Precision muon decay measurements and improved constraints on the weak interaction Academic Article uri icon


  • The TWIST Collaboration has completed its measurement of the three muon decay parameters , , and P . This paper describes our determination of , which governs the shape of the overall momentum spectrum, and , which controls the momentum dependence of the parity-violating decay asymmetry. The results are =0.749770. 00012(stat)0.00023(syst) and =0.750490.00021(stat) 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 , , and P 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. 2012 American Physical Society.

published proceedings


altmetric score

  • 0.5

author list (cited authors)

  • Hillairet, A., Bayes, R., Bueno, J. F., Davydov, Y. I., Depommier, P., Faszer, W., ... Tribble, R. E.

citation count

  • 21

complete list of authors

  • Hillairet, A||Bayes, R||Bueno, JF||Davydov, Yu I||Depommier, P||Faszer, W||Gagliardi, CA||Gaponenko, A||Gill, DR||Grossheim, A||Gumplinger, P||Hasinoff, MD||Henderson, RS||Hu, J||Koetke, DD||MacDonald, RP||Marshall, GM||Mathie, EL||Mischke, RE||Olchanski, K||Olin, A||Openshaw, R||Poutissou, J-M||Poutissou, R||Selivanov, V||Sheffer, G||Shin, B||Stanislaus, TDS||Tacik, R||Tribble, RE

publication date

  • May 2012