Jeff Tseng

Abstract:

We present a measurement of the cross section for production of two or more jets as a function of dijet mass, based on an integrated luminosity of 86 pb^-1 collected with the Collider Detector at Fermilab. Our dijet mass spectrum is described within errors by next-to-leading order QCD predictions using CTEQ4HJ parton distributions, and is in good agreement with a similar measurement from the DØ experiment. ©2000 the American Physical Society.

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.

Abstract:

Events collected by the Collider Detector at Fermilab (CDF) with an energetic jet plus large missing transverse energy can be used to search for physics beyond the standard model. We see no deviations from the expected backgrounds and set upper limits on the production of new processes. We consider in addition the production of light gravitinos and set a limit at 95% F ≥ 217GeV, which excludes gravitino masses smaller than 1.1 × 10−5eV/c2. © 2000 American Physical Society.

Abstract:

We have measured the polarization of J/ψ and ψ(2S) mesons produced in pp collisions at √ = 1.8 TeV using data collected at the Collider Detector at Fermilab during 1992–1995. The polarization of promptly produced J/ψ [ψ(2S)] mesons is isolated from those produced in B-hadron decay and measured over the kinematic range 4 [5.5] < PT < 20 GeV/c and |y| < 0.6. For PT ≾ 12 GeV/c we do not observe significant polarization in the prompt component. © 2000 The American Physical Society.