PIRSA ID: 21020017
Série : Quantum Fields and Strings
Event Type: Seminar
Domaine(s) scientifique(s) : Quantum Fields and Strings
Date de fin : 2021-02-09
Speaker(s): Francesco Riva University of Geneva (UNIGE) - Department of Theoretical Physics
I will discuss the conditions satisfied by the 2 → 2 scattering amplitude in unitarity and causal theories, presenting a simple formulation in term of moments of a positive measure. I will identify complete subsets of two-sided constraints, suitable to bound Effective Field Theories (EFTs) at any finite order in the energy expansion. I will also discuss the importance of IR loop effects on these bounds. A consequence of this study is that EFTs in which the scattering amplitude in some regime grows in energy faster than E6 (e.g. higher spin particles with masses smaller than their inverse size) cannot be UV-completed.