File:PhysRevLett.120.202002.pdf

English: Experimental studies of neutron decay,n→pe ̄ν, exhibit two anomalies. The first is a 8.6(2.1) s, roughly4σdifference between the average beam measured neutron lifetime,τbeamn¼888.0ð2.0Þs, and the moreprecise average trapped ultracold neutron determination,τtrapn¼879.4ð6Þs. The second is a5σdifferencebetween the pre2002 average axial coupling,gA, as measured in neutron decay asymmetriesgpre2002A¼1.2637ð21Þ, and the more recent, post2002, averagegpost2002A¼1.2755ð11Þ, where, followingthe UCNA Collaboration division, experiments are classified by the date of their most recent result. In thisLetter, we correlate thoseτnandgAvalues using a (slightly) updated relationτnð1þ3g2AÞ¼5172.0ð1.1Þs.Consistency with that relation and better precision suggestτfavoredn¼879.4ð6Þs andgfavoredA¼1.2755ð11Þas preferred values for those parameters. Comparisons ofgfavoredAwith recent lattice QCD and muonichydrogen capture results are made. A general constraint on exotic neutron decay branching ratios,<0.27%, is discussed and applied to a recently proposed solution to the neutron lifetime puzzle.