Wang Hong-Min

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

In a Glauber Monte Carlo framework, taking account of the transverse spatial distribution of hard partons in the nucleon, we analyse the nuclear modification factor RdAu for J/ψ in d+Au collisions with the 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 Ncoll 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. PACS: 25.75.-q, 24.85.+p, 12.38.Bx For J/ψ production is sensitive to both cold nuclear matter (CNM) and Quark-Gluon Plasma (hot-dense matter)[1], the “normal suppression”in the CNM should be subtracted in any interpretation of charmonium production in heavy ion collisions. The Glauber Monte Carlo (GMC) approach[2−6], which can simulate experimentally observable quantities and analyse real data, is an ideal tool to study the CNM effects provided in deuteron-gold (d+Au) collisions[7]. In the framework of the GMC, only the essential J/ψ production process[8], g+ g → cc̄, is considered. Thus, the subprocess cross section can be obtained by extracting from the proton-proton (p+p) experimental data[9] and given as the Monte Carlo inputs of rapidity (y) and transverse momentum (pT ) [3,4]. The shadowing and “normal nuclear absorption”effects, which are two dominant CNM effects at Relativistic Heavy Ion Collider (RHIC) and Large Hadron Collider (LHC) energies, can also be considered properly in the GMC framework. Since shadowing should depend on the spatial position of the interaction parton within the nucleus, the inhomogeneous shadowing effect[10,11] should also be taken into account. In this paper, the latest shadowing parametrization EPS09 (Eskola, Paukkunen and Salgado)[12] is used. At ultra-high energy domain, the mechanism of inelastic hadronic collisions is dominated by the contribution from small-x gluons and the influence of the transverse spatial distribution of hard partons in the nucleon become important[13,14]. Unfortunately, comparing with the longitudinal momentum distribution of partons in the nucleon, the measurements of the transverse spatial distribution of partons are rather limited[15]. In this paper, two kinds of hard partons distributions in the nucleon are used. One is assumed that the hard partons are uniformly distributed in a hard sphere nucleon, the other is derived from fits to J/ψ photo-production data at HERA and FNAL[13,15]. The corresponding results with both of them will be given in the following part of the paper. Supported by Natural Science Foundation of Hebei Province(A2008000421) E-mail:whmw@sina.comIn a Glauber Monte Carlo framework, taking into account the transverse spatial distribution of hard partons in the nucleon, we analyze the nuclear modification factor R(d) (Au) for J/psi 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 R(d Au) on N(coll) in peripheral d+Au collisions, however, an unconspicuous correction is shown for the results versus p(T). The theoretical results are in good agreement with the experimental data from PHENIX.

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 ratios 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.

Net-Baryon and Net-Kaon Rapidity Distributions in Ultrarelativistic Heavy-Ion Collisions

In this paper, the gluon distribution is extracted from the KLR-AdS/CFT saturation model and used to investigate net-baryon and net-kaon rapidity distributions in ultrarelativistic heavy-ion collisions. With the same parameters of the saturation model fitting to HERA data and an ?2 analysis of the overall constant C, the theoretical results are in good agreement with RHIC data in Au+Au collisions at ?s?=?0.2?TeV. Then, we present the predictive results for net-baryon rapidity distributions in central Pb+Pb collisions at LHC energies of ?s?=?2.76, 3.94, and 5.52 TeV, and give the corresponding values of dN/dy for net-baryon at y = 0.

Charm structure functions and gluon shadowing effects with the AdS/CFT model

By means of the UGD function extracted from an AdS/CFT inspired saturation model, the charm and bottom structure functions are studied in fixed-order perturbation theory. It is shown that the theoretical results are in good agreement with the recent HERA data. Then, this UGD function is also used to investigate net-kaon rapidity distribution in Au+Au collisions at RHIC energies and the theoretical results fit well to the BRAHMS data. In the end of this paper, we give the predicted results for nuclear charm structure function at very small x where the popular shadowing parameterizations are invalid.

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

In this paper, the J/psi nuclear absorption effect is studied at RHIC and LHC energies with the EKS98 shadowing parameterizations. By assuming that the J/psi absorption cross section, sigma(abs), increases with the charmonium-nucleon (J/psi-N) center of mass energy, root(s)J/psi N, it is found that sigma(abs) should depend on x(F) (or y) at a certain center of mass energy per nucleon pair, root 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/psi 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.

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.

Cold nuclear matter effects on J/? production in d-Au collisions

The medium modifications of J/ψ production in d-Au collisions at √sNN = 200 GeV are studied in the Glauber model. By means of the c.m. energy loss parameter per collision studied in Drell-Yan process, taking account of the inhomogeneous shadowing effect, we find that the initial-state energy loss effect can be ignored in d-Au collisions at mid-rapidity. Then, the final-state J/ψ absorption effect is also considered and the theoretical results are in good agreement with the recent experimental data given by PHENIX. Finally, the experimental results of J/ψ production in d-Pb collisions are also predicted at RHIC and LHC energies respectively.

Cold nuclear matter effects on J/ψ production in d-Au collisions

The medium modifications of J/ψ production in d-Au collisions at √sNN = 200 GeV are studied in the Glauber model. By means of the c.m. energy loss parameter per collision studied in Drell-Yan process, taking account of the inhomogeneous shadowing effect, we find that the initial-state energy loss effect can be ignored in d-Au collisions at mid-rapidity. Then, the final-state J/ψ absorption effect is also considered and the theoretical results are in good agreement with the recent experimental data given by PHENIX. Finally, the experimental results of J/ψ production in d-Pb collisions are also predicted at RHIC and LHC energies respectively.

Cold nuclear matter effects on J/ψ production in d-Au collisionsSupported by Innovation Foundation of Academy of Armored Forces Engineering of PLA (20062L10), and Natural Science Foundation of Hebei Province (A2005000535)

The medium modifications of J/ψ production in d-Au collisions at √sNN = 200 GeV are studied in the Glauber model. By means of the c.m. energy loss parameter per collision studied in Drell-Yan process, taking account of the inhomogeneous shadowing effect, we find that the initial-state energy loss effect can be ignored in d-Au collisions at mid-rapidity. Then, the final-state J/ψ absorption effect is also considered and the theoretical results are in good agreement with the recent experimental data given by PHENIX. Finally, the experimental results of J/ψ production in d-Pb collisions are also predicted at RHIC and LHC energies respectively.

Local Quark-Hadron Duality and Magnetic Form Factors of Bound Proton

We discuss the consequence of local duality for elastic scattering, and derive a model-independent equation between structure functions at x ~ 1 and elastic electromagnetic form factors. Then the electromagnetic form factors of proton are discussed using the quark-hadron duality theory. We also debate the form factor of proton in a bound state. It may be an effective approach to study the form factor of proton in media.