Maximizing the interaction strength

by Prof. Andrea Guerrieri (City University of London)

Wednesday 16 Jul 2025, 16:30 → 18:00 Europe/Berlin

The Froissart bound is the most celebrated result of the analytic S-matrix program. It sets a bound on the interaction between particles using only properties that follow from the axioms of a gapped QFT. Despite decades of efforts, the obvious shortcomings of this bound -- its asymptotic nature, and non optimality -- have never been consistently addressed. In this talk I will discuss this paper https://arxiv.org/pdf/2506.04313 in which we revisit this old problem from a modern perspective. Blending analytic wisdom and novel numerical results made possible by state-of-the-art non-perturbative S-matrix Bootstrap numerics, I will derive rigorous finite-energy bounds on the total cross-section, construct a consistent $2\to2$ scattering amplitude that maximizes the interaction strength, discuss its properties and compare them with high energy proton-proton scattering data measured at LHC.