The muon decay parameter δ has been measured by the TWIST collaboration. We find δ=0.74964±0.00066(stat.)±0.00112(syst.), consistent with the standard model value of 3/4. This result implies that the product Pμξ of the muon polarization in pion decay, Pμ, and the muon decay parameter ξ falls within the 90% confidence interval 0.9960<Pμξ≤ξ<1.0040. It also has implications for left-right-symmetric and other extensions of the standard model.
Physical Review D
- Pub Date:
- April 2005
- Decays of muons;
- Extensions of electroweak gauge sector;
- High Energy Physics - Experiment
- Extended to 5 pages. Referee's comments answered