Heavy charged Higgs boson production at the LHC

Céline Degrande,Marius Wiesemann,Marco Zaro,Maria Ubiali

doi:10.1007/jhep10(2015)145

Abstract

In this paper we study the production of a heavy charged Higgs boson in association with heavy quarks at the LHC in the two-Higgs-doublet model. We present for the first time fully-differential results obtained in the four-flavour scheme at NLO accuracy, both at fixed order and including the matching with parton showers. Relevant differential distributions are studied for two values of the charged boson mass and a thorough comparison is performed between predictions obtained in the four- and five-flavour schemes. We show that the agreement between the two schemes is improved by NLO(+PS) corrections for observables inclusive in the degrees of freedom of bottom quarks. We argue that the four-flavour scheme leads to more reliable predictions, thanks to its accurate description of the bottom-quark kinematics and its small dependence on the Monte Carlos, which in turn is rather large in the five-flavour scheme. A detailed set of recommendations for the simulation of this process in experimental analyses at the LHC is provided.

Highlights

JHEP10(2015)145 contributions) must be taken into account for a proper description
We present four-flavour scheme predictions of charged Higgs boson production at Next-to-leading order (NLO) matched to parton showers
A fully differential computation has been performed in the 4FS at fixed-order NLO (fNLO) and NLO+Parton Shower (PS) accuracy

Summary

Framework

Besides the usual tree-level Feynman rules, some extra ingredients have to be provided to the matrix-element generator in order to obtain the code for the simulation of a new physics process at NLO. These extra ingredients are the Ultra-Violet (UV) renormalisation counterterms and a sub-class of the rational terms that enter the reduction of the virtual matrix elements, the so-called R2 terms [36]. The tree-level and NLO Feynman rules are exported in the Universal Feynrules Output (UFO) [40] format, as a Python module which can be loaded by matrix-element generators, such as MadGraph aMC@NLO. With the bottom quark Yukawa renormalised on-shell and with its mass set the value of the top pole mass, we reproduce the ttH total cross section in the SM at the few per-mille level

Implementation

Results

Four-flavour scheme results

The ybyt contribution

Four- and five-flavour scheme comparison

Conclusions