# ${{\boldsymbol \pi}^{+}}$ $\rightarrow$ ${{\boldsymbol \mu}^{+}}{{\boldsymbol \nu}}$ INSPIRE search

Tests the Lorentz structure of leptonic charged weak interactions.
VALUE CL% DOCUMENT ID TECN CHG  COMMENT
• • • We do not use the following data for averages, fits, limits, etc. • • •
$\text{<(-0.9959)}$ 90 1
 1984
RVUE +
$-0.99$ $\pm0.16$ 2
 1983
SPEC - ${{\mathit \mu}}$ $\mathit X$-rays
1  FETSCHER 1984 uses only the measurement of CARR 1983 .
2  Sign of measurement reversed in ABELA 1983 to compare with ${{\mathit \mu}^{+}}$ measurements.
References:
 FETSCHER 1984
PL 140B 117 Helicity of the ${{\mathit \nu}_{{\mu}}}$ in ${{\mathit \pi}^{+}}$ Decay: a Comment on the Measurement of P$_{{{\mathit \mu}}}{{\mathit \Xi}}{{\mathit \Delta}}/{{\mathit \rho}}$ in Muon Decay
 ABELA 1983
NP A395 413 Measurements of the Polarization of the 2p and 1s States in Muonic Atoms and the Helicity of the Muon in Pion Decay