See the above “Note on Baryon Decay Parameters.” For discussions of recent results, see the references cited at the beginning of the section on the neutron mean life. For discussions of the values of the weak coupling constants ${\mathit g}_{{{\mathit A}}}$ and ${\mathit g}_{{{\mathit V}}}$ obtained using the neutron lifetime and asymmetry parameter$~\mathit A$, comparisons with other methods of obtaining these constants, and implications for particle physics and for astrophysics, see DUBBERS 1991 and WOOLCOCK 1991. For tests of the $\mathit V−\mathit A$ theory of neutron decay, see EROZOLIMSKII 1991B, MOSTOVOI 1996, NICO 2005, SEVERIJNS 2006, and ABELE 2008.
These are measurements of the component of ${{\mathit n}}$ spin perpendicular to the decay plane in $\beta $ decay. Should be zero if $\mathit T$ invariance is not violated.
S017D1
VALUE
($ 10^{-4} $)
DOCUMENT ID
TECN
COMMENT
$\bf{
-1.2 \pm2.0}$
OUR AVERAGE
$-0.94$ $\pm1.89$ $\pm0.97$
CHUPP
2012
CNTR
Cold ${{\mathit n}}$, polarized $>$ 91$\%$
$-2.8$ $\pm6.4$ $\pm3.0$
SOLDNER
2004
CNTR
Cold ${{\mathit n}}$, polarized
$-6$ $\pm12$ $\pm5$
LISING
2000
CNTR
Polarized $>$ 93$\%$
• • • We do not use the following data for averages, fits, limits, etc. • • •
1EROZOLIMSKII 1978 says asymmetric proton losses and nonuniform beam polarization may give a systematic error up to $30 \times 10^{-4}$, thus increasing the EROZOLIMSKII 1974 error to $50 \times 10^{-4}$. STEINBERG 1974 and STEINBERG 1976 estimate these systematic errors to be insignificant in their experiment.
