Search Talks

There is a fundamental tension between what string theory computes (S-matrix elements) and what you can compute in QFT on a time-dependent backgrounds (real time operator expectation values). The prescription for computing time dependent expectation values in QFT involves a path integral defined on a closed time path, known as the Keldysh contour. In this talk, we'll discuss how a worldsheet formulation of string theory must perceive the Keldysh contour and how this modifies critical string theory at tree level in the string coupling.

Detecting light dark matter that interacts weakly with electromagnetism has recently become one of the benchmark goals of near-term and futuristic direct detection experiments. In this talk, I will discuss an alternative technique to directly detecting such particles below the GeV-scale. The approach involves distorting the local flow of dark matter with time-varying fields and measuring these distortions with shielded resonant detectors, such as LC circuits.

The relative entropy is a measure of the distinguishability of two quantum states. A great deal of progress has been made in the study of the relative entropy between an excited state and the vacuum state of a conformal field theory (CFT) reduced to a spherical region. For example, when the excited state is a small perturbation of the vacuum state, the relative entropy is known to have a universal expression for all CFT’s. Specifically, the perturbative relative entropy can be written as the symplectic flux of a certain scalar field in an auxiliary AdS-Rindler spacetime. Moreover, if the CFT has a semi-classical holographic dual, the relative entropy is known to be related to conserved charges in the bulk dual spacetime. In this talk, I will introduce a one-parameter generalization of the relative entropy which I will call 'refined' Renyi relative entropy. I will use this quantity to present a one-parameter generalization of the aforementioned known results about the relative entropy. I will also discuss a new family of positive energy theorems in asymptotically locally AdS spacetimes that arises from the holographic dual of the refined Rényi relative entropy.

I will describe an example in which ER=EPR can be understood as a worldsheet string duality, by finding the Lorentzian continuation of the FZZ duality. The result is that string perturbation theory around the thermofield double state in a disconnected spacetime with a condensate of entangled folded strings is equivalent to string theory in a connected two sided black hole spacetime. Important ingredients are the Lorentzian interpretation of time winding vertex operators, and string theory with target space Schwinger-Keldysh contours. I will also discuss a related conjecture in AdS3-Rindler.