# ${{\overline{\boldsymbol \eta}}}$ PARAMETER INSPIRE search

($\mathit V−\mathit A$) theory predicts ${{\overline{\mathit \eta}}}$ = 0. ${{\overline{\mathit \eta}}}$ affects spectrum of radiative muon decay.
VALUE DOCUMENT ID TECN CHG  COMMENT
$\bf{ 0.02 \pm0.08}$ OUR AVERAGE
$-0.014$ $\pm0.090$
 1984
ELEC + ${{\mathit \rho}}$ free
$+0.09$ $\pm0.14$
 1967
CNTR +
• • • We do not use the following data for averages, fits, limits, etc. • • •
$-0.035$ $\pm0.098$
 1984
ELEC + $\rho =0.75$ assumed
References:
 EICHENBERGER 1984
NP A412 523 Measurement of the Parameter Antieta in the Radiative Decay of the Muon as a Test of the $\mathit V-A$ Structure of the Weak Interaction
 BOGART 1967
PR 156 1405 Radiative Decay of the Muon