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. The analytical oscillons solution for the $\alpha$-attractor T model with parameter $n=1$ is derived using the small amplitude analysis method. 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 the symmetric T potential and the asymmetric E potential in the $\alpha$-attractor models have similar nonlinear dynamics. And the potential parameter $n$ in monodromy model significantly influences the lifetime of transients, whereas the parameter $q$ exerts minimal impact on the nonlinear dynamics.