Top-associated Higgs-boson production using perturbative fragmentation functions at next-to-leading-order

TL;DR

This paper investigates Higgs boson production associated with top-quark pairs at colliders using perturbative fragmentation functions at NLO, analyzing mass treatment methods and their applicability at different collider energies.

Contribution

It demonstrates the reliability of the hybrid mass treatment method at LHC energies and explores the extension of the formalism to higher orders.

Findings

Hybrid prescription yields reliable results at LHC energies.

Zero-mass-top-quark prescription is viable at 100 TeV colliders.

Discusses challenges in extending to NNLO and beyond.

Abstract

Under certain conditions, the production of a Higgs boson in association with a top-anti-top pair at hadron colliders can be described via a factorisation theorem using perturbative fragmentation functions. The latter describe the nearly collinear emission of a Higgs boson from a top-quark and reproduce the leading mass dependence of the exact next-to-leading-order (NLO) calculation. Although the NLO fragmentation functions have been calculated a few years ago, it has not been possible up to now to demonstrate the applicability of the approximation in a realistic setup. At NLO, we analyse two different ways of treating the top-quark mass, called the zero-mass-top-quark (ZMTQ) and the hybrid prescription. We show that the method yields reliable results at LHC center-of-mass (cms) energies in the hybrid prescription. In the ZMTQ prescription, the results at LHC cms energies are only reliable in the quark-anti-quark channel, but become viable for the full $pp \rightarrow t\bar{t}H$ process at a 100 TeV hadron collider. In addition, we discuss some subtleties and complications arising when extending the formalism to next-to-next-to-leading-order (NNLO) and beyond.