$\bar{B}\to X_s \gamma$ in the Two Higgs Doublet Model up to Next-to-Next-to-Leading Order in QCD

TL;DR

This paper calculates advanced three-loop QCD corrections for the decay process $ar{B} o X_s \gamma$ within the Two Higgs Doublet Model, refining the theoretical prediction and setting a new lower mass limit for the charged Higgs boson.

Contribution

It provides the first three-loop matching corrections for Wilson coefficients in the 2HDM, improving the precision of branching ratio predictions for $ar{B} o X_s \gamma$.

Findings

Updated lower limit on charged Higgs mass: 380 GeV.

Reduced sensitivity to the matching scale $ $ in the predictions.

Enhanced theoretical accuracy of the branching ratio calculation.

Abstract

We compute three-loop matching corrections to the Wilson coefficients $C_7$ and $C_8$ in the Two Higgs Doublet Model by applying expansions for small, intermediate and large charged Higgs boson masses. The results are used to evaluate the branching ratio of $\bar{B}\to X_s \gamma$ to next-to-next-to leading order accuracy, and to determine an updated lower limit on the charged Higgs boson mass. We find $\mhplus \ge 380 $GeV at 95% confidence level when the recently completed BABAR data analysis is taken into account. Our results for the charged Higgs contribution to the branching ratio exhibit considerably weaker sensitivity to the matching scale $\mu_0$, as compared to previous calculations.