arXivDaily arXiv每日学术速递 周一至周五更新
arXiv 0901.3289hep-phnucl-exnucl-th
收藏

QCD和低质量双轻子的手征恢复跃迁

The Chiral Restoration Transition of QCD and Low Mass Dileptons

R. Rapp, J. Wambach, H. van Hees

摘要:

本文讨论了热密物质中矢量介子谱函数计算的最新进展,着重讨论了它与QCD中手征相变的关系。模型无关的方法,包括手征低密度展开,格点量子色动力学,手征和QCD求和规则的上下文中与模型预测的介质中的矢量谱函数,利用有效的拉格朗日。强子多体计算预测一个强大的加宽(和小的质量移动)的$ρ$光谱函数迅速增加接近强子和夸克胶子物质的预期相边界。在夸克-胶子等离子体中,相关的双轻子速率似乎随着微扰的夸克-反夸克湮灭而简并,这暗示了手征对称性的恢复。应用于重离子碰撞中的低质量双轻子谱,结果与CERN SPS最近的高质量数据定量一致。来自$T_c$周围温度的热辐射也一致地再现了在1 GeV以上质量时观察到的实验双轻子过剩。高横动量双轻子源的解释似乎更复杂。

英文摘要:

Recent developments in the evaluation of vector-meson spectral functions in hot and dense matter are discussed with emphasis on connections to the chiral phase transition in QCD. Model independent approaches including chiral low-density expansions, lattice QCD, chiral and QCD sum rules are put into context with model predictions for in-medium vector-spectral function utilizing effective Lagrangians. Hadronic many-body calculations predict a strong broadening (and little mass shift) of the $ρ$ spectral function which rapidly increases close to the expected phase boundary of hadronic and quark-gluon matter. Pertinent dilepton rates appear to degenerate with perturbative quark-antiquark annihilation in the Quark-Gluon Plasma, suggestive for chiral symmetry restoration. Applications to low-mass dilepton spectra in heavy-ion collisions result in quantitative agreement with recent high-quality data at the CERN-SPS. Thermal radiation from temperatures around $T_c$ consistently reproduces the experimental dilepton excess observed at masses above 1 GeV as well. The interpretation of dilepton sources at high transverse momentum appears to be more involved.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

↑