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arXiv · hep-ex/0410045

Measurement of the Muon Decay Parameter delta

TWIST Collaboration·A. Gaponenko·R. Bayes·Yu. I. Davydov·P. Depommier·J. Doornbos·W. Faszer·M. C. Fujiwara·C. A. Gagliardi·D. R. Gill·P. Green·P. Gumplinger·M. D. Hasinoff·R. S. Henderson·J. Hu·B. Jamieson·P. Kitching·D. D. Koetke·A. A. Krushinsky·Yu. Yu. Lachin·J. A. Macdonald·R. P. MacDonald·G. M. Marshall·E. L. Mathie·L. V. Miasoedov·R. E. Mischke·J. R. Musser·P. M. Nord·M. Nozar·K. Olchanski·A. Olin·7·R. Openshaw·T. A. Porcelli·J. -M. Poutissou·R. Poutissou·M. A. Quraan·N. L. Rodning·V. Selivanov·G. Sheffer·B. Shin·F. Sobratee·T. D. S. Stanislaus·R. Tacik·V. D. Torokhov·R. E. Tribble·M. A. Vasiliev·D. H. Wright
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Abstract

The muon decay parameter delta has been measured by the TWIST collaboration. We find delta = 0.74964 +- 0.00066(stat.) +- 0.00112(syst.), consistent with the Standard Model value of 3/4. This result implies that the product Pmuxi of the muon polarization in pion decay, Pmu, and the muon decay parameter xi falls within the 90% confidence interval 0.9960 < Pmuxi < xi < 1.0040. It also has implications for left-right-symmetric and other extensions of the Standard Model.

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TWIST Collaboration, A. Gaponenko, R. Bayes, Yu. I. Davydov, P. Depommier, J. Doornbos, W. Faszer, M. C. Fujiwara, C. A. Gagliardi, D. R. Gill, P. Green, P. Gumplinger, M. D. Hasinoff, R. S. Henderson, J. Hu, B. Jamieson, P. Kitching, D. D. Koetke, A. A. Krushinsky, Yu. Yu. Lachin, J. A. Macdonald, R. P. MacDonald, G. M. Marshall, E. L. Mathie, L. V. Miasoedov, R. E. Mischke, J. R. Musser, P. M. Nord, M. Nozar, K. Olchanski, A. Olin, 7, R. Openshaw, T. A. Porcelli, J. -M. Poutissou, R. Poutissou, M. A. Quraan, N. L. Rodning, V. Selivanov, G. Sheffer, B. Shin, F. Sobratee, T. D. S. Stanislaus, R. Tacik, V. D. Torokhov, R. E. Tribble, M. A. Vasiliev, D. H. Wright. 2005-04-14. Measurement of the Muon Decay Parameter delta. https://doi.org/10.1103/physrevd.71.071101

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