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Zhongxin, China

Hwa R.C.,University of Oregon | Zhu L.,Hua Zhong Normal University
Physical Review C - Nuclear Physics | Year: 2010

The azimuthal angular dependence of the nuclear modification factor RAA(pT,Φ,Npart) recently obtained by PHENIX is related at low pT to the trigger Φ dependence of the ridge yield as measured by STAR in a framework in which the azimuthal anisotropy is driven by semihard scattering near the surface. Careful consideration of the initial geometry leads to the determination of a surface segment in which the production of semihard partons are responsible for the Φ dependence of the inclusive distribution on the one hand and for the angular correlation in ridge phenomenology on the other. With v2 also being well reproduced along with RAA and ridge yield, all relevant Φ dependencies in heavy-ion collisions can now be understood in a unified description that emphasizes the ridge production whether or not a trigger is used. © 2010 The American Physical Society.

Hwa R.C.,University of Oregon | Yang C.B.,University of Oregon | Yang C.B.,Hua Zhong Normal University
Physical Review C - Nuclear Physics | Year: 2010

For heavy-ion collisions at the BNL Relativistic Heavy Ion Collider (RHIC) a scaling behavior is found in the dependencies on azimuthal angle and impact parameter b for pion production at high pT essentially independent of the hadronization process. The scaling variable is in terms of a dynamical path length ξ that takes into account detailed properties of geometry, medium density, and probability of hard scattering. It is shown in the recombination model how the nuclear modification factor depends on the average ξ(,b). The data for π0 production at pT=4-5 and 7-8 GeV/c at RHIC are shown to exhibit the same scaling behavior as found in the model calculation. Extension to back-to-back dijet production has been carried out, showing the existence of ξ scaling also in the away-side yield per trigger. At the CERN Large Hadron Collider the hard-parton density can be high enough to realize the likelihood of recombination of shower partons arising from neighboring jets. It is shown that such two-jet recombination can cause strong violation of ξ scaling. Furthermore, the large value of RAA that exceeds 1 can become a striking signature of such a hadronization process at high energy. © 2010 The American Physical Society.

Vitev I.,Los Alamos National Laboratory | Zhang B.-W.,Hua Zhong Normal University
Physical Review Letters | Year: 2010

We demonstrate that jet observables are highly sensitive to the characteristics of the vacuum and the in-medium QCD parton showers and propose techniques that exploit this sensitivity to constrain the mechanism of quark and gluon energy loss in strongly interacting plasmas. As a first example, we calculate the inclusive jet cross section in high-energy nucleus-nucleus collisions to O(αs3). Theoretical predictions for the medium-induced jet broadening and the suppression of the jet production rate due to cold and hot nuclear matter effects in Au+Au and Cu+Cu reactions at RHIC are presented. © 2010 The American Physical Society.

Jin M.,Hua Zhong Normal University | Urban M.,University Paris - Sud | Schuck P.,University Paris - Sud | Schuck P.,CNRS Physics and Models in Condensed Media Laboratory
Physical Review C - Nuclear Physics | Year: 2010

The effect of nucleon-nucleon correlations in symmetric nuclear matter at finite temperature is studied beyond BCS theory. Starting from a Hartree-Fock description of nuclear matter with the Gogny effective interaction, we add correlations corresponding to the formation of preformed pairs and scattering states above the superfluid critical temperature within the in-medium T-matrix approach, which is analogous to the Nozières-Schmitt-Rink theory. We calculate the critical temperature for a BEC superfluid of deuterons, of a BCS superfluid of nucleons, and in the crossover between these limits. The effect of the correlations on thermodynamic properties (equation of state, energy, entropy) and the liquid-gas phase transition is discussed. Our results show that nucleon-nucleon correlations beyond BCS play an important role for the properties of nuclear matter, especially in the low-density region. © 2010 The American Physical Society.

Shu S.,Hubei University | Li J.,Hua Zhong Normal University
Physical Review C - Nuclear Physics | Year: 2010

The Friedberg-Lee (FL) model is studied at finite temperature and density. The soliton solutions of the FL model in the deconfinement phase transition are solved and thoroughly discussed for certain boundary conditions. We indicate that the solitons before and after the deconfinement have different physical meanings: the soliton before deconfinement represents hadrons, while the soliton after the deconfinement represents the bound state of quarks which leads to a strongly interacting quark-gluon plasma phase. The corresponding phase diagram is given. © 2010 The American Physical Society.

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