Precise determination of the neutron lifetime

Determine the precise lifetime of the neutron, resolving the discrepancy between bottle and beam measurements.

Background

The paper discusses two direct methods for measuring the neutron lifetime. Bottle experiments store ultracold neutrons and infer the lifetime from the number remaining, whereas beam experiments count decay protons and infer the lifetime from the decay rate.

The reported values differ by approximately four standard deviations: the bottle measurement gives $879.6 \pm 0.6$ s, while the beam measurement gives $888.0 \pm 2.0$ s. The paper identifies the precise neutron lifetime as unresolved and then examines whether an exotic neutron decay, $n\rightarrow\bar{\nu}_e+\chi$, could account for the difference.