Transport coefficients of two-flavor quark matter from the Kubo formalism
Transport coefficients of two-flavor quark matter from the Kubo formalism
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DOI：
10.1103/physrevd.95.114021
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发表时间：
2017-02
影响因子：
5
通讯作者：
A. Harutyunyan;D. Rischke;A. Sedrakian
中科院分区：
文献类型：
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作者：
A. Harutyunyan;D. Rischke;A. Sedrakian
在双味Nambu-Jona-Lasinio模型下计算了夸克物质在非零化学势和温度下的输运系数。我们应用Kubo形式主义来获得热导率（κ）和电导率（σ），以及通过评估相应的平衡两点相关函数到1/Nc展开中的领先阶来更新剪切粘度（η）。自能和谱函数的狄拉克结构被考虑在内，因为这些是从质量壳夸克的介子交换Fock图中评估的。我们发现，热导率和电导率的Mott温度TM以上的介子溶解成夸克的温度和密度的递减函数，产生的光谱函数的时间和矢量分量的主要贡献。这些系数显示出对于不同密度的T/TM比率的普遍依赖性，即，结果的不同之处在于依赖于化学势的常数。我们还证明了σ/κ比的Wiedemann-Franz定律不成立。比率η/s（其中s是熵密度）接近于莫特温度的单位数量级（或更大），并且随着温度的升高，接近AdS/CFT界限1/4π。还证明了κT/cV的比值，其中cV是比热，从下到上以1/18为界。
The transport coefficients of quark matter at nonzero chemical potential and temperature are computed within the two-flavor Nambu–Jona-Lasinio model. We apply the Kubo formalism to obtain the thermal (κ) and electrical (σ) conductivities as well as an update of the shear viscosity (η) by evaluating the corresponding equilibrium two-point correlation functions to leading order in the 1/Nc expansion. The Dirac structure of the self-energies and spectral functions is taken into account as these are evaluated from the meson-exchange Fock diagrams for on-mass-shell quarks. We find that the thermal and electrical conductivities are decreasing functions of temperature and density above the Mott temperature TM of dissolution of mesons into quarks, the main contributions being generated by the temporal and vector components of the spectral functions. The coefficients show a universal dependence on the ratio T/TM for different densities, i.e., the results differ by a chemical-potential dependent constant. We also show that the Wiedemann-Franz law for the ratio σ/κ does not hold. The ratio η/s, where s is the entropy density, is of order of unity (or larger) close to the Mott temperature and, as the temperature increases, approaches the AdS/CFT bound 1/4π. It is also conjectured that the ratio κT/cV, with cV being the specific heat, is bounded from below by 1/18.