Higgs production via gluon fusion from kT-factorisation

TL;DR

This paper evaluates the accuracy of Higgs production predictions via gluon fusion using kT-factorisation, comparing it with collinear approaches and analyzing the impact on the Higgs transverse momentum spectrum.

Contribution

It provides a numerical analysis of the errors introduced by the effective vertex approximation in Higgs production via gluon fusion using kT-factorisation and compares different Monte Carlo methods.

Findings

kT-factorisation affects the Higgs pT spectrum predictions

Comparison shows differences between CASCADE and collinear Monte Carlos

Resummation of high-energy corrections influences parton radiation patterns

Abstract

Theoretical studies of Higgs production via gluon fusion are frequently carried out in the limit where the top quark mass is much larger than the Higgs mass, an approximation which reduces the top quark loop to an effective vertex. We present a numerical analysis of the error thus introduced by performing a Monte Carlo calculation for gg->h in kT-factorisation, using the parton shower generator CASCADE. We proceed to compare CASCADE to the collinear Monte Carlos PYTHIA, MC@NLO and POWHEG. We study the dependence of parton radiation on the resummation of high-energy corrections taken into account by kT-factorisation, and its influence on predictions for the Higgs pT spectrum.