Insights from Binary Pulsars and Laboratories into Baryon Number Violation: Implications for GeV Dark Matter

TL;DR

This paper explores how binary pulsars and astrophysical observations can set stringent limits on baryon number violation, especially in models involving TeV-scale mediators and GeV-scale fermions, surpassing some collider and laboratory constraints.

Contribution

It demonstrates the effectiveness of neutron star observations in constraining baryon-number violating interactions in minimal extensions of the standard model, highlighting potential for future astrophysical bounds.

Findings

Binary pulsar data constrains baryon-number violation models.

Neutron star decay processes can be more restrictive than collider searches.

Future hyperonic equations of state could strengthen constraints.

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 $\psi$. We find that a $\Delta B = 2$ mass-loss process in binary pulsar systems via $n \to \gamma \psi$ and the subsequent scattering $\psi n \to \pi^- K^+$ places stringent constraints on the model parameter space. These limits will become much stronger, due to the possibility of $\Lambda \rightarrow \gamma \psi$ decays at the tree level, if the neutron star equation of state is hyperonic. We compare these constraints with ongoing and future collider experiments, $n-\bar{n}$ 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.