Is the stop mass below the top mass?

Abstract

It is shown that a top mass of 174+/-17 GeV, as quoted recently by the CDF Collaboration, constrains the mixing angle between the Higgs doublets in the Minimal Supersymmmetric extension of the Standard Model (MSSM) to: 1.2<tan beta<5.5 at the 90% C.L.. The most probable value corresponds to tan beta = 1.56; such a small value causes a large mixing in the stop sector and the lightest stop is likely to be below the top mass. In this case the stop production in pp_bar collisions would contribute to the top signature, thus providing a possible explanation for the large effective tt_bar cross section observed by CDF.