标题： 热规范理论中的热通道 显示英文标题

标题： The Bulk Channel in Thermal Gauge Theories

摘要： 我们研究了SU(3)杨-米尔斯理论中能量-动量张量迹的热关联函数。 我们的目标是限制该通道中的谱函数，其低频部分决定了体粘度。 我们关注谱函数的热修正， $\rho(\omega,T)-\rho(\omega,0)$。 利用算符乘积展开，我们用热力学势表示这种差异的高频行为。 我们考虑了一个精确的delta函数位于原点的情况，这在之前的分析中被忽略了。 然后，我们将体求和规则与欧几里得关联函数的蒙特卡洛评估结合起来，以确定频率区间，在这些区间内谱密度由于热效应而增强或减弱。 我们发现证据表明，对于低于标量胶球质量 $m$的频率，热谱密度非零，并且对于 $m\lesssim\omega\lesssim 3m$显著减弱。 显示英文摘要

摘要： We investigate the thermal correlator of the trace of the energy-momentum tensor in the SU(3) Yang-Mills theory. Our goal is to constrain the spectral function in that channel, whose low-frequency part determines the bulk viscosity. We focus on the thermal modification of the spectral function, $\rho(\omega,T)-\rho(\omega,0)$. Using the operator-product expansion we give the high-frequency behavior of this difference in terms of thermodynamic potentials. We take into account the presence of an exact delta function located at the origin, which had been missed in previous analyses. We then combine the bulk sum rule and a Monte-Carlo evaluation of the Euclidean correlator to determine the intervals of frequency where the spectral density is enhanced or depleted by thermal effects. We find evidence that the thermal spectral density is non-zero for frequencies below the scalar glueball mass $m$ and is significantly depleted for $m\lesssim\omega\lesssim 3m$.