In a combined investigation of B → K ( * ) l + l - decays, constraints on the related couplings in family non-universal Z′ models are derived. We find that within the allowed parameter space, the recently observed forward-backward asymmetry in the B → K * l + l - decay can be explained by flipping the signs of the Wilson coefficients C eff 9 and C 10 . With the obtained constraints, we also calculate the branching ratio of the B s →μ + μ - decay. The upper bound of our prediction is nearly an order of magnitude smaller than the upper bound given by the CDF Collaboration recently.
In this paper,we calculated the B →(J/ψ,ηc) K decays in the perturbative QCD(pQCD) factorization approach with the inclusion of the partial next-to-leading order(NLO) contributions. With the inclusion of the significant enhancement from the NLO vertex corrections,the NLO pQCD predictions for the branching ratios agree with the data within 2σ errors:Br(B0 → J/ψK0) = 5.2-+32..58×10-4,Br(B+ → J/ψK+) = 5.6-+32..79×10-4,Br(B0 →ηcK0) = 5.5-+22..30 × 10-4,Br(B+ →ηcK+) = 5.9-+22..51 × 10-4.
Cosmic-ray data of 90 M events have been collected and used for calibration,alignment as well as detector tuning. A special tracking algorithm for the BESⅢ muon counter is developed and verified with Monte-Carlo simulation and then further confirmed with the cosmic-ray data. The obtained strip resolutions are in good agreement with the design values. A new alignment approach for the BESⅢ muon counter is confirmed with the cosmic-ray data and proposed to be used in future analysis of experimental data.
Decays of both η and η' provide very useful information in our understanding of low-energy QCD, and experimental signatures for these decays would be extremely helpful at BES-Ⅲ. The rare decays of the η and η' mesons could serve as a low-energy test of the Standard Model and its beyond. The sensitivities of the measurements of η and η' decays are discussed at BES-Ⅲ, in which the η and η' mesons are produced in the ψ decays.
We established a method on measuring the D0-■ mixing parameter y for BESⅢ experiment at the BEPCⅡ e+e-collider. In this method, the doubly tagged ψ(3770) → D0■ events, with one D decays to CP-eigenstates and the other D decays semileptonically, are used to reconstruct the signals. Since this analysis requires good e/π separation, a likelihood approach, which combines the dE/dx, time of flight and the electromagnetic shower detectors information, is used for particle identification. We estimate the sensitivity of the measurement of y to be 0.007 based on a 20 fb-1 fully simulated MC sample.
We present a phenomenological analysis of the space- and time-like charged kaon electromagnetic form factors in factorized perturbative QCD (pQCD) by employing an analytic model for αs (Q2 ) and an infrared (IR) finite gluon propagator. In the space-like region, due to the lack of available experimental data above Q2 ～ 0.2 GeV2 , we only give our results for intermediate energies and make no comparison. In the time-like region, our results agree reasonably well with the available experimental data at moderate energies, including the CLEO data and the J/ψ result.
We study the branching ratios of D+→D0e+ν,DS+→D0e+ν,BS0→B+e-ν,DS+→D+e-e+ and BS0→B0e-e+ rare semileptonic decay processes,which are induced by decays of light quarks,the heavy quarks remain unchanged.The branching ratios of these decay processes are estimated in the heavy quark limit and with SU(3) flavor symmetry.We find that the decay rates are very tiny in the framework of the Standard Model.We also estimate the sensitivities of the measurements of these rare decays at the future experiments,such as BES-Ⅲ,super-B and LHC-b.Observations of these decays may shed some light on new physics beyond the standard model.
Based on the assumption of a two-quark structure of the scalar meson f0(980) ,we calculate the branching ratios and CP-violating asymmetries for the four B → f0(980) π and B → f0(980) η(') decays by employing the perturbative QCD(pQCD) factorization approach. The leading order pQCD predictions for branching ratios are,Br(B-→ f0(980) π-) ～ 2.5×10-6,Br(Bˉ0 → f0(980) π0) ～ 2.6×10-7,Br(Bˉ0 → f0(980) η) ～ 2.5×10-7 and Br(Bˉ0 → f0(980) η ) ～ 6.7×10-7,which are consistent with both the QCD factorization predictions and the experimental upper limits.
The recent observations of the purely leptonic decay Ds+ →μ+νμ and τ+ντ at CLEO-c and B factory may allow a possible contribution from a charged Higgs boson. One such measurement of the decay constant fDs differs from the most precise unquenched lattice QCD calculation by a level of 4 σ. Meanwhile, the measured ratio, BR(D+s →μ+νμ)/BR(D+ →μ+νμ), is larger than the standard model prediction at a 2.0σ level. We discuss that the precise measurement of the ratio BR(Ds+ →μ+νμ)/BR(D+ →μ+νμ) at BES-Ⅲ will shed light on the presence of new intermediate particles by comparing the data with the theoretical predictions, especially, the predictions of high precise unquenched lattice QCD calculations.
Recently,the CDF Collaboration has measured the branching fraction and time-integrated direct CP asymmetry of Bs → K-π+ decay.The branching ratio is lower than the previous predictions based on QCD factorization.The experimental results favor a large CP asymmetry in Bs → K-π+ decay while the standard model prediction is very small.We compute the supersymmetry contributions to Bs → K-π+ decay using the mass insertion method,and find that the LR and RL mass insertions could suppress this branching ratio and increase this direct CP asymmetry well in line with the experimental data.
