Fermionic decays of neutral MSSM Higgs bosons at the one-loop level

TL;DR

This paper provides a complete on-shell one-loop calculation of fermionic decays for the neutral MSSM Higgs bosons $h^0$, $H^0$, and $A^0$ in the framework of the MSSM Higgs sector. It introduces and analyzes universal one-loop mixing-angle concepts ($\alpha_{1\text{-loop}}$, $\alpha_{eff}$, $\alpha_f$) to capture dominant radiative corrections, and presents explicit formulas for $\Gamma_1(H\to f\bar{f})$ and related quantities, including QED/QCD, weak MSSM, and gluino-vertex corrections. The results show a significant enhancement of $\Gamma_1(h^0\to b\bar{b})$ in the intermediate pseudoscalar mass range (with $M_A \lesssim 300$ GeV), sizable $m_t^4$-driven corrections, and a rapid convergence to the SM predictions as $M_A$ grows; gluino corrections can notably alter branching ratios, especially at large $\tan\beta$. The authors also provide an accurate approximation scheme for branching ratios using $\kappa_{H,\text{eff}}^f$, achieving agreement with full results at the sub-percent level, which is valuable for phenomenological analyses and collider studies.

Abstract

The results of a complete one-loop calculation for the fermionic decay width h^0, H^0, A^0 -> f bar(f) of the neutral MSSM Higgs bosons are presented and the dominant light Higgs decay channel h^0 -> b bar(b) is discussed in detail. The enhancement of the partial decay width h^0 -> b bar(b) compared to the standard Higgs decay is shown for pseudoscalar masses M_A < 300 GeV. Simpler approximation formulae for the Higgs decays are given and their quality is discussed by introducing an effective neutral scalar mixing angle sin(alpha)_eff. Finally the Higgs branching ratios in b bar(b), c bar(c), tau^+ tau^- are calculated.

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