Theory Colloquia at the Physics Department of Torino

I will review how causality constrains higher derivative corrections to general relativity. The basic tool is the twice-subtracted dispersion relations, combined with unitarity and crossing symmetry. This framework allows one to derive quantitative, two-sided bounds on the Wilson coefficients, given the spectral gap of the theory. A striking conclusion is that consistency between classical deviations from general relativity and causality can only be achieved in a theory of strings.

Friday, 11st April 2025, 14:30