The DO Collaboration has measured the inclusive jet cross section in proton-antiproton collisions at s**2 = 630 GeV. The results for pseudorapidities -0.5 to 0.5 are combined with our previous results at s**2 = 1800 GeV to form a ratio of cross sections with smaller uncertainties than either individual measurement. Next-to-leading-order QCD predictions show excellent agreement with the measurement at 630 GeV; agreement is also satisfactory for the ratio. Specifically, despite a 10% to 15% difference in the absolute normalization, the dependence of the ratio on jet transverse momentum is very similar for data and theory.
Inclusive jet cross section at 630 GeV.
Ratio of cross section at 630 and 1800 GeV (from PRL 82, 2451 (1999)).
The transition between photoproduction and deep-inelastic scattering is investigated in jet production at the HERA ep collider, using data collected by the H1 experiment. Measurements of the differential inclusive jet cross-sections dsigep/dEt* and dsigmep/deta*, where Et* and eta* are the transverse energy and the pseudorapidity of the jets in the virtual photon-proton centre of mass frame, are presented for 0 < Q2 < 49 GeV2 and 0.3 < y < 0.6. The interpretation of the results in terms of the structure of the virtual photon is discussed. The data are best described by QCD calculations which include a partonic structure of the virtual photon that evolves with Q2.
The ET differential jet cross section in the virtual-photon CM frame.
The ET differential jet cross section in the virtual-photon CM frame.
The ET differential jet cross section in the virtual-photon CM frame.
We present a measurement of the differential cross section dσ/dΣETjet for the production of multijet events in pp¯ collisions where the sum is over all jets with transverse energy ETjet>ETmin. The measured cross section for events with ΣETjet>320GeV is compared to O(αs3) perturbative QCD predictions and QCD parton shower Monte Carlo predictions. The agreement between the O(αs3) predicted and observed event rates is reasonable for ETmin=100GeV, but poorer for ETmin=20GeV.
The ET shown here (unless specified otherwise) is the sum of all the jets' individual ETs. All jets are required to have the absolute values of their pseudorapidity < 4.2 and data are given for two different minimum ET cut-offs.. The errors given are statistical only.
Integrated cross sections. Again ET is the sum of the individual ETs of thejets.
The inclusive jet differential cross section has been measured for jet transverse energies, $E_T$, from 15 to 440 GeV, in the pseudorapidity region 0.1$\leq | \eta| \leq $0.7. The results are based on 19.5 pb$~{-1}$ of data collected by the CDF collaboration at the Fermilab Tevatron collider. The data are compared with QCD predictions for various sets of parton distribution functions. The cross section for jets with $E_T>200$\ GeV is significantly higher than current predictions based on O($\alpha_s~3$) perturbative QCD calculations. Various possible explanations for the high-$E_T$\ excess are discussed.
No description provided.
Properties of the hadronic final state in photoproduction events with large transverse energy are studied at the electron-proton collider HERA. Distributions of the transverse energy, jets and underlying event energy are compared to $\overline{p}p$ data and QCD calculations. The comparisons show that the $\gamma p$ events can be consistently described by QCD models including -- in addition to the primary hard scattering process -- interactions between the two beam remnants. The differential jet cross sections $d\sigma/dE_T~{jet}$ and $d\sigma/d\eta~{jet}$ are measured.
No description provided.
Additional overall systematic error of 26 pct.
Additional overall systematic error of 26 pct.
The inclusive jet cross section in photoproduction has been measured as a function of transverse energy and pseudorapidity using the H 1 detector at the HERA electron-proton collider. The results are compared with leading order QCD calculations.
No description provided.
No description provided.
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