Neutron Lifetime and Axial Coupling Connection

Experimental studies of neutron decay, n -> pe(nu)overbar, exhibit two anomalies. The first is a 8.6(2.1) s, roughly 4 sigma difference between the average beam measured neutron lifetime, tau(beam)(n) = 888.0(2.0) s, and the more precise average trapped ultracold neutron determination, tau(trap)(n) = 879.4(6) s. The second is a 5 sigma difference between the pre2002 average axial coupling, g(A), as measured in neutron decay asymmetries g(A)(pre2002) (=) 1.2637(21), and the more recent, post2002, average g(A)(post2002) = 1.2755(11), where, following the UCNA Collaboration division, experiments are classified by the date of their most recent result. In this Letter, we correlate those tau(n) and g(A) values using a (slightly) updated relation tau(n)(1 + 3g(A)(2)) = 5172.0(1.1) s. Consistency with that relation and better precision suggest tau(faVored)(n) = 879.4(6) s and g(A)(favored) = 1.2755(11) as preferred values for those parameters. Comparisons of g(A)(favored) with recent lattice QCD and muonic hydrogen 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.