QCD corrections to the Golden decay channel of the Higgs boson

TL;DR

This paper calculates mixed QCD-electroweak corrections to the Higgs decay into four leptons, achieving a 0.27% correction to the decay width, crucial for matching future collider precision.

Contribution

It provides the first computation of mixed QCD-electroweak corrections at order ααs for the Higgs to four leptons decay channel, enhancing theoretical accuracy.

Findings

Corrections increase the decay width by about 0.27%.

Corrections are approximately 18% relative to NLO electroweak results.

Invariant mass distribution remains flat under these corrections.

Abstract

Future colliders aim to provide highly precise experimental measurements of the properties of the Higgs boson. In order to benefit from these precision machines, theoretical errors in the Higgs sector observables have to match at least the experimental uncertainties. The theoretical uncertainties in the Higgs sector observables can be reduced by including missing higher-order terms in their perturbative calculations. In this direction, we compute the mixed QCD-electroweak corrections at ${\mathcal O}(\alpha \alpha_s)$ to the Higgs decay into four charged leptons by considering the golden decay channel, $ H \to e^+e^-\mu^+\mu^-$. Due to color conservation, these corrections receive contributions only from the two-loop virtual diagrams. In the complex mass scheme, we find that the mixed QCD-electroweak corrections to the partial decay width, relative to the leading order predictions, are positive and about $0.27\%$ for $\alpha_s(M_Z)$. Relative to the next-to-leading order electroweak corrections, the mixed QCD-electroweak corrections are found to be approximately $18\%$ for $\alpha_s(M_Z)$. With respect to the leading order, we observe a flat effect of the mixed QCD-electroweak corrections on the invariant mass distribution of the lepton pairs with fixed QCD coupling. The $\phi$ distribution, due to the mixed QCD-electroweak corrections, follows a $(1-\cos \phi)$ dependence.