Dark Neutron Decay in Neutron Stars

One of the unsolved mysteries in the particle physics is the "neutron decay puzzle". Discrepancies between the neutron lifetime measured in beam and bottle experiments suggest that exotic decay channels and/or the involvement of dark matter may be in play. The proposed dark decay of the neutron may explain the existence of a wide range of objects produced from the mixing of neutron stars with dark matter, , including objects with small masses and radii, as well as those in the mass gap region. This hypothesis can more generally explain the existence of other compact objects with both small masses and radii that are to the left of and below the classical MR diagrams. In particular, we consider the case of neutron decay into a dark particle of mass m_x=939 MeV according to the hypothesis formulated by Grinstein. We consider this dark matter to interact both with itself and with neutrons, thus defining the equation of state of the neutron and dark matter mixture. In this study, we found that with the appropriate combination of interaction parameters, both masses larger than 2 solar masses can be simultaneously predicted, and at the same time, the compact objects XTE and HESS can be reproduced in a self-consistent way.