Ultralight Dark Matter from the Edge of Field Space

TL;DR

This paper proposes a new class of ultralight bosonic dark matter called wallions, characterized by boundaries in field space, with unique mass suppression and stability properties, and explores their cosmological implications and potential experimental detection.

Contribution

It introduces wallions as a novel dark matter candidate with boundary-induced properties and analyzes their cosmological evolution and possible experimental signatures.

Findings

Wallions have exponentially suppressed masses for large boundary separations.

Wallions remain radiatively stable under self-interactions.

Potential experimental probes are discussed for wallions coupled to Standard Model fields.

Abstract

We introduce a novel class of bosonic dark matter candidates that we dub wallions, featuring boundaries in field space. The wallion mass is exponentially suppressed when the separation between boundaries far exceeds their intrinsic width and remains radiatively stable under self-interactions. We study the early-universe evolution of wallions and the associated cosmological signatures. Finally, we show that instanton effects can dynamically generate field-space boundaries and discuss possible experimental probes once the wallion couples to Standard Model fields.