• DOI:10.1103/PhysRevD.106.116003
• Corpus ID: 250526449

Condensed dark matter with a Yukawa interaction

@article{Garani2022CondensedDM,
  title={Condensed dark matter with a Yukawa interaction},
  author={Raghuveer Garani and Michel H. G. Tytgat and J'erome Vandecasteele},
  journal={Physical Review D},
  year={2022}
}

• R. Garani, M. Tytgat, J'erome Vandecasteele
• Published 14 July 2022
• Physics
• Physical Review D

We explore the possible phases of a condensed dark matter (DM) candidate taken to be in the form of a fermion with a Yukawa coupling to a scalar particle, at zero temperature but at finite density. This theory essentially depends on only four parameters, the Yukawa coupling, the fermion mass, the scalar mediator mass, and the DM density. At low fermion densities we delimit the Bardeen-Cooper-Schrieffer (BCS), Bose-Einstein Condensate (BEC) and crossover phases as a function of model parameters using the notion of scattering length. We further study the BCS phase by consistently including emergent effects such as the scalar density condensate and superfluid gaps. Within the mean field approximation, we derive the consistent set of gap equations, retaining their momentum dependence, and valid in both the non-relativistic and relativistic regimes. We present numerical solutions to the set of gap equations, in particular when the mediator mass is smaller and larger than the DM mass. Finally, we discuss the equation of state (EoS) and possible astrophysical implications for asymmetric DM. κ that the dominant gap combination, ˜∆, evolves as the system changes from the non-relativistic regime to the relativistic regime. The bottom panels focus on the light mediator case with m φ /m = 0 . 13. In the left panel we present the gaps evaluated at k = k F for g = 3 (2) in solid (dashed). In the right panel we show the momentum dependence of the gap ˜∆ − ( k ), the so-called shape function, at representative values of densities, k F = 0 . 01 , 1 , 10, represented by markers. At large momentum ( k (cid:29) k F ), the momentum dependence of the gap is found to be ∼ k − 1 . 85 , ensuring self-consistent UV convergence of the gap equations. At low densities, the gap can exhibit one (or multiple) change of signs, and this is exemplified by the dip of the shape function for the lowest shown density, k F = 0 . 01. For such choice of parameters, the gap is negative at large momentum, but nevertheless goes smoothly to 0 as k → ∞