A measurement of the {tau} polarization at the Z resonance with the DELPHI detector at LEP
The polarization of {tau} leptons produced in the reaction e{sup +}e{sup {minus}} {yields} {tau}{sup +}{tau}{sup {minus}} near the peak of the Z{degrees} resonance has been measured using a sample of 24904 {tau}{sup +}{tau}{sup {minus}} events, with an estimated background of 1.5%. The authors have selected 4562 {tau} {yields} e{nu}{nu}, 2218 {tau} {yields} {pi}{nu} and 5133 {tau} {yields} {rho}{nu} candidates. The mean value obtained is P{sub {tau}} = -0.176{+-}0.029. This corresponds to a ratio of the neutral current vector to the axial-vector coupling constants of the {tau} lepton of g{sub V}{sup {tau}}/g{sub A}{sup {tau}} = 0.088 {+-} 0.014. This leads to a value of the electroweak mixing angle of sin{sup 2}{theta}{sub W} = 0.2280 {+-} 0.0036. This result is in good agreement with previous measurements of the weak mixing angle from the study of the Z{degrees} lineshape and the forward-backward asymmetries in the processes Z{degrees} {yields} l{sup +}l{sup {minus}} q{bar q}.
- Research Organization:
- Iowa State Univ. of Science and Technology, Ames, IA (United States)
- OSTI ID:
- 39341
- Country of Publication:
- United States
- Language:
- English
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