Decoupling Properties of MSSM particles in Higgs and Top Decays

TL;DR

This paper investigates how supersymmetric particles influence Higgs and top quark decays in the MSSM, revealing conditions under which these effects decouple or persist, especially considering large SUSY masses and high tan beta values.

Contribution

It provides a detailed analysis of the decoupling behavior of MSSM particles in Higgs and top decays at one-loop level, highlighting non-decoupling effects enhanced by tan beta.

Findings

Decoupling of $h^0\to b\bar{b}$ decay width occurs in the large SUSY and Higgs mass limit, delayed at high tan beta.

Non-decoupling effects are observed in $H^+\to t\bar{b}$ decay, especially at large tan beta.

Decoupling is rapid in the $t\to W^+b$ decay width with large SUSY masses.

Abstract

We study the supersymmetric (SUSY) QCD radiative corrections, at the one-loop level, to $h^0$, $H^{\pm}$ and t quark decays, in the context of the Minimal Supersymmetric Standard Model (MSSM) and in the decoupling limit. The decoupling behaviour of the various MSSM sectors is analyzed in some special cases, where some or all of the SUSY mass parameters become large as compared to the electroweak scale. We show that in the decoupling limit of both large SUSY mass parameters and large CP-odd Higgs mass, the $\Gamma (h^0\to b \bar b)$ decay width approaches its Standard Model value at one loop, with the onset of decoupling being delayed for large $\tan\beta$ values. However, this decoupling does not occur if just the SUSY mass parameters are taken large. A similar interesting non-decoupling behaviour, also enhanced by $\tan\beta$, is found in the SUSY-QCD corrections to the $\Gamma (H^+\to t \bar b)$ decay width at one loop. In contrast, the SUSY-QCD corrections in the $\Gamma (t\to W^+ b)$ decay width do decouple and this decoupling is fast.