121654775
The possible effect of scalar meson on the symmetry energy curve in the viewpoint of the quark-meson-coupling model
We give the energy density functional of quark-meson-coupling model within the Hartree-Fock approximation and make comparison with relativistic-mean-field and Skyrme-Hartree-Fock models. We find that the discrepancy of these models is mainly from the isovector channel of the energy density functional, which is also the major cause of different descriptions of symmetry energy against density. In the viewpoint of quark-meson-coupling model, the scalar meson through Fock exchange makes a density dependent form of the isovector channel which can soften the symmetry energy curve.
118555345
Alternate proof of the Rowe-Rosensteel proposition and seniority conservation
In this thesis the properties of unbound nuclei like 12,13Li are studiedby extending the multistep shell model to the complex energy plane. Thenuclei 12Li and 13Li are described starting from the one-particle states in 10Liand two-particle states in 11Li. The ground state of 12Li is found to be anantibound state. No bound or antibound state is found in 13Li. It is alsoshown that the odd proton plays a minor role in these nuclei.This framework is also applied to study the recently proposed spin-alignedproton-neutron pair coupling scheme. For this the MSM is extended to theproton-neutron space as well as the isospin space. In the model, a nonorthogonalbasis is introduced, which allows us to identify simultaneously theroles played by all configurations. The four-particle, six-particle and eightparticlenuclei in the heaviest N = Z region are evaluated using the MSMbasis within the space spanned by the single 0g9/2 hole shell.A novel Monte Carlo representation in the complex energy plane is alsodeveloped for studying nuclear excitations in the continuum. The calculationson realistic potentials show a stable performance and high accuracy in the oneparticleand two-particle cases. This will provide a convenient tool to studyopen systems with many nucleons in the continuum.
94690392
Isovector channel of quarkmeson-coupling model and its effect on symmetry energy
Abstract The non-relativistic approximation of the quark–meson-coupling model has been discussed and compared with the Skyrme–Hartree–Fock model which includes spin exchanges. Calculations show that the spin-exchange interaction has important effect on the descriptions of finite nuclei and nuclear matter through the Fock exchange. Also in the quark–meson-coupling model, it is the Fock exchange that leads to a nonlinear density-dependent isovector channel and changes the density-dependent behavior of the symmetry energy.
118524929
What hard probes tell us about the quark–gluon plasma: Theory
Abstract In the study of quark–gluon plasma in high-energy heavy-ion collisions, hard and electromagnetic (EM) processes can be used to probe a wide range of properties of the hot and dense medium, from space–time profiles of the bulk matter, bulk transport coefficients to EM responses and the jet transport parameter. These medium properties, how they can be studied through hard and EM probes and the status of recent theoretical and phenomenological investigations are reviewed in this talk.
122959126
Shear viscosity of a multi-component hadronic system
The shear viscosity and entropy density s of a hadron gas with zero baryon number density are calculated using the Chapman-Enskog and virial expansion approaches, respectively. Interactions are included via the K-matrix parametrization of cross sections preserving the unitarity of the S-matrix. In the four component mixture ( K N ), a total of 57 resonances up to 2 GeV mass are included. Interactions forming resonances reduce the magnitude of and increase s, both eects serving to progressively reduce =s as the temperature nears the QCD phase transition temperature.
118539566
Parton energy loss in cold nuclei
Within the generalized high-twist factorization formalism, we express the contribution from multiple parton scattering and induced gluon radiation to the DY dilepton spectra in terms of nuclear modified e ective beam quark distribution function. We show that beam quark energy loss is characterized by jet transport parameter ˆ q, which is related to the local gluon density of the medium. Using the value of ˆ q determined from the deeply inelastic scattering (DIS) data, we evaluate the nuclear modification factor in the Drell-Yan process in p+A collisions. E ects of parton energy loss in the DY spectra are found negligible in the Fermilab experimental data at Elab = 800 GeV relative to parton shadowing while the predicted suppression of the DY spectra are significant at Elab = 120 GeV.
120386318
Gamma-jet tomography of high-energy nuclear collisions in NLO pQCD
Within the NLO pQCD partem model study, suppression of away‐side hadron spectra associated with a high pT photon due to parton energy loss is shown to provide more complete tomographic picture of the dense matter formed in high‐energy heavy‐ion collisions. Hadron spectra at large ZT = PTh/pTλ≳ 1 are more susceptible to parton energy loss and therefore are dominated by surface emission of λ‐correlated jets, whereas small ZT hadrons mainly come from fragmentation of jets with reduced energy which is controlled by the volume emission. These lead to different centrality dependence of the hadron suppression in different region of ZT.
16258194
Energy loss effects on charm and bottom production in high-energy heavy-ion collisions
We study the effect of energy loss on charm and bottom quarks in high-energy heavy-ion collisions including longitudinal expansion and partial thermalization. We find that high-p{sub {perpendicular}} heavy quarks are greatly suppressed, and consequently, high-mass dileptons from heavy quark decays are also suppressed. We consider in detail the detector geometry and single lepton energy cuts of the PHENIX detector at the Relativistic Heavy Ion Collider. Because of the longitudinal expansion, the suppressions of ee, e{mu}, and {mu}{mu} pairs resulting from the heavy quark energy loss are very different due to the different rapidity coverages and energy cuts. The assumed energy loss rate, on the order of 1 GeV/fm, results in a large suppression on dielectrons, and dielectrons from heavy quark decays become comparable or even lower than the Drell-Yan yield. It is thus possible to probe the energy loss rate of the medium using dileptons from heavy quark decays. {copyright} {ital 1998} {ital The American Physical Society}