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arXiv 0908.2361nucl-ex
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RHIC粲偶素测量从产生到抑制

From production to suppression, a critical review of charmonium measurements at RHIC

L. A. Linden Levy

摘要:

高温致密核物质中的粲偶素抑制被认为是产生夸克-胶子等离子体(QGP)的标志。为了在重离子碰撞中寻找这种效应,人们必须清楚地了解所有可能导致这种抑制的因素。这些可能包括部分子在核环境中的遮蔽,相关$c-\bar{c}$对在穿过核碎片时的分裂,从更高质量状态以及其他初始状态相互作用的反馈的抑制。为了解开这些影响,必须测量质子+质子(p+p)和质子+核(p+A)碰撞中的粲偶素产生率。与二元标度预测相比,p+p碰撞作为搜索抑制的基线,允许人们量化从更高状态的反馈量,并作为区分粲偶素产生机制的不同理论计算的工具。为了量化核效应,还需要研究p+A碰撞中粲偶素的产生,其中系统的温度和密度比重离子碰撞低。这些测量使人们能够确定“冷”核物质中的核遮蔽和分裂的影响,其可以外推到重离子碰撞,以确定异常抑制的量。当然,依赖于基于模型的技术的外推在很大程度上取决于生产机制的假设,这一事实加强了p+p测量的重要性。

英文摘要:

Charmonium suppression in hot and dense nuclear matter has been argued to be a signature for the production of the quark gluon plasma (QGP). In order to search for this effect in heavy ion collisions one must have a clear understanding of all the factors that can contribute to such a suppression. These may include shadowing of the partons in a nuclear environment, breakup of a correlated $c-\bar{c}$ pair as it traverses the nuclear fragment, suppression of feed-down from higher mass states as well as other initial state interactions. In order to disentangle these effects one must measure charmonium production rates in both proton+proton (p+p) and proton+nucleus (p+A) collisions. The p+p collisions serve as a baseline for searching for suppression compared to binary scaling predictions, allow one to quantify the amount of feed-down from higher states as well as serve as a tool to distinguish between different theoretical calculations for charmonium production mechanisms. In order to quantify nuclear effects it is also necessary to study charmonium production in p+A collisions where the temperature and density of the system are low compared to a heavy ion collision. These measurements allow one to determine the influence of nuclear shadowing and breakup in "cold" nuclear matter which can be extrapolated to heavy ion collisions in order to determine the amount anomalous suppression. Of course, extrapolations that rely on a model based technique depend heavily on the assumption of a production mechanism, a fact that reinforces the importance of the p+p measurements...

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。

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