Measurement of the polarized forward-backward asymmetry of B quarks using momentum-weighted track charge at SLD [Thesis]
- Stanford Univ., CA (United States)
This thesis presents a direct measurement of the parity-violating parameter Ab by analyzing the polarized forward-backward asymmetry of b quarks in e+e- → Z0 → b$$\bar{b}$$. Data were taken at the Stanford Linear Accelerator Center (SLAC), with the Stanford Large Detector (SLD), which records the products of e+e- interactions at a center of mass energy √s = 91.2 GeV/c2 at the SLAC Linear Collider (SLC). The SLC/SLD experimental apparatus provides a unique and ideal environment for measuring electroweak asymmetries. Heavy flavor decays of the Z0 were identified inclusively by taking advantage of the long lifetime of B hadrons, the small, stable SLC beam spot, and SLD`s precise tracking detectors. Two analysis techniques for measuring Ab are presented: a binned fit to the left-right forward-backwards asymmetry of tagged events signed with momentum-weighted track charge, and a self-calibrating maximum-likelihood technique using momentum-weighted charge from the two hemispheres in each tagged event. From our 1994-1995 sample of 3.6 pb-1, having a luminosity-weighted average e- polarization of 77.3%, and our 1993 sample of 1.8 pb-1, having a luminosity-weighted polarization of 63.1%, we obtain Ab = 0.848 ± 0.046(stat.) ± 0.050(syst.).
- Research Organization:
- SLAC National Accelerator Laboratory (SLAC), Menlo Park, CA (United States)
- Sponsoring Organization:
- USDOE
- DOE Contract Number:
- AC03-76SF00515
- OSTI ID:
- 206415
- Report Number(s):
- SLAC-R-95-476; SLAC-R-476; ON: DE96003806; TRN: 96:009194
- Resource Relation:
- Other Information: TH: Thesis (Ph.D.); PBD: Nov 1995
- Country of Publication:
- United States
- Language:
- English
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