A Measurement Of The Left Right Cross Section Asymmetry In Z Production With Polarized Ee Collisions

Download or read book A Measurement of the Left-right Cross Section Asymmetry in Z° Production with Polarized Ee− Collisions written by and published by . This book was released on 1993 with total page 153 pages. Available in PDF, EPUB and Kindle. Book excerpt: The Stanford Linear Collider at SLAC is an ee− collider running at √s ≈ M{sub Z} and has provided an electron beam with longitudinal polarization at the SLC interaction point. The 1992 polarized run data were taken with the SLD detector. The author presents here the measurement of the left-right cross section asymmetry (A{sub LR}) for the 1992 run. The polarized run began in May and ended in September of 1992 at a mean center-of-mass energy of 91.56 GeV. Tower hit information of the liquid argon calorimeter and endcap warm iron calorimeter pads were used for selecting hadronic Z° or tau pair events. The SLD detector collected about 11,000 events during this run. The magnitude of the longitudinal polarization of the electron beam was continuously measured by a polarimeter based on Compton scattering, and was monitored by a polarimeter based on Moller scattering. The luminosity-weighted average longitudinal polarization during the 1992 run was measured as 22.4 ± 0.6 (syst.)%. From these data, the value of A{sub LR} has been measured to be 0.102 ± 0.044 (stat.) ± 0.003 (syst.), corresponding to an effective electroweak mixing angle (sin2?{sub w}{sup eff}) of 0.2375 ± 0.0056 (stat.) ± 0.0004 (syst.). The error is dominated by the statistical error. This value of sin2?{sub w}{sup eff} is in good agreement with existing measurements from other experiments. Studies of improvements in A{sub LR} event selection for future high-statistics runs are also discussed.