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STANDARD MODEL PowerPoint Presentation
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STANDARD MODEL

STANDARD MODEL

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STANDARD MODEL

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  1. STANDARD MODEL

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

  3. Theorists getting Cold Feet • Composite Higgs model? conflicts with precision electroweak data • Interpretation of EW data? consistency of measurements?Discard some? • Higgs + higher-dimensional operators? corridors to higher Higgs masses? • Little Higgs models? extra `Top’, gauge bosons, `Higgses’ • Higgsless models? strong WW scattering, extra D?

  4. 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

  5. Estimates of mH from different Measurements Spread looks natural: no significant disagreement

  6. 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

  7. 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? • Heavy scalar resonance? • Inconsistent with precision electroweak data? Cut-off Λ ~ 1 TeV with Supersymmetry?

  8. Comparison between Weakly- and Strongly-coupled Models

  9. 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

  10. Intermediate Models

  11. Effects on Higgs Decays • Dependences on ξ of Higgs branching ratios • Standard Model recovered in limit ξ0 Grojean, Giudice, Pomarol, Rattazzi

  12. Higgs as a Pseudo-Goldstone Boson ‘Little Higgs’ models (breakdown of larger symmetry) Loop cancellation mechanism Little Higgs Supersymmetry

  13. Little Higgs Models • Embed SM in larger gauge group • Higgs as pseudo-Goldstone boson • Cancel top loop with new heavy T quark • New gauge bosons, Higgses • Higgs light, other new physics heavy MT < 2 TeV (mh / 200 GeV)2 MW’ < 6 TeV (mh / 200 GeV)2 MH++ < 10 TeV Not as complete as susy: more physics > 10 TeV

  14. Examples of Higgs as Pseudo-Goldstone Boson • Parameterization of effective Lagrangian: • Examples: • To be measured!

  15. 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 • Pseudo-Goldstone boson of scale symmetry

  16. A Phenomenological Profile of a Pseudo-Dilaton • Universal suppression of couplings to Standard Model particles: a = c = v/V • Effective potential: • Self-couplings: • Γ(gg) may be enhanced • Γ(γγ) may be suppressed Compilation of constraints Updated with Dec. 11 constraints Pseudo-baryons as dark matter? Campbell, JE, Olive: arXiv:1111.4495

  17. General Analysis of ‘Less Higgs’ Models • Parameterization of effective Lagrangian: • Fits a ≠ c Azatov, Contino, Galloway: arXiv:1202.3415 Espinosa, Grojean, Muhlleitner, Trott: arXiv:1202.3697

  18. General Analysis of ‘Less Higgs’ Models • Separate fits to CMS and ATLAS data: Azatov, Contino, Galloway: arXiv:1202.3415

  19. Sum Rule for More or Less Higgs Models • What if Higgs-V-V couplings differ from SM? • Unitarity imposes sum rule on scattering in different isospin channels: • If Higgs coupling > Standard Model (a2 > 1), must have non-zero scattering with I = 2 Fialkowski, Rychkov, Urban: arXiv:1202.1532

  20. 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

  21. Particle Spectrum in Simplest Model with Extra Dimensions Lowest-lying states have flat wave functions (n = 0) Excitations (Kaluza-Klein) have nodes (n > 0): Mass ~ n/R (R = radius of circle)

  22. ‘Fold’ Circle: Orbifold • Identify two halves of circle: up to a minus sign • ‘Even’ particles include massless: odd ones all massive • A way to give masses to particles that are asymmetric

  23. Mechanism to break Gauge Symmetry • Identify two halves up to a group transformation U • Unbroken part of gauge group commutes with U • Masses for asymmetric particles: • e.g., SU(2) × U(1)  U(1)

  24. Search for Vector Resonance in Higgsless Model Simulation of resonance structure in mWZ @ LHC Vector resonance structure in WZ scattering