arXiv subjects
Publications and source records attributed to Dongsheng Du.
Combining three mechanisms, we reanalysis processes of $B \to η^{\prime} K(K^*),ηK(K^*)$ and calculate their branching ratios. The results are compared with other mechanisms in the literature. The striking feature of the gluon fusion mechanism is emphasized and its experimental test is discussed.
We present a new mechanism for $B^{\pm}\to η' K^{\pm}$, and analyze it strictly within perturbative QCD. We find that such a new mechanism may dominate non-leptonic $B$-decays to light mesons. Within a reasonable parameter space, our prediction is in good agreement with the recent CLEO data on $B^{\pm}\to η' K^{\pm}$. We conclude that there is no room for an abnormally large \bsg vertex from physics beyond the Standard Model.
With help of the recent developments in the heavy quarkonium physics, we reexamine the long distance(LD) effects in \Bsee dominantly from the charmonium resonances $J/Ψ$ and $Ψ^{\prime}$ through the decay chains $B\ra X_s J/Ψ(Ψ^{\prime}) \ra X_s e^+ e^-$. We find that the resonance to nonresonance interference are reduced substantially.
With respect to large samples of $B_c$ mesons expected to be produced at CERN Large Hadron Collider(LHC) and the large branching ratios $Br(B_{c}\to τ\barν)$ and $Br(B_{c}\to μ\barν)$, we suggest that $B_c$ purely leptonic decays could offer an unique probe of the standard model and its extensions such as two Higgs doublet models and models involving supersymmetry, and also the structure of charged weak currents.
Using the PQCD method we calculate the W-exchange and the W-annihilation processes of B mesons, which in general involve a charm quark or anti-quark in the final state. The nonvanishing amplitudes of these processes are found to be suppressed by a factor of $m_c/m_b$ compared to the tree or the time-like penguin processes, but some of them are within the reach of observation at the future B-factories, and $\bar B_d^0 \to D^+_s K^-$ whose branching ratio is found to be $6.6 \times 10^{-6}$ can be found even before the B-factory era. Comparisons with the results based on the BSW model are also given.
We study the decay $B_c \rightarrow D_s^* γ$. There are two mechanisms contributing to the process. One proceeds through the short distance $b{\rightarrow}sγ$ transition and the other occurs through weak annihilation accompanied by a photon emission.The electromagnetic penguin contribution is estimated by perturbative QCD and found to be $4.68\times10^{-18}$ GeV. In particular, we find the contribution of the weak annihilation is $6.25\times10^{-18}GeV$ which is in the same order as that of the electromagnetic penguin. The total decay rate $Γ(B_c \rightarrow D_s^* γ)$ is predicted to be $1.45\times10^{-17}GeV$ and the branching ratio $Br(B_c \rightarrow D_s^* γ)$ is predicted to be $2.98\times 10^{-5}$ for $τ_{B_c}=1.35ps$. The the decays $B_c \rightarrow D_s^* γ$ can be well studied at LHC in the near future.
Using the next-to-leading order low energy effective Hamiltonian for $|ΔB|=1$, $ΔC=ΔU=0$ transitions, the contributions of electroweak penguin operators in $ B^-(\overline {B_d^0})\rightarrow PP$ and $PV$ decays are estimated in the standard model. We find that, for some channels, the electroweak penguin effects can enhance or reduce the QCD penguin and/or tree level contributions by at least $30\%$, and can even play dominant role.
The space-like penguin contributions were ignored on little ground in many previous studies of nonleptonic B decays and CP violation. Taking the penguin-dominated channels $B^{-} _{u}\rightarrow \bar{K}^{0}π$ and $B^{-}_{u}\rightarrow K^{0} K^{-}$ for example, we illustrate the non-negligible effects of the space-like penguin diagrams on CP asymmetries. Some quali- tative remarks are given on the gluonic penguin picture and the direct CP violation in exclusive two-body decays of B mesons.
A cyclic symmetry among the left-handed doublets of the three families is proposed. This symmetry can naturally result in a realistic hierarchical pattern of the fermion masses within the framework of supersymmetry with nonvanishing sneutrino vacuum expectation values.
A careful quark-diagram analysis shows that a number of two-body nonleptonic $B$ decays can occur through the so-called hairpin diagram, a QCD loop-induced graph different from penguin in final-state hadronization of valence quarks. Using the two-loop renormalization-group-improved effective Hamiltonian and the naive factorization approximation, we demonstrate the effect of the hairpin diagram on decay rates and $CP$ asymmetries for a few interesting channels such as $B^{0}_{d},\bar{B}^{0}_{d} \rightarrow ψK_{S}$ and $B^{\pm}_{u}\rightarrow ϕK^{\pm}$. Branching ratios of some pure hairpin decay modes, e.g., $B^{-}_{u}\rightarrow ϕπ^{-},ϕρ^{-}$ and $\bar{B}^{0}_{d}\rightarrow ϕπ^{0},ϕρ^{0}, ϕω, ϕη,$ etc., are estimated to be on the order of $10^{-7}$.