Two photon decays of heavy vector mesons, $B^{\ast }\to B\gamma \gamma$,$D^{\ast }\to D\gamma \gamma$, and the possible determination of the $g_{B^{\ast }(D^{\ast })B(D)\pi }$ and $g_{B^{*}^0B^0γ}$ couplings

Abstract

We study the novel decays $B^{\ast }\to B\gamma \gamma$ and $D^{\ast }\to D\gamma \gamma$ using the framework of the Heavy Meson Chiral Lagrangian (HM$\chi$L) to leading order in chiral perturbation theory. The branching ratios of these decays are expressed in terms of the strong $g_{B^{\ast }(D^{\ast })B(D)\pi }$ and the electromagnetic $g_{B^{\ast }(D^{\ast })B(D)\gamma }$ couplings, thus providing a possible tool for their determination. In the charm case, using the experimentally determined ratios $({D^{\ast }}^{0,+}\to D\pi )/({D^{\ast }}^{0,+}\to D\gamma ),$ we are able to express the branching ratio as a function of the strong coupling only. We thus find $1.6\times 10^{-6}<\mathrm{Br}({D^{\ast }}^0\to D^0\gamma \gamma )<3.3\times 10^{-5}$ for $0.25<g<1,$ where $g$ is the strong coupling of HM$\chi$L. In the beauty sector, the $\mathrm{Br}({B^{\ast }}^0\to B^0\gamma \gamma )$ which we estimate to be in the $10^{-7}-10^{-5}$ range is a function of both $g_{B^{\ast }B\pi }$ and $g_{B^{\ast }B\gamma }.$ Its behaviour does not afford an unambiguous determination of these couplings except for the region of high $g$ values like $g>\mathrm{0.6.}$ The expected two-photon differential distributions are presented for both ${B^{\ast }}^0\to B^0\gamma \gamma$ and ${D^{\ast }}^0\to D^0\gamma \gamma ,$ for different values of the couplings involved.

22 pages, LaTeX, 5 ps-figures (uses subfigure.sty). Accepted by Phys. Rev. D

References in corpus (2)

• Extraction of the D^*Dπcoupling from D^* decays
• Observation of the Radiative Decay $D^{\ast +}\to D^{+}\gamma$

Cited by in corpus (9)

• Chiral perturbation theory for heavy hadrons and chiral effective field theory for heavy hadronic molecules
• The Radiative Leptonic Decays D^0 -> e^+ e^- gamma, mu^+ mu^- gamma in the Standard Model and Beyond
• The Rare Decay D^0 -> gamma gamma
• Precision measurement of the $D^{\ast 0}$ decay branching fractions
• Color suppressed contributions to the decay modes B_{d,s} -> D_{s,d} D_{s,d}, B_{d,s} -> D_{s,d} D^*_{s,d}, and B_{d,s} -> D^*_{s,d} D^*_{s,d}
• Information on $B\to \pi \pi$ Provided by the Semileptonic Process $B\to \pi l\nu$
• The discrete contribution to ${\psi }^{\prime }\to J/\psi +\gamma \gamma$
• Cabibbo Allowed D -> K pi gamma Decays
• Determining the quantum numbers of excited heavy mesons