Alternative approach to $b->s\gamma$ in the uMSSM

Abstract

The gluino contributions to the $C_{7,8}^{\prime }$ Wilson coefficients for $b->s\gamma$ are calculated within the unconstrained MSSM. New stringent bounds on the ${\delta }_{23}^{RL}$ and ${\delta }_{23}^{RR}$ mass insertion parameters are obtained in the limit in which the SM and SUSY contributions to $C_{7,8}$ approximately cancel. Such a cancellation can plausibly appear within several classes of SUSY breaking models in which the trilinear couplings exhibit a factorized structure proportional to the Yukawa matrices. Assuming this cancellation takes place, we perform an analysis of the $b->s\gamma$ decay. We show that in a supersymmetric world such an alternative is reasonable and it is possible to saturate the $b->s\gamma$ branching ratio and produce a CP asymmetry of up to 20%, from only the gluino contribution to $C_{7,8}^{\prime }$ coefficients. Using photon polarization a LR asymmetry can be defined that in principle allows for the $C_{7,8}$ and $C_{7,8}^{\prime }$ contributions to the $b->s\gamma$ decay to be disentangled. In this scenario no constraints on the ``sign of $\mu$'' can be derived.

Comments: LaTeX2e, 23 pages, 7 ps figure, needs package epsfig