Speaker
Description
It is useful to characterize a high energy state in a massive QFT by its particle number densities as a function of particle momenta. We describe how, in massive RG flows starting from a UV CFT, complex spin CFT data defines evolution equations for these densities as a function of the energy of the state. This picture naturally arises when considering the idea of detector matching. Detector operators are non-local operators that provide the analytic continuation of operators to complex spin, and detector matching is the statement that detectors in an IR theory can be matched onto a sum of detectors in the UV. As an explicit example, we present results showing how density evolution and matching works in the 2D Ising model and its deformations. We also present an independent derivation of evolution and matching in the case of integrable models by treating states as a classical gas and employing thermodynamic arguments.