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

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

3. 23/03/2011Alan Barr, University of Oxford3 Did you hear about the ATLAS di-photon distribution? April 2011:

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) 11/05/2011Alan Barr, University of Oxford4

5. 23/03/2011Alan Barr, University of Oxford5 Electroweak symmetry breaking Hierarchy problem? Physics at the TeV-scale? WIMPs?

6. 6 CMS LHCb ATLAS ALICE Proton - Proton Controlled environment CM energy = 7 TeV (  14) ~ 10 9 collision / second ~ decade of operation

7. Semiconductor Tracker @ Oxford 11/05/2011Alan Barr, University of Oxford7

8. 23/03/2011Alan Barr, University of Oxford8 UPDATE ME

9. 23/03/2011Alan Barr, University of Oxford9 22 July  ICHEP 2010 to same vertical scale 35 pb -1

10. Parton-parton luminosity 23/03/2011Alan Barr, University of Oxford10 Event rate at the unitary limit as a function of CM energy Exciting!

11. 11

12. Top candidate event 12 p T (μ)= 48 GeV p T (e)=23 GeV E T miss =77 GeV, H T =196 GeV p T (b-tagged jet) = 57 GeV Secondary vertex: -- distance from primary: 3.8 mm -- 3 tracks p T > 1 GeV -- mass=1.56 GeV p T (tracks) > 1 GeV

13. 23/03/2011Alan Barr, University of Oxford13 Top quark σ WW Inelastic cross-section J/Ψ suppression in Pb-Pb Interesting things I won’t discuss…

14. 23/03/2011Alan Barr, University of Oxford14 See: https://twiki.cern.ch/twiki/bin/view/AtlasPublichttps://twiki.cern.ch/twiki/bin/view/AtlasPublic ‘Standard Model’ papers Lots of other very interesting things not covered...

15. SUSY & BSM strategy Precision reliable hermetic detector Basic kinematics Understand detector and SM Look at final states with: 23/03/2011Alan Barr, University of Oxford15 Proton Lepton(s) Jet(s) Invisible(s) Photon(s) Examples given

16. 23/03/2011Alan Barr, University of Oxford16 Why Supersymmetry? top Δm 2 (h)  Λ 2 cutoff higgs stop? higgs λλ λλ

17. Basic kinematics 23/03/2011Alan Barr, University of Oxford17 Transverse mass m T = Transverse momenta, p T Scalar sums of transverse momenta: H T, m eff = H T + E T miss Missing transverse momentum, E T miss “Stransverse” mass m T2 (generalisation of m T to 2 parent particles) Azimuthal angle differences Δφ Pseudorapidity, η = - ln tan θ/2

18. 11/05/2011Alan Barr, University of Oxford18 1-lepton SUSY 0-lepton SUSY Multi-lepton SUSY SUSY with b jets Di-lepton SUSY For all public papers see: https://twiki.cern.ch/twiki/bin/view/AtlasPublic/SupersymmetryPublicResults 1-lepton SUSY 0-lepton SUSY

19. 1-lepton + Jets + E T miss 19 1-lepton SUSY 1 electron or muon p T >20 GeV 3 jets p T > {60, 30, 30} GeV E T miss > 125 GeV E T miss > 0.25 * m eff m T > 100 GeV m eff > 500 GeV Selection based heavily on pre data-taking MC studies e.g. arXiv:0901.0512 First ATLAS SUSY paper arXiv:1102.2357 accepted by PRL Lepton reduces QCD BG Expect leptons in SUSY cascade decays

20. Control regions – some examples 23/03/2011Alan Barr, University of Oxford20 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 1-lepton SUSY Great care with BG for all analyses presented

21. 1-lepton results 23/03/2011Alan Barr, University of Oxford21 1-lepton SUSY Likelihood ratio as a function of signal strength Toy MCs for p-values Profile likelihood for nuisance parameters (conservative systematics) Fully simulated backgrounds, signal points Includes systematic uncertainties on signal strength Likelihood ratio as a function of signal strength Toy MCs for p-values Profile likelihood for nuisance parameters (conservative systematics) Fully simulated backgrounds, signal points Includes systematic uncertainties on signal strength

22. SUSY: Jets + E T miss 23/03/2011Alan Barr, University of Oxford22 0-lepton SUSY Squark decays Gluino decays  more jets Conceptually simple search for squarks and gluinos Several overlapping signal regions: Four overlapping signal regions

23. Robust background determinations 23/03/2011Alan Barr, University of Oxford23 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  μμ W  eν, W  μν 0-lepton SUSY Only a couple of very many data-driven checks/BG determinations

24. 23/03/2011Alan Barr, University of Oxford24 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 Squark, Gluino interpretations Auxiliary plots (Acc x Eff) allow reinterpretation in a variety of models

25. Multi-lepton SUSY 23/03/2011Alan Barr, University of Oxford25 Multi-lepton SUSY Expect: Observe no events Top dominates after Z veto ≥ 3 leptons (electron or muon) Charginos and neutralino cascade decays

26. SUSY with b-jets 23/03/2011Alan Barr, University of Oxford26 SUSY with b jets Done for both 1-lepton, 0-lepton channels Sensitive to Stop, Sbottom, Gluino production Top background dominates after b-jet requirement Data-driven QCD background determination

27. Dilepton SUSY 23/03/2011Alan Barr, University of Oxford27 Di-lepton SUSY Two papers: 1) Opposite sign and same sign 2) Charge asymmetry analysis Majorana nature of gluinos, neutralino  same sign dilepton events Lepton number carried by sleptons  flavour correlations Majorana nature of gluinos, neutralino  same sign dilepton events Lepton number carried by sleptons  flavour correlations

28. Stable charged particle search 23/03/2011Alan Barr, University of Oxford28 95% confidence limits: Stable gluino > 586 GeV Stable stop > 309 GeV Stable sbottom 294 GeV R-hadrons Two independent detector subsystems: dE/dx: pixels (Time over threshold) β: tile (ToF resolution ~ns) Two independent detector subsystems: dE/dx: pixels (Time over threshold) β: tile (ToF resolution ~ns)

29. Combined exclusion 11/05/2011Alan Barr, University of Oxford29 1-lepton SUSY 0-lepton SUSY Statistical combination from product of likelihoods

30. Wider interpretation... 23/03/2011Alan Barr, University of Oxford30 http://arxiv.org/abs/1103.0969 Allanach, Khoo, Lester, Williams Cassel, Ghilencea, Kraml, Lessa, Ross http://arxiv.org/abs/1101.4664 Points sampled from fits to global data Global CMSSM fits Regions with low fine tuning ATLAS 0/1 lepton CMS α T Excluded by ATLAS 0-lepton search

31. A RACE THROUGH SOME EXOTIC SIGNATURES… Not only Supersymmetry... 11/05/2011Alan Barr, University of Oxford31

32. W’ searches 23/03/2011Alan Barr, University of Oxford32 Electrons Muons arxiv:1103.1391 Electron p T > 25 GeV, |η| < 1.37 or 1.52 < |η| < 2.40 Muon p T > 25 GeV, |η| < 1.05 E T miss > 25 GeV M(W’ SSM ) > 1.49 TeV

33. Z’ searches… 23/03/2011Alan Barr, University of Oxford33 Electrons Muons M(Z’ SSM ) > 1.05 TeV

34. Dijet inv. mass, angular distributions 23/03/2011Alan Barr, University of Oxford34 http://arxiv.org/abs/1103.3864 Compositeness scale, Λ > 9.6 TeV

35. Diphoton resonances 23/03/2011Alan Barr, University of Oxford35 https://atlas.web.cern.ch/Atlas/GROUPS/PHYSICS/CONFNOTES/ATLAS-CONF-2011-044/ Limits on RS graviton: 545 GeV (920 GeV), for k/MPl = 0.02 (0.1)

36. Diphoton + E T miss 23/03/2011Alan Barr, University of Oxford36 Interpret in context of Universal Extra Dimensions Vary size of extra dimension with constant ΛR = 20

37. Fourth generation Q search Di-leptonic channel 23/03/2011Alan Barr, University of Oxford37 Approximate mass reconstruction on varying Δη, Δφ Excludes m(Q) < 270 GeV (@95% CL)

38. (e,mu) resonance search Limits on RPV sneutrino  e mu Limits on flavour violating Z’ 23/03/2011Alan Barr, University of Oxford38 Paper in the pipeline

39. Story so far Excellent operation of LHC and ATLAS Commissioned physics objects: Jets, e, mu, E T miss, 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 Excellent operation of LHC and ATLAS Commissioned physics objects: Jets, e, mu, E T miss, 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 23/03/2011

40. Higgs -> WW 23/03/2011Alan Barr, University of Oxford40

41. 41 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. ATLAS-CONF-2011-025

42. Physics prospects: Higgs 23/03/2011Alan Barr, University of Oxford42

43. Current h  ττ 23/03/2011Alan Barr, University of Oxford43 https://atlas.web.cern.ch/Atlas/GROUPS/PHYSICS/CONFNOTES/ATLAS-CONF-2011-024/

44. EXPLORING NEW WORLDS... Launch is complete 11/05/2011Alan Barr, University of Oxford44

45. EXTRAS A few little 23/03/2011Alan Barr, University of Oxford45

46. Exotics conf notes 23/03/2011Alan Barr, University of Oxford46 https://twiki.cern.ch/twiki/bin/view/AtlasPublic/ExoticsPublicResults

47. 23/03/2011Alan Barr, University of Oxford47 0-lepton SUSY Missing transverse momentum

48. m eff distributions 23/03/2011Alan Barr, University of Oxford48 0-lepton SUSY Cuts shown on mass-sensitive variable in final selection

49. BG example: E T miss tails 23/03/2011Alan Barr, University of Oxford49 0-lepton SUSY One example of very, very, very many background studies

50. 23/03/2011Alan Barr, University of Oxford50 1-lepton SUSY

51. 1-lepton results 23/03/2011Alan Barr, University of Oxford51 1-lepton SUSY

52. Profile likelihood Hatted quantities maximise likelihood Double hatted quantities maximise L for given value of s s and s-hat constrained to be non-negative Likelihood ratio is the test statistic used to calculate the p-value 23/03/2011Alan Barr, University of Oxford52

53. Kinematic distributions 23/03/2011Alan Barr, University of Oxford53 1-lepton SUSY Electron channel Muon channel

54. Jets, Electrons, Muons, E T miss Charginos and neutralino cascade decays ≥ 3 leptons (electron or muon) pT > {20, 20, 20(e) or 10 (mu)} GeV ≥ 2 jets with p T > 50 GeV and |η| < 2.5 E T miss > 50 GeV m ll (ossf) Z mass veto (within 5 GeV of m Z ) m ll (ossf) photon veto (< 20 GeV) 23/03/2011Alan Barr, University of Oxford54 Multi-lepton SUSY SM: Observe no events Top dominates after Z veto

55. 55 Z →ττ mu + had e + had e + mu ATLAS-CONF-2011-010 ATLAS-CONF-2011-045

56. Stable massive particle search Two independent detector subsystems dE/dx: pixels (Time over threshold) β: tile (ToF resolution ≈ns) E T miss > 40 GeV (trigger) p T > 50 GeV 23/03/2011Alan Barr, University of Oxford56 http://arxiv.org/abs/1103.1984 R-hadrons

57. 0-lepton results Alan Barr, University of Oxford57 0-lepton SUSY Conservative systematics Jet energy scale (~7%) Luminosity (11%) Control region statistics Lepton veto Different MC b-jet fraction MC statistics Higher orders… more …