High—Energy Proton—Induced Dimuon Production from Nuclei

In the framework of the Glauber model,taking into account the energy loss of the beam proton through the nucleus,we analyse the measured Drell-Yan production cross sections for an 800 GeV proton beam incident on Be,Fe and W nuclear targets,We have found that the nuclear Drell-Yan cross section ration are suppressed due to the energy loss in the initial state.The calculated results of the energy loss are in very good agreement with the Fermilab experiment 866.     

Inhomogeneous Shadowing Effect in High-Energy p-A Drell-Yan Process

Having studied the initial state energy loss versus nuclear shadowing for the Drell- Yan dimuon pair production in the color string model, the inhomogeneous shadowing effect is considered in this paper. We find that the inhomogeneous shadowing effect does amend the rate of energy loss per unit path length, -dE/ dz. Finally, the theoretical results for the Drell Yan differential cross-section ratios are compared with the E772 and E866 data. It is found that the theoretical results are in good agreement with the experimental data.     

Study on the shadowing effect for optical wave scattering from randomly rough surface

Based on the Kirchhoff approximation for rough surface scattering and by calculating the shadowing function of the rough surface, the formula of the scattering cross section of the dielectric rough surface is presented with consideration of the shadowing effect for the optical wave incidence. It is obtained that in comparison with the conventional Kirchhoff solution, the shadowing effect should not be neglected for the optical wave scattering from the rough surface. The influence of the shadowing effect for different incidence angle, surface root mean square slope, and surface roughness on the scattering cross section is discussed in detail.     

Medium Density and Parton Energy Loss in Gold-Gold Collisions from the Recombination Model

The pion production at mid-rapidity in gold-gold collisions at √s = 200 GeV is investigated by the parton recombination model. The density of the hot medium produced in the collisions and the hard parton energy loss effect are obtained by fitting the experimental data. Both of them are found to have power-law dependence on the number of binary collisions. The implication of such dependence on the nuclear modification factor is discussed.     

Production of Λ-hypernuclei in A(p,K~ )ΛB reactions

The production of Λ-hypernuclei in the A(p,K )ΛB reaction is investigated in the framework of the distorted wave impulse approximation(DWIA). The total cross sections and differential cross sections for various nuclear targets are calculated with an elementary process pN→NKΛ where the additional contributions from the N*(1535) resonance and the final state interaction between p and Λ are included. The dependence of the production cross sections of Λ-hypernuclei on the phenomenological nuclear density and the nucleon number in the target, as well as the distortion effect of the incident proton and outgoing kaon, are also explored. It is shown that the distortion effect tends to decrease the cross sections by a factor of about 3—10. The production cross sections are sensitive to the adopted nuclear density.     

非微扰QCD和核遮蔽效应对K因子的影响

考虑非微扰量子色动力学物理真空夸克凝聚效应,计算了碳核与碳核在质心系能量分别为630和200GeV时碰撞Drell—Yan过程的K因子,以及加入核遮蔽因子后非微扰效应对K因子的影响,并把计算结果与没有考虑夸克凝聚非微扰效应的K值进行了对比。结果表明,非微扰效应和核遮蔽效应对K因子影响很小。Considering quark condensate contributions from the QCD vacuum, the non-perturbative effect on the K-factor is investigated for the C-C collision Drell-Yan process with and without nuclear shadowing respectively, at the center-of-mass energy √s= 630 and 200 GeV. Comparison of the results indicates that both the non-perturbative effect and the nuclear shadowing effect pose a weak influence on the K-factor.     

J/ψ-N center of mass energy dependence of nuclear absorption effect on J/ψ production

In this paper, the J/ψ nuclear absorption effect is studied at RHIC and LHC energies with the EKS98 shadowing parameterizations. By assuming that the J/ψ absorption cross section, σ abs , increases with the charmonium-nucleon （J/ψ-N） center of mass energy, s J/ψN , it is found that σ abs should depend on x F （or y） at a certain center of mass energy per nucleon pair,s , especially at LHC energies. The theoretical results with the x F （or y）-dependence of the absorption effect are in good agreement with the experiment data from PHENIX in d-Au collisions and the predicted results will be examined by the forthcoming experimental data from LHC in d-Pb collisions. Finally, we also present baseline calculations of cold nuclear matter effects on J/ψ production in nucleus-nucleus （A-A） collisions and find that the x F （or y）-dependence of absorption effect is very small at both RHIC and LHC energies in A-A collisions.     

Influence of the Nucleon Hard Partons Distribution on J/φ Suppression in a GMC Framework

In a Glauber Monte Carlo framework, taking into account the transverse spatial distribution of hard partons in the nudeon, we analyze the nuclear modification factor RdAu for J/φ in d＋Au collisions with EPS09 shadowing parametrization. After the influence of nucleon hard partons distribution is considered, a clearly upward correction is revealed for the dependence of RdAu on Neon in peripheral d＋Au collisions, however, an unconspicuous correction is shown for the results versus PT. The theoretical results are in good agreement with the experimental data from PHENIX.     

Energy Loss of Fast Quarks in Nuclear Drell-Yan Dimuon Production

The energy loss effect in nuclear matter, which is another nuclear effect apart from the nuclear effects on the patton distribution as in the deep inelastic scattering process, can be measured best by the nuclear dependence of the high energy nuclear Drell-Yan process. By means of the quark energy loss parametrization given in literature and the nuclear patton distribution extracted only with lepton-nucleus deep inelastic scattering experimental data, measured Drell-Yan production cross sections are analysed for 800-GeV protons incident on a variety of nuclear targets from FNAL E866. The average energy loss of quarks are given by fitting the Fe/Be and W/Be Drell-Yan cross section ratios versus the incident patton momentum fraction.     

Total Nuclear Reaction Cross Section Induced by Halo Nuclei and Stable Nuclei

We develop a method for calculation of the total reaction cross sections induced by the halo nuclei and stable nuclei. This approach is based on the Glauber theory, which is valid for nuclear reactions at high energies. It is extended for nuclear reactions at low energies and intermediate energies by including both the quantum correction and Coulomb correction under the assumption of the effective nuclear density distribution. The calculated results of the total reaction cross section induced by stable nuclei agree well with 30 experimental data within 10 percent accuracy.The comparison between the numerical results and 20 experimental data for the total nuclear reaction cross section induced by the neutron halo nuclei and the proton halo nuclei indicates a satisfactory agreement after considering the halo structure of these nuclei, which implies quite digerent mean fields for the nuclear reactions induced by halo nuclei and stable nuclei. The halo nucleon distributions and the root-mean-square radii of these nuclei can be extracted from the above comparison based on the improved Glauber model, which indicates clearly the halo structures of these nuclei. Especially,it is clear to see that the medium correction of the nucleon-nucleon collision has little effect on the total reaction cross sections, induced by the halo nuclei due to the very weak binding and the very extended density distribution.     

Single particle properties in asymmetric nuclear matter and TBF rearrangement effect

We have developed the formula and the numerical code for calculating the rearrangement contribution to the single particle (s.p.) properties in asymmetric nuclear matter induced by three-body forces within the framework of the Brueckner theory extended to include a microscopic three-body force (TBF). We have investigated systematically the TBF-induced rearrangement effect on the s.p. properties and their isospin-behavior in neutron-rich nuclear medium. It is shown that the TBF induces a repulsive rearrangement contribution to the s.p. potential in nuclear medium. The repulsion of the TBF rearrangement contribution increases rapidly as a function of density and nucleon momentum. It reduces largely the attraction of the BHF s.p. potential and enhances strongly the momentum dependence of the s.p. potential at large densities and high-momenta. The TBF rearrangement effect on symmetry potential is to enhances its repulsion (attraction) on neutrons (protons) in dense asymmetric nuclear matter.     

Isospin Effect on Nuclear Stopping in Intermediate Energy Heavy Ion Collisions

By using the isospin-dependent quantum molecular dynamics model,we study the dependence of nuclear stopping Qzz/A and R in intermediate energy heavy ion collisions on system size,initial N/Z,isospin symmetry potential and the medium correction of two-body cross sections.We find the effect of the initial N/Z ratio and isospin symmetry potential on stopping is weak.The excitation function of Qzz/A and R depends on the form of medium correction of two-body cross sections,the equation of state of nuclear matter.Our results show that the behaviour of the excitation function of Qzz/A and R can provide clearer information of the isospin dependence of the medium correction of two-body cross sections.     

不同能量下核束缚能的影响

在不同能量下， 利用核束缚能对虚光子四动量的平方项进行修正， 分别计算了Sn核碰撞中核束缚能对反应截面中湮灭项和康普顿散射项及K因子的影响。 结果表明， 核束缚能在小x区域对反应截面中湮灭项和康普顿散射项及K因子的影响明显， 并且能量越低这种影响越显著， 随着x2增大影响逐渐消失。 We made a revision of square of virtual photon four momentum by means of using nuclear bin ding energy formula in different energy， and we also made an accurate calculation for the effect of nuclear binding energy on K factor and Compton term and annihilate term in the Drell Yan process of the Sn Sn collision. The outcome indicates that the effect of nuclear binding energy on the annihilate term and the Compton term is marked in little x region and the effect will become more obvious with decrease of the energy and come to disappear with increase of the x.     

P-wave contributions to B_((s))→ψKπ decays in perturbative QCD approach

We study the quasi-two-body decays B_((s)) ψ[K~*(892) K~*(1410) K~*(1680)] ψKπ by employing the perturbative QCD(PQCD) factorization approach, where the charmonia ψ represents J/ψ and ψ(2S). The corresponding decay channels are studied by constructing the kaon-pion distribution amplitude(DA) Φ_(Kπ)~P, which comprises important final state interactions between the kaon and pion in the resonant region. Relativistic Breit-Wigner formulas are adopted to parameterize the time-like form factor F_(Kπ) appearing in the kaon-pion DAs. The SU(3) flavor symmetry breaking effect resulting from the mass difference between the kaon and pion is taken into account,which makes significant contributions to the longitudinal polarizations. The observed branching ratios and the polarization fractions of B_((s)) ψK~*(892) ψKπ are accommodated by tuning hadronic parameters for the kaon-pion DAs. The PQCD predictions for B_((s)) ψ[K~*(1410) K~*(1680)] ψKπ modes from the same set of parameters can be tested by precise data obtained in the future from LHCb and Belle Ⅱ experiments.     

K and K* Exchange Effects in Lambda Hypernuclei

We study the effects of K and K^＊ exchange between the A hyperon and the nucleon in a A hypernueleus, where the nuclear core is described by a successful relativistic mean-field （RMF） model. In general, K and K^＊ are responsible for strangeness exchange in the one-boson-exchange potential model, which are absent in the RMF calculation. We investigate the contribution of Fock terms derived from K and K^＊ exchange. We use a pseudovector coupling for K exchange, which is found to provide a repulsive potential for the A particle in hypernuclei. Both vector and tensor couplings for K^＊ exchange are taken into account, whose combined effect on the A single-particle energy is found to be small.     

Delta Excitation in Compressed Neutron Rich Double Magic Spherical Finite Nucleus 132Sn

The ground state properties of 132Sn at equilibrium and at large compression are investigated,within the framework of the radially constrained spherical Hartree-Fock(CSHF)approximation.The delta resonance effects on the properties of neutron-rich double magic spherical nucleus,132Sn,in its ground state and the state under static compression are studied.The sensitivity of the nucleon size and Δ model spaces is investigated.At equilibrium,mixing between nucleon and Δ's in the largest model space of nine major nucleon shells plus 10 Δ orbitals was found.Expanding the nucleon model space has a larger effect on reducing the static compression modulus and softe-ning the nuclear equation of state than increasing the number of Δ states.It was found that the most of the increase in the nuclear energy generated under compression is used to create the massive Δ particles.For 132Sn nucleus under compression at 12 times the normal nuclear density,the excited nucleons to Δ's increased sharply up to 13% of the total number of constituents.This result is consistent with the values extracted from relativistic heavy-ion collisions.The single particle energy levels calculated and their behaviors under compression are examined too.A good agreement between results with effective Hamiltonian and the phenomenological shell model for the low lying single-particle spectra is obtained.     

核内夸克-胶子分布

介绍与核内夸克－胶子分布的有关实验现象:ＥＭＣ效应、核遮蔽效应、核Ｄｒｅｌ－Ｙａｎ过程和Ｊ／ψ光生反应等,以及解释它们的理论模型．The experiments of the EMC effect,nuclear shadowing effect,nuclear Drell Yanprocess and J/ψ production related to the quark gluon distributions in nuclei and the theoretical models explaining them are briefly reviewed.      

J/ψ-N center of mass energy dependence of nuclear absorption effect on J/ψ production

In this paper, the J/ψ nuclear absorption effect is studied at RHIC and LHC energies with the EKS98 shadowing parameterizations. By assuming that the J/ψ absorption cross section, σ abs , increases with the charmonium-nucleon (J/ψ-N) center of mass energy, s J/ψN , it is found that σ abs should depend on x F (or y) at a certain center of mass energy per nucleon pair,s , especially at LHC energies. The theoretical results with the x F (or y)-dependence of the absorption effect are in good agreement with the experiment data from PHENIX in d-Au collisions and the predicted results will be examined by the forthcoming experimental data from LHC in d-Pb collisions. Finally, we also present baseline calculations of cold nuclear matter effects on J/ψ production in nucleus-nucleus (A-A) collisions and find that the x F (or y)-dependence of absorption effect is very small at both RHIC and LHC energies in A-A collisions.     

Effect of nuclear deformation on direct capture reactions

Direct radiative capture processes are well described by a spherical potential model. Since most nuclei are not spherical, and in order for the model to explain direct radiative captures more accurately, the effect of nuclear deformation has been analyzed with q-deformed Woods-Saxon potential in this work. The results imply that nuclear deformation largely affects the direct radiative capture, and it should be taken into account when discussing direct capture reactions.     

Optimal Truncation in Ionization of hydrogen by Electron Impact

An analytic expression for the ionization amplitude of hydrogen by electron impact is found to contain a polyno-mial by an optimal truncation in an asymptotic series and a convergent series. The ionization amplitude, i.e., the transition matrix element on the energy shell, is decomposed into two parts: the structure-scattering factor and correlation factor, based on an approximation of the projectile plane wave in coplanar asymmetric geometries.The contribution of these factors to the triple differential cross section is evaluated using the method of optional truncation of asymptotic and convergent series.