Two photon decays of heavy vector mesons B*-*Byy, D*->Dyy, and the possible determination of the £B*(D*)BDJJT an- SB*°B°-Y couplings

We study the novel decays B*-Byy and D*-+Dyy using the framework of the heavy meson chiral Lagrangian (HM-L) to leading order in chiral perturbation theory. The branching ratios of these decays are expressed in terms of the strong gB*(D*)B(D)ir ar>d the electromagnetic gβ*(D*)B(D)y couplings, thus providing a possible tool for their determination. In the charm case, using the experimentally determined ratios (D*0-+ -+DTT)/(D*O'+->Dy), we are able to express the branching ratio as a function of the strong coupling only. We thus find 1.6X KT6<Br(£>*0->D°yy)<3.3X 10-5 for 0.25<g<l, where g is the strong coupling of HM-L. In the flavored sector, the Br(β*°->β°yy) which we estimate to be in the 10-7- 10"5 range is a function of both gB*Blr and gg*By. Its behavior does not afford an unambiguous determination of these couplings except for the region of high g values such as g>0.6. The expected two-photon differential distributions are presented for both β*°->β°yy and D*°->D0yy, for different values of the couplings involved.