Research Papers in Physics and Astronomy


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Published by American Physical Society. Phys. Rev. D 61, 072005 (2000). Copyright © 2000 American Physical Society. Permission to use.


This paper reports an updated measurement of the standard model CP violation parameter sin 2β using the CDF Detector at Fermilab. The entire run I data sample of 110 pb-1 of proton-antiproton collisions at √s =1.8 TeV is used to identify a signal sample of ≈400 BJ/ ψKs0 events, where J/ψ→ μ+μ- and Ks0→ π+ π-. The flavor of the neutral B meson is identified at the time of production by combining information from three tagging algorithms: a same-side tag, a jet-charge tag, and a soft-lepton tag. A maximum likelihood fitting method is used to determine sin 2 β =0.79-0.44+0.41 (stat+syst). This value of sin 2 β is consistent with the standard model prediction, based upon existing measurements, of a large positive CP-violating asymmetry in this decay mode.

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