From a sample of about 75000 τ decays identified with the ALEPH detector, K 0 production in 1-prong hadronic decays is investigated by tagging the K L 0 component in a hadronic calorimeter. Results are given for the final states ν τ h − K 0 and ν τ h − π 0 K 0 where the h − is separated into π and K contributions by means of the dE / dx measurement in in the central detector. The resulting branching ratios are: ( Bτ → ν τ π − K 0 ) = (0.88±0.14±0.09)%, ( Bτ → ν τ K − K 0 ) = (0.29±0.12±0.03)%, ( Bτ → ν τ π − π 0 K 0 ) = (0.33±0.14±0.07)% aand ( Bτ → ν τ K − π 0 K 0 ) = (0.05±0.05±0.01)%. The K ∗ decay rate in the K 0 π channel agrees with that in the Kπ 0 mode: the combined value for the branching ratio is (Bτ → ν τ K ∗− ) = (1.45±0.13±0.11)% .
Invariant mass distribution for the $K^0\pi$ system data. The numbers have been read from the plot in the paper.
Form a sample of about 75000 τ decays measured in the ALEPH detector, 1-prong charged kaon decays are identified by the dE / dx measurement in the central detector. The resulting branching ratios for the inclusive and exclusive modes are: B ( τ → ν τ K − ≥ 0 π 0 ≥ 0 K 0 ) = (1.60±0.07±0.12)%, B ( τ → ν τ K − = (0.64±0.05±0.05)%, B ( τ → ν τ − π 0 = (0.53±0.05±0.07)% and B ( τ → ν τ K − π 0 π 0 ) = (0.04±0.03±0.02)%. Exclusive modes are corrected for measured K L 0 production. The rate for τ → ν τ K − agrees well with the prediction based on τ - μ universality.
Invariant mass distribution of the $K\pi^0$ final state, as obtained from a $dE/dx$ fit in each mass bin. The numbers have been read from the plot in the paper, with the errors simply set to zero if they are smaller than the point size.
The dijet invariant mass distribution has been measured in the region between 120 and 1000 GeV/c2, in 1.8-TeV pp¯ collisions. The data sample was collected with the Collider Detector at Fermilab (CDF). Data are compared to leading order (LO) and next-to-leading order (NLO) QCD calculations using two different clustering cone radii R in the jet definition. A quantitative test shows good agreement of data with the LO and NLO QCD predictions for a cone of R=1. The test using a cone of R=0.7 shows less agreement. The NLO calculation shows an improvement compared to LO in reproducing the shape of the spectrum for both radii, and approximately predicts the cone size dependence of the cross section.
Observed cross section using R = 1.0. The second systematic error is the theoretical uncertainty and includes only the effect of the out-of-cone losses, the underlying event energy, and the contribution of multi-jet events.
Observed cross section using R = 0.7. The second systematic error is the theoretical uncertainty and includes only the effect of the out-of-cone losses, the underlying event energy, and the contribution of multi-jet events.
The first prompt photon measurement from the CDF experiment at the Fermilab pp¯ Collider is presented. Two independent methods are used to measure the cross section: one for high transverse momentum (PT) and one for lower PT. Comparisons to various theoretical calculations are shown. The cross section agrees qualitatively with QCD calculations but has a steeper slope at low PT.
Cross section using profile method and an isolation cut of 2 GeV in a cone around the photon. There is an additional 27 pct systematic uncertainty in addition to the PT dependent systematic errors shown in the table.
Cross section using conversion method and an isolation cut of 2 GeV in a cone around the photon. There is an additional +32,-46 pct systematic uncertainty in addition to the PT dependent systematic errors shown in the table.
Cross section using profile method and an isolation cut of 15 pct of the photon PT in a cone around the photon. There is an additional 29 pct systematic uncertainty in addition to the PT dependent systematic errors shown in the table.
A measurement of the QCD jet-broadening parameter 〈QT〉 is described for high-ET jet data in the central calorimeter of the Collider Detector at Fermilab. As an alternate approach to clustering analysis, 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 QT is defined as the scalar sum of the transverse momentum perpendicular to the transverse thrust axis. Parton-level QCD predictions are made for 〈QT〉 as a function of ET, the total transverse energy in the events, and suggest that a measurement would show a dependence on the running of the strong coupling constant αs. Comparisons are made to first-order QCD parton-level calculations, as well as to fully evolved and hadronized leading-log simulations. The data are well described by the QCD predictions.
A small asymmetry in the systematic uncertainty has been ignored. Given here are the average values.
We present the dijet invariant-mass distribution in the region between 60 and 500 GeV, measured in 1.8-TeV p¯p 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<MA<210 GeV for axigluon width ΓA=NαsMA6, with N=5.
Corrected mass distributions for jets restricted to the pseudorapidity region ABS(ETARAP) <0.7.
Measurements of inclusive transverse-momentum spectra for KS0 mesons produced in proton-antiproton collisions at s of 630 and 1800 GeV are presented and compared with data taken at lower energies. The ratio, as a function of pT, of the cross section for KS0 to that for charged hadrons is very similar to what is observed at lower energies. At 1800 GeV, we calculate the strangeness-suppression factor λ=0.40±0.05.
Estimated effective cross sections for events which pass the trigger and selection criteria. The uncertainties in these represent the principal source of error in the overall normalisation of the results.
Statistical errors only.
Statistical errors only.
Inclusive jet production at s=1.8 TeV has been measured in the CDF detector at the Fermilab Tevatron p¯p Collider. Jets with transverse energies (Et) up to 250 GeV have been observed. The Et dependence of the inclusive jet cross section is consistent with leading-order quantum-chromodynamic calculations, and comparison with lower-energy data shows deviations from scaling consistent with QCD. A lower limit of 700 GeV (95% confidence level) is placed on the quark compositeness scale parameter Λc associated with an effective contact interaction.
No description provided.
The cross section for the production and subsequent decay to electron and neutrino of the W intermediate vector boson has been measured in 1.8-TeV p¯p collisions at the Fermilab Tevatron Collider. An analysis of events with missing transverse energy greater than 25 GeV and with an electron of transverse energy greater than 15 GeV from a datum sample of 25.3 nb−1 gives σB=2.6±0.6±0.5 nb.
Branching ratio to electron and neutrino.
We have measured dijet angular distributions at √s =1.8 TeV with the Collider Detector at Fermilab and the Tevatron p¯p Collider and find agreement with leading-order QCD. By comparing the distribution for the highest dijet invariant masses with the prediction of a model of quark compositeness, we set a lower limit on the associated scale parameter Λc at 330 GeV (95% C.L.).
Numerical values read from figure in preprint.
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