Kadanoff Seminar - Dispersion relations for S-matrices and CFTs, Simon Caron-Huot, McGill

Dispersion relations are statements of causality.  They give sum rules connecting low and high energies.  They are great.  I will review some recently derived consequences of causality and how they relate to dispersion relations. I will then discuss a surprising equivalence between three seemingly distinct dispersion relations in CFTs (in position space, Mellin space, and analytic functionals), and a lesson for flat-space gravity.