Parton-shower and fixed-order QCD effects in Higgs-boson production in weak-boson fusion and its decays to bottom quarks

TL;DR

This paper improves theoretical predictions for Higgs production in weak-boson fusion with decay to bottom quarks by combining NNLO QCD calculations with parton shower modeling, reducing uncertainties in high transverse momentum jet regions.

Contribution

It introduces a combined NNLO QCD and parton shower approach for Higgs in weak-boson fusion decays, addressing large QCD corrections caused by soft and collinear radiation.

Findings

Enhanced prediction accuracy for high pT b-jet events.

Remaining theoretical uncertainty estimated at 5-7%.

Parton shower effectively models soft and collinear QCD effects.

Abstract

Recently, it was observed [arXiv:2407.09363] that an aggressive cut on the $b$-jets' transverse momenta applied to Higgs-boson production in weak-boson fusion followed by the decay $H \to b \bar b$, leads to very large QCD corrections to the fiducial cross section. In this paper we show that these corrections are caused by soft and collinear QCD radiation and, therefore, can be efficiently treated by a parton shower. We combine the parton-shower description of the decay $H \to b \bar b$ with NNLO QCD corrections to Higgs production in weak-boson fusion and its subsequent decay, and demonstrate that the quality of the theoretical prediction is markedly improved even if $b$-jets with rather high transverse momenta are selected. The remaining uncertainty of the theoretical prediction, mainly driven by imprecise modelling of $H \to b \bar b$ decay, is estimated to be of the order of $\mathcal{O}(5{-}7\%)$.