Universality of next-to-leading power threshold effects for colourless final states in hadronic collisions

Understand

We consider the production of an arbitrary number of colour-singlet particles near partonic threshold, and show that next-to-leading order cross sections for this class of processes have a simple universal form at next-to-leading power (NLP) in the energy of the emitted gluon radiation.

• Our analysis relies on a recently derived factorisation formula for NLP threshold effects at amplitude level, and therefore applies both if the leading-order process is tree-level and if it is loop-induced.
• It holds for differential distributions as well.
• The results can furthermore be seen as applications of recently derived next-to-soft theorems for gauge theory amplitudes.