Possible new-physics signals in b -> s gamma and b -> sl(+)l(-)

Abstract

We consider possible new-physics contributions to b --> sl(+)l(-) assuming that new-physics modifies (chromo)magnetic and electric form factors in b --> s gamma* and b --> sg with the same chirality structure as in the standard model. Parametrizing the new-physics effects on b -->, s gamma* and b --> sg in terms of four real parameters, one finds that there is a large enough region of parameter space in which the measured branching ratio for B --> X(s)gamma can be accommodated, and the predicted CP violation effect could be as large as similar to 30%. Moreover, the branching ratio and the forward-backward asymmetry of a lepton in B --> X(s)l(+)l(-) and the tau polarization asymmetry in B --> X(s)tau(+)tau(-) can deviate from the SM predictions by a factor of similar to 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 currents (FCNC). (C) 1999 Elsevier Science B.V.