Panjab University, Chandigarh 160014, India.
Phys Rev Lett. 2010 Jul 9;105(2):022302. doi: 10.1103/PhysRevLett.105.022302.
We report the first measurements of the kurtosis (κ), skewness (S), and variance (σ2) of net-proton multiplicity (Np-Np) distributions at midrapidity for Au+Au collisions at square root of s(NN)=19.6, 62.4, and 200 GeV corresponding to baryon chemical potentials (μB) between 200 and 20 MeV. Our measurements of the products κσ2 and Sσ, which can be related to theoretical calculations sensitive to baryon number susceptibilities and long-range correlations, are constant as functions of collision centrality. We compare these products with results from lattice QCD and various models without a critical point and study the square root of s(NN) dependence of κσ2. From the measurements at the three beam energies, we find no evidence for a critical point in the QCD phase diagram for μB below 200 MeV.
我们报告了在 square root of s(NN)=19.6、62.4 和 200 GeV 下，对应于 200 到 20 MeV 的重子化学势（μB），从中能 Au+Au 碰撞中末态质子多重数（Np-Np）分布的峰度（κ）、偏度（S）和方差（σ2）的首次测量结果。我们测量的κσ2 和 Sσ 的乘积，这可以与对重子数磁化率和长程关联敏感的理论计算相关联，它们作为碰撞中心度的函数是常数。我们将这些产物与来自没有临界点的格点 QCD 和各种模型的结果进行比较，并研究κσ2 的 square root of s(NN)依赖性。从三个束流能的测量中，我们没有发现低于 200 MeV 的 μB 下 QCD 相图中存在临界点的证据。
