Top-induced contributions to $H\rightarrow b\bar{b}$ and $H\rightarrow c\bar{c}$ at $\mathcal{O}(\alpha_s^3)$

TL;DR

This paper calculates top-induced contributions to Higgs decays into bottom and charm quarks at order , providing a detailed differential analysis within an effective field theory framework and exploring the impact of tagging cuts.

Contribution

It presents the first fully differential calculation of top-induced effects in Higgs to quark-antiquark decays at  order, including implementation into a Monte Carlo tool.

Findings

Top-induced contributions are about 1% for Hbb and up to 15% for Hcc decays.

Differential distributions are sensitive to final-state cuts, especially b- and c-tagging.

Jet-tagging cuts can significantly reduce the impact of top-induced effects.

Abstract

In this paper we present a fully-differential calculation for the contributions to the partial widths $H\rightarrow b\bar{b}$ and $H\rightarrow c\bar{c}$ that are sensitive to the top quark Yukawa coupling $y_t$ to order $\alpha_s^3$. These contributions first enter at order $\alpha_s^2$ through terms proportional to $y_t y_q$ ($q=b,c$). At order $\alpha_s^3$ corrections to the mixed terms are present as well as a new contribution proportional to $y_t^2$. Our results retain the mass of the final-state quarks throughout, while the top quark is integrated out resulting in an effective field theory (EFT). Our results are implemented into a Monte Carlo code allowing for the application of arbitrary final-state selection cuts. As an example we present differential distributions for observables in the Higgs boson rest frame using the Durham jet clustering algorithm. We find that the total impact of the top-induced (i.e. EFT) pieces is sensitive to the nature of the final-state cuts, particularly b-tagging and c-tagging requirements. For bottom quarks, the EFT pieces contribute to the total width (and differential distributions) at around the percent level. The impact is much bigger for the $H\rightarrow c\bar{c}$ channel, with effects as large as 15%. We show however that their impact can be significantly reduced by the application of jet-tagging selection cuts.