Scattering properties of dark atoms and molecules

Abstract

There has been renewed interest in the possibility that dark matter exists in the form of atoms, analogous to those of the visible world. An important input for understanding the cosmological consequences of dark atoms is their self-scattering. Making use of results from atomic physics for the potentials between hydrogen atoms, we compute the low-energy elastic scattering cross sections for dark atoms. We find an intricate dependence upon the ratio of the dark proton to electron mass, allowing for the possibility to "design" low-energy features in the cross section. Dependences upon other parameters, namely the gauge coupling and reduced mass, scale out of the problem by using atomic units. We derive constraints on the parameter space of dark atoms by demanding that their scattering cross section does not exceed bounds from dark matter halo shapes. We discuss the formation of molecular dark hydrogen in the universe, and determine the analogous constraints on the model when the dark matter is predominantly in molecular form.

Scattering, damping, and acoustic oscillations: Simulating the structure of dark matter halos with relativistic force carriers

“…For in depth investigations of dark atom phenomenology, we refer the reader to Refs. [52][53][54]89]. The full range of behaviors available to these models is much broader than the subject of this paper, so for our benchmark scenarios we only present results relevant to our present work.…”

“…To facilitate comparison with previous works on SIDM, we choose to parametrize our benchmark models in terms of the commonly accepted σ tr . Due to the complex internal structure of atoms, their elastic scattering cross section generally has a highly nontrivial energy and angular dependence, with many resonances appearing as the collision energy is varied [54]. Since our goal in this work is to explore the possible interplay between dark matter self-interaction and the modified matter power spectrum caused by the relativistic force carrier, we consider simplified prescriptions for the dark matter scattering cross section.…”

“…While there are many SIDM scenarios that mediate the self-scattering interaction through a light force carrier, in this paper we will use the dark atom model as a benchmark [34][35][36][37][38][39][40][41][42]48,[50][51][52][53][54][55][56][57][58][59]. In this model, dark matter is composed of two different particles, oppositely charged under a new long-range Abelian gauge group Uð1Þ D , mediated by a dark photon ϕ.…”

“…While it is not required, such a large cross section makes it reasonable to consider the existence of light force carriers in the dark sector. This could occur, for example, in dark atom models interacting through dark photons [34,48,[50][51][52][53][54][55][56][57], in mirror dark matter models [35][36][37][38][39][40][41][42]58,59,85], or dark matter coupled to Standard Model photons [60][61][62][63][64][65][66][67], neutrinos [24][25][26][27][28][29][30][31][32][33], or to some other new light particle [68][69][70][71][72][73][86][87][88].…”

Annihilation signals from asymmetric dark matter

“…For some related discussions of composite DM see e.g. [76][77][78][79][80]. Thus, whilst composite models are an…”