重离子碰撞对QCD物质的若干检验

Some important test to the QCD matter with heavy ion collisions

采用重新拟合的σJ/ψN数据计算核吸收效应,并结合能量损失以及核遮蔽效应因子.研究了E866、RHIC和HERA上J/ψ粒子产生中微分截面比R的xF(或y)分布,结果与最新的实验数据进行了对比.结论表明:所选用的介质效应模型能较好地再现实验数据,体现冷核效应的幅度,尤其是RHIC的正快度区域(y>0)及HERA的负xF区域.文末还给出了对LHC上产值数据的预言.对冷核介质效应的研究,能协助甄别热核反应中的产值抑制是否预言中夸克-胶子等离子体形成的标志,从而有助于对QCD物质特征的检验.

By applying a new fitting parameter σJ/ψN, we＇ve calculated the differential cross section ratio R of J/ψ in high energy p-A and p-p collisions with three different nuclear medium effects.The plots of R vs.x_F（y） calculated with selected nuclear effect models have been presented under E866, HERA, RHIC and LHC energy. By a comparison with the experimental data published recently, we＇ve found that the results can reproduce the trend and magnitude of data,especially at the positive rapidity of RHIC and the negative of x_F HERA.Our conclu- sion is helpful to identify the difference between the sign of quark-gluon formation and production suppression caused by cold nuclear effects,which is also an important test to the QCD matter in heavy ion collisions.