Polarized Vector Oscillons

TL;DR

This paper demonstrates the existence of long-lived, localized, and oscillating vector field configurations called vector oscillons, which exhibit unique polarization properties and could have implications for early universe cosmology and dark matter.

Contribution

It introduces the first known vector oscillons in a low-energy effective theory, detailing their properties, types, and potential relevance to cosmology and dark matter.

Findings

Vector oscillons can be long-lived and arise from Gaussian initial conditions.

Two types of vector oscillons are identified: directional and spinning.

Vector oscillons exhibit polarization-dependent phenomenology in cosmological contexts.

Abstract

Oscillons are spatially localized, time-periodic and long-lived configurations that were primarily proposed in scalar field theories with attractive self-interactions. In this letter, we demonstrate that oscillons also exist in the low-energy effective theory of an interacting massive (real) vector field. We provide two types of vector oscillons with vanishing orbital angular momentum, and approximately spherically symmetric energy density, but not field configurations. These are: (1) "directional" oscillons (linearly polarized), with vanishing total intrinsic spin, and (2) "spinning" oscillons (circularly polarized) with a macroscopic instrinsic spin equal to $\hbar\times$ number of particles in the oscillon. In contrast to the case with only gravitational interactions, the two oscillons have different energy at a fixed particle number even in the nonrelativistic limit. By carrying out relativistic $3+1$d simulations, we show that these oscillons can be long-lived (compared to the oscillation time for the fields), and can arise from a range of Gaussian initial spatial profiles. These considerations make vector oscillons potentially relevant during the early universe and in dark photon dark matter, with novel phenomenology related to their polarization.