标题： 宇宙背景中的粒子传播 显示英文标题

标题： Particle propagation in cosmological backgrounds

摘要： 我们研究粒子在宇宙背景中的量子传播，通过考虑一个质量标量场双态在膨胀宇宙中的传播，可能充满辐射。 我们关注与膨胀率相关的耗散效应。 在一阶情况下，我们恢复了预期的结果，即衰变率由局部温度决定。 超出线性阶次后，衰变率有一个额外的贡献，由膨胀参数控制。 这种贡献甚至在真空中的稳定粒子中也存在。 最后，我们分析传播子的长时间行为，并简要讨论对超普朗克问题的应用。 显示英文摘要

摘要： We study the quantum propagation of particles in cosmological backgrounds, by considering a doublet of massive scalar fields propagating in an expanding universe, possibly filled with radiation. We focus on the dissipative effects related to the expansion rate. At first order, we recover the expected result that the decay rate is determined by the local temperature. Beyond linear order, the decay rate has an additional contribution governed by the expansion parameter. This latter contribution is present even for stable particles in the vacuum. Finally, we analyze the long time behaviour of the propagator and briefly discuss applications to the trans-Planckian question.