Phenomenology of combined resummation for Higgs and Drell--Yan

TL;DR

This paper introduces a combined resummation formalism that improves predictions for Higgs and Drell-Yan processes by integrating threshold effects with transverse momentum resummation, enhancing accuracy across all p_T ranges.

Contribution

It presents a systematic method to combine threshold and transverse momentum resummation, validated through phenomenological studies of Higgs and Z boson production.

Findings

Faster convergence at small p_T with threshold-improved resummation.

Better agreement with fixed-order results at medium and large p_T.

More pronounced effects observed in Higgs production due to slower perturbative convergence.

Abstract

We study the phenomenological impact of a recently suggested formalism for the combination of threshold and a so-called threshold-improved transverse momentum resummation, by using it to improve the fixed-order results. This formalism allows for a systematic improvement of the transverse momentum resummation that is valid in the entire range of $p_T$ by the inclusion of the threshold contribution. We use the Borel method as a suitable prescription for defining the inverse Mellin and Fourier transforms in the context of combined resummed expression. The study is applied to two QCD processes, namely the Higgs boson produced via gluon fusion and $Z$ boson production via the Drell--Yan mechanism. We compare our results to the standard transverse momentum resummation, as well as to the fixed-order results. We find that the threshold-improved transverse momentum resummation leads to faster perturbative convergence at small $p_T$ while the inclusion of threshold resummation improves the agreement with fixed-order calculations at medium and large $p_T$. These effects are more pronounced in the case of Higgs which is known to have slower perturbative convergence.