The inclusive cross section for production of isolated photons has been measured in \pbarp collisions at $\sqrt{s} = 630$ GeV with the \D0 detector at the Fermilab Tevatron Collider. The photons span ...a transverse energy range ($E_T$) from 7-49 GeV and have pseudorapidity $|\eta| 2.5$. This preliminary measurement is combined with our previous result at $\sqrt{s} = 1800$ GeV to form a ratio of the cross sections. Comparison of next-to-leading order QCD with the measured cross section at 630 GeV and ratio of cross sections show satisfactory agreement in most of the $E_T$ range.
We report on a measurement of the ratio of the differential cross sections for W and Z boson production as a function of transverse momentum in proton-antiproton collisions at sqrt(s) = 1.8 TeV. This ...measurement uses data recorded by the D0 detector at the Fermilab Tevatron in 1994-1995. It represents the first investigation of a proposal that ratios between W and Z observables can be calculated reliably using perturbative QCD, even when the individual observables are not. Using the ratio of differential cross sections reduces both experimental and theoretical uncertainties, and can therefore provide smaller overall uncertainties in the measured mass and width of the W boson than current methods used at hadron colliders.
Bottom quark production in pbar-p collisions at sqrt(s)=1.8 TeV is studied with 5 inverse picobarns of data collected in 1995 by the DO detector at the Fermilab Tevatron Collider. The differential ...production cross section for b jets in the central rapidity region (|y(b)| < 1) as a function of jet transverse energy is extracted from a muon-tagged jet sample. Within experimental and theoretical uncertainties, DO results are found to be higher than, but compatible with, next-to-leading-order QCD predictions. (arXiv)
The ital WWgamma gauge boson couplings were measured using ital pbar pr arrowlnugamma+ital X (l=ital e,mu) events at radicalital s=1.8 TeV observed with the D0 detector at the Fermilab Tevatron ...Collider. The signal, obtained from the data corresponding to an integrated luminosity of 13.8pbsup minus1, agrees well with the standard model prediction. A fit to the photon transverse energy spectrum yields limits at the 95% confidence level on the ital CP-conserving anomalous coupling parameters of minus1.6ltDeltakappalt1.8 (lambda=0) and minus0.6ltlambdalt0.6 (Deltakappa=0). Similar limits are obtained for the ital CP-violating coupling parameters.
First experimental results are presented from a search for events with a rapidity gap between jets. The D0 detector was used to examine events produced by the Fermilab Tevatron ital pbar p collider ...at radicalital s =1.8 TeV. The fraction of events with an observed rapidity gap between the two highest transverse energy (ital Esub ital T) jets is measured as a function of the pseudorapidity separation between the jet edges (Deltaetasub ital c). An upper limit at the 95% confidence level of 1.1times10sup minus2 is obtained on the fraction of events with non particles between the jets, for events with Deltaetasub ital cgt3 and jet ital Esub ital T greater than 30 GeV.
We have searched for evidence of top quark production in ital pbar p collisions at radicalital s =1.8 TeV using the ital D0 detector at the Fermilab Tevatron collider. For an integrated luminosity of ...15 pbsup minus1, we report results of a search for ital tbar t pairs in the decay modes ital tbar tr arrowital emu+jets,ital ee+jets,ital e+jets, and mu+jets. From analyses of these modes we obtain a lower limit on the top quark mass of 131 GeV/ital csup 2 at the 95% confidence level, assuming standard model branching fractions and a predicted cross section for ital tbar t production. We discuss the properties of an event for which expected backgrounds are small.
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