1 / 30

Boson Pair Production + Triple Gauge Couplings

Boson Pair Production + Triple Gauge Couplings. Results from the Tevatron San Miniato - April, 1997 WW g /WWZ Couplings W g Production WW/WZ Production ZZ g /Z gg Couplings Z g Production Prospects for Run II Summary. Tom Diehl for the D0 and CDF Collaborations.

zeheb
Download Presentation

Boson Pair Production + Triple Gauge Couplings

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. Boson Pair Production + Triple Gauge Couplings Results from the Tevatron San Miniato - April, 1997 WWg/WWZ Couplings Wg Production WW/WZ Production ZZg/Zgg Couplings Zg Production Prospects for Run II Summary Tom Diehl for the D0 and CDF Collaborations

  2. Standard Model Gauge Boson Interactions • Self-interactions are direct consequence of the non-abelian SU(2)L x U(1)Y gauge symmetry. • SM makes specific predictions. • Cancellation of t and u -channel by s-channel amplitude removes tree-level unitarity violation.

  3. Non-SM WWZ/WWg Interaction • Characterized by effective Lagrangian • CP Conserving SM Parameters: lZ = 0 lg = 0 Dk = k-1 g1Z = 1 DkZ= 0 Dkg= 0 • Static Properties QeW=-e/2 M2W(k-l) mW=e/2 MW(1+k+l)

  4. Effect of non-SM Couplings • Cross section increases especially for High ET bosons (W/Z/g). • Unitarity Violation avoided. e.g.: • L is a form factor scale WW Production s(WW) PT(W)

  5. CDF (67pb-1) |he|<1.1 |hm|<0.6 |hg|<1.1 GeV D0 (93 pb-1) |he|<1.1 |hm|<1.0 1.5<|he|<2.5 Same |h| as electron Wg Selection @ CDF + DO Lepton ID Photon ID GeV

  6. Wg Production CDF Preliminary • 109 Candidates(75 eng, 34 mng) • Background: (W+jets,Zg,Wg->tng) = • Signal vs. SM • SM Signal = • Candidates-Backgd = 82.6 events • Anomalous Coupling Limits: L=1.5 TeV @95% C.L.

  7. Wg Radiation Zero CDF • SM has “amplitude zero” at where is angle between incoming quark and photon in the Wg rest frame (W polarization -> 73% correct rest frame). • Radiative events are background so increase DR cut. Data subsample.

  8. WgProduction D0 • 127 Candidates(57 eng, 70 mng) • Background: (W+jets, Zg) = events. • Signal vs. SM • SM: sxBR = pb • D0: sxBR = pb. L = 1.5 TeV

  9. WWg A.C. Limits D0 • Tightest WWg Coupling Limits available. 95% CL. • U(1)EM point excluded. Combined limits: together with an earlier 14 pb-1publication PRL 75, 1034 (1995) Require 3-body Transverse Mass > 90 GeV/c2 for PT fit.

  10. WW->dileptons @ D0andCDF Event ID • CDF (108pb-1) • |he|<1.1 |hm|<0.6 • 75<Mee or mm<105 GeV/c2 • Veto events w/ jet of ET > 10 GeV • D0 (79pb-1) • |he|<1.1 1.5<|he|<2.5 • ee: • em: • mm: • em: DR(m,e)>0.5 • |Mee-MZ|<15 GeV/c2 • |ETrecoil|<40 GeV |hm|<1 Nearest Lepton mm: m1 em: m ee: e2

  11. 3 em, 2 ee, 0 mm Drell-Yan, fake leptons events “Evidence for WW Production” L=1000 GeV 2 em, 1 ee, 1 mm Drell-Yan, Wg,t-tbar, fake leptons events “Cross Section consistent w/ SM” WW-> dilepton Results CDF D0 Preliminary Candidates Background Results L=1000 GeV Fermilab-Pub-96/311-E To be published in PRL @95% C.L.

  12. CDF (110pb-1) |he|<1.1 |hm|<0.6 MT(en)>40 GeV/c2 2+ Jets 0.4 cone GeV 60<Mjj<110 GeV/c2 ET(jj)>200 GeV D0 (96pb-1) |he|<1.1 1.5<|he|<2.5 MT(en)>40 GeV/c2 2+ Jets 0.5 cone GeV 50<Mjj<110 GeV/c2 |ET(jj)-ET(en)| < 40 GeV WW/WZ Semi Leptonic Decay Modes @ CDF + D0 Lepton ID Jet Selection

  13. Effect of PT(W) Cut: Reduced Acceptance. Reduced Sensitivity M(WW)>450 GeV/c2 L=2000 GeV WW/WZ Production CDF Preliminary • 95% CL Limits L=1000 GeV

  14. WW/WZ -> en jj Production D0 Preliminary Run Ib, 82.3 pb-1 • 399 Candidates • Background Source: • W+2 or more jets, t-tbar • = 387+-38 events • SM Pred = 18+-3 (WW+WZ) events sSM(WW) = 9.5 ± 1.0 pb (´BR = 1.4 pb) sSM(WZ) = 2.5 ± 0.3 pb (´BR = 0.2 pb) (Updated From Greg Landsberg's Wine&Cheese Talk - 9/6/96, Fermilab)

  15. WW/WZ->enjj Production Limits from fit to PT(en) Another contour indicates W couples to Z D0 L=2 TeV Limits will superceed results of Run Ia analysis [PRL 77, 3303 (1996)]

  16. ZZg/Zgg Interaction • In SM all are couplings equal to zero • Non-SM Characterized by an effective Lagrangian w/ 8 coupling parameters. CP Violating h1V and h2V CP Conserving h3V and h4V • Transition Moments

  17. Zg Selection @ CDF + DO • CDF (67pb-1) • |he1|<1.1 |hm1|<0.6 • |he2|<4.2 |hm2|<1.2 • Same |h| as Wg • DO (96,87,14) pb-1 • (ee,mm,nn) • |he| as before, • |hm1| <1, |hm2| < 1,2.4 • Neutrino Channel • No Jets (ET>15 GeV) • Same |h| as Wg Lepton ID tight loose Photon ID eeg and mmg eeg and mmg nng

  18. Zg Results CDF Preliminary • 31 Candidates(18 eeg, 13 mmg) • Background (Z+jets) =events • Signal vs. SM • SM signal = 24.9 events expected • Candidates-Background = 29.6 events • A.C. Limits: assuming only one coupling at a time is non-zero

  19. Preliminary Z(ee,mm)g Candidates vs. SM D0 • 29 Candidates(14 eeg, 15 mmg) • Background (Z+jets, Wgmm channel only) • Signal vs. SM • SM signal = 29.1 Zg events expected. • Candidates-Background = 23.6 events. M(ee) M(eeg)

  20. Z(nn)g Candidates vs. SM D0 • 4 Candidates • Background (W->en, m Brems.) • SM signal = events expected. Fermilab-Pub-97/047-E accepted by PRL Fermilab-Pub-97/088-E submitted to PRD

  21. Limits on Anomalous ZVg Couplings D0 Run Ib (ee,mm): Run Ia (ee,mm,nn): 95% CL Limits Tightest ZVg Limits Available (From Greg Landsberg's Wine&Cheese Talk - 9/6/96, Fermilab)

  22. Prospects for Run 2 • Tevatron and detector upgrades provide 2 fb-1 data samples. • Quantitative Expectations • Factor of 20X in luminosity provides ~ 2.5X improvement in A.C. limit. (at fixed form factor scale). • Numbers of events (CDF + D0) estimate. Wg_> lng ~ 3000 Zg_> ee(mm)g ~ 700 WW _> llnn ~ 100 WZ _> llln ~ 30 ZZ_> e’s and m’s a few • Qualitative Expectations • Wg and WZ radiation zero. • Tevatron Studies probe theoretical expectations for A.C.’s.

  23. ZZ Candidate from CDF • Three Central Muons. One muon inferred from a high-PT track. • Expected 0.1 event. • Backgrounds?

  24. WZ Candidate from CDF • Approx. 1 such event expected. • Three high ET electrons and Missing Transverse energy. • Backgrounds?

  25. Summary • D0 +CDF studyWg,WW,WZ, and Zgdiboson final states with a rich variety of techniques. • WWg, WWZ, ZZg, Zgginteractions appear to be those of Standard Model. • WWg and WWZ vertices observed. • Hint of Radiation Zero in Wg (CDF). • (CDF). • Limits on anomalous WWV and ZVg Couplings. Tightest Are: ZVg: L=750 GeV limits from D0. WWV: L=2000 GeV limits from D0 and CDF (comparable). • Run II Detector and Lum. Upgrades.

  26. LEP vs Tevatron • LEP experiments use 3 variables to parameterize WWV anomalous couplings. • LEP sensitivity highest to aWf. • Limits on aW correspond to limits on l. • Limits on aWf correspond to limits on Dk if aBf and aW are fixed to zero.

  27. Z(nn)g Candidate from D0 n g g Run: 58766 Event: 10750 Recorded: 01/09/93 ETg = 67.9 GeV ET = 56.6 GeV hg = 0.02 g n

  28. Z(ee)g Candidate from D0 e1 e1 g e2 g Run 79096, Event 15782, recorded 05/22/94 ETg = 73.3 GeV, Mee = 89.4 GeV, Meeg = 200.3 GeV

  29. } Z(nn)g: @ 95% CL Z(ee+mm+nn)g: Storage

  30. CDF (67pb-1) |he1|<1.1 |hm1|<0.6 |he2|<4.2 |hm2|<1.2 |hg|<1.1 GeV DO (73 pb-1) |he|<1.1 1.5<|he|<2.5 Same |h| as electron Zg Selection @ CDF + DO Lepton ID mm Channel in progress Photon ID GeV

More Related