Weak Radiative Decay Width B ->K* in COQM Including Long-Range Contributions

Abstract

The study of the weak radiative decay B → K∗γ has attracted considerable attention as a test of the Standard Model (SM) since the CLEO experiment 1) gave the preliminary value of the branching ratio Br(B → K∗γ) = (4.0±1.7±0.8)×10−5. This decay mode arises from the quark level process b → sγ via flavor changing neutral current (FCNC). There are two essential contributions to the amplitude of the weak radiative decay b → sγ, the short distance (SD) contribution due to the electromagnetic penguin and the long distance (LD) contribution due to strong interactions. The LD contribution is calculated using the vector meson dominance (VMD) method 2) at the quark level as b → s[cc], followed by the conversion [cc] → γ. In order to obtain the relevant ratio Br(B → K∗γ), it is necessary to take into account the quark confined effect. The estimation of this effect is a problem of non-perturbative QCD, and we must use some models presently. In a previous work 3) we studied the problem of determining the width of this decay by using the covariant oscillator quark model (COQM), 4) where we have taken into account only the leading SD contribution. In the present work we improve our calculation by adding the LD contribution.