The one-loop amplitudes for Higgs + 4 partons with full mass effects

Lucy Budge,R Keith Ellis,John M Campbell,Satyajit Seth,Giuseppe De Laurentis

doi:10.1007/jhep05(2020)079

Lucy Budge, R Keith Ellis + Show 3 more

Open Access

https://doi.org/10.1007/jhep05(2020)079

Copy DOI

Abstract

We present compact analytic formulae for the one-loop amplitudes for Higgs + 4 parton scattering, 0 → ggggh, 0 → overline{q} qggh and 0 → overline{q} q {overline{q}}^{prime } q′h, mediated by a loop of massive coloured quarks. We exploit the correspondence with a theory in which a massive coloured scalar circulates in the loop to avoid a proliferation in the number of terms in the result. In addition, we use momentum twistors and high precision numerical evaluations to simplify the expressions. The analytic results in this paper, in terms of spinor products, allow construction of an efficient numerical program to calculate the amplitude.

Highlights

At the Large Hadron Collider (LHC) the primary mechanism for producing and detectingHiggs bosons is the process gg → h
In the limit in which only a very heavy top quark contributes, the corresponding amplitude is independent of the top quark mass; this gives rise to an effective field theory (EFT) in which the loop of heavy top quarks is replaced by an effective gs2 48π2v h GAμν GA,μν where gs is the strong coupling constant, v is the vacuum expectation value of the Higgs field, Gμν is QCD field strength, and h is the Higgs boson field
We have presented analytic results for all helicity amplitudes representing the processes 0 → ggggh, 0 → qqggh and 0 → qqqq h, where the interaction is mediated by a loop of massive fermions and all dependence on the fermion mass is retained

Summary

Introduction

At the Large Hadron Collider (LHC) the primary mechanism for producing and detectingHiggs bosons is the process gg → h. The effective field theory description is expected to break down when, for example, the transverse momentum of produced gluons is of order of the top quark mass. This breakdown has most recently been investigated at NLO in ref. This kinematic regime is beginning to be explored at the LHC [6] and can give important information about the mediators in the loop that couple to the Higgs For such configurations it is important to make use of a superior calculation in which the full dependence on the top quark mass is retained. Such a calculation allows a direct quantification of the breakdown of the EFT approach

Objectives

Methods

Conclusion