Effective lagrangian for the tbH^+ interaction in the MSSM and charged Higgs phenomenology

TL;DR

This paper develops an effective Lagrangian approach within the MSSM to accurately compute charged Higgs decay rates, incorporating dominant quantum corrections and resummations, impacting experimental exclusion limits.

Contribution

It introduces a comprehensive resummation method for supersymmetric and QCD corrections to charged Higgs interactions in the MSSM, providing simplified formulas for large b regimes.

Findings

Resummation of dominant SUSY corrections to all orders.

Accurate decay rate calculations for bH and extbf{H}tb processes.

Implications for Tevatron exclusion limits on charged Higgs mass.

Abstract

In the framework of a 2HDM effective lagrangian for the MSSM, we analyse important phenomenological aspects associated with quantum soft SUSY-breaking effects that modify the relation between the bottom mass and the bottom Yukawa coupling. We derive a resummation of the dominant supersymmetric corrections for large values of \tb to all orders in perturbation theory. With the help of the operator product expansion we also perform the resummation of the leading and next-to-leading logarithms of the standard QCD corrections. We use these resummation procedures to compute the radiative corrections to the \tbH, \Htb decay rates. In the large \tb regime, we derive simple formulae embodying all the dominant contributions to these decay rates and we compute the corresponding branching ratios. We show, as an example, the effect of these new results on determining the region of the \mH--\tb plane excluded by the Tevatron searches for a supersymmetric charged Higgs boson in top quark decays, as a function of the MSSM parameter space.