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 University of Arizona Tucson, AZ University of Arizona Tucson, AZ DØ Collaboration Batavia, IL DØ Collaboration Batavia, IL 1999 D  Workshop June 27 - July 2, D  Workshop June 27 - July 2, 1999 University of Washington Seattle Washington USA University of Washington Seattle Washington USA

1999 D  Workshop Seattle, Washington29 June 1999 To be published in Phys. Rev. Lett. 82, 2451 (1999) Also see hep-ex/ To be published in Phys. Rev. Lett. 82, 2451 (1999) Also see hep-ex/ The DØ Central Inclusive Jet Cross Section DØ Run 1B m 0.0    0.5  JETRAD statistical errors only PDF, substructure, … ? d 2  /dE T d  ETET l How well do we know proton structure (PDF)? l Is NLO ( ) QCD “sufficient”? l Are quarks composite?

1999 D  Workshop Seattle, Washington29 June 1999 Inclusive Jet Cross Section as a Test of the Standard Model (pQCD) Inclusive Jet Cross Section as a Test of the Standard Model (pQCD) Single Inclusive Jets:

1999 D  Workshop Seattle, Washington29 June 1999 Data Sample Run #  December 1993  July 1995 Run #  December 1993  July 1995 Run 1B The four single jet triggers are used for different jet E T ranges where at least 99% efficient: The four single jet triggers are used for different jet E T ranges where at least 99% efficient: Jet_30: Jet_50: Jet_85: Jet_Max: Jet_30: Jet_50: Jet_85: Jet_Max: E T ~ 60  90 GeV E T ~ 90  130 GeV E T ~ 130  170 GeV E T ~ 170  Max GeV E T ~ 60  90 GeV E T ~ 90  130 GeV E T ~ 130  170 GeV E T ~ 170  Max GeV Jet_30 Jet_50 Jet_85Jet_Max Luminosity profiles of Run 1B single jet filters: Luminosity profiles of Run 1B single jet filters:

1999 D  Workshop Seattle, Washington29 June 1999 Jet Production and Reconstruction Time parton jet particle jet calorimeter jet hadrons  CH FH EM RECO v.12 l Fixed-cone jets l Add up towers l Iterative process l Jet quantities RECO v.12 l Fixed-cone jets l Add up towers l Iterative process l Jet quantities Corrections to RECO :  AIDA Cell Restoration  H T Re-vertexing  Total  -Bias Correction (TEB)  AIDA Cell Restoration  H T Re-vertexing  Total  -Bias Correction (TEB)

1999 D  Workshop Seattle, Washington29 June 1999 Effects of RECO Effects of D  vs. Snowmass definitions SNPJ SNCJ D  CJD  PJ 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 For any jet quantity ( , , E T,... ), 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: Origin of  -Bias

1999 D  Workshop Seattle, Washington29 June 1999 < > 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. Closer Look at  -Bias

1999 D  Workshop Seattle, Washington29 June 1999 Total  -Bias Correction Closure  R < 0.7 E T > 10 GeV All energies before the correction  after the correction TEB parameterized as a function of  in various bins of jet energy. (1) Snow/D  -- same E T. (2) RECO  bias does not cause different towers to be assigned to the jet -- no E T bias. Jet  only is corrected for TEB because: TEB parameterization closure is excellent! Total  -Bias Correction

1999 D  Workshop Seattle, Washington29 June 1999 Highest E T dijet event at DØ Data Selection 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). 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). Acceptance: |Z vrt | < 50 cm  ~ 90% Acceptance: |Z vrt | < 50 cm  ~ 90% Event Quality:  ~ % Jet Quality Cuts (  comb =  EMF   CHF   HCF ~ %):

1999 D  Workshop Seattle, Washington29 June 1999 Luminosity Dependence Ruled Out      No significant Lum. dep. of the “shape” established For the “shape” dependence, studied ratios of E T 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.:

1999 D  Workshop Seattle, Washington29 June 1999 The Jet Energy Scale Correction (JES) Goal: Calorimeter jet  Particle jet (Energy correction) No central tracking B field at DØ  Jet calibration real challenge JES has been verified by an independent test based on E T balance in the  -jet and jet-jet sub-samples JES has been verified by an independent test based on E T balance in the  -jet and jet-jet sub-samples To be published in Nucl. Instr. Meth. A424, 352 (1999) Offset (O): Ur noise, pileup, & underlying event Showering (1/S cone ): out-of-cone shower losses Response (Rjet): E meas / E true (from E T balance in  -jet data) CH FH EM hadrons  Cafix 5.2

1999 D  Workshop Seattle, Washington29 June 1999 Jet Energy Scale Closure Test x y  or Jet 1 Jet 2 Jet 3 Based on P T balance in  -jet and jet-jet data.  -jet and jet-jet data in excellent agreement in the region of overlap. Major systematics of the jet-jet method: (a) Resolution Bias. (b) UnClustered Energy (UCE) Correction. R is to be studied as a function of forward jet energy in various jet  regions.

1999 D  Workshop Seattle, Washington29 June 1999 Resolution Bias and UCE Correction The new variable: removes bias to within 0.5  1%. The UCE correction (~0.5  1.5%) derived entirely from the data and confirmed in the MC study.

1999 D  Workshop Seattle, Washington29 June 1999 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

1999 D  Workshop Seattle, Washington29 June 1999 E T : 210  240 GeV 0.0    0.5 Cafix 5.2 Asymmetry Entries “observed”“true” “smearing” “unsmearing” or “unfolding” E0E0 Dijet Asymmetry: In case of small     Z When  Z  0 consider Same Side (SS) and Opposite Side (OS) dijet events separately!... but need to consider effects of  E &  Z separately!... but need to consider effects of  E &  Z separately! Resolutions and Smearing

1999 D  Workshop Seattle, Washington29 June 1999 Measuring Jet Energy Resolutions Select good dijet events: (1) “back-to-back”  cut. (2) E T 3 cut. Fit Asymmetry to Gaussian. Apply Soft Radiation Correction by extrapolating resolutions obtained with various E T 3 cuts down to “ideal” dijet with E T 3 = 0. 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. 1.5    2.0, Cafix 5.2, E T : 95  150 GeV Derivation of Soft Radiation Correction E T 3 < 8 GeV E T 3 < 12 GeV E T 3 < 10 GeV E T 3 < 15 GeV E T 3 < 20 GeV Extrapolation to E T 3 = 0 GeV Asymmetry E T (GeV)

1999 D  Workshop Seattle, Washington29 June 1999 Jet Energy Resolutions 0.0                3.0 Jet energy resolutions are measured from SS dijet Asymmetry and are parameterized as a function of jet E T in various  regions.

1999 D  Workshop Seattle, Washington29 June 1999 Effects of Vertex Resolution l 0.5    1.0 l 0.0    0.5 l 1.0    1.5 l 1.5    2.0 l 2.0    3.0 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! Effect on the cross section is ~ 1 - 2% in ALL  regions  negligible!

1999 D  Workshop Seattle, Washington29 June 1999 Unfolding of Jet Energy Resolutions The Ansatz function smeared by energy resolutions is fitted to data fixing the four free parameters.

1999 D  Workshop Seattle, Washington29 June 1999 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 E T bin and  region. Unfolding Correction for all  Regions

1999 D  Workshop Seattle, Washington29 June 1999 E T (GeV)  d 2  dE T d  (fb/GeV) l 0.0    0.5 H 0.5    1.0 s 1.0    1.5 n 1.5    2.0 t 2.0    3.0 DØ Preliminary Run 1B Nominal cross sections & statistical errors only Rapidity Dependence of the Inclusive Jet Cross Section Rapidity Dependence of the Inclusive Jet Cross Section

1999 D  Workshop Seattle, Washington29 June 1999 E T (GeV) Fractional Errors (%) 0.0          1.5 Sources of Systematic Uncertainties DØ Preliminary Run 1B E T (GeV) 1.5       3.0  Total  Jet Energy Scale  Resolutions & Unfolding  Luminosity  Selection efficiency

1999 D  Workshop Seattle, Washington29 June 1999 E T (GeV) Fractional Errors (%) 0.0          1.5 Sources of Systematic Uncertainties

1999 D  Workshop Seattle, Washington29 June 1999 E T (GeV) Fractional Errors (%) Sources of Systematic Uncertainties 1.5       3.0  Total  Jet Energy Scale  Resolutions & Unfolding  Luminosity  Selection efficiency

1999 D  Workshop Seattle, Washington29 June 1999 l 0.5    1.0 l 0.0    0.5 l 1.0    1.5 E T (GeV) DØ Preliminary Comparisons to Theoretical ( JETRAD ) Predictions DØ Preliminary ( Data - Theory ) / Theory l 1.5    2.0 l 2.0    3.0 DØ Preliminary E T (GeV) Comparisons to JETRAD with: PDF: CTEQ3M R sep = 1.3 Good agreement with theory over seven orders. Deviations from QCD at highest E T not significant within errors. Good agreement with theory over seven orders. Deviations from QCD at highest E T not significant within errors.

1999 D  Workshop Seattle, Washington29 June 1999 l 0.5    1.0 l 0.0    0.5 l 1.0    1.5 E T (GeV) DØ Preliminary Comparisons to Theoretical ( JETRAD ) Predictions DØ Preliminary ( Data - Theory ) / Theory PDF: CTEQ3M R sep = 1.3 DØ Preliminary

1999 D  Workshop Seattle, Washington29 June 1999 Comparisons to Theoretical ( JETRAD ) Predictions ( Data - Theory ) / Theory l 1.5    2.0 l 2.0    3.0 DØ Preliminary E T (GeV) Comparisons to JETRAD with: PDF: CTEQ3M R sep = 1.3

1999 D  Workshop Seattle, Washington29 June 1999 Summary Reported on Rapidity Dependence of the Inclusive Jet Production Cross Section (up to |  | of 3.0). Good agreement with NLO pQCD is observed with no statistically significant discrepancy. Summary Reported on Rapidity Dependence of the Inclusive 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. 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.

1999 D  Workshop Seattle, Washington29 June 1999 Data Sample The four single jet triggers are used for different jet E T ranges where at least 99% efficient: The four single jet triggers are used for different jet E T ranges where at least 99% efficient: Run #  December 1993  July 1995 Run #  December 1993  July 1995 Run 1B Jet_30: Jet_50: Jet_85: Jet_Max: Jet_30: Jet_50: Jet_85: Jet_Max: E T ~ 60  90 GeV E T ~ 90  130 GeV E T ~ 130  170 GeV E T ~ 170  Max GeV E T ~ 60  90 GeV E T ~ 90  130 GeV E T ~ 130  170 GeV E T ~ 170  Max GeV Jet_30 Jet_50 Jet_85 Jet_Max Instantaneous luminosity profiles of Run 1B single jet filters Instantaneous luminosity profiles of Run 1B single jet filters Jet_30 & Jet_50 were matched to Jet_85: single interac. requirement introduced ineff. in lowest triggers additional error of 1.8% & 1.1% resp. Jet_30 & Jet_50 were matched to Jet_85: single interac. requirement introduced ineff. in lowest triggers additional error of 1.8% & 1.1% resp.

1999 D  Workshop Seattle, Washington29 June 1999 Corrections to RECO - AIDA Cell Restoration Hot Cell Killer AIDA was implemented first online, then offline in RECO during Run 1B Hot Cell Killer AIDA was implemented first online, then offline in RECO during Run 1B AIDA removed “isolated” cells with E T >10 GeV and > 20x average ET of longitudinal neighbors AIDA removed “isolated” cells with E T >10 GeV and > 20x average ET of longitudinal neighbors Unfortunately most often this resulted in damaging good jets! ~ 5% of 200 GeV, increasing to ~15% at 400 GeV, suffer suppression (Luckily, forward jets are damaged less because of AIDA “bug”) Unfortunately most often this resulted in damaging good jets! ~ 5% of 200 GeV, increasing to ~15% at 400 GeV, suffer suppression (Luckily, forward jets are damaged less because of AIDA “bug”) To repair the damage: (1) First identify cells correctly removed by AIDA (2) Restore the remaining cells if  R < 0.7 & ETFR < 50% To repair the damage: (1) First identify cells correctly removed by AIDA (2) Restore the remaining cells if  R < 0.7 & ETFR < 50% These restoration criteria resulted from: (1) the detailed study of the AIDA effects & (2) fine tunings of the restoration algorithm at all |  |  3.0. These restoration criteria resulted from: (1) the detailed study of the AIDA effects & (2) fine tunings of the restoration algorithm at all |  |  3.0.

1999 D  Workshop Seattle, Washington29 June 1999 Corrections to RECO - H T Revertexing Multiple interactions at highest luminosities may lead to mis-vertexing. H T -revertexing correction chooses the correct primary vertex -- the one with minimal H T, when two vertices have been reconstructed. Multiple interactions at highest luminosities may lead to mis-vertexing. H T -revertexing correction chooses the correct primary vertex -- the one with minimal H T, when two vertices have been reconstructed.

1999 D  Workshop Seattle, Washington29 June 1999 Luminosity Dependence

1999 D  Workshop Seattle, Washington29 June 1999 JES Closure (  -jet and jet-jet)

1999 D  Workshop Seattle, Washington29 June 1999 JES Closure (Cafix 5.1 vs. Cafix 5.2) with Cafix 5.2  with Cafix 5.1

Uncertainties in Theoretical Predictions 2R 1.3R NLO QCD predictions  s 3  Ellis, Kunszt, Soper, Phys. Rev. D, 64, (1990) Aversa, et al., Phys. Rev. Lett., 65, (1990) Giele, Glover, Kosower, Phys. Rev. Lett., 73, (1994) JETRAD Choices ( hep-ph/ , Eur. Phys. J. C. 5, ): Renormalization Scale (10%) PDFs (~20% with E T dependence) Clustering Alg. (5% with E T dependence) D0 uses: JETRAD  0.5E T Max, R rsep =1.3 CDF uses: EKS  F =  R =0.5E T Jet, R sep =2.0

x-Q 2 Range of the Tevatron Jet Data