The Michel parameters and the average tau-neutrino helicity are measured using correlations between the decays of the tau(+) and tau(-) produced on the Z resonance and observed in the ALEPH detector at LEP. The Michel parameters, rho(l), eta(l), xi(l), (delta xi)(l), are determined from tau - ->l nubar_l nu_tau with l = (e, mu), and the average tau neutrino helicity, <h(nu_tau)>, from tau -> h nu_tau with h = (pi, rho, a(1)). The results obtained with e-mu universality are: rho(l) = 0.751 +/- 0.039 +/- 0.022, eta(l) = -0.04 +/- 0.15 +/- 0.11, xi(l) = 1.18 +/- 0.15 +/- 0.06, (delta xi)(l) = 0.88 +/- 0.11 +/- 0.07, and the average tau neutrino helicity <h(nu_tau)> = -1.006 +/- 0.032 +/- 0.019. No significant deviation from the Standard Model V-A prediction is observed.
Michel Parameters and tau neutrino Helicity From Decay Correlations In Z->tau+tau-
BATIGNANI, GIOVANNI;BETTARINI, STEFANO;CIOCCI, MARIA AGNESE;FERRANTE, ISIDORO;FIDECARO, FRANCESCO;FORTI, FRANCESCO;GIORGI, MARCELLO;MESSINEO, ALBERTO MARIA;RIZZO, GIULIANA;TONELLI, GUIDO EMILIO;G. TRIGGIANI;
1995-01-01
Abstract
The Michel parameters and the average tau-neutrino helicity are measured using correlations between the decays of the tau(+) and tau(-) produced on the Z resonance and observed in the ALEPH detector at LEP. The Michel parameters, rho(l), eta(l), xi(l), (delta xi)(l), are determined from tau - ->l nubar_l nu_tau with l = (e, mu), and the average tau neutrino helicity,I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
