论文标题
宇宙学预热模型的后反应效应的数值研究
Numerical studies of back-reaction effects in an analog model of cosmological pre-heating
论文作者
论文摘要
从理论上讲，我们在早期宇宙的预热阶段提出了一种原子玻璃体凝结物作为后反应效应的模拟模型。特别是，我们解决了不平衡的动力学，其中最初激发的充气场通过参数刺激物质字段而引起的衰减。我们在紧密的横向限制下考虑了二维环形的BEC，其横向呼吸模式和金石和偶极激发分支分别模拟了充气和量子问题场。对呼吸模式的强烈激发会导致通过参数对创建偶极子和金石激发的指数增长：我们对BEC动力学的数值模拟表明，相关的后反应效果如何不仅导致呼吸模式的有效摩擦，而且还导致了远程空间相干性的最初效果的快速损失。最终讨论了这种结果对后反应的通常半经典描述的有效性的含义。
We theoretically propose an atomic Bose-Einstein condensate as an analog model of back-reaction effects during the pre-heating stage of early Universe. In particular, we address the out-of-equilibrium dynamics where the initially excited inflaton field decays by parametrically exciting the matter fields. We consider a two-dimensional, ring-shaped BEC under a tight transverse confinement whose transverse breathing mode and the Goldstone and dipole excitation branches simulate the inflaton and quantum matter fields, respectively. A strong excitation of the breathing mode leads to an exponentially-growing emission of dipole and Goldstone excitations via parametric pair creation: our numerical simulations of the BEC dynamics show how the associated back-reaction effect not only results in an effective friction of the breathing mode but also in a quick loss of longitudinal spatial coherence of the initially in-phase excitations. Implications of this result on the validity of the usual semiclassical description of back-reaction are finally discussed.
