Roles of axial anomaly on neutral quark matter with color superconducting phase
Roles of axial anomaly on neutral quark matter with color superconducting phase
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轴异常对彩色超导相中性夸克物质的作用
DOI：
10.1103/physrevd.83.114003
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发表时间：
2011
影响因子：
5
通讯作者：
T. Kunihiro
中科院分区：
文献类型：
--
作者：
Zhao Zhang;T. Kunihiro
我们研究了在电荷中性和 $\beta$ 平衡约束下，具有手性双夸克耦合的轴异常项对二加一风味 Nambu-Jona-Lasinio (NJL) 模型中相图的影响。我们发现，当施加这样的约束时，新的异常项起着与相图上的矢量相互作用非常相似的作用，本作者在之前的工作中对此进行了澄清。因此，在低温 $T$ 下出现了几种具有多个临界点的相结构，尽管即使在同一拉格朗日模型中，如果没有这些约束，也永远不会实现具有中间 $T$ 临界点的相图。这种剧烈的变化归因于有限温度下的反常项导致手性凝聚体和双夸克凝聚体之间的相互作用增强。 u-d双夸克耦合通过反常项被奇夸克相对较大的手性凝聚体加强，这反过来又必然导致双夸克凝聚体在有限$T$下的异常行为，这是不对称夸克物质固有的。我们注意到，只有当矢量相互作用的强度大于临界值时，交叉区域延伸到零温度的临界点才会出现。我们还表明，中性不对称同质双味彩色超导（2CSC）相的色磁不稳定性受到抑制，甚至可以通过由于反常项和/或矢量相互作用而增强的双夸克耦合来完全消除。
We investigate effects of the axial anomaly term with a chiral-diquark coupling on the phase diagram within a two-plus-one-flavor Nambu-Jona-Lasinio (NJL) model under the charge-neutrality and $\beta$-equilibrium constraints. We find that when such constraints are imposed, the new anomaly term plays a quite similar role as the vector interaction does on the phase diagram, which the present authors clarified in a previous work. Thus, there appear several types of phase structures with multiple critical points at low temperature $T$, although the phase diagrams with intermediate-$T$ critical point(s) are never realized without these constraints even within the same model Lagrangian. This drastic change is attributed to an enhanced interplay between the chiral and diquark condensates due to the anomaly term at finite temperature; the u-d diquark coupling is strengthened by the relatively large chiral condensate of the strange quark through the anomaly term, which in turn definitely leads to the abnormal behavior of the diquark condensate at finite $T$, inherent to the asymmetric quark matter. We note that the critical point from which the crossover region extends to zero temperature appears only when the strength of the vector interaction is larger than a critical value. We also show that the chromomagnetic instability of the neutral asymmetric homogenous two-flavor color superconducting(2CSC) phase is suppressed and can be even completely cured by the enhanced diquark coupling due to the anomaly term and/or by the vector interaction.