Bound states of pseudo-Dirac dark matter

• Published in: Journal of cosmology and astroparticle physics Vol. 2019; no. 3; p. 29
• Main Authors: Bhattacharya, Arindam, Slatyer, Tracy R.
• Format: Journal Article
• Language: English
• Published: Bristol IOP Publishing 18.03.2019; Institute of Physics (IOP)
• Subjects: Dark matter; dark matter theory; particle physics - cosmology connection; PHYSICS OF ELEMENTARY PARTICLES AND FIELDS; Splitting
• ISSN: 1475-7516; 1475-7516
• DOI: 10.1088/1475-7516/2019/03/029

We study the bound-state spectrum in a simple model of pseudo-Dirac dark matter, and examine how the rate of bound-state formation through radiative capture compares to Sommerfeld-enhanced annihilation. We use this model as an example to delineate the new features induced by the presence of a mass splitting between the dark matter and a nearly-degenerate partner, compared to the case where only a single dark-matter-like state is present. We provide a simple analytic prescription for estimating the spectrum of bound states in systems containing a mass splitting, which in turn allows characterization of the resonances due to near-zero-energy bound states, and validate this estimate both for pseudo-Dirac dark matter and for the more complex case of wino dark matter. We demonstrate that for pseudo-Dirac dark matter the capture rate into deeply bound states is, to a good approximation, simply related to the Sommerfeld enhancement factor.