Constraints on PDF uncertainties from CDF DIS 2006, Tsukuba 22.04.2006 Cigdem Issever for the CDF Collaboration University of Oxford

Outline Introduction Tevatron & CDF detector EWK Results (95% of the talk) Jet results (see talk “Inclusive jet production at the Tevatron (CDF)” of Olga Norniella in (HFS-5)) Conclusion DIS 2006 22.04.06 C. Issever

Tevatron proton-antiproton collisions s = 1.96 TeV (Run I  1.8 TeV) Main Injector (new) Tevatron DØ CDF Chicago  p source Booster Tevatron proton-antiproton collisions s = 1.96 TeV (Run I  1.8 TeV) 36 bunches: 396 ns crossing time Peak luminosity is now ~ 1032 cm-2 s-1 Ultimately 4 – 9 fb-1 by 2009 DIS 2006 22.04.06 C. Issever

CDF Recorded Data 1.6 fb-1 delivered EWK results 1.2 fb-1 recorded Jet results with 1.0 fb-1 1.6 fb-1 delivered 1.2 fb-1 recorded EWK results DIS 2006 22.04.06 C. Issever

CDF RUN II Detector Upgraded for RUN II New silicon tracking PLUG Muon New drift chamber Increased muon coveraged New TOF New plug calorimeters Muon COT Tracker Si Detector PLUG EM Cal Had Cal CDF Data taking effi 80% - 85%. Silicon Detector DIS 2006 22.04.06 C. Issever

EWK Physics – Input to PDFs Motivation Test SM (precise measurements) Constraints on PDFs Search for physics beyond SM Important input to LHC Outlook W forward cross section, 223/pb Z →ττ and μμ cross Section, 330/pb W charge asymmetry, 170/pb DIS 2006 22.04.06 C. Issever

W/Z Gauge Bosons Identification At hadronic collider W and Z bosons hadronic decays are overwhelmed by QCD background.  identification through leptonic decays We Z ET>20GeV PT>20GeV Position of μ consistent with extrapolated track ET>25GeV PT>20GeV W± signature: Isolated Energetic Lepton + ET Z Signature: Two Isolated Energetic Leptons (opposite charge) DIS 2006 22.04.06 C. Issever

W cross section in the forward region Extension into forward region: 1.2 < |η| < 2.8 using calorimeter seeded tracking Complementary to central DIS 2006 22.04.06 C. Issever

W cross section in the forward region Systematics on A = 0.2567: 48165 ~4.8% 2% 0.07 Axε DIS 2006 22.04.06 C. Issever

W cross section in the forward region 223pb-1 σ = 2.796 +/-0.013(stat) + 0.095 – 0.090 (syst) +/- 0.168 (lum.)nb. NNLO σ(pp→W) @ 1.96 TeV, Stirling, van Neerven = 2.687 +- 0.054(Th) DIS 2006 22.04.06 C. Issever

Central-to-Forward W vis. cross section ratio s(visible)=sTOT*A where A is the kin. and geo accept. Strategy: assign sys uncertainties but PDF, NLO/NNLO effect to svis In this way: Most of the luminosity uncertainty cancels in the ratio All other uncertainties are uncorrelated Accuracy can be used to constrain PDFs DIS 2006 22.04.06 C. Issever

Central-to-Forward W vis. cross section ratio svis(central) =664.2±11.7 pb (Ete>25, ETn>25, |hele|<1) svis(forward) =718±21 pb (Ete>20, ETn>25, 1.2<|hele|<2.8) svis(central)/svis(forward) =0.925±0.033 1% assigned as luminosity syst. (slightly overestimate) NLO ratios (taking into account correlations between central and forward): CTEQ= 0.9243±0.037 MRST01E= 0.94137±0.011 Most uncertainties will go down with more data  useful to constrain PDFs DIS 2006 22.04.06 C. Issever

Z → μμ cross section (|η| < 1) using 337 pb-1 116 66 σ=261.2 ± 2.7 (stat) + 5.8 - 6.9 (sys) ± 15.1 (lum) pb NNLO @ 1.96 TeV Stirling, van Neerven σ(pp→Z)=251.3+-0.5(Th) DIS 2006 22.04.06 C. Issever

Z →τe τh cross section using 349 pb-1 316 signal events 60 % τ identification efficiency and 5% acceptance Most systematics are data driven will be reduced with more stat. σ=265+-20(stat)+-21(syst)+-15(lumi) pb DIS 2006 22.04.06 C. Issever

Cross section summary new DIS 2006 22.04.06 C. Issever

W Charge Asymmetry e+ W+ W- W+ n yW proton anti-proton W- W+ yW proton antiproton Asymmetry in W production complicated by unknown n pz use lepton asymmetry: which convolves W production with V-A decay. DIS 2006 22.04.06 C. Issever

W Charge Asymmetry Run II 170pb-1 A as function of ET provides better probe of x dependence. Statistic allowed two bins. Will be included into next generation of PDFs. DIS 2006 22.04.06 C. Issever

W Charge Asymmetry – new method Lepton asymmetry has turn over at high |η| due to V-A W charge asymmetry does not have this effect, so we don’t purely probe high yW Determination of yW with W mass constrain gives 2 possible solutions. Evaluate weight factor F1,2 for each y1,2 solution. Parameterize F1,2 with the angular distribution of (1+-cosΘ*)2 with W cross section, σ(yW), but this depends on asymmetry Iterative procedure!! DIS 2006 22.04.06 C. Issever

W charge asymmetry – new method Iterative procedure Smaller statistical errors Greater sensitivity No additional systematics due to new method DIS 2006 22.04.06 C. Issever

Midpoint jet cross section Good agreement with NLO More details see talk of Olga Norniella in (HFS-5): Jets 1 DIS 2006 22.04.06 C. Issever

Results with KT: Data/NLO; 1fb-1 IR and CL safe No splitting or merging Measurements in the forward region will allow to reduce the PDFs uncertainties DIS 2006 22.04.06 C. Issever

New generation of W&Z measurements (R, W Charge Asymmetry, … ) Conclusions New cross section measurements from CDF W → eν in forward region (1.2 < |η| < 2.8) using 223 pb-1 Central-to-forward W vis cross section ratio Z → μμ using 337 pb-1 Z → τe τh using 349pb-1 Inclusive Jets with Mitpoint using 1.04 fb-1 Inclusive Jet s with Kt algorithm using 0.96 fb-1 Excellent base for next set of analyses dσ/dy for W → eν dσ/dpt for Z → μμ Tau widely used in SM measurements and SUSY, Higgs New generation of W&Z measurements (R, W Charge Asymmetry, … ) on the way !! DIS 2006 22.04.06 C. Issever

Backup Slides DIS 2006 22.04.06 C. Issever

W forward cross section Electron: Et > 20GeV 1.2 < |η |<2.8 Neutrino: MEt > 25 GeV Vertex: |z0| < 60 cm Electron ID: Had/Em<0.05 Isolation<0.1  Δ(XPES,XTrk) < 3 cm  Δ(YPES,YTrk) < 3 cm E/P < 2.0 DIS 2006 22.04.06 C. Issever

Z → μμ cross section (|η| < 1) DIS 2006 22.04.06 C. Issever

Z →τe τh cross section taus difficult to reconstruct at hadron colliders Z→ττ exploits event topology to suppress backgrounds (QCD&W+jet) CDF strategy for hadronic tau reconstruction: Charge tracks  define signal and isolation cone (shrinking cone vs. E) isolation: require no tracks in isolation cone Hadronic calorimeter cluster (to suppress e background) π0 required in isolation cone (identified by shower maximum detector) = 30o Z→ττ event selection: τ→e: electron + isolated track (ET>10 GeV) τ→h: PT(seed) > 6 GeV & PT(signal)>15 GeV remove backgrounds by event topology cuts DIS 2006 22.04.06 C. Issever

Z→ττ cross section DIS 2006 22.04.06 C. Issever

Z→ττ cross section -- Systematics DIS 2006 22.04.06 C. Issever

W Asymmetry – new method Leading order W production from Bo Young Han DIS 2006 22.04.06 C. Issever

ratio of two angular distributions at each rapidity I. The angular distribution of ( )2 from W production in Collin-Soper frame The W production Probability from angular distribution ratio of two angular distributions at each rapidity from Bo Young Han DIS 2006 22.04.06 C. Issever

II. Weight must also depend on W+- cross-section. But cross-sections depend on W asymmetry! This method must be iterated. III. Iteration procedure Input data reconstruction measuring asymmetry if no, min( ) F1 Fn the closest asymmetry to data assumed sample new assumed sample No Yes from Bo Young Han DIS 2006 22.04.06 C. Issever

Sensitivity Study Selecting W events , 400pb-1 MC data generated by Pythia Selecting W events high PT electron : ET > 25 GeV Missing ET > 25 GeV Used CTEQ6M errors PDF 40 sets for PDF uncertainty Comparison of statistical uncertainty between lepton and W boson asymmetry Our method has statistical sensitivity to probe PDFs from Bo Young Han DIS 2006 22.04.06 C. Issever

Systematic Uncertainty Weight Factors depend on Q(yW, PtW) and σ(yW) Ratio of two angular distributions, Q(yW, PtW) PDF dependence W cross section, σ(yW) from Bo Young Han DIS 2006 22.04.06 C. Issever

Systematic Uncertainty (cont.) The uncertainties from the energy measurement Energy scale Energy resolution (not yet) Electron ET scale ±0.1%(1σ) : |η| < 1.1 ±0.15%(1σ) : |η| > 1.1 Missing ET scale W boson Recoil energy tuning from Bo Young Han DIS 2006 22.04.06 C. Issever