Measurement of τ polarisation at LEP

• Autores: Dova, María Teresa; L3 Collaboration
• Año de publicación: 2003
• Idioma: inglés
• Tipo de recurso: artículo
• Materia: Ciencias Exactas; Física; τ polarisation; L3 detector
• Institución: Universidad Nacional de La Plata

Using the data collected with the L3 detector at LEP between 1990 and 1995, corresponding to an integrated luminosity of 149 pb−1, the τ longitudinal polarisation has been measured as a function of the production polar angle using the τ decays τ−→h−ντ (h=π,ρ,a1) and $\text{τ}{}^{\mathrm{-}}\text{→ℓ}{}^{\mathrm{-}}\text{ν}\text{̄}{}_{\mathrm{\ell }}\text{ν}{}_{\mathrm{\tau }}$ (ℓ=e,μ). From this measurement the quantities Ae and Aτ, which depend on the couplings of the electron and the τ to the Z, are determined to be Ae=0.1678±0.0127±0.0030 and Aτ=01540±0.0088±0.0062, consistent with the hypothesis of e–τ universality. Under this assumption a value of $\text{A}{}_{\mathrm{\ell }}\text{=0.1540±0.0074±0.0044}$ is obtained, yielding the value of the effective weak mixing angle $\text{sin}{}^2\text{θ}{}_{\mathrm{<mtext>W</mtext>}}\text{=0.2306±0.0011}$.
Facultad de Ciencias Exactas