Quantum Radiation of Oscillons

TL;DR

This paper investigates the quantum decay rates of oscillons, revealing they decay via a power law rather than exponential suppression, with implications for early universe phenomena.

Contribution

It provides the first detailed analysis of quantum decay rates of oscillons, showing they differ significantly from classical decay and can involve parametric resonance effects.

Findings

Quantum decay rate follows a power law in amplitude and couplings.

Oscillons eventually decay by producing outgoing radiation.

Coupling to other bosons can cause exponential growth in radiation.

Abstract

Many classical scalar field theories possess remarkable solutions: coherently oscillating, localized clumps, known as oscillons. In many cases, the decay rate of classical small amplitude oscillons is known to be exponentially suppressed and so they are extremely long lived. In this work we compute the decay rate of quantized oscillons. We find it to be a power law in the amplitude and couplings of the theory. Therefore, the quantum decay rate is very different to the classical decay rate and is often dominant. We show that essentially all oscillons eventually decay by producing outgoing radiation. In single field theories the outgoing radiation has typically linear growth, while if the oscillon is coupled to other bosons the outgoing radiation can have exponential growth. The latter is a form of parametric resonance: explosive energy transfer from a localized clump into daughter fields. This may lead to interesting phenomenology in the early universe. Our results are obtained from a perturbative analysis, a non-perturbative Floquet analysis, and numerics.