Musser JR, Bayes R, Davydov YI, Depommier P, Doornbos J, Faszer W, Gagliardi CA, Gaponenko A, Gill DR, Green P, Gumplinger P, Hasinoff MD, Henderson RS, Hu J, Jamieson B, Kitching P, Koetke DD, Krushinsky AA, Lachin YY, Macdonald JA, MacDonald RP, Marshall GM, Mathie EL, Miasoedov LV, Mischke RE, Nord PM, Olchanski K, Olin A, Openshaw R, Porcelli TA, Poutissou JM, Poutissou R, Quraan MA, Rodning NL, Selivanov V, Sheffer G, Shin B, Sobratee F, Stanislaus TDS, Tacik R, Torokhov VD, Tribble RE, Vasiliev MA, Wright DH. Measurement of the Michel parameter rho in muon decay.
Phys Rev Lett 2005;
94:101805. [PMID:
15783475 DOI:
10.1103/physrevlett.94.101805]
[Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/29/2004] [Indexed: 05/24/2023]
Abstract
The TWIST Collaboration has measured the Michel parameter rho in normal muon decay, mu(+)--> e(+)nu(e)nu (mu). In the standard model, rho = 3/4. Deviations from this value imply mixing of left- and right-handed muon and electron couplings. We find rho=0.750 80+/-0.000 32(stat) +/- 0.000 97(syst) +/- 0.000 23, where the last uncertainty represents the dependence of rho on the Michel parameter eta. This result sets new limits on the W(L)-W(R) mixing angle in left-right symmetric models.
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