Bonanno Luca, Drago Alessandro, Lavagno Andrea
Dipartimento di Fisica, Università di Ferrara and INFN, Sezione di Ferrara, 44100 Ferrara, Italy.
Phys Rev Lett. 2007 Dec 14;99(24):242301. doi: 10.1103/PhysRevLett.99.242301. Epub 2007 Dec 13.
We discuss two models in which a softening of the equation of state takes place due to the appearance of new degrees of freedom. The first is a hadronic model in which the softening is due to chiral symmetry restoration. In the second model the softening is associated with the formation of clusters of quarks in the mixed phase. We show that in the first case the bulk modulus is mainly dependent on the density, while in the mixed-phase model the bulk modulus strongly depends on the temperature and it is not vanishing due to the presence of two conserved charges, the baryon and the isospin one.
我们讨论了两种模型，在这两种模型中，由于新自由度的出现，状态方程发生了软化。第一种是强子模型，其中软化是由于手征对称性恢复。在第二种模型中，软化与混合相中夸克团簇的形成有关。我们表明，在第一种情况下，体积模量主要取决于密度，而在混合相模型中，体积模量强烈依赖于温度，并且由于重子和同位旋这两个守恒电荷的存在而不会消失。
