
sically incompatible with a trivially gapped phase. We give an explicit re
alization of this duality defect in the free Maxwell theory where it is re
alized by a Chern-Simons coupling between the gauge fields from the two si
des.\n
LOCATION:https://researchseminars.org/talk/WHCGP/44/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Pavel Etingof (MIT)
DTSTART;VALUE=DATE-TIME:20210913T190000Z
DTEND;VALUE=DATE-TIME:20210913T200000Z
DTSTAMP;VALUE=DATE-TIME:20230208T060818Z
UID:WHCGP/45
DESCRIPTION:Title: H
ecke operators over local fields and an analytic approach to the geometric
Langlands correspondence\nby Pavel Etingof (MIT) as part of Western H
emisphere colloquium on geometry and physics\n\n\nAbstract\nI will review
an analytic approach to the geometric Langlands correspondence\, following
my work with E. Frenkel and D. Kazhdan\, arXiv:1908.09677\, arXiv:2103.01
509\, arXiv:2106.05243. This approach was developed by us in the last coup
le of years and involves ideas from previous and ongoing works of a number
of mathematicians and mathematical physicists\, Kontsevich\, Langlands\,
Teschner\, and Gaiotto-Witten. One of the goals of this approach is to und
erstand single-valued real analytic eigenfunctions of the quantum Hitchin
integrable system. The main method of studying these functions is realizin
g them as the eigenbasis for certain compact normal commuting integral ope
rators the Hilbert space of L2 half-densities on the (complex points of) t
he moduli space Bun_G of principal G-bundles on a smooth projective curve
X\, possibly with parabolic points. These operators actually make sense ov
er any local field\, and over non-archimedian fields are a replacement for
the quantum Hitchin system. We conjecture them to be compact and prove th
is conjecture in the genus zero case (with parabolic points) for G=PGL(2).
I will first discuss the simplest non-trivial example of Hecke operators
over local fields\, namely G=PGL(2) and genus 0 curve with 4 parabolic poi
nts. 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 the theo
ry of single-valued eigenfunctions of the Lame operator with coupling para
meter -1/2 (previously studied by Beukers and later in a more functional-a
nalytic sense in our work with Frenkel and Kazhdan). I will consider the c
orresponding spectral theory and then explain its generalization to N>4 po
ints and conjecturally to higher genus curves.\n
LOCATION:https://researchseminars.org/talk/WHCGP/45/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Hirosi Ooguri (Cal Tech)
DTSTART;VALUE=DATE-TIME:20220124T200000Z
DTEND;VALUE=DATE-TIME:20220124T210000Z
DTSTAMP;VALUE=DATE-TIME:20230208T060818Z
UID:WHCGP/46
DESCRIPTION:Title: S
ymmetry in QFT and Gravity\nby Hirosi Ooguri (Cal Tech) as part of Wes
tern Hemisphere colloquium on geometry and physics\n\nAbstract: TBA\n
LOCATION:https://researchseminars.org/talk/WHCGP/46/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Emily Cliff (Université de Sherbrooke)
DTSTART;VALUE=DATE-TIME:20220207T200000Z
DTEND;VALUE=DATE-TIME:20220207T210000Z
DTSTAMP;VALUE=DATE-TIME:20230208T060818Z
UID:WHCGP/47
DESCRIPTION:Title: M
oduli spaces of principal 2-group bundles and a categorification of the Fr
eed--Quinn line bundle\nby Emily Cliff (Université de Sherbrooke) as
part of Western Hemisphere colloquium on geometry and physics\n\nAbstract:
TBA\n
LOCATION:https://researchseminars.org/talk/WHCGP/47/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Heeyeon Kim (Rutgers University)
DTSTART;VALUE=DATE-TIME:20220509T190000Z
DTEND;VALUE=DATE-TIME:20220509T200000Z
DTSTAMP;VALUE=DATE-TIME:20230208T060818Z
UID:WHCGP/48
DESCRIPTION:Title: P
ath integral derivations of K-theoretic Donaldson invariants\nby Heeye
on Kim (Rutgers University) as part of Western Hemisphere colloquium on ge
ometry and physics\n\n\nAbstract\nWe discuss path integral derivations of
topologically twisted partition functions of 5d SU(2) supersymmetric Yang-
Mills theory on M4 x S1\, where M4 is a smooth closed four-manifold. Mathe
matically\, they can be identified with the K-theoretic version of the Don
aldson invariants. In particular\, we provide two different path integral
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 instanton
counting. We briefly discuss the generalization to b_2^+(M4)>1.\n
LOCATION:https://researchseminars.org/talk/WHCGP/48/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Constantin Teleman (U. C. Berkeley)
DTSTART;VALUE=DATE-TIME:20220425T190000Z
DTEND;VALUE=DATE-TIME:20220425T200000Z
DTSTAMP;VALUE=DATE-TIME:20230208T060818Z
UID:WHCGP/49
DESCRIPTION:Title: C
oulomb branches and Drinfeld centers\nby Constantin Teleman (U. C. Ber
keley) as part of Western Hemisphere colloquium on geometry and physics\n\
n\nAbstract\nWe discuss a construction of Coulomb branches of a compact Li
e group G from the Toda integrable systems and speculate on their origins
as Drinfeld centers of modifications of (a variant of) the tensor category
of topological representations of G.\n
LOCATION:https://researchseminars.org/talk/WHCGP/49/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Eric Zaslow (Northwestern University)
DTSTART;VALUE=DATE-TIME:20220228T200000Z
DTEND;VALUE=DATE-TIME:20220228T210000Z
DTSTAMP;VALUE=DATE-TIME:20230208T060818Z
UID:WHCGP/50
DESCRIPTION:Title: F
raming Duality\nby Eric Zaslow (Northwestern University) as part of We
stern Hemisphere colloquium on geometry and physics\n\n\nAbstract\nI will
describe joint work in progress with Linhui Shen and Gus Schrader\, in whi
ch we study moduli spaces of Fukaya objects and conjecture about their rel
ationship to BPS and open Gromov-Witten invariants. This unabashedly synth
esize previous works of many other groups\, whom I will credit in the talk
. I will try to highlight some new aspects: 1) a definition of phases and
framings and their combinatorial origins\; 2) conjectures on open Gromov-W
itten invariants for Lagrangians bounding certain Legendrian surfaces\; 3)
a “framing duality” relating Dondaldson-Thomas and open Gromov-Witten
invariants.\n
LOCATION:https://researchseminars.org/talk/WHCGP/50/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Joerg Teschner (DESY)
DTSTART;VALUE=DATE-TIME:20220314T190000Z
DTEND;VALUE=DATE-TIME:20220314T200000Z
DTSTAMP;VALUE=DATE-TIME:20230208T060818Z
UID:WHCGP/51
DESCRIPTION:Title: T
he complex geometry of topological string partition functions\nby Joer
g Teschner (DESY) as part of Western Hemisphere colloquium on geometry and
physics\n\n\nAbstract\nThe goal of this talk will be to review some aspec
ts of a program inspired by work of Tom Bridgeland aiming at a non-perturb
ative characterisation of topological string partition functions. The prog
ram is based on two main ingredients: The complex geometry of the underlyi
ng moduli spaces on the one hand\, and cluster algebra structures defined
by BPS- or DT-invariants on the other hand. The general picture is nicely
illustrated by the Borel summation of the conifold partition functions rec
ently studied with M. Alim\, A. Saha and I. Tulli\, with Stokes jumps of t
he partition functions getting related to wall-crossing phenomena in the t
heory of DT-invariants. Based on this and other examples we will propose a
conjectural characterisation of the partition functions for local Calabi-
Yau manifolds\, generalising earlier proposals by Marino and collaborators
\, and related to earlier proposals by Alexandrov\, Pioline and collaborat
ors based on the geometry of hypermultiplet moduli spaces.\n
LOCATION:https://researchseminars.org/talk/WHCGP/51/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Washington Taylor (MIT)
DTSTART;VALUE=DATE-TIME:20220328T190000Z
DTEND;VALUE=DATE-TIME:20220328T200000Z
DTSTAMP;VALUE=DATE-TIME:20230208T060818Z
UID:WHCGP/52
DESCRIPTION:Title: M
iddle intersection forms on singular elliptic Calabi-Yau fourfolds\, and a
pplications to the standard model and mirror symmetry\nby Washington T
aylor (MIT) as part of Western Hemisphere colloquium on geometry and physi
cs\n\n\nAbstract\nRecent work with Jefferson and Turner indicates that the
intersection form on the vertical part of middle cohomology of singular e
lliptic Calabi-Yau fourfolds is independent of resolution. This suggests t
hat the intersection structure should have a natural definition even in th
ese singular geometries. The resulting intersection form has a simple bloc
k-diagonal structure in terms of Kodaira singularities and the geometry of
the base of the elliptic fibration\; the talk will describe applications
of this intersection form to analysis of chiral matter and standard model
constructions in F-theory as well as new insights into mirror symmetry\, i
n particular providing in some cases a complete description of the interse
ction form on H_4 (X\, Z) for a smooth Calabi-Yau fourfold including both
vertical and horizontal parts.\n
LOCATION:https://researchseminars.org/talk/WHCGP/52/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Daniel Halpern-Leistner (Cornell)
DTSTART;VALUE=DATE-TIME:20220411T190000Z
DTEND;VALUE=DATE-TIME:20220411T200000Z
DTSTAMP;VALUE=DATE-TIME:20230208T060818Z
UID:WHCGP/53
DESCRIPTION:Title: I
nfinite dimensional geometric invariant theory and gauged Gromov-Witten th
eory\nby Daniel Halpern-Leistner (Cornell) as part of Western Hemisphe
re colloquium on geometry and physics\n\n\nAbstract\nHarder-Narasimhan (HN
) theory gives a structure theorem for holomorphic vector bundles on a Rie
mann surface. A bundle is either semistable\, or it admits a canonical fil
tration whose associated graded bundle is semistable in a graded sense. Af
ter reviewing recent advances in extending HN theory to arbitrary moduli p
roblems in algebraic geometry I will discuss work in progress with Andres
Fernandez Herrero and Eduardo Gonzalez to apply this general machinery 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 gauged Gr
omov-Witten invariants. This problem is interesting more broadly because i
t can be formulated as an example of an infinite dimensional analog of the
usual set up of geometric invariant theory\, which has applications to ot
her moduli problems.\n
LOCATION:https://researchseminars.org/talk/WHCGP/53/
END:VEVENT
END:VCALENDAR