Atomic Dark Matter

TL;DR

This paper proposes that dark matter consists of atomic bound states, exploring their formation in the early universe and implications for cosmology and detection, including potential explanations for DAMA data.

Contribution

It introduces a simple model of atomic dark matter, analyzes its formation, and discusses its cosmological and detection implications, including hyperfine splittings.

Findings

Dark atoms can form in the early universe under certain conditions.

Atomic dark matter can suppress protohalo formation below specific mass scales.

Weak-scale dark atoms can explain DAMA data via hyperfine splittings.

Abstract

We propose that dark matter is dominantly comprised of atomic bound states. We build a simple model and map the parameter space that results in the early universe formation of hydrogen-like dark atoms. We find that atomic dark matter has interesting implications for cosmology as well as direct detection: Protohalo formation can be suppressed below $M_{proto} \sim 10^3 - 10^6 M_{\odot}$ for weak scale dark matter due to Ion-Radiation interactions in the dark sector. Moreover, weak-scale dark atoms can accommodate hyperfine splittings of order $100 \kev$, consistent with the inelastic dark matter interpretation of the DAMA data while naturally evading direct detection bounds.