${{\mathit \Lambda}}$ DECAY PARAMETERS

See the ``Note on Baryon Decay Parameters'' in the neutron Listings. Some early results have been omitted.

${\mathit g}_{{{\mathit A}}}$ $/$ ${\mathit g}_{{{\mathit V}}}$ FOR ${{\mathit \Lambda}}$ $\rightarrow$ ${{\mathit p}}{{\mathit e}^{-}}{{\overline{\mathit \nu}}_{{{e}}}}$

INSPIRE   PDGID:
S018AV
Measurements with fewer than 500 events have been omitted. Where necessary, signs have been changed to agree with our conventions, which are given in the “Note on Baryon Decay Parameters” in the neutron Listings. The measurements all assume that the form factor $\mathit g_{2}$ = 0. See also the footnote on DWORKIN 1990.
VALUE EVTS DOCUMENT ID TECN  COMMENT
$\bf{ -0.718 \pm0.015}$ OUR AVERAGE
$-0.719$ $\pm0.016$ $\pm0.012$ 37k 1
DWORKIN
1990
SPEC ${{\mathit e}}{{\mathit \nu}}$ angular corr.
$-0.70$ $\pm0.03$ 7111
BOURQUIN
1983
SPEC ${{\mathit \Xi}}$ $\rightarrow$ ${{\mathit \Lambda}}{{\mathit \pi}^{-}}$
$-0.734$ $\pm0.031$ 10k 2
WISE
1981
SPEC ${{\mathit e}}{{\mathit \nu}}$ angular correl.
• • We do not use the following data for averages, fits, limits, etc. • •
$-0.63$ $\pm0.06$ 817
ALTHOFF
1973
OSPK Polarized ${{\mathit \Lambda}}$
1  The tabulated result assumes the weak-magnetism coupling $\mathit w$ ${}\equiv$ ${\mathit g}_{{{\mathit w}}}(0)/{\mathit g}_{{{\mathit v}}}$(0) to be $0.97$, as given by the CVC hypothesis and as assumed by the other listed measurements. However, DWORKIN 1990 $\mathit measures$ $\mathit w$ to be $0.15$ $\pm0.30$, and then ${\mathit g}_{{{\mathit A}}}/{\mathit g}_{{{\mathit V}}}$ = $-0.731$ $\pm0.016$.
2  This experiment measures only the absolute value of ${\mathit g}_{{{\mathit A}}}/{\mathit g}_{{{\mathit V}}}$.
References