重离子碰撞对QCD物质的若干检验
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摘要
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. xF( 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 xFHERA.Our conclusion 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.
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. xF( 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 xFHERA.Our conclusion 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.
引文
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[2]GLUECK M,REYA E,VOGT A.Dynamical parton distributions revisited[J].Eur Phys J C,1998,5:461-470.
[3]HIRAI M,KUMANO S,NAGAI T H.Nuclear parton distribution functions and their uncertainties[J].Phys Rev C,2004,70:044905.
[4]ESKOLA K J,KOLHINEN V J,RUUSKANEN P V.Scale evolution of nuclear parton distributions[J].Nucl Phys B,1998,535:351-371.
[5]ESKOLA K J,PAUKKUNEN H,SALGADO C A.EPS09-a new generation of NLO and LO nuclear parton distribution functions[J].JHEP,2009,0904:065.
[6]宋丽华,王凤鸣.入射夸克的能量损失效应[J].云南大学学报:自然科学版,2014,36(1):45-50.SONG L H,WANG F M.The energy loss effect of incoming quark[J].Journal of Yunnan University:Natural Sciences Edition,2014,36(1):45-50.
[7]BAIER R,DOKSHITSER Y L,MUELLER A H,et al.Medium-induced radiative energy loss equivalance between the BDMPS and ZAKHAROV formalisms[J].Nucl Phys B,1998,531:403-426.
[8]ARLEO F,GOSSIAUX P B,GOUSSET T,et al.Energy loss and x2scaling breakdown in J/Psi nuclear production[R].Les Arcs France:Talk given at XXXVth Rencontres de Moriond:QCD and High Energy Hadronic Interactions,2000.
[9]SHAHOYAN R.Measurement of nuclear effects in the production of J/ψmesons with the HERA-B detector[D].Portugal:Universidade Tecnica de Lisboa,2005.
[10]TRAM V N,ARLEO F.Global analysis of J/ψsuppression in cold nuclear matter[J].Eur Phys J C,2009,61:847-852.
[11]LEITCH M J,LEE W M,BEDDO M E,et al.Measurement of differences between J/Psi and Psi'suppression in p-A collisions[J].Phys Rev Lett,2000,84:3 256-3 260.
[12]ARLEO F,PEIGNE S.J/Psi suppression in p-A collisions from parton energy loss in cold QCD matter[J].Phys Rev Lett,2012,109:122 301.
[13]ADARE A,AFANASIEV S,AIDALA C,et al.Suppression of back-to-back hadron pairs at forward rapidity in d+Au collisions at sqrt(s_NN)=200 Ge V[J].Phys Rev Lett,2011,107:172 301.
[14]GOUSSET T,PIRNER H J.The ratio of gluon distributions in Sn and C[J].Phys Lett B,1996,375:349-354.