大涨落非平衡量子场
Nonequilibrium quantum fields with large fluctuations
摘要：
考虑了O（N）对称标量量子场论的非平衡演化，其中包含了散射和记忆效应。相应的“完整的Kadanoff-Baym方程”在没有进一步近似的情况下数值求解。这使得人们能够获得一个控制的非微扰描述远离平衡动力学和后期的量子热平衡的方法。采用另外一个一阶梯度展开的维格纳变换的双光子，我们推导出动力学方程。与基于循环展开的标准描述相比，我们的方程对非微扰大波动仍然有效。作为应用，我们讨论了量子场论中参量共振后的涨落占优区。
英文摘要：
We consider the nonequilibrium evolution of an O(N)-symmetric scalar quantum field theory using a systematic two-particle irreducible 1/N-expansion to next-to-leading order, which includes scattering and memory effects. The corresponding ``full Kadanoff-Baym equations'' are solved numerically without further approximations. This allows one to obtain a controlled nonperturbative description of far-from-equilibrium dynamics and the late-time approach to quantum thermal equilibrium. Employing in addition a first-order gradient expansion for the Wigner transformed correlators we derive kinetic equations. In contrast to standard descriptions based on loop expansions, our equations remain valid for nonperturbatively large fluctuations. As an application, we discuss the fluctuation dominated regime following parametric resonance in quantum field theory.
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