1. Hunting the invisible at the LHC Alan Barr https://twiki.cern.ch/twiki/bin/view/AtlasPublic/SupersymmetryPublicResults

2. Alan Barr Motivation  The usual blah blah?  Dark Matter …  Naturalness of the Higgs boson mass…  Electroweak unification…  Radiative electroweak symmetry breaking… [Page 2

3. Alan Barr Motivation – as a pragmatist [Page 3 Lots of effort to build it: let’s make good use of it…

4. Alan Barr 1 pb 1 fb Integrated luminosity: 2 fb -1 (Mid 2012) 5 fb -1 (All of 2011) Page 4

5. Alan Barr Missing momentum… invisibles [Page 5

6. Alan Barr Missing momentum (E T miss ) signatures: challenges in 2011 Data collected Int. Lumi: ~5 fb -1 Page 6

7. Alan Barr Pile-up: track ↔ jet association A spectacular 9-jet + E T miss event All nine jets associated to same primary vertex (even in presence of many other vertices) Page 7

8. Alan Barr Uncertainties? Standard Model backgrounds Instrumental backgrounds Expected Signal?

9. Alan Barr Momentum imbalance…  Mismeasurement?  Cosmics?  Noise?  Beam halo?  Neutrinos?  WIMPs? PATHOLOGIES PHYSICS

10. Alan Barr JETS + MISSING MOMENTUM From collisions Jets P T miss Jets

11. Alan Barr JETS From collisions Jets: Had. Calorimeter E.M. Calorimeter Tracks from vertex In-time b,c quark jets  can decay to neutrinos

12. Alan Barr JETS + MISSING MOMENTUM Measurements Jets:  cut Reduce: Had. Calorimeter E.M. Calorimeter Tracks from vertex Measure remainder at small 

13. Alan Barr JETS + MISSING MOMENTUM From cosmics Reduce by: (a) requiring tracks with jets (b) look for muon hits Measure remainder: (a) no beam (b) timing

14. Alan Barr JETS + MISSING MOMENTUM From beam halo Reduce by requiring tracks with jets Measure remainder with single beam / timing

15. Alan Barr JETS + MISSING MOMENTUM Calorimeter noise Reduce by requiring tracks with jets Measure remainder (a) no beam (b) timing

16. Alan Barr Neutrinos Z (   ) + jets W (  l  ) + jets

17. Alan Barr Analysis philosophy  Dedicated analysis for different final states  State of the art Monte Carlo  Validated GEANT-4 detector simulation*  Multiple redundant control regions (CR)  Multiple cross-checks & validation regions (VR)  Appropriate kinematic & ID variables  Uncertainties based on measurements wherever possible  Signal systematics in limits [ 17 ] * We have some fast-sim for signal

18. Alan Barr [ 18 ] Try to make it simple… Lots of different final states…

19. Alan Barr Page 19 Jets: anti k T, R=0.4, em  had calibration E T Miss : Missing transverse momentum -ve sum p T of: jets, leptons, unclustered E T Tau: 1- or 3- prong hadronic p T > 20 GeV B-tagged jets: secondary vertex fitter Typically at point: (ε B ~60%, ε light <1%) Leptons (either e or µ), isolated Trigger requires: (e > 25, µ > 20), soft lep down to (7,6) GeV Photon: isolated ? Disappearing track LEGEND

20. Alan Barr ATLAS SUSY review: missing momentum [ 20 ] ArXiv:1111.4116 1fb -1 ATLAS-CONF-2011-096 ATLAS-CONF-2012- 036 2 fb -1 ATLAS-CONF-2012-003 arXiv:1112.3832 arXiv:1203.5763 ATLAS-CONF-2012-023 ATLAS-CONF-2012-001 ATLAS-CONF-2012-005 ATLAS-CONF-2012-002 2 fb -1 ATLAS-CONF-2012-037 ATLAS-CONF-2012-033 ATLAS-CONF-2012-041 5 fb -1 ATLAS-CONF-2012-034 ?

21. Alan Barr [ 21 ] ATLAS-CONF-2012-037 ATLAS-CONF-2012-033 ATLAS-CONF-2012-041 5fb -1 ATLAS-CONF-2012-034 ? Full 2011 dataset

22. Alan Barr ATLAS-CONF-2012-033 No leptons, ≥(2-6) jets + E T miss Page 22 Squarks, Gluinos Page 22

23. Alan Barr Page 23 ATLAS-CONF-2012-033 Squarks Gluinos/cascades Small Δm Different mass scales Total of 11 signal regions

24. Alan Barr Page 24 ATLAS-CONF-2012-033 Control regions for each significant BG Multijet BG determined from data-driven smearing method Smaller backgrounds, e.g. diboson: MC only

25. Alan Barr m eff (incl.): scalar sum of E T of all jets and E T miss Page 25 ATLAS-CONF-2012-033 MC scaled by ~0.75 (based on control regions) Band shows JES, JER, MC stats

26. Alan Barr Page 26 ATLAS-CONF-2012-033

27. Alan Barr Page 27 Simplified gluino-squark- neutralino model ATLAS-CONF-2012-033 MSUGRA/CMSSM Non-disjoint SRs: exclusion based on best expected significance

28. Alan Barr ATLAS-CONF-2012-037 No leptons ≥(6-9) jets + E T miss Page 28 Gluinos  cascades Gluinos  4 x tops Page 28

29. Alan Barr Page 29 ATLAS-CONF-2012-037 Final variable quantifies significance of E t miss  Multi-jets dominated control regions  Subtract (subdominant) “leptonic” backgrounds  QCD background is reliably predicted (~20%)  Tested in further control regions and cross-checked with jet-smearing method QCD background: stochastic term  H T Independent of jet multiplicity

30. Alan Barr Page 30 ATLAS-CONF-2012-037 Top validation region SR: 7j80 SR: 9j55

31. Alan Barr Page 31 ATLAS-CONF-2012-037 Most discrepant 7j80p-value 0.07

32. Alan Barr Page 32 Simplified gluino/top model ATLAS-CONF-2012-037 ATLAS-CONF-2012-003 arXiv:1203.5763

33. Alan Barr ATLAS-CONF-2012-037 ATLAS-CONF-2012-033 ATLAS-CONF-2012-041 Gluino mass > ~850 GeV MSUGRA/CMSSM interpretation Page 33 5 fb -1

34. Alan Barr NOTHING SO FAR… [Page 34

35. Alan Barr …AND TO KNOWLEDGE, SELF-CONTROL; AND TO SELF-CONTROL, PERSEVERANCE… [Page 35 Forecast of fraction of “interesting” points “discovered” 1105.1024 Allanach, AJB, Dafinca, Gwenlan

36. Alan Barr [Page 36 Tough points…. 1105.1024

37. Alan Barr [Page 37 1105.1024 Tough points….

38. Alan Barr [Page 38 1105.1024 Tough points….

39. Alan Barr [Page 39 1105.1024 Tough points….

40. Alan Barr [ 40 ] arXiv:1203.5763 ATLAS-CONF-2012-023 ATLAS-CONF-2012-001 ATLAS-CONF-2012-005 ATLAS-CONF-2012-002 2 fb -1 ATLAS-CONF-2012- 036 2 fb -1 ATLAS-CONF-2012-003 ArXiv:1111.4116 1 fb -1 ATLAS-CONF-2011-096 ArXiv:1112.3832 ATLAS-CONF-2012-037 ATLAS-CONF-2012-033 ATLAS-CONF-2012-041 5 fb -1 ATLAS-CONF-2012-034 ?

41. Alan Barr [ 41 ] arXiv:1203.5763 ATLAS-CONF-2012-023 ATLAS-CONF-2012-001 ATLAS-CONF-2012-005 2 fb -1 EW gauginos, staus ATLAS-CONF-2012-002

42. Alan Barr [ 42 ] ATLAS-CONF-2012-023 Three-lepton + E T miss Direct EW gaugino

43. Alan Barr Three-lepton + E T miss [ 43 ] Z depleted (+b jet veto) Z enriched (within 10 GeV of m Z ) pT (µ) > 20,10,10 GeV pT (e) > 25,10,10 GeV E T miss > 50 GeV Searches for direct gaugino production Chargino + neutralino  3 leptons + 2 LSP OSSF pair(s) allowed (m ll > 20) ATLAS-CONF-2012-023

44. Alan Barr 3-lepton + E t miss - gauginos [ 44 ] ATLAS-CONF-2012-023 Chargino-1 LSP Via slepton

45. Alan Barr [ 45 ] ATLAS-CONF-2012-001 ATLAS-CONF-2012-035 Direct gauginos L-violating RPV 4 lepton + E T miss

46. Alan Barr [ 46 ] L-violating RPV  LSP λ 121 gut ~ 0.032 ATLAS-CONF-2012-001 ATLAS-CONF-2012-035

47. Alan Barr ATLAS-CONF-2012-036 Page 47 arXiv:1111.4116 2 fb -1 1 fb -1 ATLAS-CONF-2012-003 ATLAS-CONF-2011-096 arXiv:1112.3832

48. Alan Barr [ 48 ] arXiv:1112.3832 Direct sbottom 2 jets only (veto on third jet)

49. Alan Barr Direct sbottom [ 49 ] ArXiv:1112.3832 (Pure MC predictions in parentheses) 2 jets only – veto on third jet

50. Alan Barr Direct Sbottom [ 50 ] ArXiv:1112.3832 2 jets only – veto on third jet

51. Alan Barr SUSY / invisibles: summary  Analysis of 2011 data still in flow  Several analyses with full 5 fb -1, more on the way  Lower limits* of:  squark ~ 1400 GeV  gluino ~ 900 GeV  sbottom ~ 400 GeV  [stop ~ 300 GeV] **  [gauginos ~ 200-300 GeV] **  Also: taus, photons, monojets, disappearing tracks, … + E T miss  Preparations for 2012, 8 TeV in full swing [ 51 ] * indicative & for particular scenarios Direct production Particular decays

52. Alan Barr 2012 data taking [Page 52

53. Alan Barr Further motivation: the future… [Page 53 ~1 TeV ? Multi-TeV ? LH-LHC? HE-LHC?

54. Alan Barr A luminosity upgrade: additional reach… Page 54 Perhaps measuring properties…

55. Alan Barr EXTRAS [ 55 ]

56. Alan Barr Page 56 ATLAS-CONF-2012-041 1-lepton + jets + E T miss Strong  chargino  neutralino Page 56

57. Alan Barr Chargino cascade decays etc: One-lepton Page 57 Small Δm ATLAS-CONF-2012-041

58. Alan Barr 1-lepton: background determination  Control regions split by jet multiplicity (up to 9 jets)  Nuisance parameters fitted  B-tagging  k T fact (Alpgen)  Normalisations  Over-constrained system Page 58 Control & validation regions ATLAS-CONF-2012-041

59. Alan Barr Control regions – jet multiplicity [ 59 ] ATLAS-CONF-2012-041

60. Alan Barr 1-lepton results [ 60 ] Fit allows different backgrounds to adjust, based on CR (Also relative fraction of different multiplicities in Alpgen) ATLAS-CONF-2012-041

61. Alan Barr Significantly improved [ 61 ] ATLAS-CONF-2012-041 3j, 4j signal regions statistically combined (first time) Shape of m eff used when making exclusion (6 bins 400  1600 GeV)

62. Alan Barr Simplified model limits Page 62 Near-degenerate region: gain factor of 20-30 from soft lepton Soft lepton analysisHard lepton analyses ATLAS-CONF-2012-041

63. Alan Barr [ 63 ] ATLAS-CONF-2012-041 1-lepton channel: improvement in limit using soft lepton

64. Alan Barr Multijet control regions [ 64 ] ATLAS-CONF-2012-033

65. Alan Barr Three-lepton + E T miss [ 65 ] ATLAS-CONF-2012-023 Limits in pMSSM space (Wino  Bino decays) M1 = 100

66. Alan Barr Top pair with extra E T Miss Limit interpreted in terms of fermionic top partner Page 66 Phys. Rev. Lett. 108 (2012) 041805

67. Alan Barr t + tbar + E T miss [ 67 ] Phys. Rev. Lett. 108 (2012) 041805 Not yet sensitive to stop production

68. Alan Barr ATLAS-CONF-2011-096 Page 68

69. Alan Barr [ 69 ] ATLAS-CONF-2012-036 Direct Stop pair  Hino  LSP + Z b-jet, same flavour, opposite sign leptons m ll ~ m Z

70. Alan Barr [ 70 ] E t miss > 50 GeV 80 GeV SR2 SR1 Decays via sbottom, h also included ATLAS-CONF-2012-036

71. Alan Barr Disappearing track [ 71 ] ATLAS-CONF-2012-034 ? Light winos, AMSB Finally…

72. Alan Barr Disappearing tracks [ 72 ] ATLAS-CONF-2012-034 ? Chargino mass=90.2GeV

73. Alan Barr Page 73 https://twiki.cern.ch/twiki/bin/view/AtlasPublic / SupersymmetryPublicResults https://twiki.cern.ch/twiki/bin/view/AtlasPublic / SupersymmetryPublicResults Good reading…

74. Alan Barr https://twiki.cern.ch/twiki/bin/view/AtlasPublic/ ExoticsPublicResult s Page 74 ATLAS-CONF-2011-096 Monojet Found elsewhere…

75. Alan Barr ATLAS-CONF-2012-037 ATLAS-CONF-2012-033 ATLAS-CONF-2012-041 arXiv:1203.5763 ATLAS-CONF-2012-023 ATLAS-CONF-2012-001 ATLAS-CONF-2012-005 ATLAS-CONF-2012-002 5fb -1 2 fb -1 Page 75 ATLAS-CONF-2012-034 ?

76. Alan Barr [ 76 ] arXiv:1203.5763 ATLAS-CONF-2012-023 ATLAS-CONF-2012-001 ATLAS-CONF-2012-005 ATLAS-CONF-2012-002 2 fb -1 ATLAS-CONF-2012- 036 2 fb -1 ATLAS-CONF-2012-003 ArXiv:1111.4116 1 fb -1 ATLAS-CONF-2011-096 arXiv:1112.3832 ATLAS-CONF-2012-037 ATLAS-CONF-2012-033 ATLAS-CONF-2012-041 5fb -1 ATLAS-CONF-2012-034 ? Analyses/searches

77. Alan Barr Page 77 ATLAS-CONF-2012-005 ≥1 tau or ≥2 taus + Jet(s) + E T miss GMSB, stau NLSP ATLAS-CONF-2012-002

78. Alan Barr Final states with taus Page 78 Same trig m Eff > 600 GeV m T (  1) > 110 GeV ATLAS-CONF-2012-002 Expect: 5.3 ±1.3(stat)±2.2(sys) Observe: 3 ε(1p  ) ~ 30% ε(j) ~ 0.5% ε(3p  ) ~ 50% ε(j) ~ 3% ATLAS-CONF-2012-005 Jet (130) + E T miss (130) trig. m Eff > 700 GeV m T (  1) + m T (  1) > 80 GeV

79. Alan Barr Page 79 ATLAS-CONF-2011-156 1fb -1 ATLAS-CONF-2011-156 ATLAS-CONF-2012-002 ATLAS-CONF-2012-005 2 fb -1

80. Alan Barr [ 80 ] ATLAS-CONF-2012-003 b-jet(s) (+ 1 lepton) + jet(s) + E T miss Gluino  Sbottom/Stop

81. Alan Barr [ 81 ] ATLAS-CONF-2012-003 B jet(s) (+ 1 lepton) + jet(s) + E T miss

82. Alan Barr [ 82 ] 0-lepton ≥2 b-tags 1-electron ≥1 b-tag ATLAS-CONF-2012-003

83. Alan Barr [ 83 ] (MC yields in parentheses) 1-lepton 0-lepton ATLAS-CONF-2012-003

84. Alan Barr [ 84 ] Virtual sbottomReal sbottom ATLAS-CONF-2012-003