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arXiv 1012.0252nucl-th
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强相互作用夸克-胶子等离子体中双轻子的产生

Dilepton production in the strongly interacting quark-gluon plasma

O. Linnyk, W. Cassing, E. L. Bratkovskaya, J. Manninen

摘要:

采用微观粒子-强子-弦动力学(PHSD)输运方法研究了相对论性重离子碰撞中双轻子的产生。PHSD方法基于动力学准粒子模型(DQPM),模拟了热力学平衡下的格点量子色动力学结果。与NA 60合作组158 AGeV的In+In碰撞数据的比较表明,如果考虑矢量介子的碰撞加宽以及QGP中的离壳夸克-反夸克湮灭(q+qbar->l^+l^-和q+qbar->gl^+l^-),双轻子谱可以很好地用强子源和部分子源之和来描述.特别是,所观察到的软化的mT谱在中间群众再现。PHENIX合作组在sqrt(s)=200 GeV的Au+Au碰撞中双轻子产生的实验数据表明,当质量大于1 GeV时,QGP辐射和粲介子衰变的贡献占主导地位,而在0.2 ~ 0.6 GeV的质量范围内,测量的谱被低估了.

英文摘要:

Dilepton production in relativistic heavy-ion collisions is studied within the microscopic Parton-Hadron-String Dynamics (PHSD) transport approach, which is based on a dynamical quasiparticle model (DQPM) matched to reproduce lattice QCD results in thermodynamic equilibrium. A comparison to the data of the NA60 Collaboration for In+In collisions at 158 AGeV shows that the dilepton spectra are well described by the sum of hadronic and partonic sources, if a collisional broadening of vector mesons is taken into account as well as the off-shell quark-antiquark annihilation (q+qbar->l^+l^- and q+qbar->gl^+l^-) in the QGP. In particular, the observed softening of the mT spectra at intermediate masses is reproduced. The data of the PHENIX collaboration on dilepton production in Au+Au collisions at sqrt(s)=200 GeV for masses above 1 GeV are found to be dominated by the contributions of the QGP radiation and the charm meson decays, while the measured spectrum is underestimated in the mass range from 0.2 to 0.6 GeV.

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