[en] A measurement of the QCD jet-broadening parameter left-angle Q_T right-angle is described for high-E_T jet data in the central calorimeter of the Collider Detector at Fermilab. This method involves the use of a global event parameter which is free from the ambiguities associated with the definition and separation of individual clusters. The parameter Q_T is defined as the scalar sum of the transverse momentum perpendicular to the transverse thrust axis. Parton-level QCD predictions are made for left-angle Q_T right-angle as a function of E_T, the total transverse energy in the events, and suggest that a measurement would show a dependence on the running of the strong coupling constant α_s. Comparisons are made to first-order QCD parton-level calculations, as well as to fully evolved and hadronized leading-log simulations

[en] We present the dijet invariant-mass distribution in the region between 60 and 500 GeV, measured in 1.8-TeV bar pp collisions in the Collider Detector at Fermilab. Jets are restricted to the pseudorapidity interval |η|<0.7. Data are compared with QCD calculations; axigluons are excluded with 95% confidence in the region 120< M_A<210 GeV for axigluon width Γ_A=Nα_sM_A/6, with N=5

[en] The two-jet differential cross section d³σ(bar pp→jet 1+jet 2+X)/dE_tdη₁dη₂, averaged over -0.6≤η₁≤0.6, at √s =1.8 TeV, has been measured in the Collider Detector at Fermilab. The predictions of leading-order quantum chromodynamics for most choices of structure functions show agreement with the data

[en] We present measurements of the pseudorapidity (η) distribution of charged particles (dN_ch/dη) produced with |η|≤3.5 in proton-antiproton collisions at √s of 630 and 1800 GeV. We measure dN_ch/dη at η=0 to be 3.18±0.06(stat)±0.10(syst) at 630 GeV, and 3.95±0.03(stat)±0.13(syst) at 1800 GeV. Many systematic errors in the ratio of dN_ch/dη at the two energies cancel, and we measure 1.26±0.01±0.04 for the ratio of dN_ch/dη at 1800 GeV to that at 630 GeV within |η|≤3. Comparing to lower-energy data, we observe an increase faster than ln(s) in dN_ch/dη at η=0

[en] The charged-particle fractional momentum distribution within jets, D(z), has been measured in dijet events from 1.8-TeV bar pp collisions in the Collider Detector at Fermilab. As expected from scale breaking in quantum chromodynamics, the fragmentation function D(z) falls more steeply as dijet invariant mass increases from 60 to 200 GeV/c². The average fraction of the jet momentum carried by charged particles is 0.65±0.02(stat)±0.08(syst)

[en] The production rate of charged D^* mesons in jets has been measured in 1.8-TeV bar pp collisions at the Fermilab Tevatron with the Collider Detector at Fermilab. In a sample of approximately 32 300 jets with a mean transverse energy of 47 GeV obtained from an exposure of 21.1 nb^-1, a signal corresponding to 25.0±7.5(stat)±2.0(syst) D^*±→K^minus-plusπ^±π^± events is seen above background. This corresponds to a ratio N(D^*++D^*-)/N(jet) =0.10±0.03±0.03 for D^* mesons with fractional momentum z greater than 0.1