Cosmological and astrophysical probes of dark baryons

Abstract

We examine the cosmological and astrophysical signatures of a "dark baryon," a neutral fermion that mixes with the neutron. As the mixing is through a higher-dimensional operator at the quark level, production of the dark baryon at high energies is enhanced so that its abundance in the early universe may be significant. Treating its initial abundance as a free parameter, we derive new, powerful limits on the properties of the dark baryon. Primordial nucleosynthesis and the cosmic microwave background provide strong constraints due to the inter-conversion of neutrons to dark baryons through their induced transition dipole, and due to late decays of the dark baryon. Additionally, neutrons in a neutron star could decay slowly to dark baryons, providing a novel source of heat that is constrained by measurements of pulsar temperatures. Taking all the constraints into account, we identify parameter space where the dark baryon can be a viable dark matter candidate and discuss promising avenues for probing it.

Neutron Star Internal Heating Constraints on Mirror Matter

“…Another scenario probed by NS heating is neutron decay to any exotic final state, as we had studied for dark baryons in Ref. [13] and will explore in more detail in forthcoming work [21]. Here NS heating is the sole probe of dark baryons for tiny mixings with neutrons.…”

“…bient dark matter [33,34] and exotic neutron decay [13]). The ceiling here corresponds to Γ −1 n = 10 7 yr, describing the age of an NS beyond which we expect it to have O( 103 ) K temperatures [18,27].…”

“…In the NS system ∆E 10 − 100 MeV due to nuclear interactions, thus our limits apply to |m n − m n | O(10 MeV), a much wider range of m n than that of terrestrial UCN searches. We recently used this novel NS heating mechanism to set extensive limits on exotic neutron decay modes (n → BSM states) [13]. While in that study we had used a simplified picture of the NS to obtain order of magnitude estimates, in the present work we treat in more careful detail (i) the dynamics and constituents of the NS core and their implications for neutron disappearance, and (ii) astronomical measurements.…”

Collider Signals of Baryogenesis and Dark Matter from $B$ Mesons: A Roadmap to Discovery

“…(12) We note that since both ψ and φ carry baryon number, they can potentially be produced in high-density environments, even if they interact very weakly with regular matter. One of the most favourable environments for this is the interior of a neutron star, where light baryons can be produced provided that they are lighter than the chemical potential of a neutron µ n ∼ 1.2 GeV within the star [49] (see also [50][51][52][53][54][55]). In [1], this motivated the additional restriction to only consider masses above this threshold, i.e.…”