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

## TL;DR

This paper demonstrates a universal form for next-to-leading power threshold effects in the production of colourless particles in hadronic collisions, applicable at NLO and beyond, with new analytic results for Higgs pair production.

## Contribution

It introduces a universal expression for NLP threshold effects in colourless final states, applicable to both tree-level and loop-induced processes, and provides new analytic results for Higgs pair production.

## Key findings

- Universal NLP threshold effect formula at NLO
- Re-derivation of Higgs and gauge boson production results
- New analytic results for Higgs pair production with top-mass dependence

## Abstract

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. We use our universal expression to re-derive known results for the production of up to three Higgs bosons at NLO in the large top mass limit, and for the hadro-production of a pair of electroweak gauge bosons. Finally, we present new analytic results for Higgs boson pair production at NLO and NLP, with exact top-mass dependence.