Bottom-tau unification in a supersymmetric SU(5) grand unified theory and constraints fromb→sγand muong−2

Abstract

An analysis is made on bottom-tau Yukawa unification in supersymmetric (SUSY) SU(5) grand unified theory (GUT) in the framework of minimal supergravity, in which the parameter space is restricted by some experimental constraints including $\mathrm{Br}(\stackrel{\ensuremath{\rightarrow}}{b}s\ensuremath{\gamma})$ and muon $g\ensuremath{-}2.$ The bottom-tau unification can be accommodated to the measured branching ratio $\mathrm{Br}(\stackrel{\ensuremath{\rightarrow}}{b}s\ensuremath{\gamma})$ if superparticle masses are relatively heavy and the Higgsino mass parameter $\ensuremath{\mu}$ is negative. On the other hand, if we take the latest muon $g\ensuremath{-}2$ data to require positive SUSY contributions, then wrong-sign threshold corrections at the SUSY scale upset the Yukawa unification with more than $20%$ discrepancy. It has to be compensated by superheavy threshold corrections around the GUT scale, which constrains models of flavor in SUSY GUT. A pattern of the superparticle masses preferred by the three requirements is also commented upon.