  The existing discrepancy between neutron lifetime measurements in bottle and
beam experiments has been interpreted as a sign of the neutron decaying to dark
particles. We summarize the current status of this proposal, including a
discussion of particle physics models involving such a portal between the
Standard Model and a baryonic dark sector. We also review further theoretical
developments around this idea and elaborate on the prospects for verifying the
neutron dark decay hypothesis in current and upcoming experiments.
