Multiple soft radiation at one-loop order and the emission of a soft quark-antiquark pair

by Leandro Cieri (University of Valencia)

Friday 10 Dec 2021, 14:00 → 16:00 Europe/Zurich

4/3-006 - TH Conference Room (CERN)

In this talk we will consider the radiation of two or more soft  partons in QCD hard-scattering at one-loop order. Using  regularization in d = 4 - 2epsilon space-time dimensions, we will explicitly show the ultraviolet and infrared divergent (epsilon-pole) terms of the one-loop soft current for emission of  an arbitrary number of soft partons in a generic hard-scattering  process.

Then we will consider the specific case of soft quark–antiquark (qqbar) emission and we will write the one-loop current by including the finite terms. We will show that the one-loop soft-qqbar current exhibits a new type of transverse-momentum singularity, which has a quantum  (absorptive) origin and a purely non-abelian character. At the squared amplitude (cross section) level, this transverse-momentum  singularity produces contributions to multijet production processes in hadron collisions.