Oscillon

An oscillon is a spatially localized, time-periodic and long-lived (possibly infinitely lived) configuration of a classical field, often found in scalar field theories. They are non-topological solitons, meaning their stability does not arise from topological constraints but rather from a dynamical balance between forces.

Oscillons typically arise in nonlinear field theories with a potential possessing multiple minima or a nearly flat region. Their existence relies on the nonlinear nature of the field equations, preventing linear dispersion from dissipating the localized energy. While sometimes referred to as "breathers," a true breather is typically an exact solution of the field equations, whereas oscillons are generally long-lived but not perfectly stable in all contexts, slowly radiating energy over time.

The longevity of oscillons is dependent on parameters of the field theory, and their lifespan can range from many oscillation periods to effectively infinite, making them significant in the dynamics of the system. Oscillons are often formed after phase transitions in the early universe, and their potential role in baryogenesis and dark matter has been explored. They have been observed in numerical simulations across various dimensions and field theory models.

Key characteristics of oscillons include:

• Spatial Localization: They are confined to a specific region of space, with the field amplitude decaying away from the center.

• Time Periodicity: The field configuration oscillates in time, returning to a similar state after a characteristic period.

• Non-Topological Soliton: Their stability is not guaranteed by topology.

• Long Lifespan: They can persist for many oscillation periods, making them dynamically relevant.

• Formation in Nonlinear Systems: They arise from the nonlinear dynamics of the underlying field theory.