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Higgs, more Higgs, less Higgs, or Higgsless ?

Higgs, more Higgs, less Higgs, or Higgsless ?. John Ellis King ’ s College, London (& CERN). Tested by experiments at CERN & elsewhere. Perfect agreement between theory and experiments in all laboratories. The ‘ Standard Model ’ of Particle Physics. Proposed byAbdus Salam,

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Higgs, more Higgs, less Higgs, or Higgsless ?

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  1. Higgs, more Higgs, less Higgs, or Higgsless? John Ellis King’s College, London (& CERN)

  2. Tested by experiments atCERN & elsewhere Perfect agreement between theory and experiments in all laboratories The ‘Standard Model’ of Particle Physics ProposedbyAbdus Salam, Glashow and Weinberg

  3. Open Questions beyond the Standard Model • What is the origin of particle masses? due to a Higgs boson? • Why so many flavours of matter particles? • What is the dark matter in the Universe? • Unification of fundamental forces? • Quantum theory of gravity? LHC LHC LHC LHC LHC

  4. Where do the masses come from ? Why do Things Weigh? Newton: Weight proportional toMass Einstein: Energy related toMass Neither explained origin of Mass 0 Are masses due to Higgs boson? (the physicists’ Holy Grail)

  5. The Seminal Papers

  6. The Englert-Brout-Higgs Mechanism Englert & Brout Guralnik, Hagen & Kibble

  7. The Higgs Boson • Higgs pointed out a massive scalar boson • “… an essential feature of [this] type of theory … is the prediction of incomplete multiplets of vector and scalar bosons” • Englert, Brout, Guralnik, Hagen & Kibble did not comment on its existence • Discussed in detail by Higgs in 1966 paper

  8. Mysterious Higgs Potential Mass2 of Higgs ~ curvature of potential at minimum Vertical scale ~ 1060 × dark energy

  9. A Phenomenological Profile of the Higgs Boson • Neutral currents (1973) • Charm (1974) • Heavy lepton τ (1975) • Attention to search for W±, Z0 • For us, the Big Issue: is there a Higgs boson? • Previously ~ 10 papers on Higgs bosons • MH > 18 MeV • First attempt at systematic survey

  10. Higgs decay modes and searches in 1975: A Phenomenological Profile of the Higgs Boson

  11. Higgs Boson placed on the Experimental Agenda • Searches at LEP: (EG, Yellow report 76-18) • e+e-Z + H (EGN 76, Ioffe & Khoze 76, Lee, Quigg & Thacker 77) • Z  H + μ+μ- (EG 76, Bjorken 1976) • LEP: MH > 114.4 GeV

  12. The State of the Higgs in Mid-2011 • High-energy search: • Limit from LEP: mH> 114.4 GeV • High-precision electroweak data: • Sensitive to Higgs mass: mH = 96+30–24 GeV • Combined upper limit: mH < 161 GeV, or 190 GeV including direct limit • Exclusion from high-energy search at Tevatron: mH < 158 GeV or > 173 GeV

  13. Latest Higgs Searches @ Tevatron Experimental upper limit Standard Model prediction Exclude (100,109); (156,177) GeV

  14. Higgs Hunting @ LHC: Status reported on Dec. 13th, 2011 Exclude 112.7 GeV to 115.5 GeV, 131 GeV to 237 GeV, 251 GeV to 453 GeV Exclude 127 to 600 GeV

  15. Has the Higgs Boson been Discovered? Interesting hints around Mh = 125 GeV ? CMS sees broad enhancement ATLAS prefers 125 GeV

  16. Has the Higgs Boson been Discovered? Interesting hints around 125 GeV in both experiments - but could also be 119 GeV ?

  17. ATLASSignals • γγ: 2.8σ • ZZ: 2.1σ • WW: 1.4σ • Combined: 3.6σ

  18. CMS Signals • Combined: 2.6σ

  19. Has the Higgs Boson been Discovered? Unofficial blogger’s combination NOT ENDORSED BY EXPERIMENTS but he was right last time !

  20. Assuming the Standard Model Combining the Information from Previous Direct Searches and Indirect Data mH = 125 ± 10 GeV mH = 124.5 ± 0.8 GeV Erler: arXiv:1201.0695

  21. There must be New Physics Beyond the Standard Model viXra Blogger’s Combination of Dec.13th Data Higgs potential collapses Precision Electroweak data?? Higgs coupling blows up!! Higgs coupling less than in Standard Model

  22. What attitude towards LEP, NuTeV? Heretical Interpretation of EW Data Do all the data tell the same story? e.g., AL vs AH What most of us think Chanowitz

  23. But conspiracies are possible: mH could be large, even if believe EW data …? Higgs + Higher-Order Operators Corridor to heavy Higgs? Precision EW data suggest they are small: why? Do not discard possibility of heavy Higgs Barbieri, Strumia

  24. Higgs field: <0|H|0> ≠ 0 Quantum loop problems Fermion-antifermion condensate Just like QCD, BCS superconductivity Top-antitop condensate? needed mt > 200 GeV Elementary Higgs or Composite? Cutoff Λ = 10 TeV New technicolour force? inconsistent with precision electroweak data? Cut-off Λ ~ 1 TeV with Supersymmetry?

  25. Interpolating Models • Combination of Higgs boson and vector ρ • Two main parameters: mρ and coupling gρ • Equivalently ratio weak/strong scale: gρ / mρ Grojean, Giudice, Pomarol, Rattazzi

  26. What if the Higgs is not quite a Higgs? • Tree-level Higgs couplings ~ masses • Coefficient ~ 1/v • Couplings ~ dilaton of scale invariance • Broken by Higgs mass term –μ2, anomalies • Cannot remove μ2 (Coleman-Weinberg) • Anomalies give couplings to γγ, gg • Generalize to pseudo-dilaton of new (nearly) conformal strongly-interacting sector • Couplings ~ m/V (V > v?), additions to anomalies

  27. A Phenomenological Profile of a Pseudo-Dilaton • New strongly-interacting sector at scale ~ V • Pseudo-dilaton only particle with mass << V • Universal suppression of couplings to Standard Model particles ~ v/V • Γ(gg) may be enhanced • Γ(γγ) may be suppressed • Modified self-couplings • Pseudo-baryons as dark matter? Compilation of constraints Updated with Dec. 11 constraints Campbell, JE, Olive: arXiv:1111.4495

  28. Higgsless Models? • Four-dimensional versions: Strong WW scattering @ TeV, incompatible with precision data? • Break EW symmetry by boundary conditions in extra dimension: delaystrong WW scattering to ~ 10 TeV? Kaluza-Klein modes: mKK > 300 GeV? compatibility with precision data? • Warped extra dimension + brane kinetic terms? Lightest KK mode @ few 00 GeV, strong WW @ 6-7 TeV

  29. Theoretical Constraints on Higgs Mass • Large Mh → large self-coupling → blow up at low-energy scale Λ due to renormalization • Small: renormalization due to t quark drives quartic coupling < 0 at some scale Λ → vacuum unstable • Vacuum could be stabilized by supersymmetry LHC 95% exclusion Espinosa, JE, Giudice, Hoecker, Riotto, arXiv0906.0954

  30. SUSY vs Data • Electroweak precision observables • Flavour physics observables • gμ - 2 • Higgs mass • Dark matter • LHC MasterCode: O.Buchmueller, JE et al.

  31. 68% & 95% CL contours ….. pre-LHC ___ LHC 1/fb

  32. Higgs mass χ2 price to pay if Mh = 125 GeV is < 2 Buchmueller, JE et al: arXiv:1112.3564 Favoured values of Mh ~ 119 GeV: Range consistent with evidence from LHC !

  33. 68% & 95% CL contours ….. pre-Higgs ___ Higgs @ 125 Buchmueller, JE et al: arXiv:1112.3564

  34. Gluino mass --- pre-Higgs ___ Higgs @ 125 … H@125, no g-2 Buchmueller, JE et al: arXiv:1112.3564 Favoured values of gluino mass significantly above pre-LHC, > 2 TeV

  35. The Stakes in the Higgs Search • How is gauge symmetry broken? • Is there any elementary scalar field? • Would have caused phase transition in the Universe when it was about 10-12 seconds old • May have generated then the matter in the Universe: electroweak baryogenesis • A related inflaton might have expanded the Universe when it was about 10-35 seconds old • Contributes to today’s dark energy: 1060 too much!

  36. Measurements of Higgs Couplings • Some decays limited by statistics • Others limited by systematics

  37. The Spin of the Higgs Boson @ LHC Low mass: if H →γγ, It cannot have spin 1 Higher mass: angular correlations in H → ZZ decays

  38. Higgs Self-coupling @ Hi-Lumi LHC? Measure triple-Higgs-boson coupling with accuracy comparable to 0.5 TeV ILC? Awaits confirmation by detailed experimental simulation

  39. The Fun is just Beginning • LHC7 may well resolve Higgs issue • LHC7 (or 8) unlikely to resolve SUSY issue (or other BSM scenarios) • Premium on increasing Ecm towards 14 TeV • Prospects for L factor 500 with Hi-Lumi LHC • What will follow the LHC? • Higgs factory? CLIC? High-E LHC? • A new era about to open: AH (anno Higgsi)

  40. Quo Vadisgμ - 2? Strong discrepancy between BNL experiment and e+e- data: now ~ 3.6 σ Better agreement between e+e- experiments Increased discrepancy between BNL experiment and τ decay data now ~ 2.4 σ Convergence between e+e- experiments and τ decay More credibility?

  41. MSSM: > 100 parameters String? SU(5) unification: 7 parameters NUHM2: 6 parameters NUHM1 = SO(10): 5 parameters CMSSM: 4 parameters Minimal Flavour Violation: 13 parameters (+ 6 violating CP) mSUGRA: 3 parameters

  42. … nevertheless Supersymmetric Dark Matter in View of 1/fb of LHC Data

  43. 68% & 95% CL contours ….. pre-LHC ___ LHC 1/fb MasterCode: O.Buchmueller, JE et al.

  44. Impact of dropping gμ-2constraint ….. pre-LHC ___ LHC 1/fb MasterCode: O.Buchmueller, JE et al. Dropping gμ - 2 allows masses up to dark matter limit

  45. Gluino mass ….. pre-LHC ___ LHC 1/fb MasterCode: O.Buchmueller, JE et al. Favoured values of gluino mass significantly above pre-LHC, > 1 TeV

  46. + LHCb Bsμ+μ- ….. pre-LHC ___ LHC 1/fb --- with CDF MasterCode: O.Buchmueller, JE et al. Favoured values of BR(Bsμ+μ-) above SM value ! (due to increase in tan β)

  47. Higgs mass Favoured values of Mh ~ 119 GeV: Coincides with value consistent with LHC !

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