${{\boldsymbol n}}$ $\rightarrow$ ${{\boldsymbol p}}{{\boldsymbol e}^{-}}{{\overline{\boldsymbol \nu}}_{{e}}}$ DECAY PARAMETERS

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 .

${{\overline{\boldsymbol \nu}}_{{e}}}$ ASYMMETRY PARAMETER $\boldsymbol B$ INSPIRE search

This is the neutron-spin antineutrino-momentum correlation coefficient. In the Standard Model, $\mathit B$ is related to $\lambda {}\equiv\mathit g_{A}/\mathit g_{V}$ by $\mathit B$ = 2$\lambda (\lambda$ $−$ 1) $/$ (1 + 3$\lambda {}^{2}$); this assumes that $\mathit g_{A}$ and $\mathit g_{V}$ are real.
VALUE DOCUMENT ID TECN  COMMENT
$\bf{ 0.9807 \pm0.0030}$ OUR AVERAGE
$0.9802$ $\pm0.0034$ $\pm0.0036$
 2007
CNTR Cold ${{\mathit n}}$, polarized
$0.967$ $\pm0.006$ $\pm0.010$
 2005
CNTR Cold ${{\mathit n}}$, polarized
$0.9801$ $\pm0.0046$
 1998
CNTR Cold ${{\mathit n}}$, polarized
$0.9894$ $\pm0.0083$
 1995
CNTR Cold ${{\mathit n}}$, polarized
$1.00$ $\pm0.05$
 1970
CNTR Cold ${{\mathit n}}$, polarized
$0.995$ $\pm0.034$
 1970 C
CNTR Cold ${{\mathit n}}$, polarized
• • • We do not use the following data for averages, fits, limits, etc. • • •
$0.9876$ $\pm0.0004$ 1
 2001
CNTR Inferred
1  MOSTOVOI 2001 calculates this from its measurement of $\lambda =\mathit g_{\mathit A}/\mathit g_{\mathit V}$ above.
References:
 SCHUMANN 2007
PRL 99 191803 Measurement of the Neutrino Asymmetry Parameter $\mathit B$ in Neutron Decay
 KREUZ 2005
PL B619 263 A Measurement of the Antineutrino Asymmetry $\mathit B$ in Free Neutron Decay
 MOSTOVOI 2001
PAN 64 1955 Experimental Value of $\mathit G_{a}/G_{v}$ from a Measurement of Both $\mathit P$-odd Correlations in Free-neutron Decay
 SEREBROV 1998
JETP 86 1074 Measurement of the Antineutrino Escape Asymmetry with Respect to the Spin of the Decaying Neutron
 KUZNETSOV 1995
PRL 75 794 Measurements of the Antineutrino Spin Asymmetry in $\beta$ Decay of the Neutron and Restrictions on the Mass of a Right Handed Gauge Boson
 CHRISTENSEN 1970
PR C1 1693 Measurement of Angular Correlations in the Decay of Polarized Neutrons
 EROZOLIMSKII 1970C
PL 33B 351 Angular Correlation between the Neutron Spin and the Antineutrino Momentum in the Neutron Decay