This biweekly online colloquium features geometers and physicists presenting current research on a wide range of topics in the interface of the two fields. The talks are aimed at a broad audience. They will take place via Zoom on alternate Mondays at 3pm Eastern, noon Pacific, 4pm BRT. Each session features a 60 minute talk, followed by 15 minutes for questions and discussion. You may join the meeting 15 minutes in advance. Questions and comments may be submitted to the moderator via the chat interface during the talk, or presented in person during the Q&A session. These colloquia will be recorded and will be available (linked from here) asap after the event.
As an alternative to Zoom, you may watch a live stream of the lecture at: https://youtu.be/48BSjfAYk6o
To receive announcements about the colloquia (including Zoom links to individual meetings), sign up for the WHCGP mailing list here.
Organizing committee: Tudor Dimofte, Ron Donagi, Dan Freed, Sheldon Katz, Dave Morrison, Andy Neitzke.
April 13, 2020 
Edward Witten (IAS)Volumes and Random MatricesAbstract: I will describe recent results relating twodimensional gravity and supergravity; volumes of moduli spaces of Riemann surfaces and super Riemann surfaces; and random matrix ensembles. See https://arxiv.org/abs/1903.11115 by Saad, Shenker, and Stanford; https://arxiv.org/abs/1907.03363 by Stanford and me. Video of lecture OR Video of lecture (alternate version, same content as the other) 
April 27, 2020 
Kevin Costello (Perimeter Institute)Topological strings, twistors, and SkyrmionsAbstract: It 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 topological B model on twistor space. The corresponding theory on Minkowski space is a sigmamodel with target the group SO(8). This is a variant of the Skyrme model that appears as the lowenergy effective theory of mesons in QCD. (The group SO(8) appears because of the GreenSchwarz mechanism in the topological string). The origin of this model in the topological string implies many remarkable properties. For one thing, the model is, in a certain sense, integrable. Further, although the Lagrangian is powercounting nonrenormalizable, counterterms at all loops can be uniquely fixed.
Video of lecture OR Video of lecture (alternate version, same content as the other) 
May 11, 2020 
Mark Gross (Cambridge)Intrinsic Mirror SymmetryAbstract: I will talk about joint work with Bernd Siebert, proposing a general mirror construction for log CalabiYau pairs, i.e., a pair (X,D) with D a "maximally degenerate" boundary divisor and K_X+D=0, and for maximally unipotent degenerations of CalabiYau manifolds. We accomplish this by constructing the coordinate ring or homogeneous coordinate ring respectively in the two cases, using certain kinds of GromovWitten invariants we call "punctured invariants", developed jointly with Abramovich and Chen. Video of lecture OR Video of lecture (alternate version, same content as the other) 
May 18, 2020 
Miranda Cheng (Univ. of Amsterdam/National Taiwan University)Quantum Modularity from 3ManifoldsAbstract: Quantum modular forms are functions on rational numbers that have rather mysterious weak modular properties. Mock modular forms and false theta functions are examples of holomorphic functions on the upperhalf plane which lead to quantum modular forms. Inspired by the 3d3d correspondence in string theory, a new topological invariants named homological blocks for (in particular plumbed) threemanifolds have been proposed 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 relation to logarithmic vertex algebras. The talk will be based on a series of work in collaboration with Sungbong Chun, Boris Feigin, Francesca Ferrari, Sergei Gukov, Sarah Harrison, and Gabriele Sgroi. Video of Lecture OR Video of lecture (alternate version, same content as the other) 
June 1, 2020 
Davide Gaiotto (Perimeter Institute)Integrable Kondo problems and affine Geometric LanglandsAbstract: I will present some work on integrable line defects in WZW models and their relation to 4d CS theory, the IM/ODe correspondence and affine generalizations of Geometric Langlands constructions. Video of lecture OR Video of lecture (alternate version, same content as the other) 
June 15, 2020 
Maxim Kontsevich (IHES)Spacetime analyticity in QFTAbstact: I will talk on a joint work with Graeme Segal. We propose a new axiomatics for unitary quantum field theory which includes both Lorentzian and Euclidean signatures for curved spacetime manifolds. The key to the definition is certain open domain in the space of complexvalued symmetric bilinear forms on a real vector space. The justification comes from holomorphic convexity (lower bound) and from higher gauge theories (upper bound).

June 22, 2020 
Anton Kapustin (Cal Tech)

June 29, 2020 
Sakura SchaferNameki (Oxford)

July 6, 2020 
Nima ArkaniHamed (IAS)

July 13, 2020 
Mina Aganagic (UC Berkeley)

July 20, 2020 
Greg Moore (Rutgers)

July 27, 2020 
Laura Fredrickson (Stanford/U. Oregon)

August 3, 2020 
TBA

August 10, 2020 
TBA

August 17, 2020 
TBA

August 24, 2020 
TBA
