${{\mathit \mu}}$ DECAY PARAMETERS

$\xi {{}^\prime}$ = LONGITUDINAL POLARIZATION OF ${{\mathit e}^{+}}$

INSPIRE  
($\mathit V−\mathit A$) theory predicts the longitudinal polarization = $\pm1$ for ${{\mathit e}^{\pm}}$ , respectively. We have flipped the sign for ${{\mathit e}^{-}}$ so our programs can average.
VALUE EVTS DOCUMENT ID TECN CHG  COMMENT
$\bf{ 1.00 \pm0.04}$ OUR AVERAGE
$0.998$ $\pm0.045$ 1M
BURKARD
1985
CNTR + Bhabha + annihil
$0.89$ $\pm0.28$ 29k
SCHWARTZ
1967
OSPK - Moller scattering
$0.94$ $\pm0.38$
BLOOM
1964
CNTR + Brems. transmiss.
$1.04$ $\pm0.18$
DUCLOS
1964
CNTR + Bhabha scattering
$1.05$ $\pm0.30$
BUHLER
1963
CNTR + Annihilation
References:
BURKARD 1985
PL 150B 242 Muon Decay: Measurement of the Positron Polarization and Implications for the Spectrum Shape Parameter ${{\mathit \eta}}$ , $\mathit V-A$ and $\mathit T$ Invariance
SCHWARTZ 1967
PR 162 1306 Helicity of Electrons from ${{\mathit \mu}^{-}}$ Decay
BLOOM 1964
PL 8 87 Measurement, by Bremsstrahlung Transmission, of the Polarization of ${{\mathit e}^{+}}$ from ${{\mathit \mu}^{+}}$ $\rightarrow$ ${{\mathit e}^{+}}{{\mathit \nu}_{{e}}}{{\overline{\mathit \nu}}_{{\mu}}}$
DUCLOS 1964
PL 9 62 Measurement of the ${{\mathit e}^{+}}$ Polarization in Muon Decay by Means of Bhabha Scattering
BUHLER 1963
PL 7 368 A Measurement of the ${{\mathit e}^{+}}$ Polarization in Muon Decay: the ${{\mathit e}^{+}}$ Annihilation Method