# Decay of I-ball/Oscillon in Classical Field Theory

## TL;DR

This paper derives an analytical formula for the decay rate of I-balls/oscillons in classical scalar field theory and confirms it through numerical lattice simulations, enhancing understanding of their longevity in early universe scenarios.

## Contribution

The paper introduces a new analytical method to calculate the decay rate of I-balls/oscillons and validates it with numerical simulations.

## Key findings

- Analytical decay rate formula matches numerical results.
- Decay process characterized by Poynting vector calculations.
- I-balls/oscillons have quantifiable decay rates in classical field theory.

## Abstract

I-balls/oscillons are long-lived and spatially localized solutions of real scalar fields. They are produced in various contexts of the early universe in, such as, the inflaton evolution and the axion evolution. However, their decay process has long been unclear. In this paper, we derive an analytic formula of the decay rate of the I-balls/oscillons within the classical field theory. In our approach, we calculate the Poynting vector of the perturbation around the I-ball/oscillon profile by solving a relativistic field equation, with which the decay rate of the I-ball/oscillon is obtained. We also perform a classical lattice simulation and confirm the validity of our analytical formula of the decay rate numerically.