Possible New Physics Signals in b -> s gamma and b -> s l^+ l^-

Abstract

We consider possible new physics contributions to b\to s l^+ l^- assuming the new physics modifies (chromo)magnetic and electric form factors in b\to s γ^* and b\to s g with the same chirality structure as in the standard model. Parametrizing the new physics effects on b\to s γ^* and b\to s g in terms of four real parameters, one finds that there are enough region of parameter space in which the measured branching ratio for B \to X_s γcan be accomodated, and the predicted CP violation effect could be as large as \sim 30%. Moreover, the branching ratio and the forward-backward asymmetry of a lepton in B \to X_s l^+ l^- and the tau polarization asymmetry in B \to X_s τ^+ τ^- can be deviated from the SM predictions by a factor of \sim 2, which can be accessible at B factories. We also discuss these observables in a specific class of supersymmetric models with gluino-mediated flavor changing neutral current (FCNC).