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New physics @ ATLAS

New physics @ ATLAS. Alan Barr University of Oxford. Freiburg 11 th May 2011. December 2008:. British press report the turn on of the LHC…. Did you hear about the ATLAS di-photon distribution?.

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New physics @ ATLAS

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  1. New physics @ ATLAS Alan Barr University of Oxford Freiburg 11th May 2011

  2. December 2008: British press reportthe turn on of the LHC…

  3. Did you hear about the ATLAS di-photon distribution? April 2011: Alan Barr, University of Oxford

  4. This talk • Why a Large Hadron Collider? • Accelerator and detector status • 100 years of discovery in 10 months • The energy-frontier measurements • Supersymmetry • Exotics • Prospects for the future (inc. Higgs) Alan Barr, University of Oxford

  5. Electroweak symmetry breaking Hierarchy problem? WIMPs? Physics at the TeV-scale? Alan Barr, University of Oxford

  6. Proton - Proton Controlled environment CM energy = 7 TeV (14) ~ 109 collision / second ~ decade of operation LHCb ATLAS ALICE CMS

  7. Semiconductor Tracker @ Oxford Alan Barr, University of Oxford

  8. UPDATE ME Alan Barr, University of Oxford

  9. 35 pb-1 22 July  ICHEP 2010 to same vertical scale Alan Barr, University of Oxford

  10. Parton-parton luminosity Exciting! Event rate at the unitary limit as a function of CM energy Alan Barr, University of Oxford

  11. Top candidate event pT (tracks) > 1 GeV pT(μ)= 48 GeVpT(e)=23 GeV ETmiss=77 GeV, HT=196 GeV pT (b-tagged jet) = 57 GeV Secondary vertex: -- distance from primary: 3.8 mm -- 3 tracks pT> 1 GeV -- mass=1.56 GeV 12

  12. Interesting things I won’t discuss… WW Top quark σ J/Ψ suppression in Pb-Pb Alan Barr, University of Oxford Inelastic cross-section

  13. Lots of other very interesting things notcovered ... ‘Standard Model’ papers See: https://twiki.cern.ch/twiki/bin/view/AtlasPublic Alan Barr, University of Oxford

  14. SUSY & BSM strategy • Precision reliable hermetic detector • Basic kinematics • Understand detector and SM • Look at final states with: Examples given Lepton(s) Proton Jet(s) Photon(s) Proton Invisible(s) Alan Barr, University of Oxford

  15. 1/α +SUSY Log10 (μ / GeV) Lots of interesting physics at ~ 1 TeV Why Supersymmetry? top stop? λ λ λ λ higgs higgs higgs higgs Δm2(h) Λ2cutoff Alan Barr, University of Oxford

  16. Basic kinematics Transverse momenta, pT Missing transverse momentum, ETmiss Pseudorapidity, η = - ln tan θ/2 Azimuthal angle differences Δφ Scalar sums of transverse momenta: HT, meff = HT + ETmiss Transverse mass mT = “Stransverse” mass mT2(generalisation of mT to 2 parent particles) Alan Barr, University of Oxford

  17. 1-lepton SUSY 0-lepton SUSY Multi-lepton SUSY SUSY with b jets Di-lepton SUSY 1-lepton SUSY 0-lepton SUSY For all public papers see: https://twiki.cern.ch/twiki/bin/view/AtlasPublic/SupersymmetryPublicResults Alan Barr, University of Oxford

  18. 1-lepton SUSY 1-lepton + Jets + ETmiss Lepton reduces QCD BGExpect leptons in SUSY cascade decays 1 electron or muonpT>20 GeV 3 jetspT > {60, 30, 30} GeV ETmiss > 125 GeVETmiss > 0.25 * meff mT > 100 GeV meff> 500 GeV First ATLAS SUSY paperarXiv:1102.2357 accepted by PRL Selection based heavily on pre data-takingMC studies e.g. arXiv:0901.0512

  19. 1-lepton SUSY Control regions – some examples Multiple redundant control regions QCD background separately Systematics include (not only) JES, JER, lumi, lepton efficiency, CR stats, extrapolation, … Top C/R distinguished from W+jets using b-tagging Alan Barr, University of Oxford Great care with BG for all analyses presented

  20. 1-lepton SUSY 1-lepton results Likelihood ratio as a function of signal strength Toy MCs for p-values Profile likelihood for nuisance parameters (conservative systematics)Fully simulated backgrounds, signal pointsIncludes systematic uncertainties on signal strength Alan Barr, University of Oxford

  21. 0-lepton SUSY SUSY: Jets + ETmiss Conceptually simple search for squarks and gluinosSeveral overlapping signal regions: Four overlapping signal regions Squarkdecays Gluinodecays more jets Alan Barr, University of Oxford

  22. 0-lepton SUSY Robust background determinations • 2-4 measurement methods per background • Examples: • Reversal of cuts & kinematic control regions • Fully data-driven inc. jet transfer functions • Tau re-decay, smear • Z  νν from:Z  ee, Z  μμW  eν, W  μν Only a couple of very many data-driven checks/BG determinations Alan Barr, University of Oxford

  23. Squark, Gluino interpretations 0-lepton SUSY Exclude non-SM effective cross sections (σ x BR x Acc x Eff):A: 1.3 pb B: 0.35 pb C: 1.1 pb D: 0.11 pb Auxiliary plots (Acc x Eff) allow reinterpretation in a variety of models Alan Barr, University of Oxford

  24. Multi-lepton SUSY Multi-lepton SUSY ≥ 3 leptons (electron or muon) Expect: Observe no events Top dominates after Z veto Charginos and neutralino cascade decays Alan Barr, University of Oxford

  25. SUSY with b jets SUSY with b-jets Done for both 1-lepton, 0-lepton channels Sensitive to Stop, Sbottom, Gluinoproduction Top background dominates after b-jet requirementData-driven QCD background determination Alan Barr, University of Oxford

  26. Di-lepton SUSY Dilepton SUSY Majorana nature of gluinos, neutralino same sign dilepton events Lepton number carried by sleptons  flavour correlations 1) Opposite sign and same sign 2) Charge asymmetry analysis Two papers: Alan Barr, University of Oxford

  27. R-hadrons Stable charged particle search 95% confidence limits: Stable gluino > 586 GeV Stable stop > 309 GeV Stable sbottom 294 GeV Two independentdetector subsystems: dE/dx: pixels (Time over threshold) β: tile (ToF resolution ~ns) Alan Barr, University of Oxford

  28. Combined exclusion 1-lepton SUSY Statistical combination fromproduct of likelihoods 0-lepton SUSY Alan Barr, University of Oxford

  29. Wider interpretation... Excluded by ATLAS 0-lepton search CMS αT ATLAS 0/1 lepton Cassel, Ghilencea, Kraml, Lessa, Ross http://arxiv.org/abs/1101.4664 Allanach, Khoo, Lester, Williams http://arxiv.org/abs/1103.0969 Regions with low fine tuning Points sampled from fits to global dataGlobal CMSSM fits Alan Barr, University of Oxford

  30. Not only Supersymmetry... A race through some exotic signatures… Alan Barr, University of Oxford

  31. W’ searches Electrons Muons Electron pT> 25 GeV, |η| < 1.37 or 1.52 < |η| < 2.40 MuonpT> 25 GeV, |η| < 1.05 ETmiss > 25 GeV M(W’SSM) > 1.49 TeV arxiv:1103.1391 Alan Barr, University of Oxford

  32. Muons Electrons Z’ searches… M(Z’SSM) > 1.05 TeV Alan Barr, University of Oxford

  33. Dijet inv. mass, angular distributions Compositeness scale, Λ > 9.6 TeV http://arxiv.org/abs/1103.3864 Alan Barr, University of Oxford

  34. Diphoton resonances Limits on RS graviton: 545 GeV (920 GeV), for k/MPl = 0.02 (0.1) https://atlas.web.cern.ch/Atlas/GROUPS/PHYSICS/CONFNOTES/ATLAS-CONF-2011-044/ Alan Barr, University of Oxford

  35. Diphoton + ETmiss Interpret in context of Universal Extra Dimensions Vary size of extra dimension with constant ΛR = 20 Alan Barr, University of Oxford

  36. Fourth generation Q search • Di-leptonic channel Approximate mass reconstruction on varying Δη,Δφ Excludes m(Q) < 270 GeV(@95% CL) Alan Barr, University of Oxford

  37. (e,mu) resonance search • Limits on RPV sneutrino e mu • Limits on flavour violating Z’ Paper in the pipeline Alan Barr, University of Oxford

  38. Story so far • Excellent operation of LHC and ATLAS • Commissioned physics objects:Jets, e, mu, ETmiss, photons, b-jets, (tau) • Monte Carlo doing very well • Data-driven backgrounds proven • Wide variety of final states studied • Also exotics… R-hadrons, multi-charged particles, stopped gluinos… • Many limits well beyond previous colliders

  39. Higgs -> WW Alan Barr, University of Oxford

  40. ATLAS-CONF-2011-025 SM: H→γγ • Mass range: 110 GeV - 140 GeV • Data-driven estimation of all background components • γγ, γj, jj • Inclusive • only discriminant diphoton inv. mass Sensitivity close to the current Tevatron limits.

  41. Physics prospects: Higgs Alan Barr, University of Oxford

  42. Current h  ττ https://atlas.web.cern.ch/Atlas/GROUPS/PHYSICS/CONFNOTES/ATLAS-CONF-2011-024/ Alan Barr, University of Oxford

  43. Launch is complete Exploring new worlds... Alan Barr, University of Oxford

  44. A few little Extras Alan Barr, University of Oxford

  45. Exotics conf notes https://twiki.cern.ch/twiki/bin/view/AtlasPublic/ExoticsPublicResults Alan Barr, University of Oxford

  46. 0-lepton SUSY Missing transverse momentum Alan Barr, University of Oxford

  47. 0-lepton SUSY meff distributions Cuts shown on mass-sensitive variable in final selection Alan Barr, University of Oxford

  48. 0-lepton SUSY BG example: ETmiss tails One example of very, very, very many background studies Alan Barr, University of Oxford

  49. 1-lepton SUSY Alan Barr, University of Oxford

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