1 / 22

Exploring Diboson Physics at CDF: Anomalous Couplings and Measurements

This presentation by Alberto Annovi from INFN-Frascati details the potential of diboson production as a unique probe of triple gauge couplings. Utilizing data from the CDF detector at Fermilab's Tevatron, the study focuses on measuring the couplings between gluons, W, and Z bosons, which can vary with q². The talk covers significant results from W+γ and Z+γ production, including event selections and the sensitivity of these measurements to anomalous couplings. The extensive analysis provides insights into the behavior of dibosons and their implications for particle physics.

annona
Télécharger la présentation

Exploring Diboson Physics at CDF: Anomalous Couplings and Measurements

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Diboson physics @ CDF  Alberto Annovi INFN - Frascati

  2. The CDF detector @ Fermilab Muon Extension ||<1.1 Central Muon ||<0.6 Solenoid Fwd Muon 1<||<1.5 m e HAD Calorimeter Drift Chamber EM Calorimeter Silicon Microstrip Tracker Alberto Annovi, INFN - Frascati n e

  3. Physic Motivation • Dibosons are a unique probe of the triple gauge couplings • Measure the couplings between g , W, and Z • Couplings can depend on the q2 • Tevatron has the highest q2 available • Anomalous couplings can affect cross-sections and kinematics pp  H WW, pp -> WH -> Wbb ..may be hiding in the diboson data Alberto Annovi, INFN - Frascati

  4. W + g production Event selection: W  lepton + n g with ET>7 GeV, DR(l, g)>0.7 Sensitive to WWg aTGC http://www-cdf.fnal.gov/physics/ewk/2007/wgzg/ Alberto Annovi, INFN - Frascati

  5. Z+g production & aTGC limits 1 fb-1 (ee), 2 fb-1 (mm) • Sensitive to ZZg aTGC • Event selection: • 2 leptons (ET>20 GeV) • mll > 40 GeV • central photon ET>7 GeV • DR (lep-g) > 0.7 ISR FSR http://www-cdf.fnal.gov/physics/ewk/2008/Zgamma/ σobs = 4.6 ± 0.2 (stat) pb ± 0.3 (syst) ± 0.3 (lum) σNLO = 4.5 ± 0.3 pb s(ISR): Mμμγ > 100 GeV/c2 σobs = 1.2 ± 0.1 (stat) ± 0.2 (syst) ± 0.1 (lum) pb Alberto Annovi, INFN - Frascati

  6. a WW  llnn event @ CDF Neutrinos show up as missing transverse energy WW will produce em events, while Drell-Yan is only ee and mm

  7. WW  llnn data selection Events prediction and backgrounds • Trigger lepton ET (pT) > 20 GeV • Second lepton ET (pT) > 10 GeV • Include also isolated tracks • Supress ttbar  WWbbbar <= 0 jets (ET>15 GeV, |h|<2.5) • Drell-Yan is O(105) bigger suppress w/ Missing ET transv. to each lepton (jet) > 25 GeV • (> 15 GeV) for em events • Mll> 16 GeV suppress HF Systematic errors only Alberto Annovi, INFN - Frascati

  8. WW Cross Section with 3.6 fb-1 Likelihood fit of Matrix Element Likelihood ratio MCFM used for Matrix elements input WW xsec @ 15% !! MC@NLO + CTEQ6.6 PRD78, 013008 Analysis web page: http://www-cdf.fnal.gov/physics/ewk/wwllll/index.html

  9. Extended leptons All multi-leptons (e, m) analyses use extened leptons to increase acceptance Alberto Annovi, INFN - Frascati

  10. WZ xsec & WWZ aTGC Select events with 3 leptons + Z l l + W  l + n Sensitivity to the WWZ vertex coupling. Unique access to WWZ separately from the WWγ coupling. Alberto Annovi, INFN - Frascati

  11. WZ production results http://www-cdf.fnal.gov/physics/ewk/2007/WZ_2fb/ s(WZ) = NLO cross section 3.7 ± 0.3 pb Alberto Annovi, INFN - Frascati

  12. WWZ aTGC limits from Z0 pT 1D limits 2D limits http://www-cdf.fnal.gov/physics/ewk/2008/WZatgc/ High-pT region sensitive to aTGC Alberto Annovi, INFN - Frascati

  13. Z0Z0 production Expected s*BR O(10fb) Two signatures: • Z0Z0 l+l-l+l- • Intensive use of extended leptons • s*BR ≈ 6.3 fb • Z0Z0 l+l- + • s*BR ≈ 38 fb Alberto Annovi, INFN - Frascati

  14. Z0Z0 production 2 leptons + MET combined 4lep 2lep+MET s(Z0Z0) = NLO prediction is s(Z0Z0) = 1.4 ± 0.1 pb http://www-cdf.fnal.gov/physics/ewk/2008/ZZ/ PRL 100, 201801 (2008) Alberto Annovi, INFN - Frascati

  15. aTGC in ZW/ZZ events Zll + W/Z  jets Data with MC expectations (Z+jets) • Trigger lepton ET (pT) > 20 GeV • Second lepton ET (pT) > 10 GeV • Include also isolated tracks • 76 < Mll < 106 GeV • suppress non Z production • 2 jets (cone DR<0.4, |h|<2.5) • select the 2 highest pT jets Med pT mJJ Use 3 pT(Zll) bins aTGC Med pT High-pT High-pT SM control 140 pT(Zll) mJJ

  16. aTGC in ZW and ZZ events BKG + LEP limit (medium pt bin) 95% CL limits on s(ZW+ZZ) by Z0 pT mJJ High pt bin fit (result -0.13±0.20) http://www-cdf.fnal.gov/physics/ewk/2008/ZZZatGC/ZZZaTGC.html … 2008/WWZaTGC/ Full table of aTGC limits in backup slide Alberto Annovi, INFN - Frascati

  17. WZ+WW -> lnjj (1.2fb-1) RESULTS: NN selection cut NSignal = 410 ± 212(stat) ± 107(sys) events σ × Br = 1.47 ± 0.77(stat) ± 0.38(sys) pb 95% CL σ × Br < 2.88 pb SM: σ × Br = 2.09 ± 0.14 pb http://www-cdf.fnal.gov/physics/ewk/2008/wwwz/ Update in progress: see APS meeting in Denver mJJ

  18. Search for VV  MET + jets WW, WZ, ZZ Four Pillars of This Analysis • Select jj+MET events • Benefited from L2 met/cal trigger upgrade • doi: 10.1109/NSSMIC.2006.354160 • Acceptance to νν and lνevents (WW, WZ, ZZ) • QCD rejection: MetModel • Reduced to only 16% out of selected events • Remaining QCD: based on Δφ(calMET-trkMET) • EWK mJJ shape: checked with γ+jj • Significantly reduces systematics n j n, lep j • SELECTION: • MET > 60 GeV • 2 jets ET>25, |h|<2.0 • MET significance > 4 • MET-jet df > 0.4 Alberto Annovi, INFN - Frascati

  19. First Had. Coll. Observation of VV  leptons + jets Dibosonphyics entered the jet era!!! 5.3s significance s(WW+WZ+ZZ) 18.0 ± 2.8(stat) ± 2.4(syst) ± 1.1(lumi) pb SM: 16.8±0.5 pb (MCFM + CTEQ6M) PRL just submitted! arXiv:0905.4714 Fermilab result of the week: http://www.fnal.gov/pub/today/

  20. Conclusions • Significant DiBoson samples being collected • Measuring Triple Gauge Couplings at high-q2 • First observation of diboson with leptons+jets • Opens the way to diboson studies with jets • The Higgs is getting closer CDF preliminary includes recent updates of published papers Alberto Annovi, INFN - Frascati

  21. BACKUP Alberto Annovi, INFN - Frascati

  22. aTGC limits from ZW and ZZ ZZ Alberto Annovi, INFN - Frascati

More Related