We study the bulk viscosity of moderately hot and dense, neutrino-transparent color superconducting quark matter arising from weak-interaction-driven direct URCA processes. The quark matter is modeled using the Nambu–Jona-Lasinio model improved to account for vector and ’t Hooft interactions as well as antisymmetric pairing among the red/green up and down quarks. The unpaired excitations are the strange quarks and the blue up or down quarks. We compute the relaxation rates associated with $d$- and $s$-quark decay and electron capture processes on the $u$ quark for blue color. The resulting bulk viscosity for density oscillations in the 1–10 kHz range shows a resonant peak at $T\sim 5\mathrm{MeV}$, and the damping time may drop below 10 ms. This is short enough to affect the postmerger evolution and is very similar to the damping predicted in nuclear matter.

中文翻译：

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中子星并合中双色超导夸克物质的体积粘度


我们 $s$ t $u$ $d$ y 由弱相互作用驱动的直接 URCA 过程产生的中等热度和密度、中微子透明的彩色超导夸克物质的体积粘度。夸克物质是使用 Nambu-Jona-Lasinio 模型进行建模的，该模型经过改进，可以解释矢量和 't Hooft 相互作用以及红/绿上夸克和下夸克之间的反对称配对。不成对的激发是奇异夸克和蓝色上夸克或下夸克。我们计算了与 d 夸克和 s 夸克衰变以及蓝色 u 夸克上的电子捕获过程相关的弛豫率。由此产生的 1-10 kHz 范围内密度振荡的体积粘度显示出一个共振峰 $T\sim 5\mathrm{MeV}$ ，阻尼时间可能会降至 10 ms 以下。这足够短，足以影响合并后的演化，并且与核物质中预测的阻尼非常相似。