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.     

B→ηK and B→φKs Decays in the Two Higgs Doublet Model Ⅲ

Using the QCD factorization approach, we investigate the large branching ratios of B→ηK^＊ decays and the SCKs anomaly of B→φKs decay in the two Higgs doublet model Ⅲ. With the contributions of flavour-changing neutral current mediated by the neutral Higgs bosons H^0, h^0 and A^0 at the tree level, we provide a coherent resolution to these anomalies within the constrained parameter spaces, which are 120 〈｜λbs λss｜ 〈136. This will be really interesting in searching for the signs of new physics.     

QCD Approach to B →Dπ Decays and CP Violation

The branching ratios and CP violations of the B →Dπ decays, including both the color-allowed and the color-suppressed modes, are investigated in detail within QCD framework by considering all diagrams that lead to three effective currents of two quarks. An intrinsic mass scale as a dynamical gluon mass is introduced to treat the infrared divergence caused by the soft collinear approximation in the endpoint regions, and the Cutkosky rule is adopted to deal with a physical-region singularity of the on mass-shell quark propagators. When the dynamical gluon mass μg is regarded as a universal sca/e, it is extracted to be around μg = 440 MeV from one of the well-measured B →Dπ decay modes. The resulting predictions for all branching ratios are in agreement with the current experimental measurements. As these decays have no penguin contributions, there are no direct CP asymmetries. Due to interference between the Cabibbo-suppressed and the Cabibbo-favored amplitudes, mixing-induced CP violations are predicted in the B →D^±π^±↓ decays to be consistent with the experimental data at 1-σ level. More precise measurements will be helpful to extracting weak angle 2β＋γ.     

A Monte Carlo Study on the Identification of Quark and Gluon Jets

Three-jet events in e^ e^- collisions at 91.2 GeV are investigated using both HERWIG and JETSET Monte Carlo generators.The angles among the three jets are used to identify the quark and gluon jets.An analysis at the parton level is carried out to ensure the reasonableness of this method and an angular cut is utilized to improve the purity of this identification.The multiplicity inside the identified quark or gluon jets agrees with the quantum chromodynamic predictions qualitatively.     

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.     

Gluon Transport Properties in the Region of Coexistence of Both Hadronic and QGP Phases

The transport properties of gluon in color space in a system of coexistence of both hadronic and QGP phases are investigated from the quantum transport equation of gluon.     

B→KK衰变中的软胶子修正

应用光维QCD求和规则研究了B→KK衰变的软胶子交换修正,虽然QCD因子化方法已经计算了领头阶的因子化和硬胶子交换的α_s阶辐射修正部分,然而系统地估算所有树图和企鹅图的非因子化软胶子贡献是有价值的,我们的结果表明在B→KK衰变中软胶子效应总是使分支比值减小,约为几个百分点.     

Search for Exotic States in J／ψ→ρηπ

It is an ideal place to search for exotic states through J/ψ hadronic decays.In this paper,we discuss the way to use the partial wave analysis (PWA) based on covariant helicity amplitude analysis to study the invariant mass spectrum of ηπ and to find the evidence of the existence of exotic states in this channel.The formula for PWA is also given.It is the theoretical foundation of experimental physics analysis on exotic states searching in J/ψ hadronic decays.The theoretical formula can also be used in physics analysis of J/ψ decays into ωππ,φππ,ωKK,φKK and K^* (892)Kπ.     

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.     

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．     

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.     

B-Meson Wavefunction by a Comparative Analysis of the B → π, K Transition Form Factors

Properties of the B-meson light-cone wavefunction up to next-to-leading order Fock state expansion are studied by a comparative study of the B → π, K form factors within the kT factorization approach and the light-cone sum rule analysis. The form factors F＋,0,T^B→ π and F＋,0,T^B→ K are carefully re-calculated up to O（1/mb^2） within the kT factorization approach in the large recoil region. The QCD light-cone sum rule is applicable in the large and intermediate energy regions, and the QCD light-cone sum rule results in Ref. [12] are adopted for such a comparative study. It is found that when the two phenomenological parameters ∧^-∈ [0.50, 0.55] and δ∈ [0.25, 0.30], the results of F＋,0,T^B→ π （Q^2 ） and F＋,0,T^B→ K（Q ^2） from these two approaches are consistent with each other in the large recoil energy region.     

Quantum Dynamics of Cooled Atoms in the Presence of Bose—Einstein Condensates

Under the Markov approximation,the quantum dynamics of cooled atoms in the presence of Bose-Einstein condensates is studied.A master equation governing the evolution of such a system is derved.Using this master equation,the distribution of the atoms in the excited states at finite temperature and the dynamics of the excited atom at zero temperature are given and discussed.     

Analysis on B → VV with the Flavour SU（3） Symmetry

It is noted that the rescattering and annihilation effects are significant in the penguin-dominant B→ VV decays. In this work, we suggest to use a unique operator at the quark level to describe all the rescattering and the penguin-induced annihilation effects in B→ φK^＊, and the coefficient of the operator depends on the polarizations of the produced mesons. By the flavour SU（3） symmetry, we apply the same scenario to all the penguin-dominant B0190 VV modes.     

Effective Lagrangian of SU（2） Yang—Mills Theory in the Presence of Fermions

We derive the one-loop effective action of SU(2) Yang-Mills theory in the presence of fermions in the low energy limit.This result is presented by separating the topological degrees,which describe the non-Abelian monopoles from the dynamical degrees of the gauge potential and integrate out all the dynamical degrees and fermions in SU(2) Yang-Mills theory.     

Bs →φπ^0 Decay in the Extra Down-Type Quark Model

Using the QCD factorization approach, we investigate the electro-weak penguin dominated process 13~ --, q57r~ in the extra down-type quark （EDQS） model. We calculate the effects of new physics （NP） on the branching fraction and direct CP asymmetry of the decay mode. It is found that the branching fraction can be increased by 15~o points or dropped by 13~o points than the standard model （SM） value, and its direct CP asymmetry can be increased by 35% points or dropped by 37% points than the SM one. The effects of NP on the direct CP asymmetry are more obvious than on the branching fraction. If this decay mode could be measured in the upcoming LHCb experiment, these results we obtain will be useful for further studies of the EDQS model.     

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.     

Effect of the Electron—Phonon Coupling on Barrier D^— Quantum Dots in Magnetic Fields

The influence of the electron-phonon coupling of the energy of low-lying states of the barrier D^- center,which consists of a positive ion located on the z-azis at a distance from the two-dimensional quantum dot plane and two electrons in the dot plane bound by the ion,is investigated at arbitrary strength of maguetic field by mading use of the method of few-body physics.Discontinuous ground-state energy transitions induced by the magnetic field are reported.The dependence of the binding energy of the D^- ground state on the quantum dot radius is obtained.A considerable enhancement of the binding is found for the D^- ground state,which results from the confinement of electrons and electron-phonon coupling.     

Chemical Potential Dependence of the Dressed-Quark Propagator in a Simple Confining QCD Model

Based on the Dyson-Schwinger approach, a method for obtaining the chemical potential dependence of the dressed quark propagator in the ‘Nambu-Goldstone‘ and the ‘Wigner‘ phase is developed. The bag constant in the presence of the non-zero chemical potential is analysed.