Numerical resummation at subleading color in the strongly ordered soft gluon limit

Abstract

We present a Monte-Carlo approach to soft-gluon resummation at sub-leading color which can be used to improve existing parton shower algorithms. At the single emission level, soft-collinear enhancements of the splitting functions are explicitly linked to quadratic Casimir operators, while wide angle single-soft enhancements are connected to non-trivial color correlators. We focus on a numerically stable implementation of color matrix element corrections to all orders and approximate the virtual corrections by requiring unitarity at the single-emission level. We provide a proof-of-concept implementation to compute non-global event shapes at lepton colliders.