A New Measurement of the Weak Mixing Angle
نویسنده
چکیده
The E158 experiment at SLAC has made the first measurement of parity violation in electron-electron (Møller) scattering. We report a preliminary result using 50% of the accumulated data sample for the right-left parity-violating cross-section asymmetry (APV ) in the elastic scattering of 45 and 48 GeV polarized electron beams with unpolarized electrons in a liquid hydrogen target. We find APV = (−160 ± 21(stat.) ± 17(syst.)) · 10, with a significance of 6.3σ for observing parity violation. In the context of the Standard Model, this yields a measurement of the weak mixing angle, sin θ W (Q 2 = 0.026GeV) = 0.2367± 0.0017(stat.)± 0.0014(syst.). We also present preliminary results for the first observation of a single-spin transverse asymmetry in Møller scattering.
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تاریخ انتشار 2004