A determination of electroweak parameters from Z\u3csup\u3e0\u3c/sup\u3e→μ\u3csup\u3e+\u3c/sup\u3eμ\u3csup\u3e-\u3c/sup\u3e (γ)

Abstract

\u3cp\u3eWe have measured the partial width and forward-backward charge asymmetry for the reaction e\u3csup\u3e+\u3c/sup\u3ee\u3csup\u3e-\u3c/sup\u3e→Z\u3csup\u3e0\u3c/sup\u3e→μ\u3csup\u3e+\u3c/sup\u3eμ \u3csup\u3e-\u3c/sup\u3e(γ). We obtain a partial width Γ\u3csub\u3eμμ\u3c/sub\u3e of 83.3±1.3(stat)±0.9(sys) MeV and the following values for the vector and axial vector couplings: g\u3csub\u3ev\u3c/sub\u3e=-0.062\u3csub\u3e-0.015\u3c/sub\u3e \u3csup\u3e+0.020\u3c/sup\u3e and g\u3csub\u3eA\u3c/sub\u3e=-0.497\u3csub\u3e-0.005\u3c/sub\u3e \u3csup\u3e+0.005\u3c/sup\u3e. From our measurement of the partial width and the mass of the Z\u3csup\u3e0\u3c/sup\u3e boson we determine the effective electroweak mixing angle, sin\u3csup\u3e2\u3c/sup\u3eθ\u3csub\u3ew\u3c/sub\u3e=0.232±0.005, and the neutral current coupling strength parameter, ρ{variant}=0.998±0.016.\u3c/p\u3