Measurement of the polarized forward-backward asymmetry of Z{sup 0} yields b{bar b} using a lifetime tag and momentum-weighted track charge
The authors present a direct measurement of the parity-violating parameter A{sub b} by analyzing the left-right forward-backward asymmetry of b quarks in e(+)e({minus}) yields Z{sup 0} yields b{bar b}. The SLD experiment observes hadronic decays of Z{sup 0} bosons produced at resonance in collisions of longitudinally polarized electrons and unpolarized positrons at the SLC. Heavy flavor decays of the Z{sup 0} are identified by taking advantage of the long lifetime of B hadrons, the small, stable SLC beam spot, and precise tracking from SLD. The asymmetry A{sub b} is measured with a self-calibrating technique employing momentum-weighted track charge from both hemispheres in the tagged events. From the 1994--1995 sample of 3.6 pb{sup {minus}1} of e(+)e({minus}) annihilation data with a luminosity-weighted average e({minus}) polarization of 77.3%, and the 1993 sample of 1.8 pb{sup {minus}1} with a luminosity-weighted polarization of 63.1%, the authors obtain A{sub b}(preliminary) = 0.843 +/- 0.046(stat. ) +/- 0.051(syst.).
- Research Organization:
- Stanford Linear Accelerator Center, Menlo Park, CA (United States)
- DOE Contract Number:
- AC03-76SF00515
- OSTI ID:
- 382978
- Report Number(s):
- SLAC-PUB--95-6979; CONF-950705--34; DE--96-002433; NIPS--96-34994
- Country of Publication:
- United States
- Language:
- English
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