String Theory Seminar Series
Except where otherwise noted, seminars are held on Tuesdays at 11 a.m. in Abelson 307 (directions to Abelson). The length of the talk depends on the mode of presentation: 60 minutes for a computer talk and 80 minutes for a blackboard talk.
Please note: There are currently no seminars scheduled for Oct. 29 and Nov. 26.
Fall 2019 Seminars
September 6, 2019
Quantum Gravity in a Finite Box
September 10, 2019
All-Loop Singularities of Scattering Amplitudes in Massless Planar Theories
September 17, 2019
Gauge Theories With Nonstandard Gauge Constraints
Abstract: Pure Yang-Mills theory obeys a local constraint given by the Gauss law div E = 0. Alternative gauge constraints are known to exist: the most notable example is provided by Chern-Simons theory. However, detailed explorations of theories with nonstandard gauge constraints in the UV (e.g. on a lattice) have not been performed until very recently, when their importance was affirmed on several different fronts. In this talk I will discuss two new classes of nonstandard gauge theories. The first class involves theories in arbitrary dimension that can be shown to dualize to theories of ordinary fermions (these are higher-dimensional exact bosonization dualities). The second class involves theories of fractons, pioneered by condensed matter and quantum information communities, which are some of the most interesting examples of gapped theories not described by any kind of conventional topological order.
September 24, 2019
D-instantons and the non-perturbative completion of c=1 string theory
Abstract: I will discuss the effect of ZZ instantons in c=1 string theory, which leads to a new proposal for the non-perturbative completion of the duality between c=1 string and the matrix quantum mechanics.
October 1, 2019
Anomalies and Bounds on Charged Operators
Abstract: We study the implications of ’t Hooft anomaly (i.e. obstruction to gauging) on conformal field theory, focusing on the case when the global symmetry is Z2. Using the modular bootstrap, universal bounds on (1+1)-dimensional bosonic conformal field theories with an internal Z2 global symmetry are derived. The bootstrap bounds depend dramatically on the ’t Hooft anomaly. In particular, there is a universal upper bound on the lightest Z2 odd operator if the symmetry is anomalous, but there is no bound if the symmetry is non-anomalous. We comment on the implication to the Weak Gravity Conjecture in AdS3.
October 8, 2019
Hamiltonian fluid dynamics and the quasilinear approximation
October 15, 2019
Different perspectives on AdS3/CFT2 holography
Abstract: I will discuss AdS3/CFT2 holography from the two perspectives of integrability and worldsheet CFT and comment on their relations and recent results. In particular, I will show how to match null-vector constraints on correlation functions and explain how some structure constants can be explicitly derived and matched on the two sides of the duality. This amounts to one of the very first holographic matches of non-protected AdS3/CFT2 correlators.
October 22, 2019
November 5, 2019
November 12, 2019
The Schottky Anomaly of de Sitter Black Holes
Abstract: Black holes with Λ > 0 (SdS) have fascinating properties that are distinct from the asymptotically flat or AdS cases, starting with the fact that there are two horizons in the spacetime, one black hole and one cosmological. The two horizons have different temperatures and the total gravitational entropy is the sum of the horizon areas. As a result, both the mass M and entropy S are bounded between minimum and maximum values. Intriguingly, there is an extremum in the specific heat δM/δTb as well as in the curve δS/δTb, which resemble the Schottky anomaly of a two level system in statistical mechanics. In this talk we investigate classical and quantum mechanical features of SdS thermodynamics that make it resemble the physics of a paramagnet. We start by showing that the Schottky behavior is to be expected for classical fluctuations based on the first laws for SdS black holes. Second, we present calculations of black hole and cosmological particle production in SdS and find that the quantum fluctuations share the behavior of classical ones.
November 19, 2019
December 3, 2019
December 10, 2019