Decay of the charged Higgs boson and the top quark in two-Higgs-doublet model at NNLO in QCD

TL;DR

This paper calculates NNLO QCD corrections to charged Higgs boson and top quark decay widths, reducing theoretical uncertainties and providing results applicable across various two-Higgs-doublet models.

Contribution

It provides the first NNLO QCD calculations for these decay processes, improving precision and model-independence in charged Higgs phenomenology.

Findings

NNLO corrections reduce scale dependence significantly.

Corrections are about 16% for 200 GeV charged Higgs, smaller at higher masses.

Results are applicable to various two-Higgs-doublet models.

Abstract

We present numerical calculations of the partial width of the charged Higgs boson decay into a top quark, $H^- \rightarrow \bar{t} + b + X$, and the partial width of the top quark decay into a light charged Higgs boson $t \rightarrow H^+ + b + X$ at next-to-next-to-leading order (NNLO) in QCD, based on a factorization formula of the jet mass. The NNLO corrections significantly reduce the renormalization scale dependence of the partial decay width in both cases. We show relative size of the NNLO corrections for different charged Higgs boson masses and for different renormalization scales. The NNLO corrections are about 16% (1%) of the leading order widths for the charged Higgs boson mass of 200GeV (2000GeV), while it is quite small for the top quark decay. Our analyses are independent of the detailed structure of the Yukawa couplings, and can be applied to various new physics models, as demonstrated by the decay branching ratio in different types of the two-Higgs-doublet models.