pdgLive

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

${{\overline{\mathit \eta}}}$ PARAMETER

($\mathit V−\mathit A$) 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

$-0.014$ $\pm0.090$

ELEC

+

${{\mathit \rho}}$ free

$+0.09$ $\pm0.14$

CNTR

+

• • We do not use the following data for averages, fits, limits, etc. • •

$-0.035$ $\pm0.098$

ELEC

+

$\rho =0.75$ assumed

References:

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

PR 156 1405

Radiative Decay of the Muon

Except where otherwise noted, content of the 2023 Review of Particle Physics is licensed under a Creative Commons Attribution-NonCommercial 4.0 International (CC BY-NC 4.0) license. The publication of the Review of Particle Physics is supported by US DOE, MEXT (Japan), INFN (Italy), JPS and CERN. Individual collaborators receive support for their PDG activities from their respective institutes or funding agencies. © 2023. See LBNL disclaimers.