Inflaton fragmentation in E-models of cosmological $\alpha$-attractors

TL;DR

This paper explores the formation of I-balls in E-models of $oldsymbol{ ext{α}}$-attractors, showing that for very small α, the inflaton field fragments into localized objects due to negative pressure effects.

Contribution

It demonstrates, through linear analysis and lattice simulations, that inflaton fragmentation into I-balls occurs in E-models of $ ext{α}$-attractors when α is sufficiently small.

Findings

I-balls form in E-models for α ≲ 10^{-3}.

Negative pressure persists long enough to cause fragmentation.

Fragmentation confirmed via lattice simulations.

Abstract

Cosmological $\alpha$-attractors are observationally favored due to the asymptotic flatness of the potential. Since its flatness induces the negative pressure even after inflation, the coherent oscillation of the inflaton field could fragment into quasi-stable localized objects called I-balls (or "oscillons"). We investigated the possibility of I-ball formation in E-models of $\alpha$-attractors. Using linear analysis and the lattice simulations, we find that for $\alpha\lesssim10^{-3}$, the inflaton feels the negative pressure long enough and actually fragments into I-balls.