从介子和重子不同可能的热涨落看π介子和核子组分的剪切粘性
Shear viscosity of pionic and nucleonic components from their different possible mesonic and baryonic thermal fluctuations
摘要：
由于Kubo关系，π介子和核子组分的剪切粘度已经从它们相应的粘性应力张量在静态极限下的延迟因子中计算出来，该延迟因子仅对于组分粒子的非零热宽度才变得不发散。在实时热场论中，分别由不同介子、重子圈的π介子自能和不同π介子-重子圈的核子自能得到π介子和核子的热宽度。我们发现π介子和核子热宽度的动量分布是非单调的，在计算它们的剪切粘度时，这些动量分布是由它们各自的玻色增强相空间因子和Pauli阻塞相空间因子积分出来的。在强子物质的相关区域内，随着温度和重子化学势的增加，这种π-核子混合气体的粘数与熵密度之比减小并趋于其下界。
英文摘要：
Owing to the Kubo relation, the shear viscosities of pionic and nucleonic components have been evaluated from their corresponding retarded correlators of viscous stress tensor in the static limit, which become non-divergent only for the non-zero thermal widths of the constituent particles. In the real-time thermal field theory, the pion and nucleon thermal widths have respectively been obtained from the pion self-energy for different meson, baryon loops and the nucleon self-energy for different pion-baryon loops. We have found a non-monotonic momentum distributions of pion and nucleon thermal widths, which have been integrated out by their respective Bose-enhanced and Pauli-blocked phase space factors during evaluation of their shear viscosities. The viscosity to entropy density ratio for this mixed gas of pion-nucleon system decreases and approaches toward its lower bound as the temperature and baryon chemical potential increase within the relevant domain of hadronic matter.
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