Muon decay spin asymmetry
High Energy Physics - Phenomenology
2014-09-10 v1
Abstract
We compute the spin asymmetry of the muon decay through O(alpha^2) in perturbative QED. These two-loop corrections are about a factor five (twenty) smaller than the current statistical (systematic) uncertainty of the most precise measurement, performed by the TWIST collaboration. We point out that at O(alpha^2) the asymmetry requires a careful definition due to multi-lepton final states and suggest to use familiar QCD techniques to define it in an infra-red safe way. We find that the TWIST measurement of the asymmetry is in excellent agreement with the Standard Model.
Cite
@article{arxiv.1403.3386,
title = {Muon decay spin asymmetry},
author = {Fabrizio Caola and Andrzej Czarnecki and Yi Liang and Kirill Melnikov and Robert Szafron},
journal= {arXiv preprint arXiv:1403.3386},
year = {2014}
}
Comments
5 pages, 2 figures