Neutron Star Constraints on Neutron Dark Decays

Motivated by the neutron lifetime puzzle, it is proposed that neutrons may decay into new states yet to be observed. We review the neutron star constraints on dark fermions carrying unit baryon number with masses around 939 MeV, and discuss the interaction strengths required for the new particle. The possibility of neutrons decaying into three dark fermions is investigated. While up to six flavors of dark quarks with masses around 313 MeV can be compatible with massive pulsars, any such exotic states lighter than about 270 MeV are excluded by the existence of low-mass neutron stars around similar to 1.2M circle dot. Light dark quarks in the allowed mass range may form a halo surrounding normal neutron stars. We discuss the potential observable signatures of the halo during binary neutron star mergers.

Automated summary

Motivated by the neutron lifetime puzzle, the authors propose the possibility of neutron decay into new, yet-to-be-observed states. They review the constraints on these dark fermions from neutron stars and discuss the required interaction strengths for the new particles. They investigate the possibility of neutrons decaying into three dark fermions and find that up to six flavors of dark quarks with masses around 313 MeV can be compatible with massive pulsars, but any exotic states lighter than about 270 MeV are excluded due to the existence of low-mass neutron stars around 1.2 solar masses. Light dark quarks in the allowed mass range may form a halo surrounding normal neutron stars, and the authors discuss their potential observable signatures during binary neutron star mergers.