Nonlinear dynamics of oscillons and transients during preheating after single field inflation

Abstract: In the single-field model, the preheating process occurs through self-resonance of inflaton field. We study the nonlinear structures generated during preheating in the $\alpha$-attractor models and monodromy models. The potentials have a power law form $\propto\left|\phi\right|^{2n}$ near the origin and a flat region away from bottom, which are consistent with current cosmological observations. The Floquet analysis shows that potential parameters in monodromy model have a significant influence on the region of resonance bands. Besides we investigate the formation of nonlinear structures, the equation of state and the energy transfer through the (3+1) dimensional lattice simulation. We find that all the models exhibit similar nonlinear dynamics. Furthermore, our analysis reveals that the behavior of the inflation model at small field values, which is governed by the parameter $n$, exerts a more substantial influence on the nonlinear dynamics. The behavior at large field values, controlled by the parameter $q$, has a negligible impact.