## Causality Constraints in Conformal Field Theory

**Speaker:**Tom Hartman , Cornell

**When:**November 18, 2015 (Wed), 03:30PM to 04:30PM (add to my calendar)

**Location:**PRB 595

*This event is part of the HET Seminar Series. *

It is well known that some effective field theories cannot be UV completed -- perturbative amplitudes in the infrared may be at odds with ultraviolet consistency conditions, like the optical theorem. In this talk I will describe an analogue of these constraints in strongly coupled conformal field theory. Correlation functions (in position space) obey a sum rule that constrains the couplings among low-dimension operators. If the constraints are violated, then the low-dimension sector cannot be embedded into a full causal CFT. In large-N holographic theories, this strong-coupling constraint matches known weak-coupling constraints in the bulk effective field theory.