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

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 <a:math xmlns:a="http://www.w3.org/1998/Math/MathML" display="inline"><a:mi>ψ</a:mi></a:math>. We find that a <c:math xmlns:c="http://www.w3.org/1998/Math/MathML" display="inline"><c:mi mathvariant="normal">Δ</c:mi><c:mi>B</c:mi><c:mo>=</c:mo><c:mn>2</c:mn></c:math> mass-loss process in binary pulsar systems via <f:math xmlns:f="http://www.w3.org/1998/Math/MathML" display="inline"><f:mi>n</f:mi><f:mo stretchy="false">→</f:mo><f:mi>γ</f:mi><f:mi>ψ</f:mi></f:math> and the subsequent scattering <i:math xmlns:i="http://www.w3.org/1998/Math/MathML" display="inline"><i:mi>ψ</i:mi><i:mi>n</i:mi><i:mo stretchy="false">→</i:mo><i:msup><i:mi>π</i:mi><i:mo>−</i:mo></i:msup><i:msup><i:mi>K</i:mi><i:mo>+</i:mo></i:msup></i:math> places stringent constraints on the model parameter space. These limits will become much stronger, due to the possibility of <l:math xmlns:l="http://www.w3.org/1998/Math/MathML" display="inline"><l:mi mathvariant="normal">Λ</l:mi><l:mo stretchy="false">→</l:mo><l:mi>γ</l:mi><l:mi>ψ</l:mi></l:math> decays at the tree level, if the neutron star equation of state is hyperonic. We compare these constraints with ongoing and future collider experiments, <p:math xmlns:p="http://www.w3.org/1998/Math/MathML" display="inline"><p:mi>n</p:mi><p:mo>−</p:mo><p:mover accent="true"><p:mi>n</p:mi><p:mo stretchy="false">¯</p:mo></p:mover></p:math> 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