Precision muon decay measurements and improved constraints on the weak interaction
Abstract
The TWIST Collaboration has completed its measurement of the three muon decay parameters \rho, \delta, and P_\mu\xi. This paper describes our determination of \rho, which governs the shape of the overall momentum spectrum, and \delta, which controls the momentum dependence of the parity-violating decay asymmetry. The results are \rho=0.74977\pm 0.00012(stat.)\pm 0.00023(syst.) and \delta = 0.75049\pm 0.00021(stat.)\pm 0.00027(syst.). These are consistent with the value of 3/4 given for both parameters in the standard model, and each is over a factor of 10 more precise than the measurements published prior to TWIST. Our final results on \rho, \delta, and P_\mu\xi have been incorporated into a new global analysis of all available muon decay data, resulting in improved model-independent constraints on the possible weak interactions of right-handed particles.
Keywords
Cite
@article{arxiv.1112.3606,
title = {Precision muon decay measurements and improved constraints on the weak interaction},
author = {TWIST Collaboration and A. Hillairet and R. Bayes and J. F. Bueno and Yu. I. Davydov and P. Depommier and W. Faszer and C. A. Gagliardi and A. Gaponenko and D. R. Gill and A. Grossheim and P. Gumplinger and M. D. Hasinoff and R. S. Henderson and J. Hu and D. D. Koetke and R. P. MacDonald and G. M. Marshall and E. L. Mathie and R. E. Mischke and K. Olchanski and A. Olin and R. Openshaw and J. -M. Poutissou and R. Poutissou and V. Selivanov and G. Sheffer and B. Shin and T. D. S. Stanislaus and R. Tacik and R. E. Tribble},
journal= {arXiv preprint arXiv:1112.3606},
year = {2012}
}
Comments
19 pages, 10 figures