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arXiv 1002.2336hep-ph
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热力学和夸克亲和性:PNJL模型的Monte-Carlo方法

Thermodynamics and quark susceptibilities: a Monte-Carlo approach to the PNJL model

M. Cristoforetti, T. Hell, B. Klein, W. Weise

摘要:

本文将Monte-Carlo方法应用于Polyakov圈扩展Nambu-Jona-Lasinio(PNJL)模型。这导致了平均场计算中的鞍点近似,并在平均场周围引入了波动。我们研究了涨落对模型热力学的影响,无论是在纯规范理论的情况下,包括两个夸克的味道。在双味情形下,我们计算了热力学巨正则配分函数关于夸克化学势的二阶泰勒展开系数,并与格点量子色动力学的外推结果进行了比较.我们发现,波动的引入产生的手征对称性恢复和退禁闭过渡的序参量的行为只有很小的变化。另一方面,我们发现,为了重现味非对角夸克的晶格数据的波动是必要的。特别重要的是π介子场,其贡献在鞍点近似中严格为零。

英文摘要:

The Monte-Carlo method is applied to the Polyakov-loop extended Nambu--Jona-Lasinio (PNJL) model. This leads beyond the saddle-point approximation in a mean-field calculation and introduces fluctuations around the mean fields. We study the impact of fluctuations on the thermodynamics of the model, both in the case of pure gauge theory and including two quark flavors. In the two-flavor case, we calculate the second-order Taylor expansion coefficients of the thermodynamic grand canonical partition function with respect to the quark chemical potential and present a comparison with extrapolations from lattice QCD. We show that the introduction of fluctuations produces only small changes in the behavior of the order parameters for chiral symmetry restoration and the deconfinement transition. On the other hand, we find that fluctuations are necessary in order to reproduce lattice data for the flavor non-diagonal quark susceptibilities. Of particular importance are pion fields, the contribution of which is strictly zero in the saddle point approximation.

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