Da-Xin Zhang

Radiative Dileptonic Decays of B Mesons

Abstract We investigate the radiative dileptonic decays B s ( B d ) → γl + l − within the standard model. Using the constituent quark model, the branching ratios turn out to be around 5 × 10 −9 for B s → γμ + μ − and around 6 × 10 −10 for B d → γμ + μ − , with slightly larger values for B s ( B d ) → γe + e − . The differential rate as a function of the dilepton invariant mass is given. The possibility of using these processes to determine the decay constants of B s or B d is discussed.

Re-examination of long distance effects in b → sl+l−

Abstract We re-analyse the long distance contributions to the process b → sl + l − . Full q 2 -behavior of the vector meson dominance amplitude is used together with the effect of Terasaki suppression, and comparisons with the previous results are given. We show that the interference between short- and long distance contributions makes it difficult to extract the short distance information from the dominant long distance background, either in the dilepton invariant mass distribution or in the single lepton energy spectrum.

Bs(Bd) → γνν

Abstract We study the loop induced rare decays B s (B d ) → γν ν within the standard model. Both constituent quark model and pole model are used and the branching ratios turn out to be of the orders of 10 −8 for B s → γν ν and 10 −9 for B d → γν ν . These processes can be served to determine the decay constants of B s and B d .We study the loop induced rare decays

Weak radiative decays of beauty baryons

B_s(B_d)\to\gamma\nu\bar\nu

W exchange and W annihilation processes of B mesons

within the standard model. Both constituent quark model and pole model are used and the branching ratios turn out to be of the orders of

Proton lifetime, Yukawa couplings and dynamical SUSY breaking in SU(5) GUT

10^{-8}

Theoretical update on two non-resonant three-body channels in charmed meson decays

for

Calculations of penguin diagrams in B decays

B_s\to \gamma \nu \bar \nu

The Long Distance Contribution to

and

D\to\pi l^+l^-

10^{-9}