Virtual corrections to $gg\to ZH$ via a transverse momentum expansion

TL;DR

This paper presents a new method for calculating virtual QCD corrections to gg→ZH production using a transverse momentum expansion, providing accurate approximations for energies relevant to the LHC.

Contribution

The authors extend the transverse momentum expansion method to handle different masses and asymmetric processes in gg→ZH production, improving computational efficiency.

Findings

Achieves better than 1% accuracy in the center of mass energy up to 750 GeV.

Provides a practical analytic approximation for LHC energy ranges.

Enhances the understanding of Higgs-Z boson associated production in gluon fusion.

Abstract

We compute the next-to-leading virtual QCD corrections to the partonic cross section of the production of a Higgs boson in association with a $Z$ boson in gluon fusion. The calculation is based on the recently introduced method of evaluating the amplitude via an expansion in terms of a small transverse momentum. We generalize the method to the case of different masses in the final state and of a process not symmetric in the forward-backward direction exchange. Our analytic approach gives a very good approximation (better than percent) of the partonic cross section in the center of mass energy region up to $\sim 750 \,\textrm{GeV}$, where at the LHC $\sim 98\%$ of the total hadronic cross section is concentrated.