LHC: Higgs, less Higgs, or more Higgs?

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

2. Has the Higgs been Excluded? Interesting hints around Mh = 125 GeV ? ATLAS excludes < 122.5, > 129, < 539 GeV CMS excludes > 127.5, < 600 GeV

3. Has the Higgs been Discovered? Interesting hints around Mh = 125 GeV ? ATLAS prefers > 125 GeV CMS prefers < 125 GeV

4. Unofficial Combination of Higgs Search Data from March 7th Is this the Higgs Boson? No Higgs here! No Higgs here!

5. The Particle Higgsaw Puzzle Is LHC finding the missing piece? Is it the right shape? Is it the right size?

6. Do we already know the ‘Higgs’ has Spin Zero ? • Decays into γγ, so cannot have spin 1 • 0 or 2? • If it decays into ττ or b-bar: spin 0 or 1 or orbital angular momentum • Can diagnose spin via • angular distribution of γγ • angular correlations of leptons in WW, ZZ decays • Does selection of WW events mean spin 2?

7. Does the ‘Higgs’ have Spin Zero ? • Polar angle distribution: X2γγ (flat for X0) • Azimuthal angle distribution: X0WW (flat for X2) JE, Hwang: arXiv:1202.6660

8. Does the ‘Higgs’ have Spin Zero ? • Polar angle distribution for X2W+W- • Polar angle distribution for X0W+W- (for φ = π) JE, Hwang: arXiv:1202.6660

9. Measuring Higgs Couplings @ LHC Current LHC hint @ Mh = 125 GeV

10. Flavour-Changing Couplings? • Upper limits from FCNC, EDMs, … • Quark FCNC bounds exclude observability of quark-flavour-violating h decays • Lepton-flavour-violating h decays could be large: BR(τμ) or BR(τe) could be O(10)% B BR(μe) must be < 2 ✕ 10-5 Blankenburg, JE, Isidori: arXiv:1202.5704

11. STANDARD MODEL John Ellis, King’s College London (& CERN)

12. There must be New Physics Beyond the Standard Model viXra Blogger’s Combination of March 7th Data Precision Electroweak data?? Higgs coupling blows up!! Higgs potential collapses Higgs coupling less than in Standard Model

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

14. 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

15. 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?

16. 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

17. 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

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

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

20. 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

21. Effective Lagrangian Framework • Standard Model Higgs sector = linear σ model • Replace by nonlinear chiral Lagrangian • Assume ~ scale (conformal) symmetry • Realized via (pseudo-)dilaton field χ • Effective χ potential à la Coleman-Weinberg, with small coefficient B: • Large <0|χ|0> = V >> electroweak scale v JE 1970

22. 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

23. 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

24. Analysis of ‘Less Higgs’ Models • Rescale couplings: to bosons by a to fermions by c • Standard Model: a = c = 1 JE & Tevong You

25. Electroweak Pseudo-Baryons • Chiral Lagrangian has soliton solutions whenever higher-order term present (generic): • Have non-zero topological quantum number • B is integer, can be identified with baryon # • Underlying SU(N) gauge theory: bosons (fermions) with I = J = 0 (1/2) if N even (odd) • SO(N) gauge theory: B is Z2 quantum number • Sp(N) gauge theory: baryons decay to mesons Campbell, JE, Olive: arXiv:1111.4495

26. Behaviour at Finite Temperature • Corrections to nonlinear effective theory: • Correction to effective dilaton potential: • Critical temperature when equal free energies • More degrees of freedom in confined phase: Campbell, JE, Olive: arXiv:1111.4495

27. Cosmological Phase Transition • Critical temperature with <0|χ|0> ~ V: • But supercooling to nucleation temperature: • First-order phase transition • Percolation ~ immediate • Short phase of non-adiabatic expansion Campbell, JE, Olive: arXiv:1111.4495

28. Evolution of the Universe • Universe supercoools • Expansion briefly dominated by field energy • Growth in entropy by factor ~ 7 to 200 • Identify confinement, appearance of electroweak ‘baryons’ with transition to <0|χ|0> ≠ 0 Campbell, JE, Olive: arXiv:1111.4495

29. Baryon-to-Entropy Ratio • ‘Kibble’ estimate would be large • But thermal equilibrium thought to be restored • Expect smaller density: : freeze-out • Density smaller than required for cold dark matter: • Need electroweak ‘pseudo-baryon’ asymmetry Campbell, JE, Olive: arXiv:1111.4495

30. Electroweak baryons ? Can we look for them with the LHC?

31. Electroweak Baryons as Dark Matter • Fermions with I = J = ½? • Expect mass of charged partner > neutral: • Estimate mass difference ~ GeV • β-decay lifetime ~ 10-11 sec • thermal equilibrium down to T ~ MeV • Small abundance of charged state • BUT some might be trapped in stable charged ‘pseudo-nuclei’✕ experiment Campbell, JE, Olive: arXiv:1111.4495

32. Pseudo-Baryonic Dark Matter? • No problem if I = J = 0 bosons • Estimate scattering cross section: where: with • Within range of future experiments Dark mattter Scattering rate Campbell, JE, Olive: arXiv:1111.4495

34. Classic Supersymmetric Signature Missing transverse energy carried away by dark matter particles

35. Limits on Heavy MSSM Higgses

37. 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

38. 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!

39. Conversation with Mrs Thatcher: 1982 Wouldn’t it be better if they found what you predicted? Think of things for the experiments to look for, and hope they find something different What do you do? Then we would not learn anything!