Simultaneous decoupling of bottom and charm quarks

TL;DR

This paper calculates three-loop decoupling relations in QCD for heavy charm and bottom quarks, accurately accounting for their mass ratio, and derives an effective Higgs-gluon coupling relevant for beyond Standard Model physics.

Contribution

It provides the first three-loop decoupling relations in QCD considering the exact charm-bottom mass ratio and connects these to effective Higgs-gluon couplings.

Findings

Decoupling relations computed to three-loop accuracy.

Exact dependence on $m_c/m_b$ included.

Effective Higgs-gluon coupling derived for BSM extensions.

Abstract

We compute the decoupling relations for the strong coupling, the light quark masses, the gauge-fixing parameter, and the light fields in QCD with heavy charm and bottom quarks to three-loop accuracy taking into account the exact dependence on $m_c/m_b$. The application of a low-energy theorem allows the extraction of the three-loop effective Higgs-gluon coupling valid for extensions of the Standard Model with additional heavy quarks from the decoupling constant of $\alpha_s$.