Study of the decay b→sgγ in the standard model

We consider the decay b→sgγ (where the gluon is hard) in the standard model. For a reasonable choice of the t-quark mass mt, we find that it has a branching ratio approximately of the order 10-5--10-6. Moreover, for different values of mt, the polarization of the photon is different. An accurate measurement on the photon polarization should, therefore, provide some useful information on mt. In addition, a CP-violating asymmetry parameter related to the correlation between the photon polarization and the decay plane is shown to be of the order of a few percent. This provides an effect which is accessible to the future high-luminosity B factories, but obviously poses a challenge