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arXiv 0908.1361hep-phnucl-th
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稠密物质中另一种手征对称性破缺模式对夸克数磁化率的增强

Enhancement of quark number susceptibility with an alternative pattern of chiral symmetry breaking in dense matter

M. Harada, C. Sasaki, S. Takemoto

摘要:

我们探讨了一个可能的阶段,手性$SU(2)_L \times SU(2)_R$对称性自发破缺,而其中心$Z_2$对称性保持不破缺,其后果的热量。在这个阶段,手征对称性破缺是由四次夸克凝聚驱动的,尽管双线性夸克凝聚消失了。一个Ginzburg-Landau自由能导致一个新的三临界点(TCP)之间的$Z_2$破碎和未破碎的阶段。此外,一个临界点,甚至可以出现在手征限制,明确打破关闭,而不是TCP在恢复手征和它的中心对称性同时发生。净夸克数密度在中心对称性恢复附近而不是手征对称性恢复附近出现突变。在线性西格玛模型中还研究了可能相的强子质量。我们证明了在$Z_2$对称相中,具有零同位旋I=0的$\bar{q}q$型标量介子从I=1的$\bar{q}q$型赝标量介子分裂出来.

英文摘要:

We explore a possible phase where chiral $SU(2)_L \times SU(2)_R$ symmetry is spontaneously broken while its center $Z_2$ symmetry remains unbroken and its consequence on thermal quantities. In this phase, chiral symmetry breaking is driven by a quartic quark condensate although a bilinear quark condensate vanishes. A Ginzburg-Landau free energy leads to a new tricritical point (TCP) between the $Z_2$ broken and unbroken phases. Furthermore, a critical point can appear even in the chiral limit where explicit breaking is turned off, instead of a TCP at which restoration of chiral and its center symmetries takes place simultaneously. The net quark number density exhibits an abrupt change near the restoration of the center symmetry rather than that of the chiral symmetry. Hadron masses in possible phases are also studied in a linear sigma model. We show that, in the $Z_2$ symmetric phase, the $\bar{q}q$-type scalar meson with zero isospin I=0 splits from the $\bar{q}q$-type pseudoscalar meson with I=1.

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