Dijet mass spectrum and a search for quark compositeness in (p)p collisions at sqrt(s) = 1.8 TeV
Physical Review Letters 82:12 (1999) 2457-2462
Abstract:
Using the DZero detector at the 1.8 TeV pbarp Fermilab Tevatron collider, we have measured the inclusive dijet mass spectrum in the central pseudorapidity region |eta_jet| < 1.0 for dijet masses greater than 200 Gev/c^2. We have also measured the ratio of spectra sigma(|eta_jet| < 0.5)/sigma(0.5 < |eta_jet| < 1.0). The order alpha_s^3 QCD predictions are in good agreement with the data and we rule out models of quark compositeness with a contact interaction scale < 2.4 TeV at the 95% confidence level. © 1999 The American Physical Society.Evidence of color coherence effects in W + jets events from pp collisions at √s = 1.8 TeV
Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics 464:1-2 (1999) 145-155
Abstract:
We report the results of a study of color coherence effects in pp collisions based on data collected by the DØ detector during the 1994-1995 run of the Fermilab Tevatron Collider, at a center of mass energy √s = 1.8 TeV. Initial-to-final state color interference effects are observed by examining particle distribution patterns in events with a W boson and at least one jet. The data are compared to Monte Carlo simulations with different color coherence implementations and to an analytic modified-leading-logarithm perturbative calculation based on the local parton-hadron duality hypothesis. © 1999 Published by Elsevier Science B.V. All rights reserved.Exclusive electroproduction of ρ0 and J/ψ mesons at HERA
European Physical Journal C 6:4 (1999) 603-627
Abstract:
Exclusive production of ρ0 and J/ψ mesons in e+p collisions has been studied with the ZEUS detector in the kinematic range 0.25 < Q2 < 50 GeV2, 20 < W < 167 GeV for the ρ0 data and 2 < Q2 < 40 GeV2, 50 < W < 150 GeV for the J/ψ data. Cross sections for exclusive ρ0 and J/ψ production have been measured as a function of Q2, W and t. The spin-density matrix elements r04Forward jet production in deep inelastic scattering at HERA
European Physical Journal C 6:2 (1999) 239-252
Abstract:
The inclusive forward jet cross section in deep inelastic e+p scattering has been measured in the region of cursive Greek chi-Bjorken, 4.5 · 10-4 to 4.5 · 10-2. This measurement is motivated by the search for effects of BFKL-like parton shower evolution. The cross section at hadron level as a function of cursive Greek chi is compared to cross sections predicted by various Monte Carlo models. An excess of forward jet production at small cursive Greek chi is observed, which is not reproduced by models based on DGLAP parton shower evolution. The Colour Dipole model describes the data reasonably well. Predictions of perturbative QCD calculations at the parton level based on BFKL and DGLAP parton evolution are discussed in the context of this measurement.Inclusive jet cross section in p̄p collisions at √ = 1.8 TeV
Physical Review Letters 82:12 (1999) 2451-2456