Cosmic bubble and domain wall instabilities II: Fracturing of colliding walls

TL;DR

This paper investigates the nonlinear dynamics of colliding domain walls, revealing that nonplanar fluctuations lead to wall dissolution and oscillon formation, emphasizing the importance of full 3D simulations for accurate analysis.

Contribution

It provides the first full 3D nonlinear simulation of colliding domain walls including initial fluctuations, showing their critical role in the evolution and instability of the walls.

Findings

Nonplanar fluctuations cause domain wall dissolution.

Collision leads to formation of oscillons.

Full 3D dynamics are essential for accurate modeling.

Abstract

We study collisions between nearly planar domain walls including the effects of small initial nonplanar fluctuations. These perturbations represent the small fluctuations that must exist in a quantum treatment of the problem. In a previous paper, we demonstrated that at the linear level a subset of these fluctuations experience parametric amplification as a result of their coupling to the planar symmetric background. Here we study the full three-dimensional nonlinear dynamics using lattice simulations, including both the early time regime when the fluctuations are well described by linear perturbation theory as well as the subsequent stage of fully nonlinear evolution. We find that the nonplanar fluctuations have a dramatic effect on the overall evolution of the system. Specifically, once these fluctuations begin to interact nonlinearly the split into a planar symmetric part of the field and the nonplanar fluctuations loses its utility. At this point the colliding domain walls dissolve, with the endpoint of this being the creation of a population of oscillons in the collision region. The original (nearly) planar symmetry has been completely destroyed at this point and an accurate study of the system requires the full three-dimensional simulation.