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${{\mathit \Lambda}}$ 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:

DWORKIN 1990 PR D41 780 High Statistics Measurement of $\mathit g_{a}$/g$_{v}$ in ${{\mathit \Lambda}}$ $\rightarrow$ ${{\mathit p}}{{\mathit e}^{-}}{{\overline{\mathit \nu}}}$ BOURQUIN 1983 ZPHY C21 1 Measurements of Hyperon Semileptonic Decays at the CERN Super Proton Synchrotron. 2. The ${{\mathit \Lambda}}$ $\rightarrow$ ${{\mathit p}}{{\mathit e}^{-}}{{\overline{\mathit \nu}}_{{e}}}$ , ${{\mathit \Xi}^{-}}$ $\rightarrow$ ${{\mathit \Lambda}}{{\mathit e}^{-}}{{\overline{\mathit \nu}}_{{e}}}$ , and ${{\mathit \Xi}^{-}}$ $\rightarrow$ ${{\mathit \Sigma}^{0}}{{\mathit e}^{-}}{{\overline{\mathit \nu}}_{{e}}}$ Decay Modes WISE 1981 PL 98B 123 Precise Measurement of the Ratio of the Axial Vector Coupling to Vector Coupling in ${{\mathit \Lambda}^{0}}$ $\rightarrow$ ${{\mathit p}}{{\mathit e}^{-}}{{\overline{\mathit \nu}}_{{e}}}$ ALTHOFF 1973 PL 43B 237 $\beta $ Decay of Polarized ${{\mathit \Lambda}}$ Hyperons III. Correlations in the ${{\mathit \Lambda}}$ Centre-of-Mass System and the Proton Recoil Spectrum

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