标题： 热规范理论中的准粒子结构 显示英文标题

标题： The quasiparticle structure of hot gauge theories

摘要： 在微扰理论中研究极端相对论等离子体时，会受到红外发散的困扰，这些发散无法通过屏蔽修正来消除。 特别是它们会影响基本激发态寿命的计算，从而对准粒子图像的有效性产生怀疑。 我们表明，至少对于阿贝尔等离子体，阻尼率的红外问题可以通过基于布洛赫-诺尔迪克近似的非微扰处理来解决。 得到的费米子传播子表达式没有发散，并在长时间内表现出{\it 非指数型}的阻尼：$S_R(t)\sim \exp\{-\alpha T t \ln\omega_pt\}$，其中$\omega_p=gT/3$是等离子体频率，$\alpha=g^2/4\pi$。 显示英文摘要

摘要： The study of the ultrarelativistic plasmas in perturbation theory is plagued with infrared divergences which are not eliminated by the screening corrections. They affect, in particular, the computation of the lifetime of the elementary excitations, thus casting doubt on the validity of the quasiparticle picture. We show that, for Abelian plasmas at least, the infrared problem of the damping rate can be solved by a non-perturbative treatment based on the Bloch-Nordsieck approximation. The resulting expression of the fermion propagator is free of divergences, and exhibits a {\it non-exponential} damping at large times: $S_R(t)\sim \exp\{-\alpha T t \ln\omega_pt\}$, where $\omega_p=gT/3$ is the plasma frequency and $\alpha=g^2/4\pi$.