Professor Daniela Bortoletto

Abstract:

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 B→J/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 sin2β=0.19-0.44+0.41(stat+syst). This value of sin 2β is consistent with the standard model prediction, based upon existing measurements, of a large positive CP-violating asymmetry in this decay mode. ©2000 The American Physical Society.

Abstract:

We report the first direct measurement of bb̄ rapidity correlations in pp̄ collisions at √=1.8 TeV. We select events with a high transverse momentum muon accompanied by a jet, and a second jet associated with a decay vertex displaced from the pp̄ interaction vertex. Two independent samples are obtained corresponding to events with a forward (2.0<|η|<2.6) or central (|η|<0.6) muon. We measure the ratio of forward to central bb̄ production to be 0.361±0.033(stat)-0.031+0.015(syst), in good agreement with the next-to-leading order QCD prediction 0.338-0.097+0.014. ©2000 The American Physical Society.