Theory Group Seminar

Dr. Sandipan Kundu, Cornell University

"Causality constraints in conformal field theory"

2:00pm, RLM 7.104

Abstract: Causality places nontrivial constraints on QFT in Lorentzian signature, for example fixing the signs of certain terms in the low energy Lagrangian. In conformal field theory, I will show how such constraints are encoded in crossing symmetry and reflection positivity of Euclidean correlators, and derive analogous constraints directly from the conformal bootstrap. Causality fixes the signs of certain log terms that appear in the conformal block expansion, which constrains the interactions of low-lying operators. Finally, I will explain the connection between the Hofman-Maldacena conditions for positive energy deposition and causality.