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arXiv 2402.14788hep-thcond-mat.stat-mech
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热平衡外可积量子场论中守恒荷的期望值

Expectation Values of Conserved Charges in Integrable Quantum Field Theories out of Thermal Equilibrium

Michele Mazzoni, Riccardo Travaglino, Olalla A. Castro-Alvaredo

AI总结:

本文利用热力学Bethe Ansatz和广义流体力学计算(1+1)维可积量子场论非平衡稳态中守恒荷的平均值,将Bernard-Doyon结果推广到自旋大于1的守恒量,并给出自由费米子情形的精确系数。

摘要:

在这项工作中,我们给出了(1+1)维可积量子场论在广义吉布斯系综中守恒荷密度和流的平均值计算。我们的方法基于热力学Bethe Ansatz提供的准粒子描述,并结合广义流体力学原理,重点关注非平衡稳态平均值。当考虑这些平均值的紫外(即高温)极限时,我们恢复了Bernard和Doyon(2012)关于共形场论中能量流和密度的著名结果,并将其推广到自旋为$s > 1$的守恒量。我们证明它们的平均值正比于$T_L^{s+1}\pm T_R^{s+1}$,其中$T_L$、$T_R$是两个渐近热库的温度。当考虑某些非热广义吉布斯态时,也能得到相同的幂律。在共形场论中,该幂律是守恒荷算符变换性质的结果,而比例系数取决于算符的自旋和理论的中心荷。我们给出了有质量自由费米子情形下该系数的精确解析表达式。在平衡态下,自旋-$s$密度平均值正比于$T^{s+1}$可以视为Stefan-Boltzmann定律的推广,该定律指出黑体单位表面积辐射的能量按$T^4$标度。

英文摘要:

In this work we present a computation of the averages of conserved charge densities and currents of (1+1)-dimensional Integrable Quantum Field Theories in Generalised Gibbs Ensembles. Our approach is based on the quasi-particle description provided by the Thermodynamic Bethe Ansatz combined with the principles of Generalised Hydrodynamics, and we focus on Non-Equilibrium Steady State averages. When considering the ultraviolet (i.e. high temperature) limit of such averages, we recover the famous result by Bernard and Doyon (2012) for the energy current and density in Conformal Field Theories, and we extend it to conserved quantities with spin $s > 1$. We show that their averages are proportional to $T_L^{s+1}\pm T_R^{s+1}$, with $T_L$, $T_R$ the temperatures of two asymptotic thermal reservoirs. The same power law is obtained when considering some non-thermal generalised Gibbs states. In Conformal Field Theory, the power law is a consequence of the transformation properties of conserved charge operators, while the proportionality coefficient depends on the spin of the operator and on the central charge of the theory. We present an exact analytic expression for this coefficient in the case of a massive free fermion. At equilibrium, proportionality of spin-$s$ density averages to $T^{s+1}$ can be thought of as a generalisation of Stefan-Boltzmann's law, which states that the energy per unit surface area radiated by a black body scales as $T^4$.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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