Higgs boson decays to a fermion pair and a polarized $Z$ boson at NLO accuracy

TL;DR

This paper calculates the Higgs boson decay into a fermion pair and a polarized Z boson at NLO accuracy, providing more precise predictions and a method to extract relevant decay widths from experimental data.

Contribution

It introduces a detailed NLO calculation of Higgs decay to fermions and Z boson with polarization states, improving prediction accuracy and proposing a new extraction method for decay widths.

Findings

NLO corrections are 1-4% of LO contributions.

Non-resonant background is negligible with proper cuts.

NLO corrections reduce electroweak scheme dependence.

Abstract

In this paper, we investigate the Higgs boson decay process $H\to f\bar{f}Z\to f\bar{f}\mu^-\mu^+$, where $f$ denotes any light fermions, at the next-to-leading order (NLO) accuracy. The calculation is performed within the framework of single-pole approximation, in which the contributions of different polarization states of the $Z$ boson are considered separately. Numerical results show that, by taking appropriate cut, the non-resonant background is negligible, and the NLO corrections are $1\%$--$4\%$ of the LO contributions. We also find that the inclusion of NLO corrections can greatly reduce the dependence on the electroweak coupling scheme, and enhance the prediction reliability. We formulate a method for the extraction of the pseudo-observable $\Gamma^{H\to ffZ}$ from the $f\bar{f}\mu^-\mu^+$ signal.