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Other Particle Searches at the Tevatron

Other Particle Searches at the Tevatron. Arnold Pompoš The University of Oklahoma For the CDF & DØ Collaborations. Štrbské Pleso. April 14-18. DIS 2004. Slovakia. 2004. Outline. In this talk we report on. Search for Large Extra Dimensions (LED) in Monojet + MET channel

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Other Particle Searches at the Tevatron

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  1. Other Particle Searches at the Tevatron Arnold Pompoš The University of Oklahoma For the CDF & DØ Collaborations Štrbské Pleso April 14-18 DIS 2004 Slovakia 2004

  2. Outline In this talk we report on • Search for Large Extra Dimensions (LED) • in Monojet + MET channel • in ee combined with γγchannel • via dedicated search with ee • in μμ channel • Search for heavy gauge boson • in ee channel • in μμ channel • Search for excited electrons For search for Higgs, SUSY and LQ see S. Beauceron, T. Kurca & D. Ryan’s talks

  3. - Tevatron - pp collider • Run I (1992 – 1995) √s = 1.8 TeV • delivered ~ 130 pb-1 • Run II (2002 – ong. ) √s = 1.96 TeV • 36p x 36p bunches • collisions every 396 ns • record peak lumi. 6.7x 1031 cm-2 s-1 • delivers ~ 10 pb-1/week • 1.5 interactions/bunch crossing • rate to tape 50 Hz - ~ 290 pb-1 on tape per experiment data for physics Feb 2002 April 2001 • High data taking efficiency • in the range 80-90% • So far analyzed • around 200 pb-1, which is already 2x the total Run I data. Jul 2002 first data for analyses detector commissioning

  4. CDF & DZero Experiments • Extended spatial e, μ coverage • New plug calorimeter improves also METmeasurement • Improved MET triggers • Added triggers to identify leptons at early stage • New silicon and fiber tracker • Solenoid (2 Tesla) • Upgrade of muon system • Upgrade of Trigger/DAQ

  5. New Phenomena Search Strategies Both CDF & DZero start searches with • signature based strategy • categorize data into bins of various event signatures • compare bins to SM predictions and search for signs of deviations and then the searches are tuned for best sensitivity on • specific models • show us the signatures of your favorite model • we tell you if data contains any event with such signature

  6. New Phenomena Search Challenges • Production cross sections very small • σ(new phenomena) ~ 1pb • σ(pp inelastic) ~ 5x1010 pb • Detectors are great, but not perfect • particle detection efficiency < 100% • Often hard to distinguish signal from background • jet based strategies overwhelmed by SM processes • we employ lepton based signatures, but the rates are often suppressed -

  7. Large Extra Dimensions

  8. Motivations for Extra Dimensions • Newton’s 1/r2 law needs to be tested on submillimeter scales • Hierarchy puzzle - Why is gravity so weak? • EWK scale is MEWK~1TeV • Gravity scale is MPL=1/√GN = 1016 TeV • Hierarchy solution – Extra Dimensions. • Gravity is localized (Randal Sundrum) on a different “brane” at d≠0 from the “brane” we live on • - Gravity propagation to extra D (us) is exponentially damped • Gravity is not weak! (Arkani-Ahmed, Dimopoulos,Dvali) It is diluted into many dimensions, 4+n, with n of them compactified to radius R • M2PL(4 D) = M2+nPL(4+n D)Rn • - IF MPL(4+n D) ~ MEWK ~ 1TeV then • if n=1 then R ~ 1013 m (excluded by Newton’s 1/r2 law) • if n=2 then R~ 10-3 m (WORTH OF TESTING!)

  9. Strong Gravity ( ADD ) • Compactified n dim. implies massive KK towers GKK of massless graviton G in each extra dim. • SM lives in 3+1D, GKK live in 4+n D  strength of gravity diluted • GKK couple to SM matter proportional 1/MPL (very weak coupling) • Huge number of KK modes sum up and yield to measurable effects V g q g g q g Gkk Gkk Gkk _ Gkk g Gkk q _ g q V Possible real graviton emmission Enable Graviton Mediated Processes Monojet+MET event signature Dilepton and diphoton event signature

  10. LED with Monojet + MET After all selection cuts Observe 63, Expect 100 with ~60% uncertainty Search for Real Graviton Emission q g g g _ Gkk Gkk g q Analysis sensitive to jet energy scale (JES) uncertainty. Data versus SM heavy G escapes to extra D large MET recoil jet very energetic Limit on Planck Scale Md DØ ∫Ldt = 85 pb-1 • Data Selection: • MET > 150 GeV, • Jet1 > 150 GeV • Jet2 < 50 (reduce ISR, FSR) • ΔΦJ-MET > 30o (reduce chance that MET comes from jet mismeasurement) • Irreducible Background: • Z-> νν + 1 or 2 jets (60% of total bckg.) LEP

  11. LED with ee & γγ - Theory Search for enhanced dilepton production Gravity effect parametrized byhG ee, γγ invariant mass scatter. angle Functions ofM & cosq* determined by theory • DØ Search Strategy: • Combine dielectron and diphoton to diEM signature • Fit distribution of M vs cosq* of Data – SM • Extract ηGfrom the fit • Translate ηG into Ms limit • ηG = F/MS4 • F is a model dependent dimensionless parameter ~ 1: • GRW: F = 1 • HLZ: F = log(Ms2/M2), n =2 • F = 2/(n-2), n > 2 • Hewett: F = 2 λ/π, λ = ±1 • Ms is the UV cutoff = MPL(4+n dim)

  12. LED with ee & γγ - Event Selection DØ ∫Ldt = 200 pb-1 700 million events  9400 + 6800 events selected Central-Central Central-Forward • LED search focuses on very high mass Drell-Yan region (graviton is heavy) • We are not searching for dilepton mass peaks (will do so in Z’ searches) • Region of interest is way above the Z mass  very energetic e & γ • Triggers • high pT single or dielectron triggers • diphoton triggers Unprescaled, >99% efficient due to high pT of EM objects • Event Selection • Two fiducial, central-central or central-forward, isolated EM objects • ET > 25 GeV for both EM objects • No track selection. Treat dielectron and diphoton samples together

  13. LED with ee & γγ - Data vs Background • Background estimation: • Drell-Yan and direct diphoton production estimated from MC • Instrumental backgrounds estimated from data that fail electron quality cuts • Normalize backgrounds by fitting to the low di-em mass spectrum, where no LED signal is expected Data Data vs MC Signal prediction QCD SM prediction DØ ∫Ldt = 200 pb-1

  14. LED with ee & γγ - DØ Limits • Data agrees with SM prediction • Extract ηg parameter from fit • Translate hG95% limits to 95% CL lower limits on Planck scale MS, in TeV, using different formalisms for F *NLO k=1.3 scale applied to signal MC DØ RunII DØ RunI + Run II

  15. LED with ee - CDF Limits • Data agrees with SM prediction • Extract parameter from M(ee) fit • Usecosq* as a cross check hG95%= 1.17 TeV-4 hG95%= 1.05 TeV-4 λ = -1 λ = +1 • Translate hG95% limits to 95% CL lower limits on Planck scale MS, in TeV, using different formalisms for F * No NLO k factor applied to signal MC

  16. LED with μμ - DØ • Event selection • pT > 15 GeV for both muon objects • Isolated tracks • M(mumu) > 50 GeV • Cosmics removed DØ ∫Ldt = 100 pb-1 Observed events 3,000 events No deviation from SM in data Soon see results from 200pb-1

  17. LED with μμ - CDF • Data agrees very well with SM predictions • New LED results are around the corner @ CDF from μμ channel

  18. LED with KK modes of Z & Photon • Model: • compactified n extra dimensions • chiral matter lives on 3D • gauge bosons live in all dimensions -> existence Z & γ KK modes • Task: • measure the effect of KK modes of Z and γ on ee production is bilinearly in  same tools as LED ηC = π2/3*M2PL(4+n dim) and depends on dilepton mass and scattering angle • Note: • at high masses the dilepton production is enhanced • at intermediate masses M(Z)  MC the negative interference causes event deficit. • Search strategy same as in LED: • extract ηC from fit and translate into a limit on Mc

  19. LED with KK modes of Z & Photon- Limit • Event Selection • same as in diEM search, but • >1 e must have track • no electron isolation required Data SM prediction QCD Signal prediction Observed 14200 events DØ ∫Ldt = 200 pb-1 Data vs MC No deviation from SM in data MC>1.12 TeV

  20. Localized Gravity ( RS ) with ee • Gravity Propagates in Compactified 5th dim. -> Towers of Kaluza-Klein modes of the graviton • Coupling of GKK to Standard Model is of the order of TeV (determined by parameter k/MPL) • Graviton mediated ee production searched • CDF searched its high pT ee & μμ sample First direct constraints on RS

  21. Localized Gravity ( RS ) with μμ

  22. Heavy Extra Gauge Boson

  23. Z’ Search Motivation • Extra U(1) gauge boson is predicted by BSM theories (SO(10),E6) SSM : Z ’ couplings to fermions considered identical to the SM Z E6 inspired models:E6 SU(3) x SU(2) x U(1)y x U(1) x U(1), Z ’ = Z sin + Zcos Z if  = 0 Zη if  = tan-1√(3/5) Z if  = π/2 ZI if  = tan-1(-√(3/5)) Z’ • We search for leptonic Z’ decays. (Br ~ 4% but very small bckg.) • Same high pT ee & μμ datasets searched as in LED analysis • Looking for a mass peak in M(dilepton) distribution, located beyond the Z peak (different from LED searches, where we fit the high mass continuum).

  24. Z’ in ee channel • Same event selection as for the search for LED in ee channel (KK modes of gauge bosons) . • Different data interpretation DØ ∫Ldt = 200 pb-1 Data SM prediction Signal prediction QCD Limits (in GeV) SM Couplings CDF : 750 DØ: 780 E6 ZI Zχ Zψ Zη CDF: 570 610 625 650 DØ: 575 640 650 680 SM coupling ZIZχZψZη 95% CL limit

  25. Z’ in μμ channel – Limits DØ ∫Ldt = 100 pb-1 DØ result with 200 pb-1 is coming soon.

  26. Excited Electron

  27. Electron compositeness? Contact Interaction • CDF has searched for excited electrons (e*), whose existence would indicate compositeness of electrons • At Tevatron, e* can be produced via contact interactions or gauge mediated interactions • We select events with eeg in the final state • Look for resonances in M(eg) • Region of interest lies beyond the Z mass • ET(e1)>25 GeV, ET(e2)>25 GeV, ET(g)>25 GeV • 81 GeV < M(ee) < 101 GeV (veto SM Z) • SM background: Zgevents M(e*)/Λ, Λ is the compositness scale Gauge Mediated Interaction f/Λ, f is the coupling to Z In CDF ∫Ldt = 200 pb-1 we observed 3 events and expected 3 events

  28. Excited Electron Limits Contact Interaction Limit Gauge Mediated Interaction Limit

  29. Spectacular eeee Event • We are not only excluding, we are also measuring  • ZZ candidate in eeee channel • σxBr ~ 9x10-4 Calorimeter eta-phi lego plot Et(e1)=44 GeV Et(e2)=42 GeV Et(p1)=46 GeV Et(p2)=26 GeV MET=13 GeV Central tracker

  30. Conclusion

  31. Conclusion • Tevatron keeps breaking peak luminosity records and is steadily delivering collisions • CDF and DØ detectors are recording high quality data • We searched CDF’s and DØ’s high energy electron, muon and photon samples for signs of new phenomena • We set world leading limits on parameters of theories which consider the existence of extra dimensions, extra gauge boson or composite electron • We are still in only a fraction of the expected total luminosity of 8fb-1 (2009) MORE GREAT PHYSICS RESULTS are coming soon and even more in few years .

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