Flavor changing neutral current processes and the muon anomalous magnetic moment in the supergravity model

Abstract

Flavor changing neutral current processes in B and K decays in the supergravity model are revisited taking into account the recent progress of Higgs boson search experiments at LEP. Possible deviations of B^0--${\bar{B}}^0$ mixing, the CP violating K^0--${\bar{K}}^0$ mixing parameter ${ϵ}_K$ from the standard model predictions are reduced significantly in a small $\tan \beta$ region due to the constraints on the SUSY parameter space imposed by the Higgs boson search. With the present bound on the Higgs boson mass, the magnitude of the B^0--${\bar{B}}^0$ mixing amplitude can be enhanced up to 12% for $\text{tanb}=3$ in the minimal supergravity. If we relax the strict universality of SUSY breaking scalar masses at the GUT scale, the deviation can be 25%. We also investigate SUSY contributions to the muon anomalous magnetic moment in the supergravity model and show that there is a correlation with the $b\to s\gamma$ amplitude. The SUSY contribution to $a_{\mu }=\frac{(g-2{)}_{\mu }}{2}$ can be (-30 -- $+80)\times 10^{-10}$ for $\tan \beta =10$ and even larger for larger $\tan \beta$. The improved measurement of the muon anomalous magnetic moment in the on-going experiment at BNL will put a strong constraint on SUSY parameter space, especially for a large $\tan \beta$ region.

Comments: LaTeX-2e, 42 pages, 23 figures