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arXiv 1111.3688nucl-th
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手征核热力学

Chiral nuclear thermodynamics

Salvatore Fiorilla, Norbert Kaiser, Wolfram Weise

摘要:

本文在介质手征微扰理论的框架下,计算了自由能量密度中三圈级以上任意同位旋不对称的核物质的物态方程。在我们的方法中,1π-和2π-交换动力学与包含的Δ-同量异位素激发作为一个明确的自由度,相应的远程和中程相关,明确处理。很少有固定的接触项来再现核物质的某些已知性质,这些接触项编码了短程物理学。系统地包括了两体力和三体力。我们发现对称核物质的临界温度约为15 MeV。我们研究了液-气一级相变对同位旋不对称性的依赖性。在同样的手征框架下,我们计算了有限温度下同位旋对称核物质的手征凝聚体。Δ-同量异位素激发的贡献对于稳定凝聚体是必不可少的。因此,我们发现没有迹象表明,在密度ρ \lesssim 2 ρ_0和温度T \lesssim 100兆电子伏的手征相变。

英文摘要:

We calculate the equation of state of nuclear matter for arbitrary isospin-asymmetry up to three loop order in the free energy density in the framework of in-medium chiral perturbation theory. In our approach 1π- and 2π-exchange dynamics with the inclusion of the Δ-isobar excitation as an explicit degree of freedom, corresponding to the long- and intermediate-range correlations, are treated explicitly. Few contact terms fixed to reproduce selected known properties of nuclear matter encode the short-distance physics. Two-body as well as three-body forces are systematically included. We find a critical temperature of about 15 MeV for symmetric nuclear matter. We investigate the dependence of the liquid-gas first-order phase transition on isospin-asymmetry. In the same chiral framework we calculate the chiral condensate of isospin-symmetric nuclear matter at finite temperatures. The contribution of the Δ-isobar excitation is essential for stabilizing the condensate. As a result, we find no indication of a chiral phase transition for densities ρ\lesssim 2 ρ_0 and at temperatures T \lesssim 100 MeV.

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