Insights from binary pulsars and laboratories into baryon number violation: Implications for GeV dark matter

Abstract

Rare processes in laboratory and within astrophysical environments can be highly sensitive probes of baryon-number-violating interactions at the TeV scale. We demonstrate the power of neutron stars to constrain baryon-number violation by considering a minimal extension of the standard model involving a TeV-mass scalar mediator and a GeV scale Majorana fermion ψ. We find that a ΔB=2 mass-loss process in binary pulsar systems via n→γψ and the subsequent scattering ψn→π−K+ places stringent constraints on the model parameter space. These limits will become much stronger, due to the possibility of Λ→γψ decays at the tree level, if the neutron star equation of state is hyperonic. We compare these constraints with ongoing and future collider experiments, n−n¯ oscillations, and dinucleon decay searches at future large-scale neutrino experiments, finding that the binary pulsars bounds on couplings are significantly tighter for specific flavor combinations. Published by the American Physical Society 2024