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Inclusive Jet Production at the Tevatron, PDFs, and the Search for New Physics

Inclusive Jet Production at the Tevatron, PDFs, and the Search for New Physics. Hung-Liang Lai. Taipei Municipal Teachers College, TAIWAN. Motivation/Introduction Uncertainty analysis of the inclusive jet x-section at the Tevatron Reliability of NLO prediction Room for new Physics

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Inclusive Jet Production at the Tevatron, PDFs, and the Search for New Physics

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  1. Inclusive Jet Production at the Tevatron, PDFs, and the Search for New Physics Hung-Liang Lai Taipei Municipal Teachers College, TAIWAN Motivation/Introduction Uncertainty analysis of the inclusive jet x-section at the Tevatron Reliability of NLO prediction Room for new Physics Prediction for Run II Summary Work in collaboration with: J. Huston, S. Kuhlmann, J. Owens, J. Pumplin, D. Stump, and W.K.Tung. (arXive: hep-ph/0303013) Hung-Liang Lai (hllai@tmtc.edu.tw) Talk given at Hard QCD session, EPS03

  2. Motivation/Introduction • Jet production cross-sections at hadron colliders probe the shortest distances available in the laboratories. • Jet X-section is sensitive to Gluon distribution. • Better determination of G(x,Q) provides better predictions of many new physics processes at higher energies. • Any deviation from QCD predictions at high energies can indicate signals for new physics.

  3. Uncertainties of PDFs: CTEQ6

  4. Subprocess contributions to jet production

  5. CTEQ: JHEP 2002 0207:012 HEPDATA: http://durpdg.dur.ac.uk/hepdata/pdf3.html MRST: hep- ph/ 0211080 Quantifying uncertaintiesSystematic error propagation and uncertainty studies: • Effective (Hessian and Lagrangian) methods in the Global Analysis context developed by Pumplin, Stump, et.al. (CTEQ): These were first applied to the CTEQ5/6 analyses (2001/2002); • They have now also been adopted by the MRST2002 analysis.

  6. D0 D0 D0 D0 CDF D0 Current Hadronic inclusive jet cross-section (Tevatron Run I) and Parton uncertainties (CTEQ6.1)

  7. Range of gluon distribution spanned by eigenvector sets 15- and 15+

  8. Theoretical uncertainties on Jet Inclusive Xsec (effect is largest at large rapidities) “NLO + 2-loop”: based on threshold resummation results of:

  9. Comparison of gluon distributions fitted in different scales

  10. L = 1.6, 2.0, 2.4 TeV Calculation involves re-doing the global fits with the new interaction Limits on New Physics Curves: New Physics with (effective) contact term interactions.

  11. Comparison: prediction vs. first data from Tevatron Run II • 8 orders of magnitude! • Highest ET jets ever! (CDF collaboration, hep-ex/0304211)

  12. Comparison: prediction vs. preliminary data -- linear plot Good agreement (within uncertainties)

  13. (D0 collaboration, hep-ex/0305072)

  14. Summary • The uncertainties on the jet cross section predictions still remain sizable, primarily due to the uncertainty on gluon. They are comparable to current experimental uncertainties. • With better consistency between experimental data and theoretical calculations, we have produced an improved version of the CTEQ6 PDFs --- CTEQ6.1. • Scale dependence and higher order corrections are estimated to be well within the PDF uncertainty band. • The allowed range for any new physics such as compositeness model must have a scale larger than 1.6 TeV, given the Run 1 jet data.

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