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 $\epsilon_K$ 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 $\tanb=3$ 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.