Impact of bosonic decays on the search for t~_1 and b~_1 squarks

Abstract

We perform a detailed study of the decays of the lighter top and bottom squarks (t~_1 and b~_1) in the Minimal Supersymmetric Standard Model (MSSM). We show that the decays into Higgs or gauge bosons, i.e. t~_1 -> b~_1 + (H^+ or W^+) and b~_1 -> t~_1 + (H^- or W^-), can be dominant in a wide range of the MSSM parameters due to the large Yukawa couplings and mixings of t~ and b~. Compared to the decays into fermions, such as t~_1 -> t + (neutralino_i or gluino) and t~_1 -> b + chargino_j, these bosonic decay modes can have significantly different decay distributions. We also show that the effect of the supersymmetric QCD running of the quark and squark parameters on the t~_1 and b~_1 decay branching ratios is quite dramatic. These could have an important impact on the search for t~_1 and b~_1 and the determination of the MSSM parameters at future colliders.