Constraints on $\tan \beta$ in SUSY SU(5) GUT

Abstract

On the evaluation of $\tan \beta$ is revisited by the method of the renormalization group with the criteria of the bottom-tau unification in the SUSY SU(5) GUT model. Among the conventional supersymmetric theories, an energy-scale constant $M_{SUSY}$ is introduced by-hand to decouple the lower energy-scale region from the effects of the supersymmetric particles. Provided that $M_{SUSY}$ really exists, only small $\tan \beta \simeq 2$ is allowed theoretically. While, medium value as $\tan \beta =6\sim 25$ is also supported if $M_{SUSY}$ is vanished away from the model.

21 pages, 12 figures, 2 tabels