Speaker
Description
Over the past decade, S-matrix-based methods have undergone a remarkable resurgence as elegant and powerful tools for extracting physical information without relying on an underlying Lagrangian formulation. A central question is: given the exact S-matrix of a quantum field theory, what can we learn about its thermodynamic properties?
In this talk, I will review the Dashen–Ma–Bernstein formalism, which relates thermodynamics directly to scattering amplitudes. I will illustrate it with the perturbative QCD equation of state and with the effective theory of long confining flux tubes, including non-universal corrections and comparisons with Thermodynamic Bethe Ansatz results. More broadly, these methods offer a way to extract thermodynamic observables directly from on-shell data, with potential applications to EFTs constrained by modern bootstrap and positivity techniques.