$t\bar{t}b\bar{b}$ hadroproduction with massive bottom quarks with PowHel

TL;DR

This paper presents a new implementation of $t\bar{t}b\bar{b}$ production with massive bottom quarks in the PowHel generator, providing more accurate predictions for background modeling in Higgs analyses at the LHC.

Contribution

It introduces a massive bottom quark treatment in the PowHel framework for $t\bar{t}b\bar{b}$ production, improving the realism of theoretical predictions.

Findings

Predictions with massive bottom quarks differ from massless approximations.

NLO QCD + Parton Shower predictions are validated against previous schemes.

Results are relevant for Higgs background estimations in top physics.

Abstract

The associated production of top-antitop-bottom-antibottom quarks is a relevant irreducible background for Higgs boson analyses in the top-antitop-Higgs production channel, with Higgs decaying into a bottom-antibottom quark pair. We implement this process in the PowHel event generator, considering the bottom quarks as massive in all steps of the computation which involves hard-scattering matrix-elements in the 4-flavour number scheme combined with 4-flavour Parton Distribution Functions. Predictions with NLO QCD + Parton Shower accuracy, as obtained by PowHel + PYTHIA, are compared to those which resulted from a previous PowHel implementation with hard-scattering matrix-elements in the 5-flavour number scheme, considering as a baseline the example of a realistic analysis of top-antitop hadroproduction with additional $b$-jet activity, performed by the CMS collaboration at the Large Hadron Collider.