Critical Opalescence: An Optical Signature for a QCD Critical Point
T. Csorgo
备注：
15 pages, 5 pages. Contribution to the 5th International Workshop on Critical Point and Onset of Deconfinement, Brookhaven National Laboratory, Long Island, New York, USA, June 8-12, 2009
Four possible scenarios are considered for a transition from a quark-gluon matter to hadronic matter, and their corresponding correlation signatures are discussed. Four criteria are highlighted for a definitive experimental search for a QCD critical point. An old-new experimental measure, the optical opacity (or its inverse the nuclear attenuation length) is determined, in terms of a combination of nuclear suppression factors and a measurement of the relevant fireball length scales. Length scale estimates using either the Hanbury Brown -- Twiss radii or that of the initial nuclear geometry for measurements of optical opacity with respect to the reaction plane yield, somewhat surprizingly, nearly the same nuclear attenuation lenght in 0-5 % most central 200 GeV Au+Au collisions, corresponding to 2.9 $\pm$ 0.3 fm. The necessity and the possibility of measuring critical exponents is also discussed in the context of determination of the universality class of the QCD critical point. Critical opalescence is proposed to locate such a critical point on the QCD phase diagram, corresponding to a maximum of optical opacity in heavy ion experiments.
Functional renormalization group study of the jet quenching parameter near the QCD critical end point
School of Physics, Dalian University of Technology（大连理工大学物理学院）；Institut für Theoretische Physik, Justus-Liebig-Universität Gießen（吉森大学理论物理研究所）；School of Physical Science and Technology, Lanzhou University（兰州大学物理科学与技术学院）；Energy Singularity Fusion Power Technology (SH) Ltd.（能量奇点融合电力技术（上海）有限公司）
Signature of QCD critical point: Anomalous transverse velocity dependence of antiproton-proton ratio
我们将Asakawa { \it et al.}最近提出的QCD临界点聚焦效应对反质子与质子（$\bar{p}/p$）之比的横向速度（$β_{t}$）依赖性公式化。作为高能重离子碰撞中QCD临界点的实验信号。在定量分析方面，利用超相对论量子分子动力学（UrQMD）输运模型和THERMal重离子发生器（THERMINATOR）计算了QCD相图上三种不同聚焦程度的Gedanken聚焦等熵轨线对应的$β_{t}$与$\bar{p}/p$比值的关系.最后，我们得到了一个$β_{t}$依赖于$\bar{p}/p$比的可观测反常，它可以作为QCD临界点的一个特征。
Quantifying fluctuation signatures of the QCD critical point using maximum entropy freeze-out
Center for Theoretical Physics – a Leinweber Institute, Massachusetts Institute of Technology（麻省理工学院理论物理中心）；University of Maryland（马里兰大学）；University of Illinois, Chicago（伊利诺伊大学芝加哥分校）；The Chinese University of Hong Kong, Shenzhen（香港中文大学（深圳））
