Form factors and branching ratio for the B -> l nu gamma decay

Abstract

Form factors parameterizing radiative leptonic decays of heavy mesons for photon energy are computed in the language of dispersion relation. The contributing states to the absorptive part in the dispersion relation are the multiparticle continum, estimated by quark triangle graph and resonances with quantum numbers $1^{-}$ and $1^{+}$ which includes $B^{\ast }$ and $B_A^{\ast }$ and thier radial excitations, which model the higher state contributions. Constraints provided by the asymptotic behavior of the structure dependent amplitude, Ward Identities and gauge invariance are used to provide useful information for parameters needed. The couplings $g_{B{B}^{\ast }\gamma }$ and are predicted if we restrict to first radial excitation; otherwise using these as an input the radiative decay coupling constants for radial excitations are predicted. The value of the branching ratio for the process $B^{+}\to \gamma {\mu }^{+}{\nu }_{\mu }$ is found to be in the range $0.5\times 10^{-6}$. A detailed comparison is given with other approaches.

22 pages+two ps figures; Paper has been throughly revised and Sudakov resummation has been discussed; published version

References in corpus (8)

• Big-Bang nucleosynthesis (Particle Data Group mini-review)
• The Cosmological Parameters 2006
• Factorization in leptonic radiative B -> gamma eνdecays
• Factorization, the light-cone distribution amplitude of the B-meson and the radiative decay B -> gamma l nu_l
• B->gamma e nu Transitions from QCD Sum Rules
• Ward Identities, B-> ρForm Factors and |V_ub|
• Radiative leptonic B decays in the instantaneous Bethe-Salpeter approach
• Role of gauge invariance in B -> V gamma radiative weak decays

Cited by in corpus (4)

• Soft Photon Problem in Leptonic B-decays
• Methods for high-precision determinations of radiative-leptonic decay form factors using lattice QCD
• Semileptonic charmed $B$ meson decays in Universal Extra Dimension Model
• Efficient lattice QCD computation of radiative-leptonic-decay form factors at multiple positive and negative photon virtualities