A measurement of the effective electron neutral current-coupling parameters from polarized Bhabha scattering at the Z0 resonance
Abstract
The effective electron neutral current coupling parameters, gVe and gAe, have been measured from analyzing 43,222 polarized Bhabha scattered events (e+ e- -> e+ e-) using the SLAC Large Detector (SLD) experiment at the Stanford Linear Accelerator Center (SLAC). The SLAC Linear Collider (SLC) produced the Bhabha scattered events by colliding polarized electrons, with an average polarization of 74%, with unpolarized positrons at an average center-of-mass energy of 91.25 GeV. The analysis used the entire SLD data sample collected between 1994 and 1998 (the last year the SLD detector collected data). The results are gVe = -0.0469 +/- 0.0024 (stat.) +/- 0.0004 (sys.); gAe = -0.5038 +/- 0.0010 (stat.) +/- 0.0043 (sys.). All Bhabha scattered events within the angular acceptance of the SLD calorimeter subsystems were used in this analysis, including both small-angle events (28 mrad. <= theta <= 68 mrad.) measured by the Silicon/Tungsten Luminosity Monitor (LUM), and large angle events (0 <= |cos (theta)| <= 0.9655) measured by the Liquid Argon Calorimeter (LAC). Using all of the data in this manner allows for the high-precision measurement of the luminosity provided by the LUM to constrain the uncertainty on gVe and gAe. The measured integrated luminosity for the combined 1993 through 1998 SLD data sample is L(integrated) = 19,247 +/- 17 (stat.) +/- 146 (sys.) nb-1. In contrast with other SLD precision measurements of the effective weak mixing angle, which are sensitive to the ratio gVe/gAe, this result independently determines gVe and gAe. The analysis techniques to measure gVe and gAe are described, and the results are compared with other SLD measurements as well as other experiments.
- Publication:
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Ph.D. Thesis
- Pub Date:
- 2003
- Bibcode:
- 2003PhDT.......104L