Reexamined radiative Decay $B_q^{\ast }\to B_q\gamma$ in Light Cone QCD

Abstract

The radiative decay $B_q^{\ast }\to B_q\gamma (q=u,d,ors)$ is reexamined with a modified light-cone QCD sum rule method, in which adequate chiral operators are chosen as the interpolating fields in the correlators used for a sum rule estimate of the relevant coupling $g_{B_q^{\ast }{B}_q\gamma }$. The resulting sum rules not only show the physical picture consistent with the underlying physics in $B_q^{\ast }\to B_q\gamma$ but also avoid the pollution by the nonlocal matrix element $<\gamma (q)|\bar{q}(x){\gamma }_{\mu }{\gamma }_{5}q(0)|0>$, which starts with twist-3 and thus may bring a large uncertainty to the sum rule predictions. Also, a comparison is made with the previous results from light-cone QCD sum rules and chiral perturbation theory.

Comments: Latex, 15 pages, 2 figures. To appear in JPG