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arXiv 1705.09124hep-ph
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通过有限尺寸标度定位QCD关键终点

Locating the QCD critical endpoint through finite-size scaling

N. G. Antoniou, F. K. Diakonos, X. N. Maintas, C. E. Tsagkarakis

摘要:

考虑到QCD临界点的3d Ising普适性类,我们用普适有效作用量来描述临界区附近的重子数密度涨落。计算了重子数多重数矩,并确定了它们随系统尺寸的标度,结果表明:对于$T > T_c$,临界区在重子化学势$T$方向上很窄,在温度方向上很宽.在此背景下,发表的实验结果的局部质子密度涨落测量获得的横向动量空间的双折射分析在NA49中心A+A碰撞在$\sqrt{s_{NN}}=17.2$ GeV(A=C,Si,Pb),显着限制的位置$(μ_c,T_c)$的QCD临界端点。主要的约束是由Si+Si系统的冻结化学势提供的,其显示出非常规的重子密度波动,将$(μ_c,T_c)$限制在相图的窄域$119~\textrm{MeV} \leq T_c \leq 162~\textrm{MeV}$、$252~\textrm{MeV} \leq μ_c \leq 258~\textrm{MeV}$内。

英文摘要:

Considering the 3d Ising universality class of the QCD critical endpoint we use a universal effective action for the description of the baryon-number density fluctuations around the critical region. Calculating the baryon-number multiplicity moments and determining their scaling with system's size we show that the critical region is very narrow in the direction of the baryon chemical potential $μ$ and wide in the temperature direction $T$ for $T > T_c$. In this context, published experimental results on local proton density-fluctuation measurements obtained by intermittency analysis in transverse momentum space in NA49 central A+A collisions at $\sqrt{s_{NN}}=17.2$ GeV (A=C,Si,Pb), restrict significantly the location $(μ_c,T_c)$ of the QCD critical endpoint. The main constraint is provided by the freeze-out chemical potential of the Si+Si system, which shows non-conventional baryon density fluctuations, restricting $(μ_c,T_c)$ within a narrow domain, $119~\textrm{MeV} \leq T_c \leq 162~\textrm{MeV}$, $252~\textrm{MeV} \leq μ_c \leq 258~\textrm{MeV}$, of the phase diagram.

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