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arXiv 2005.00433astro-ph.COhep-phhep-th
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非最小耦合多场暴胀后非线性预热过程的时标

Time-Scales for Nonlinear Processes in Preheating after Multifield Inflation with Nonminimal Couplings

Jorinde van de Vis, Rachel Nguyen, Evangelos I. Sfakianakis, John T. Giblin,, David I. Kaiser

备注：
32 pages (plus appendices), 17 figures. References added and minor edits to match published version
发表信息：
Phys. Rev. D 102, 043528 (2020)
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摘要：

我们已经进行了广泛的晶格模拟研究后膨胀动力学的多场模型涉及非最小耦合。我们探讨了这些模型中的预热参数依赖性，并描述了控制能量转移，再散射等非线性过程的各种时间尺度，以及辐射控制和热化的方法。在大的非最小耦合（$ξ_I \sim 100$）的限制，我们发现，从暴胀凝聚体的辐射自由度的能量的有效转移，出现一个辐射占主导地位的状态方程，和热化的发病始终发生在$N_{\rm reh} \lesssim 3$ $e$ -折叠结束后的通货膨胀，在很大程度上独立的其他耦合模型中的值。例外的是负椭圆率的情况下，有一个不对齐的主导方向在场空间沿系统的发展和较大的非最小耦合$ξ_I$。在这些情况下，场空间驱动的参数共振被有效地关闭。更一般地说，标量场的势和场空间流形结构之间的竞争可以产生有趣的现象，例如两级共振。尽管爆炸性粒子的产生，这可能会导致背景能量密度的快速耗尽，非线性过程不会引起任何超视界相关后，在这些模型中的膨胀，这保持预测CMB观测不受后期放大的等曲率波动。因此，原始观测值和最近的观测值之间的极好的协议是保留这类模型，即使当我们考虑后膨胀动力学。

英文摘要：

We have conducted extensive lattice simulations to study the post-inflation dynamics of multifield models involving nonminimal couplings. We explore the parameter dependence of preheating in these models and describe the various time-scales that control such nonlinear processes as energy transfer, re-scattering, and the approach to radiation-domination and thermalization. In the limit of large nonminimal couplings ($ξ_I \sim 100$), we find that efficient transfer of energy from the inflaton condensate to radiative degrees of freedom, emergence of a radiation-dominated equation of state, and the onset of thermalization each consistently occur within $N_{\rm reh} \lesssim 3$ $e$-folds after the end of inflation, largely independent of the values of the other couplings in the models. The exception is the case of negative ellipticity, in which there is a misalignment between the dominant direction in field-space along which the system evolves and the larger of the nonminimal couplings $ξ_I$. In those cases, the field-space-driven parametric resonance is effectively shut off. More generally, the competition between the scalar fields' potential and the field-space manifold structure can yield interesting phenomena such as two-stage resonances. Despite the explosive particle production, which can lead to a quick depletion of the background energy density, the nonlinear processes do not induce any super-horizon correlations after the end of inflation in these models, which keeps predictions for CMB observables unaffected by the late-time amplification of isocurvature fluctuations. Hence the excellent agreement between primordial observables and recent observations is preserved for this class of models, even when we consider post-inflation dynamics.

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