Dark decay of the neutron

New decay channels for the neutron into dark matter plus other particles have been suggested for explaining a long-standing discrepancy between the neutron lifetime measured from trapped neutrons versus those decaying in flight. Many such scenarios are already ruled out by their effects on neutron stars, and the decay into dark matter plus photon has been experimentally excluded. Here we explore the decay into a dark Dirac fermion chi and a dark photon A', which can be consistent with all constraints if chi is a subdominant component of the dark matter. Neutron star constraints are evaded if the dark photon mass to coupling ratio is m(A'/g') less than or similar to (45-60) MeV, depending upon the nuclear equation of state. g' and the kinetic mixing between U(1)' and electromagnetism are tightly constrained by direct and indirect dark matter detection, supernova constraints, and cosmological limits.