Study of the heavy molecular states in the quark model with meson exchange interaction

Some charmonium-like resonances such as X(3872) can be interpreted as possible D^(*)D^(*) molecular states. Within the quark model, we study the structure of such molecular states and the similar B^(*)D^(*) molecular states by taking into account the light meson exchange (π, η, ρ, ω and σ) between two light quarks from different mesons.     

Influence of quark energy loss on extracting nuclear sea quark distribution from nuclear Drell-Yan experimental data

By means of two typical kinds of quark energy loss parametrization and the nuclear parton distribu-tions determined only with lepton-nuclear deep inelastic scattering experimental data, a leading order analysis is performed on the proton-induced Drell-Yau differential cross section ratios of tungsten versus deuterium as a function of the quark momentum fraction in the beam proton and target nuclei. It is found that the theoretical results with quark energy loss are in good agreement with the experimental data. The quark energy loss effect produces approximately 3% to 11% suppression on the Drell-Yan differential cross section ratios RW/D in the range 0.05 ≤ x2≤ 0.3. The application of nuclear Drell-Yan data with heavy targets is remarkably subject to difficulty in the constraint of the nuclear sea quark distribution.     

Top pair production in the littlest Higgs model with T-parity

In the framework of the littlest Higgs model with T-parity,we study the top pair production at the next generation colliders like LHC and ILC.We find that the order O(αs) corrections to the standard model top pair production cross section at LHC can be very small and the magnitude is below 1%.However,the magnitude of corrections to the standard model top pair production rate at ILC may be over 5% for reasonable values'of the parameters.Besides this,the corrections to the asymmetry ALR(tt) may be more sizable. Therefore,the top pair production at ILC may serve as a probe of the littlest Higgs model with T-parity,especially the asymmetry ALR(tt).     

Non-perturbative Aspects of QCD and Parameterized Quark Propagator

Based on the Global Color Symmetry Model, the non-perturbative Q, CD vacuum is investigated in the parameterized fully dressed quark propagator. Our theoretical predictions for various quantities characterized the QCD vacuum are in agreement with those predicted by many other phenomenologieal QCD inspired models. The successful predictions clearly indicate the extensive validity of our parameterized quark propagator used here. A detailed discussion on the arbitrariness in determining the integration cut-off parameter ofμ in calculating QCD vacuum condensates and a good method, which avoided the dependence of calculating results on the cut-off parameter is also strongly recommended to readers.     

Top Quark Chromomagnetic Dipole Moment in the Littlest Higgs Model with T-Parity

The littlest Higgs model with T-parity, which is called LHT model, predicts the existence of the new particles, such as heavy top quarks, heavy gauge bosons, and mirror fermions. We calculate the one-loop contributions of these new particles to the top quark chromomagnetic dipole moment (CMDM) ΔK. We find that the contribution of the LHT model is one order of magnitude smaller than the standard model prediction value.     

Study of Top Quark FCNC

We study the one-loop contribution of the effective flavor changing neutral couplings (FCNC) tcZ on the charm quark electric dipole moment. Using the known limits on the top and charm quarks electric dipole moments, we place limits on these FCNC anomalous couplings.     

Cooling Curve of Strange Star in Strong Magnetic Field

In this paper, firstly, we investigate the neutrino emissivity from quark Urca process in strong magnetic field. Then, we discuss the heat capacity of strange stars in strong magnetic field. Finally, we give the cooling curve in strong magnetic field. In order to make a comparison, we also give the corresponding cooling curve in the case of null magnetic field. It turns out that strange stars cool faster in strong magnetic field than that without magnetic field.     

Strong coupling, charm-and bottom-quark masses from electron-positron annihilation

The cross section for electron-positron annihilation into hadrons allows for a precise determination of the strong coupling constant and the charm- and bottom-quark masses. Recent theoretical and experimental results are presented with emphasis on the energy region accessible by B-meson factories and below.     

Nuclear Matter in a Chiral SU(3) Quark Mean-Field Model

A quark meson coupling model based on SU(3)_L×SU(3)_R symmetry and scale invariance is proposed. The quarks and mesons get masses through symmetry broken. We apply this SU(3) chiral constituent quark model to investigating the nuclear matter at finite temperature and density. The effective baryon masses, compression modulus and hyperon potentials are all reasonable. The critical temperature of liquid-gas phase transition is also calculated in this model.