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Levan Babukhadia

1999 D  Workshop June 27 - July 2, 1999. University of Washington Seattle Washington USA. This presentation will probably involve audience discussion, which will create action items. Use PowerPoint to keep track of these action items during your presentation

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Levan Babukhadia

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  1. 1999 D Workshop June 27 - July 2, 1999 University of Washington Seattle Washington USA This presentation will probably involve audience discussion, which will create action items. Use PowerPoint to keep track of these action items during your presentation • In Slide Show, click on the right mouse button • Select “Meeting Minder” • Select the “Action Items” tab • Type in action items as they come up • Click OK to dismiss this box This will automatically create an Action Item slide at the end of your presentation with your points entered. Levan Babukhadia http://www-d0.fnal.gov/~blevan/stl99/index.htm University of Arizona Tucson, AZ DØ Collaboration Batavia, IL

  2. How well do we know proton structure (PDF)? • Is NLO ( ) QCD “sufficient”? • Are quarks composite? • 0.0    0.5 • JETRAD statistical errors only PDF, substructure, … ? To be published in Phys. Rev. Lett. 82, 2451 (1999) Also see hep-ex/9807018 DØ Run 1B d2/dET d ET The DØ Central Inclusive Jet Cross Section

  3. Single Inclusive Jets: Inclusive Jet Cross Section as a Test of the Standard Model (pQCD)

  4. Run 1B Run # 72250  93115 December 1993  July 1995 Jet_50 Jet_30 The four single jet triggers are used for different jet ET ranges where at least 99% efficient: Jet_30: Jet_50: Jet_85: Jet_Max: ET ~ 60  90 GeV ET ~ 90  130 GeV ET ~ 130  170 GeV ET ~ 170  Max GeV Jet_85 Jet_Max Data Sample Luminosity profiles of Run 1B single jet filters:

  5. CH calorimeter jet hadrons FH  EM particle jet Time Corrections to RECO: parton jet • AIDA Cell Restoration • HT Re-vertexing • Total -Bias Correction (TEB) Jet Production and Reconstruction • RECO v.12 • Fixed-cone jets • Add up towers • Iterative process • Jet quantities

  6. Effects of RECO SNPJ SNCJ Effects of D vs. Snowmass definitions DPJ DCJ Origin of -Bias For any jet quantity (,  , ET , ... ), one of the five biases from the cartoon on the left (i.e.  with corresponding super- and subscripts, also represented by a vector) is defined as:  = 1 - 2, where 1 is the jet quantity at the endpoint of the corresponding vector and 2 is the quantity at the origin of the vector. It is also obvious that following hold: SNPJ - Particle Jets Reconstructed with Snowmass Accord SNCJ - Calorimeter Jets Reconstructed with Snowmass Accord DPJ - Particle Jets Reconstructed with D Algorithm DCJ - Calorimeter Jets Reconstructed with D Algorithm

  7. < > Closer Look at -Bias Herwig-Showerlib MC. Biases due to algorithms and reconstruction go in opposite directions, nearly canceling each other out. The residual or the Total of these two is what we measure and correct for.

  8. Total -Bias Correction Closure • before the correction • after the correction R < 0.7 ET > 10 GeV All energies Total -Bias Correction TEB parameterized as a function of  in various bins of jet energy. Jet  only is corrected for TEB because: (1) Snow/D -- same ET. (2) RECO  bias does not cause different towers to be assigned to the jet -- no ET bias. TEB parameterization closure is excellent!

  9. Highest ET dijet event at DØ Event Quality:  ~ 98 - 99% Data Selection Acceptance: |Zvrt| < 50 cm  ~ 90% Jet Quality Cuts (comb = EMF CHF HCF ~ 98 - 99%): • EMF < 0.95 in the ICR, 0.05 < EMF < 0.95 everywhere else. • CHF < 0.60 in the ICR, CHF < 0.40 everywhere else. • HCF > 0.05 everywhere (applied on non-restored jets only).

  10. No significant Lum. dep. of the “shape” established 2.0  |h| < 3.0 1.5  |h| < 2.0 1.0  |h| < 1.5 0.5  |h| < 1.0 0.0  |h| < 0.5 Luminosity Dependence Ruled Out For the “shape” dependence, studied ratios of ET spectra from low, high, medium, and total inst. Lum. sub-samples: For the “normalization” dep., studied ratios from various Lum. sub-samples by Runs, recalculating integrated Lum.:

  11. Offset (O): Ur noise, pileup, & underlying event • Showering (1/Scone): out-of-cone shower losses CH hadrons FH  EM • Response (Rjet): Emeas / Etrue (from ET balance in -jet data) The Jet Energy Scale Correction (JES) To be published in Nucl. Instr. Meth. A424, 352 (1999) Goal: Calorimeter jetParticle jet (Energy correction) No central tracking B field at DØJet calibration real challenge Cafix 5.2 JES has been verified by an independent test based on ET balance in the -jet and jet-jet sub-samples

  12. y Major systematics of the jet-jet method: g or Jet 1 (a) Resolution Bias. (b) UnClustered Energy (UCE) Correction. x Jet 2 Jet 3 Jet Energy Scale Closure Test Based on PT balance in g -jet and jet-jet data. g -jet and jet-jet data in excellent agreement in the region of overlap. R is to be studied as a function of forward jet energy in various jet  regions.

  13. The new variable: The UCE correction (~0.5  1.5%) derived entirely from the data and removes bias to within 0.5  1%. confirmed in the MC study. Resolution Bias and UCE Correction

  14. Results of the JES Closure Test Cafix 5.2 Closure good within the uncertainties of JES (2  5%) and the test itself (1  1.5%), and Cafix 5.2 does better at highest  than Cafix 5.1. We recommend this Closure test as a standard for verifying any future D JES. Cafix 5.2 Cafix 5.2 Cafix 5.2 Cafix 5.2 Cafix 5.2 Cafix 5.2

  15. “smearing” “true” “observed” “unsmearing” or “unfolding” E0 Resolutions and Smearing Dijet Asymmetry: In case of small   Z When Z  0 consider Same Side (SS) and Opposite Side (OS) dijet events separately! ET: 210  240 GeV 0.0    0.5 Cafix 5.2 Entries ... but need to consider effects of E & Z separately! Asymmetry

  16. Measuring Jet Energy Resolutions Select good dijet events: (1) “back-to-back”  cut. (2) ET3 cut. Derivation of Soft Radiation Correction 1.5    2.0, Cafix 5.2, ET: 95  150 GeV ET3 < 8 GeV ET3 < 10 GeV Fit Asymmetry to Gaussian. Apply Soft Radiation Correction by extrapolating resolutions obtained with various ET3 cuts down to “ideal” dijet with ET3 = 0. Asymmetry Asymmetry ET3 < 15 GeV ET3 < 12 GeV Subtract Particle Level Imbalance (PLI) measured from Herwig MC: even in the particle level, dijets do not perfectly balance due to the finite cone-size and particles fluctuating outside algorithm cone. Asymmetry Asymmetry Extrapolation to ET3 = 0 GeV ET3 < 20 GeV Asymmetry ET (GeV)

  17. Jet Energy Resolutions 0.0    0.5 0.5    1.0 1.0    1.5 Jet energy resolutions are measured from SS dijet Asymmetry and are parameterized as a function of jet ET in various  regions. 1.5    2.0 2.0    3.0

  18. Effects of Vertex Resolution Effects of non-zero Z studied in JETRAD. Conservative estimate of Z measured from the differences in SS/OS asymmetry resolutions is 7.5 cm. Study ratios of raw cross sections from Jetrad with and without vertex smearing of Z = 7.5 cm. Effect on the cross section is ~ 1 - 2% in ALL  regions  negligible! • 0.0    0.5 • 0.5    1.0 • 1.5    2.0 • 1.0    1.5 • 2.0    3.0

  19. Unfolding of Jet Energy Resolutions The Ansatz function smeared by energy resolutions is fitted to data fixing the four free parameters.

  20. Unfolding Correction for all  Regions Unfolding correction is given by bin-by-bin ratio of the ”true” to smeared ansatz functions. Data is re-scaled by these factors in every ET bin and h region.

  21. DØ Preliminary Run 1B • 0.0    0.5 • 0.5    1.0 • 1.0    1.5 • 1.5    2.0 • 2.0    3.0 d2 dET d (fb/GeV) Nominal cross sections & statistical errors only ET (GeV) Rapidity Dependence of the Inclusive Jet Cross Section

  22. Sources of Systematic Uncertainties DØ Preliminary Run 1B  Total  Jet Energy Scale  Resolutions & Unfolding  Luminosity  Selection efficiency 0.0    0.5 0.5    1.0 1.5    2.0 Fractional Errors (%) 1.0    1.5 2.0    3.0 ET (GeV) ET (GeV)

  23. Sources of Systematic Uncertainties 0.0    0.5 0.5    1.0 Fractional Errors (%) 1.0    1.5 ET (GeV)

  24. Sources of Systematic Uncertainties  Total  Jet Energy Scale  Resolutions & Unfolding  Luminosity  Selection efficiency 1.5    2.0 Fractional Errors (%) 2.0    3.0 ET (GeV)

  25. PDF: CTEQ3M Rsep= 1.3 Comparisons to Theoretical (JETRAD) Predictions Comparisons to JETRAD with: Good agreement with theory over seven orders. Deviations from QCD at highest ET not significant within errors. • 0.0    0.5 DØ Preliminary • 1.5    2.0 • 0.5    1.0 ( Data - Theory ) / Theory DØ Preliminary DØ Preliminary • 2.0    3.0 • 1.0    1.5 DØ Preliminary DØ Preliminary ET (GeV) ET (GeV)

  26. PDF: CTEQ3M Rsep= 1.3 Comparisons to Theoretical (JETRAD) Predictions • 0.0    0.5 DØ Preliminary • 0.5    1.0 ( Data - Theory ) / Theory DØ Preliminary • 1.0    1.5 DØ Preliminary DØ Preliminary ET (GeV)

  27. PDF: CTEQ3M Comparisons to JETRAD with: Rsep= 1.3 Comparisons to Theoretical (JETRAD) Predictions • 1.5    2.0 DØ Preliminary ( Data - Theory ) / Theory • 2.0    3.0 DØ Preliminary ET (GeV)

  28. Summary • Reported on Rapidity Dependence of theInclusive Jet Production Cross Section(up to | | of 3.0). • Good agreement with NLO pQCD is observed with no statistically significant discrepancy. Outlook Error correlation MC study underway to facilitate quantitative Data to Theory comparisons (such as the 2 tests). First draft of the paper ready by the end of summer.

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