Measurement of [formula presented] rapidity correlations in [formula presented] collisions at [formula presented]
Physical Review D - Particles, Fields, Gravitation and Cosmology 61:3 (2000)
Abstract:
We report the first direct measurement of (Formula presented) rapidity correlations in (Formula presented) collisions at (Formula presented) 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 (Formula presented) interaction vertex. Two independent samples are obtained corresponding to events with a forward (Formula presented) or central (Formula presented) muon. We measure the ratio of forward to central (Formula presented) production to be (Formula presented) in good agreement with the next-to-leading order QCD prediction (Formula presented) © 1999 The American Physical Society.Measurement of the helicity of W bosons in top quark decays
Physical review letters 84:2 (2000) 216-221
Abstract:
We use the transverse momentum spectrum of leptons in the decay chain t-->bW with W-->lnu to measure the helicity of the W bosons in the top quark rest frame. Our measurement uses a t&tmacr; sample isolated in 106+/-4 pb(-1) of data collected in p&pmacr; collisions at sqrt[s] = 1.8 TeV with the CDF detector at the Fermilab Tevatron. Assuming a standard V-A weak decay, we find that the fraction of W's with zero helicity in the top rest frame is F0 = 0.91+/-0. 37(stat)+/-0.13(syst), consistent with the standard model prediction of F0 = 0.70 for a top mass of 175 GeV/c(2).Observation of diffractive b-quark production at the fermilab tevatron
Physical review letters 84:2 (2000) 232-237
Abstract:
We report a measurement of the fraction of b quarks produced diffractively in &pmacr;p collisions at sqrt[s] = 1.8 TeV. Diffraction is identified by the absence of particles in a forward pseudorapidity region. From events with an electron of transverse momentum 9.5Search for a fourth-generation quark more massive than the Z0 boson in p&pmacr; collisions at radicals = 1.8 TeV
Physical review letters 84:5 (2000) 835-840
Abstract:
We present the results of a search for pair production of a fourth-generation charge -1 / 3 quark (b(')) in sqrt[s] = 1.8 TeV p&pmacr; collisions using 88 pb(-1) of data obtained with the Collider Detector at Fermilab. We assume that both quarks decay via the flavor-changing neutral current process b(')-->bZ(0) and that the b(') mass is greater than m(Z)+m(b). We studied the decay mode b(')b(');-->Z(0)Z(0)b&bmacr; where one Z0 decays into e(+)e(-) or &mgr;(+)&mgr;(-) and the other decays hadronically, giving a signature of two leptons plus jets. An upper limit on the sigma(p&pmacr;-->b(')b(');)x[B(b(')-->bZ(0))](2) is established as a function of the b(') mass. We exclude at 95% confidence level a b(') quark with mass between 100 and 199 GeV/c(2) for B(b(')-->bZ(0)) = 100%.Transverse momentum and total cross section of e(+)e(-) pairs in the Z-boson region from p&pmacr; collisions at sqrt
Physical review letters 84:5 (2000) 845-850