Speaker
Description
The high-energy limit of 2->2 scattering amplitudes offers an excellent setting to explore the analytic properties and universal features of gauge theories. At leading logarithmic (LL) accuracy the amplitude is governed by Regge poles in the complex angular momentum plane. Beyond LL, Regge cuts in this plane begin to play an important role. Specifically, the signature-odd amplitude at Next-to-Next-to-Leading logarithmic (NNLL) accuracy presents for the first time both a Regge pole and a Regge cut. Analysing this tower of logarithms and computing it explicitly through four loops we are able to systematically separate between the Regge pole and the Regge cut. We explain how to consistently define the impact factors at two loops, and the Regge trajectory at three loops and we confirm that singularities of the trajectory are given by the cusp anomalous dimension. We also show explicitly that the Regge cut contribution at four loop is non-planar.
