Diffusion of dark matter in a hot and dense nuclear environment

Abstract

We calculate the mean free path in a hot and dense nuclear environment for a fermionic dark matter particle candidate in the ∼GeV mass range interacting with nucleons via scalar and vector effective couplings. We focus on the effects of density and temperature in the nuclear medium in order to evaluate the importance of the final state blocking in the scattering process. We discuss qualitatively possible implications for opacities in stellar nuclear scenarios, where dark matter may be gravitationally accreted.

Fermionic Light Dark Matter Particles and the New Physics of Neutron Stars

“…For the dark sector, it can be assumed that all outgoing DM particles states are in principle allowed and 1 − f χ (E) ≈ 1 since the fraction of DM inside the star remains tiny at all times. The validity of this approximation is discussed in Cermeño et al (2016a). Let us mention here that effective values of nucleon mass and chemical potential define the quasiparticle nature of the nucleon in the medium and differ from the nude values by the presence of average meson fields Serot & Walecka (1986).…”

“…(7) and (8), are discussed step by step in Cermeño et al (2016a). We have to remark that this scenario is restricted to temperatures and densities typical for the thermodynamical evolution of the stellar core region, that is T 50 MeV and n ≃ (1−3)n 0 .…”

“…(1) of Cermeño et al (2016a) where the differential cross-section per unit volume as a function of the energy transfer q 0 for different values of the transferred momentum | q| is shown for a pure neutron system. We use n = n 0 , setting T = 0 and m χ = 0.5 GeV.…”

Enhanced Neutrino Emissivities in Pseudoscalar-mediated Dark Matter Annihilation in Neutron Stars

“…Note that the presence of the phase space factor f ( f 1 , f 2 , f 3 , f 4 ) in Equation (2) will introduce further DM density and T dependence into the vacuum standard calculation as a thermalized DM distribution exists inside the NS core. As for the outgoing fermions, the medium density effects will generally arise from the phase space blocking factors and collective effects (Cermeño et al 2016a). In the case of neutrinos, we assume f ν ∼0, although in cases where a trapped fraction Y ν >0 exists it would further decrease the response.…”

“…It is defined as r R 2 th x = and indicates the radial fraction where DM particles can be found. Since the crust region has a tiny mass, we will not consider this refinement here (Cermeño et al 2016b T . As has been thoroughly studied, enhanced emissivities in the medium can have an impact on internal temperatures, temporal cooling sequence, and (un)gapped matter phases (Page & Reddy 2006;Page et al 2013).…”