J／φ→γBB Decays and the Quark—pair Creation Model

We generalize the quark-pair creation model to a study of the radiative decays J/φ→γBB by assuming that the u.d,or s quark pairs are created with the same interaction strength,From the calculation of the ratio of the decay widths （J/φ→γpp)/Γ（J/φ→pp),we extract the quark-pari creation strength gI=15.40GeV,Based on the SU(6)spin-flavour basis and the “uds” basis,the radiative decay branching ratios cotaining strange baryons are evaluated.Measurements for these decay widths from the BESII data are suggested.     

Top Quark Flavor Changing Decay t→ cH^0 in Little Higgs Model

We study theoretically the quantum effects of the littlest Higgs model （LH） mediated by flavor changing one-loop Feynman diagrams on the rare decay process t→ cH^0. The comparison of the decay width in the LH model with that in the standard model （SM） is made. We find that the decay branch ratio of t→ cH^0 in the LH model is at most of the order-10^-12, which is two order larger than in the SM. The numerical results show that the difference between the branch ratios in the LH model and the SM is generally sensitive to the LH model parameters, such as symmetry breaking scale f, Higgs boson mass mH0, and x=v＇4f/v^2 in our chosen parameter space, but relatively insensitive to the value choice of the cosine of the mixing angle c and the ratio λ1/λ2.     

B→f0（980）（π,η^（＇）） decays in the PQCD approach

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（Bˉ^0 → f0（980） π^0） ～ 2.6×10^-7,Br（Bˉ^0 → f0（980） η） ～ 2.5×10^-7 and Br（Bˉ^0 → f0（980） η ） ～ 6.7×10^-7,which are consistent with both the QCD factorization predictions and the experimental upper limits.     

B→K0^＊（1430）K Decays in Perturbative QCD Approach

In this article, we calculate the branching ratios of B→K0^＊ （1430）K decays by employing the pertur-bative QCD （pQCD） approach at leading order. We perform the evaluations in the two scenarios for the scalar meson spectrum. We find that （i） The leading order pQCD predictions for the branching ratio Br（B^＋→K^＋K0^＊（1430）^0）are in good agreement with the experimental upper limit in both scenarios, while the pQCD predictions for other considered B→K0^＊（1430）K decay modes are also presented and will be tested by the LHC experiments; （ii） The annihilation contributions play an important role in these considered decays, for B^0→K0^＊（1430）^±K^± decays,for example,which are found to be （1-4）×10^-6.     

The Effects from the Complex Parameters on t→ch^0 Within the Minimal Supersymmetric Standard Model

We investigate the effects from complex parameters on the branching ratio (BR) of the flavor changing rare decay t→ch^0 contributed by the electroweak interactions in the framework of the minimal supersymmetric standard model with complex parameters. We study the dependence of the BR on the possible relevant additional parameter swhich could be the originalsources inducing CP-violation, i.e., the complex phase angles φμ and φAb in squark and chargino sectors and δ13 appearing in Cabibbo-Kobayashi-Maskawa matrix. We find that these parameters influence the BR obviously and the effects induced by φμ and φAb are much larger than by δ13. With the different chosen values of the complex parameters, the BR is in the range between 10^-10 and 10^-8, depending mainly on the phase angles of the higgsino mass parameter μ and the trilinear coupling Ab.     

Extended Quark Potential Model From Random Phase Approximation

The quark potential model is extended to include the sea quark excitation using the random phase approximation.The effective quark interaction preserves the important QCD properties-chiral symmetry and confinement simultaneously.A primary qualitative analysis shows that the π meson as a well-known typical Goldstone boson and the other mesons made up of valence qq quark pair such as the ρ meson can also be described in this extended quark potential model.     

Top Quark Decay t → cb-↑b in Topcolor-Assisted Technicolor Models

The topcolor-assisted technicolor （TC2） model predicts the existence of the top-pions and the CP-even top-Higgs with large flavor-changing couplings to the top quark, which at tree-level can mediate the top quark three-body decay t → cb-↑b. We study this decay, show the dependence of the decay rate on the relevant TC2 parameters and compare the results with the predictions in the minimal supersymmetric model. We find that the decay rate in the TC2 model is much larger than that in the minimal supersymmetric model if the new particles are not too heavy. However, in consideration of the ODF and the LEP experiment limits, the top-pion mass is greater than 340 GeV in a more realistic parameter space, so the decay width of the channel t → cb-↑b intermediated by top-pions will be depressed greatly and difficult to be detected at the future collider. Thus, to observe this channel at the future collider, considering the top-higgs contribution may be the possible way when the masses of the top-pions and the top-higgs are not degenerate.     

Bs,d → μ^μ^- decays in a flavor changing Z＇ model

We study the pure leptonic decays Bs,d → μ^μ^- in a Flavor Changing ZI Model. From the recent measurements of the branching ratios B（Bs,d → μ^μ^-）, we have derived the bounds on the effective μ-μ-Z＇ lepton coupling Bμμ^L. We find that, （i） if neglecting the contribution from the right-handed lepton coupling R L Bμμ^R, we obtain 1.32 〈 Bμμ^L 〈 3.32; （ii） if considering the contribution from the right-handed lepton coupling Bμμ^R and setting Bμμ^R and setting Bμμ^L= Bμμ^R, we obtain 0.99 〈 Bμμ^L 〈 2.19. Our results could be useful for researching Z＇ effects.     

Lepton Polarization Asymmetry in B → e^＋e^- Decay beyond the Standard Model

The lepton polarization asymmetry in the B → e^＋e^- decay, when one of the leptons is polarized, is investigated by using the most general form of the effective Hamiltonian. We find allowed regions for the new scalar Wilson coefficients, assuming that the experimental branching ratio is measured within 10% percent uncertainty. Then using these restrictions to the new coefficients the sensitivity of the lepton polarization asymmetry to them is studied. Moreover, it is observed that there are regions of terms describing the scalar interactions, where lepton polarization asymmetry differs from zero, which can serve as a good test for searching new physics beyond the standard model.     

New physical effects on the decay Bs →γγ in the technicolor model

In this paper we calculate the contributions to the branching ratio of Bs →γγ from charged pseudo-Goldstone bosons appearing in the one generation Technicolor model. We find that the theoretical value of the branching ratio, BR（Bs →γγ）, including the contributions of PGBs, P^± and P8^±, is very different from the standard model （SM） prediction. The new physical effects can provide a one to two order of magnitude enhancement of the SM results. It is shown that the decay Bs →γγ can test new physical signals from the technicolor model.     

Nucleon—Nucleon Phase Shifts in the Extended Quark—Delocalization Colour—Screening Model

An alternative method is applied to the study of nocleon-nucleon scattering phase shifts within the framework of the extended quark delocalization colour-screening model,in which the one-pion exchange with short-range cutoff is included.     

关于B-0→K-0π0衰变过程研究

系统地计算B^0→K^0π^0衰变过程的强子矩阵元，它包括领头阶因子化部分，αs修正的硬胶子交换部分和软胶子交换部分．其中软胶子交换部分，无论在量子色动力学(QCD)因子化方法中，还是在微扰QCD中都不能进行计算．用光锥QCD求和规则系统地计算了这部分贡献．并发现在该衰变道中软胶子交换部分与领头阶因子化部分以及αs修正的硬胶子交换部分有相同的数量级，因此不能忽略．最后计算了该衰变过程的分支比，计算结果与实验结果相一致．     

Supersymmetric contributions to B_s → K~-π~＋ decay

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.     

Study on Bd → φKs Decay in EDQS Model

We study Bd → φKs decay in extra down-type quarks （EDQS） model with a non-universal Z boson associated with flavor changing neutral currents （FCNCs） at the tree level. With the up-to-date experimental data of Br（Bd → φKs）, SCKs, and ACKs, we derive the bounds on the Z-b-s coupling parameter ｜Ubs ｜ and the new weak phase φ, using the constrained parameter spaces, we finally give predictions for Bd → φφ decay, which could be tested at the Fermilab Tevatron and the LHC-b experiments.     

Non-factorizable contributions in D0→π+π- decay

We have analyzed the D^0→π^+π^- decay with α_s corrections in quantum chromodynamic (QCD) factorization and with the soft-gluon corrections in the light cone QCD sum rules. The soft-gluon effects are firstly calculated in the decay channel. The results show that once the factorization contributions, the α_s corrections, and the soft-gluon effects are all considered, we can satisfactorily explain the experimental data in the decay channel.     

Rare Decay B→Xsvv in the Two—Higgs—Doublet Model of Type—Ⅲ

In this paper, we calculated the new physics contribution to theoretically very clean rare decay B→X_sνν in the general two-Higgs-doublet model (model III). Within the considered parameter space, we found that (a) the new physics contribution can provide one to two orders of enhancement to the branching ratio B(B→X_sνν) and can saturate the experimental bound on B(B→X_sνν) in some regions of the parameter space; (b) besides the CLEO data of B→X_sγ, the ALEPH upper limit on B(B→X_sνν) also leads to further constraint on the size of the Yukawa coupling λ_tt: λ_tt< 6.4 for λ_bb=2.7 and m_H⁺=200 GeV.     

Rare Decay Process K→πvv^- in Three-Site Higgsless Model]

Rare decay processes K→πvv^- and KL→π^0vv^- are considered in the framework of three-site Higgsless model. The contributions of this new physics model to these two decay processes come from the new heavy gauge bosons and the correction terms for the couplings of the ordinary gauge bosons with fermions. Our numerical results show that the branching ratios of these two decay processes can be enhanced by 40% and 50% relative to those predicted by the standard model.