The energy loss effect in nuclear matter ,which is another nuclear effect apart from the nuclear effect on the parton distribution as in deep inelastic scattering process ,can be measured best by the nuclear dependence of the high energy nuclear Drell-Yan process. By means of the nuclear parton distribution studied only with lepton deep inelastic scattering experimental data, measured Drell-Yan production cross sections for 800GeV proton incident on a variety of nuclear targets are analyzed within Glauber framework which takes into account energy loss of the beam proton. It is shown that the theoretical results with considering the energy loss effect are in good agreement with the FNAL E866.

Within the framework of the Uð3Þ chiral perturbation theory, we revisit the masses, decay constants, and the mixing parameters of the light pseudoscalar mesons π, K, η, and η 0 . The low energy constants up to next-to-next-to-leading order are determined by including the light-quark mass dependences of the various quantities from different lattice QCD simulations and relevant phenomenological inputs. Then we study the finite-temperature behaviors of the masses of the light pseudoscalar mesons. The thermal behaviors of the η-η 0 mixing angles in singlet-octet and quark-flavor bases are also explored. While the masses of the π, K, and η are increased when increasing the temperatures, the mass of the η 0 turns out to be slightly decreased in the low-temperature region.

The investigation into the fast parton energy loss in cold nuclear matter is crucial for a good understanding of the parton propagation in hot-dense medium. By means of four typical sets of nuclear parton distributions and three parametrizations of quark energy loss, the parameter values in quark energy loss expressions are determined from a leading order statistical analysis of the existing experimental data on nuclear Drell-Yan differential cross section ratio as a function of the quark momentum fraction. It is found that with independence on the nuclear modification of parton distributions, the available experimental data from lower incident beam energy rule out the incident-parton momentum fraction quark energy loss. Whether the quark energy loss is linear or quadratic with the path length is not discriminated. The global fit of all selected data gives the quark energy loss per unit path length α = 1.21±0.09 GeV/fm by using nuclear parton distribution functions determined only by means of the world data on nuclear structure function. Our result does not support the theoretical prediction: the energy loss of an outgoing quark is three times larger than that of an incoming quark approaching the nuclear medium. It is desirable that the present work can provide useful reference for the Fermilab E906/SeaQuest experiment.

The study of nuclear effects for J/ψ production in proton-nucleus collisions is crucial for a correct interpretation of the J/ψ suppression patterns experimentally observed in heavy-ion collisions.By means of three representative sets of nuclear parton distributions, the energy loss effect in initial state and nuclear absorption effect in final state are taken into account in the uniform framework of the Glauber model. A leading order phenomenological analysis is performed on J/ψ production cross section ratios R W/Be (x F ) for the E866 experimental data. The J/ψ suppression is investigated quantitatively due to the different nuclear effects. It is shown that the energy loss effect with resulting in the suppression on R W/Be (x F ) is more important than the nuclear effects on parton distributions in high x F region. The E866 data in the small x F keep out the nuclear gluon distribution with a large anti-shadowing effect. However, the new HERA-B measurement is not in support of the anti-shadowing effect in nuclear gluon distribution. It is found that the J/ψ-nucleon inelastic cross section σ J/ψ abs depends on the kinematical variable x F , and increases as x F in the region x F > 0.2.