Measurement of the Polarized Forward � Backward
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چکیده
We present a direct measurement of the parity-violating parameter A b by analyzing the left-right forward-backward asymmetry of b quarks in e + e ; !Z 0 ! bb. The SLD experiment observes hadronic decays of Z 0 bosons produced at resonance in collisions of longitudinally polarized electrons and unpolarized positrons at the SLC. Heavy avor decays of the Z 0 are identiied by using the topologically reconstructed mass of B hadrons. The asymmetry A b is measured with a self-calibrating technique employing momentum-weighted track charge from both hemispheres in the tagged events. From our 1994{1995 sample of 3.6 pb ;1 of e + e ; annihilation data with a luminosity-weighted average e ; polarization of 77%, and our 1993 sample of 1.8 pb ;1 with a luminosity-weighted polarization of 63%, we obtain A b = 0 :911 0:045(stat.)0:045(syst.).
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