We investigate the formation and decay of oscillons during the post-inflationary reheating epoch from inflaton oscillations around asymptotically flat potentials V(φ) in the presence of an external coupling of the form 1/2 g ² φ ² χ ². It is well-known that in the absence of such an external coupling, the attractive self-interaction term in the potential leads to the formation of copious amounts of long-lived oscillons both for symmetric and asymmetric plateau potentials. We perform a detailed numerical analysis to study the formation of oscillons in the α-attractor E- and T-model potentials using the publicly available lattice simulation code CosmoLattice. We observe the formation of nonlinear oscillon-like structures with the average equation of state ⟨w_φ ⟩ ≃ 0 for a range of values of the inflaton self-coupling λ and the external coupling g ². Our results demonstrate that oscillons form even in the presence of an external coupling and we determine the upper bound on g ² which facilitates oscillon formation. We also find that eventually, these oscillons decay into the scalar inflaton radiation as well as into the quanta of the offspring field χ. Thus, we establish the possibility that reheating could have proceeded through the channel of oscillon decay, along with the usual decay of the oscillating inflaton condensate into χ particles. For a given value of the self-coupling λ, we notice that the lifetime of a population of oscillons decreases with an increase in the strength of the external coupling, following an (approximately) inverse power-law dependence on g ².

中文翻译：

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在外部耦合存在下膨胀后振荡的形成和衰变。第 I 部分 晶格模拟


我们研究了在存在 1/2 g²φ²χ² 形式的外部耦合的情况下，围绕渐近平坦电位 V（φ） 的充气振荡在充气后再加热时期的振荡的形成和衰变。众所周知，在没有这种外部耦合的情况下，势能中的吸引自相互作用项会导致对称和不对称平台电位形成大量的长寿命振荡。我们使用公开的晶格仿真代码 CosmoLattice 进行了详细的数值分析，以研究α吸引子 E 和 T 模型电位中振荡的形成。对于充气自耦合 λ 和外部耦合 g² 的一系列值，我们观察到非线性振荡状结构的形成，状态的平均方程 ⟨w_φ ⟩ ≃ 0。我们的结果表明，即使在存在外部耦合的情况下也会形成振荡，我们确定了 g² 的上限，这促进了振荡的形成。我们还发现，最终，这些振荡衰变为标量膨胀子辐射以及后代场 χ 的量子。因此，我们确定了再加热可能通过振荡衰变通道进行的可能性，以及振荡膨胀子凝聚物通常衰变成 χ 粒子。对于给定的自耦合 λ 值，我们注意到，在对 g² 的（近似）逆幂律依赖性之后，一组振荡的寿命随着外部耦合强度的增加而减小。