High-p_T Jets in pbarp Collisions at sqrt{s} = 630 and 1800 GeV

TL;DR

DO tests of perturbative QCD using high-pT jets in pbarp collisions at 630 and 1800 GeV compare inclusive jet cross sections, dijet mass spectra, and dijet angular distributions to NLO predictions across multiple PDFs and renormalization scales. The analysis demonstrates good agreement with SM QCD, while placing competitive limits on quark compositeness and coloron scenarios; it additionally develops a robust jet-energy calibration, resolution unfolding, and systematic-uncertainty framework. The ratio of cross sections at the two energies provides a stringent, largely PDF-insensitive cross-check of QCD matrix elements. Overall, the results strengthen confidence in SM predictions at Tevatron energies and tighten constraints on beyond-Standard-Model physics in the jet sector.

Abstract

Results are presented from analyses of jet data produced in pbarp collisions at sqrt{s} = 630 and 1800 GeV collected with the DO detector during the 1994-95 Fermilab Tevatron Collider run. We discuss details of detector calibration, and jet selection criteria in measurements of various jet production cross sections at sqrt{s} = 630 and 1800 GeV. The inclusive jet cross sections, the dijet mass spectrum, the dijet angular distributions, and the ratio of inclusive jet cross sections at sqrt{s} = 630 and 1800 GeV are compared to next-to-leading-order QCD predictions. The order alpha_s^3 calculations are in good agreement with the data. We also use the data at sqrt{s} = 1800 GeV to rule out models of quark compositeness with a contact interaction scale less than 2.2 TeV at the 95% confidence level.

Figures (105)

• Figure 1: The $x$ and $Q^2$ range of the data set analyzed by the DØ experiment at $\sqrt{s} = 1.8$ TeV (DØ [8] and CDF [7] Inclusive Jets with $\hbox{$\mid \! \eta \! \mid$} < 0.7$) compared with the data used to produce PDFs [27]. Also shown is the extended $x$ and $Q^2$ reach of the DØ measurement of the inclusive jet cross section with $\hbox{$\mid \! \eta \! \mid$} < 3$ as presented in Ref. [26].
• Figure 2: A schematic view of one quarter of the DØ calorimeters. The shading pattern indicates the distinct readout cells. The rays indicate the pseudorapidity intervals defined from the center of the detector.
• Figure 3: The average difference between the $\hbox{$\mid \! \eta \! \mid$}$ of jets reconstructed using the DØ algorithm and the Snowmass algorithm for DØ data.
• Figure 4: Illustration and description of the jet definitions at NLO parton level as used by the DØ experiment. a) The jet definition in NLO according to Snowmas. Parton -1- and -2- are combined into jet -J-, if the parton distance to the jet axis is less than R. The jet axis is defined by partons 1 and 2, according to the Snowmass definition. b) The jet definition in NLO according to the modified Snowmass with ${\mathcal{R}}_{\rm sep}$ . Use the standard Snowmass clustering, but in addition require the distance between the two partons to be less than ${\mathcal{R}}_{\rm sep}$ .
• Figure 5: Seed tower distributions for ${\cal{R}}=0.7$ cone jets with an $E_{\rm T}$ range of 18--20 GeV. The data is represented by the solid histogram and the fit is given by the dashed curve.