arXivDaily arXiv每日学术速递 周一至周五更新
arXiv nucl-ex/0209024nucl-ex
收藏

在CERN上40次AGeV Pb-Au碰撞中低质量电子对的增强产生

Enhanced Production of Low-Mass Electron Pairs in 40 AGeV Pb-Au Collisions at the CERN SPS

D. Adamova, CERES/NA45 Collaboration

摘要:

我们报告的第一次测量低质量的电子对Pb-Au碰撞在较低的SPS束能量为40 AGeV。在不变质量为0.2<m<1 GeV/c^2的范围内积分得到的电子对产额比中性介子衰变的预期值提高了5.1+-1.3(统计)+-1.0/1.5(系统数据/衰变),比先前在158 AGeV的较高能量下观察到的结果要高。结果进行了讨论,参考模型计算的基础上,pi+ pi- -> e+ e-湮没与修改后的ρ-传播。它们可能与手征对称性恢复有关,并支持rho的介质内修改更多地由重子密度而不是温度驱动的观点。

英文摘要:

We report on first measurements of low-mass electron pairs in Pb-Au collisions at the lower SPS beam energy of 40 AGeV. The pair yield integrated over the range of invariant masses 0.2<m<1 GeV/c^2 is enhanced by a factor of 5.1+-1.3(stat)+-1.0/1.5(syst data/decays) over the expectation from neutral meson decays, more than previously observed at the higher energy of 158 AGeV. The results are discussed with reference to model calculations based on pi+ pi- -> e+ e- annihilation with a modified rho-propagator. They may be linked to chiral symmetry restoration and support the notion that the in-medium modifications of the rho are more driven by baryon density than by temperature.

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。

↑