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

$\xi $ ${\times }$ (${{\mathit \mu}}$ LONGITUDINAL POLARIZATION) ${\times }$ $\delta $ $/$ $\rho $

INSPIRE   PDGID:
S004XID
VALUE CL% DOCUMENT ID TECN CHG  COMMENT
$1.00179$ ${}^{+0.00156}_{-0.00071}$ 1
BAYES
2011
TWST + Surface ${{\mathit \mu}^{+}}$ beam
• • We do not use the following data for averages, fits, limits, etc. • •
$>0.99682$ 90 2
JODIDIO
1986
SPEC + TRIUMF
$>0.9966$ 90 3
STOKER
1985
SPEC + ${{\mathit \mu}}$-spin rotation
$>0.9959$ 90
CARR
1983
SPEC + 11 kG
1  BAYES 2011 obtains the limit $>$ 0.99909 (90$\%$ CL) with the constraint that $\xi {\times }({{\mathit \mu}}$ LONGITUDINAL POLARIZATION)${\times }\delta /\rho $ ${}\leq{}$ 1.0.
2  JODIDIO 1986 includes data from CARR 1983 and STOKER 1985. The value here is from the erratum.
3  STOKER 1985 find ($\xi {}P_{\mu }{}\delta /\rho $) $>$0.9955 and $>$0.9966, where the first limit is from new ${{\mathit \mu}}$ spin-rotation data and the second is from combination with CARR 1983 data. In $\mathit V−\mathit A$ theory, ($\delta /\rho $) = 1.0.
References