Fragileness of Exact I-ball/Oscillon

Understand

I-ball/oscillon is a soliton-like oscillating configuration of a real scalar field which lasts for a long time.

• I-ball/oscillon is a minimum energy state for a given adiabatic invariant, and its approximate conservation guarantees the longevity.
• In this paper, we examine the stability of a special type of I-ball/oscillon, the "exact" I-ball/oscillon, whose adiabatic invariant is exactly conserved.
• We show that the exact I-ball/oscillon is stable in classical field theory, but not stable against small perturbations depending on the value of its adiabatic invariant.