We investigate general frameworks for calculating transport coefficients for quasiparticle theories at finite temperature. Hadronic transport coefficients are then computed using the linear $\ensuremath{\sigma}$ model (LSM). The bulk viscosity over entropy density ($\ensuremath{\zeta}/s$) is evaluated in the relaxation time approximation (RTA) and the specific shear viscosity ($\ensuremath{\eta}/s$) and static electrical conductivity (${\ensuremath{\sigma}}_{\mathrm{el}}/T$) are both obtained in the RTA and using a functional variational approach. Results are shown for different values of the scalar-isoscalar hadron vacuum mass with in-medium masses for the interacting fields. The advantages and limitations of the LSM for studies of strongly interacting matter out of equilibrium are discussed and results are compared with others in the literature.

中文翻译：

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有限温度下线性 σ 模型的强子输运系数

我们研究了在有限温度下计算准粒子理论输运系数的一般框架。然后使用线性 $\ensuremath{\sigma}$ 模型 (LSM) 计算强子传输系数。体积粘度超过熵密度 ($\ensuremath{\zeta}/s$) 在弛豫时间近似值 (RTA) 和比剪切粘度 ($\ensuremath{\eta}/s$) 和静电电导率 ( ${\ensuremath{\sigma}}_{\mathrm{el}}/T$) 都是在 RTA 中获得并使用函数变分方法获得的。结果显示了标量-等标量强子真空质量与相互作用场的介质质量的不同值。讨论了 LSM 在研究非平衡强相互作用物质的优点和局限性，并将结果与​​文献中的其他结果进行了比较。