arXiv subjects
Publications and source records attributed to Dongsheng Du.
The $B_{c}$ ${\to}$ $J/ψπ$, $η_{c}π$ decays are studied in the scheme of the QCD factorization approach. The branching ratios are calculated with the asymptotic distribution amplitude of the pion. The charm quark mass effect is considered. We find that the mass effect on the branching ratios is small.
We firstly address the recent efforts on calculations of the next-to-leading order corrections to the color-suppressed tree amplitude in QCD factorization method which may be essential to solve the puzzles in $B\to ππ$ and $πK$ decays. Then we discuss the polarization puzzles in $B\to ϕK^*$ and $ρK^*$. The impacts of the newly measured $B_s-\bar B_s$ mixing and $B^+\to τ^+ν$ on the CKM unitarity triangle global fitting are mentioned. We also briefly review the recent measurements of the new resonances at BaBar and Belle. Finally, some new results from hadron colliders, especially the $b$-flavored hadron spectra, are discussed.
In this paper penguin contribution has not been included, so it is not suitable to be published.
CP asymmetries for neutral charmed meson decays to CP eigenstates are carefully studied. The formulas and numerical results are presented. The impact on experiments is briefly discussed.
Some recent progress in China in the study of charmless B decays with QCD factorization is reviewed. Chirally enhanced power corrections and infrared divergence problem are stressed.
The global analysis of B-->PP, PV charmless decays with QCD factorization (QCDF) is presented. The predictions of QCDF are in good agreement with experiments. The best fitted CKM angel gamma is around 79 degree. The predicted branching ratios of B --> pi^0 pi^0, omega K^+, omega pi^+, pi^+ K^{{\ast}0} etc. are also in good agreement with new data of BaBar and Belle
In this paper, we perform a global analysis of $B \to PP$ and $PV$ decays with the QCD factorization approach. It is encouraging to observe that the predictions of QCD factorization are in good agreement with experiment. The best fit $γ$ is around $79^\circ$. The penguin-to-tree ratio $|P_{ππ}/T_{ππ}|$ of $π^+ π^-$ decays is preferred to be larger than 0.3. We also show the confidence levels for some interesting channels: $B^0 \to π^0 π^0$, $K^+ K^-$ and $B^+ \to ωπ^+$, $ωK^+$. For $B \to πK^\ast$ decays, they are expected to have smaller branching ratios with more precise measurements.
We calculated the CP averaged branching ratios and CP-violating asymmetries of two-body charmless hadronic Bs->PP,PV decays with the QCDF approach, including the contributions from the chirally enhanced power corrections and weak annihilations. Only several decay modes, such as Bs -> K^(*)K, K^(*{\pm})π^{\mp}, K^{\pm}ρ^{\mp}, η^(')η^('), have large branching ratios, which may be observed in the near future. The penguin-to-tree ratio P_{ππ}/T_{ππ} and a bound on angle $γ$ are given.
We study the hadronic charmless two-body B decays to final states involving pseudoscalar and vector mesons with QCD factorization approach, including the contributions from the chirally enhanced power corrections and weak annihilations. The CP-averaged branching ratios and CP-violating asymmetries are given. Most of our results are in agreement with the present measurements, but the branching ratios of some decay channels are only marginally consistent with the experimental observations. Considering the large uncertainties, great advances in both experiment and theory in the near future are strongly expected.
In this paper, we study nonleptonic charmless B decays to two light pseudoscalar mesons within the frame of QCD factorization, including the contributions from the chirally enhanced power corrections and weak annihilation. Predictions for the CP-averaged branching ratios and CP-violating asymmetries are given. Within the reasonable range of the parameters, we find that our predictions for the branching ratios of B -> PP are consistent with the present experimental data. But because of the logarithmic divergences at the endpoints in the hard spectator scatterings and weak annihilation, there are still large uncertainties in these predictions.
We analyze the decay $D_s\to ϕπ$ with QCD factorization in the heavy quark limit. The nonfactorizable contributions, including hard spectator contribution are discussed and numerical results are presented. Our predictions on the branching ratio of the decay are in agreement with the experiment. We also use a pure phenomenological method to estimate the branching ratio for $D_s\to ϕπ$ with the existed $D^0\to K^{*}π$ data.
In this work, we give a detailed discussion for QCD factorization involved the complete chirally enhanced power corrections for B decays to two light pseudoscalar mesons, and present some detailed calculations of radiative corrections at the order of alpha_s. We point out that the infrared finiteness of the vertex corrections in the chirally enhanced power corrections requires twist-3 light-cone distribution amplitudes (LCDAs) of the light pseudoscalar symmetric. However, even in the symmetric condition, there is also logarithmic divergence from the endpoints of the twist-3 LCDAs in the hard spectator scattering. We point out that the decay amplitudes of B --> PP predicted by QCD factorization are really free of the renormalization scale dependence, at least at the order of alpha_s. At last, we briefly compare the QCD factorization with the generalized factorization and PQCD method.
Since b quark mass is not asymptotically large, chirally enhanced corrections which arise from twist-3 wave functions may be important in B decays. We thus evaluate the hadronic matrix elements with the final light pseudoscalar mesons described by leading twist and twist-3 distribution amplitudes. We find that chirally enhanced corrections can be included consistently in the framework of QCD factorization only if the twist-3 distribution amplitudes are symmetric. We then give explicit expressions of $a_i^p$ for $B \to ππ$ at the next-to-leading order of $α_s$ including chirally enhanced corrections. We also briefly discuss the divergence appeared in the hard spectator contributions.
Since b quark mass is not asymptotically large, chirally enhanced corrections which arise from twist-3 wave functions may be important in B decays. We thus evaluate the hadronic matrix elements with the emitted meson described by leading twist and twist-3 distribution amplitudes $Φ_p(x)$. After summing over the four "vertex correction" diagrams, we obtain the results with infrared finiteness which shows that chirally enhanced corrections arise from $Φ_p(x)$ can be consistently included in QCD factorization. We also briefly discuss the contributions from "hard spectator" diagrams.
T violation should be tested independently of CP violation. Besides K system, B meson decays provide another good place to study T violation. In the Standard Model, T violation in $B^0 \rightleftharpoons \bar{B^0}$ oscillation is expected to be small. The angular distribution of $B\to VV$ decay permits one to extract the T-odd correlation. In the absence of final state interaction, T violation in $B\to J/ψ(l^+ l^-) K^*(K_Sπ^0)$ decay can reach $4-7%$ via $B^0-\bar{B^0}$ mixing.
Di-gluon fusion mechanism might account for the large branching ratios of $B\to K η^{\prime}$. But because we know little about the effective $η^{\prime}gg$ vertex, there are large uncertainties in perturbative QCD estimations. In this paper, we try several kinds of $η^{\prime}gg$ form factors and compare the numerical results with the experiment. We find that, though we know little about $η^{\prime}gg$ form factor, if di-gluon fusion mechanism is important in $B\to K η^{\prime}$, the branching ratios of the decays $B\to K^{\ast} η^{\prime}$ would be around $10^{-5}$ which can be tested by future experiments.
With the generalized factorization approximation, we calculate the branching ratios and CP asymmetries in B meson decays into two charmless pseudoscalar mesons. We give a new estimation of the matrix elements of (S+P)(S-P) current products with the PQCD method instead of equation of motion. We find that our results are comparatively smaller than those in the literature.
Using the next-to-leading order low energy effective Hamiltonian, the CP asymmetries for the $B_{c}$ meson decays into meson pair are calculated in the spectator approximation. We do not compute the hadronic matrix elements directly, instead, we use the amplitude ratios to estimate the CP asymmetries. This is quite,different from the previous works in the literature. The values of the momentum squared carried by the virtual particles in timelike penguin dirgrams are also carefully discussed. From our calculated results, the best decay modes to observe CP violation in $B_{c}$ decays would be $B_{c}^-\to{\bar D}^{*0}K^{*-}$, ${\bar D}^{0}K^{*-}$, ${\bar D}^{*0} K^{-}$, ${\bar D}^{0}K^{-}$ and $B_{c}^-\toη_{c}D^{-}$, which need about $10^8$ of $B_{c}^{\pm}$ events in experiment.