Measurement of the Michel parameter rho in muon decay. Academic Article uri icon


  • 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.

published proceedings

  • Phys Rev Lett

author list (cited authors)

  • Musser, J. R., Bayes, R., Davydov, Y. I., Depommier, P., Doornbos, J., Faszer, W., ... TWIST Collaboration.

citation count

  • 38

complete list of authors

  • Musser, JR||Bayes, R||Davydov, Yu I||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, Yu Yu||Macdonald, JA||MacDonald, RP||Marshall, GM||Mathie, EL||Miasoedov, LV||Mischke, RE||Nord, PM||Olchanski, K||Olin, A||Openshaw, R||Porcelli, TA||Poutissou, J-M||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

publication date

  • March 2005