Higgs more Higgs less Higgs or Higgsless John

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

The ‘Standard Model’ of Particle Physics Proposed by. Abdus Salam, Glashow and Weinberg Tested by experiments at CERN & elsewhere Perfect agreement between theory and experiments in all laboratories

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

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

The Seminal Papers

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

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

Mysterious Higgs Potential Mass 2 of Higgs ~ curvature of potential at minimum Vertical scale ~ 1060 × dark energy

A Phenomenological Profile of the Higgs Boson • • Neutral currents (1973) Charm (1974) Heavy lepton τ (1975) Attention to search for W±, Z 0 For us, the Big Issue: is there a Higgs boson? Previously ~ 10 papers on Higgs bosons MH > 18 Me. V First attempt at systematic survey

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

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 Ge. V

The State of the Higgs in Mid-2011 • High-energy search: – Limit from LEP: m. H > 114. 4 Ge. V • High-precision electroweak data: – Sensitive to Higgs mass: m. H = 96+30– 24 Ge. V • Combined upper limit: m. H < 161 Ge. V, or 190 Ge. V including direct limit • Exclusion from high-energy search at Tevatron: m. H < 158 Ge. V or > 173 Ge. V

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

Higgs Hunting @ LHC: Status th reported on Dec. 13 , 2011 Exclude 127 to 600 Ge. V Exclude 112. 7 Ge. V to 115. 5 Ge. V, 131 Ge. V to 237 Ge. V, 251 Ge. V to 453 Ge. V

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

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

ATLAS Signals • • γγ: 2. 8σ ZZ: 2. 1σ WW: 1. 4σ Combined: 3. 6σ

CMS Signals • Combined: 2. 6σ

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

Combining the Information from Previous Direct Searches and Indirect Data Assuming the Standard Model m. H = 125 ± 10 Ge. V m. H = 124. 5 ± 0. 8 Ge. V Erler: ar. Xiv: 1201. 0695

There be New Physics vi. Xramust Blogger’s Combination th Data Model Beyondofthe Standard Dec. 13 Higgs potential collapses Higgs coupling less than in Standard Model Precision Electroweak data? ? Higgs coupling blows up!!

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

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

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

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

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 –μ 2, anomalies – Cannot remove μ 2 (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

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 Compilation Updated ofwith constraints Dec. 11 • Γ(gg) may be enhanced constraints • Γ(γγ) may be suppressed • Modified self-couplings • Pseudo-baryons as dark matter? Campbell, JE, Olive: ar. Xiv: 1111. 4495

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

Theoretical Constraints on Higgs Mass • Large Mh → large self-coupling → blow up at low-energy scale Λ due to LHC 95% exclusion renormalization • Small: renormalization due to t quark drives quartic coupling < 0 at some scale Λ → vacuum unstable • Vacuum could be stabilized by supersymmetry Espinosa, JE, Giudice, Hoecker, Riotto, ar. Xiv 0906. 0954

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

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

Higgs mass χ2 price to pay if Mh = 125 Ge. V is < 2 Buchmueller, JE et al: ar. Xiv: 1112. 3564 Favoured values of Mh ~ 119 Ge. V: Range consistent with evidence from LHC !

68% & 95% CL contours pre-Higgs ___ Higgs @ 125 …. . Buchmueller, JE et al: ar. Xiv: 1112. 3564

Gluino mass --- pre-Higgs ___ Higgs @ 125 … H@125, no g-2 Buchmueller, JE et al: ar. Xiv: 1112. 3564 Favoured values of gluino mass significantly above pre-LHC, > 2 Te. V

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!

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

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

Higgs Self-coupling @ Hi-Lumi LHC? Measure triple-Higgs-boson coupling with accuracy comparable to 0. 5 Te. V ILC? Awaits confirmation by detailed experimental simulation

The Fun is just Beginning • LHC 7 may well resolve Higgs issue • LHC 7 (or 8) unlikely to resolve SUSY issue (or other BSM scenarios) • Premium on increasing Ecm towards 14 Te. V • 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)

Quo Vadis gμ - 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+eexperiments and τ decay • More credibility?

MSSM: > 100 parameters Minimal Flavour Violation: 13 parameters (+ 6 violating CP) SU(5) unification: 7 parameters NUHM 2: 6 parameters NUHM 1 = SO(10): 5 parameters CMSSM: 4 parameters m. SUGRA: 3 parameters String?

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

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

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

Gluino mass pre-LHC ___ LHC 1/fb …. . Master. Code: O. Buchmueller, JE et al. Favoured values of gluino mass significantly above pre-LHC, > 1 Te. V

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

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

Generic Little Higgs Models (Higgs as pseudo-Goldstone boson of larger symmetry) Loop cancellation mechanism Little Higgs Supersymmetry

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 MT < 2 Te. V (mh / 200 Ge. V)2 MW’ < 6 Te. V (mh / 200 Ge. V) • Higgs light, other new MH++ < 10 Te. V physics heavy Not as complete as susy: more physics >

Searches for Extra Particles in Little Higgs Models

Estimates of m. H from different Measurements Spread looks natural: no significant disagreemen

Intermediate Models

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

What if no Higgs? • Higgs must discriminate between different types of particles: – Some have masses, some do not – Masses of different particles are different • In mathematical jargon, symmetry must be broken: how? – Break symmetry in equations? – Or in solutions to symmetric equations? • This is the route proposed by Higgs – Is there another way?

Where to Break the Symmetry? • Throughout all space? – Route proposed by Higgs – Universal Higgs (snow)field breaks symmetry – If so, what type of field? • Or at the edge of space? – Break symmetry at the boundary? • Not possible in 3 -dimensional space – No boundaries – Postulate extra dimensions of space • Different particles behave differently in the extra dimension(s)

Higgs Hunting @ Tevatron Exclude (100, 109); (156, 177) Ge. V

Comparison between Weakly- and Strongly-coupled Models

XENON 100 & other Experiments Aprile et al: ar. Xiv: 1104. 2549

Supersymmetry Searches in ATLAS Jets + missing energy + 0 lepton

XENON 100 Experiment Aprile et al: ar. Xiv: 1104. 2549

Early Phenomenological Bounds • Emission from stars: MH > 0. 7 me (Sato & Sato, 1975) • Neutron-electron scattering: MH > 0. 7 Me. V (Rafelski, Muller, Soff & Greiner; Watson & Sundaresan; Adler, Dashen & Treiman; 1974) • Neutron-nucleus scattering: MH > 13 Me. V (Barbieri & Ericson, 1975) • Nuclear 0+ – 0+ transitions: MH > 18 Me. V (Kohler, Watson & Becker, 1974)

Supersymmetry Searches @ LHC Jets + missing energy (+ lepton(s)) Applicable to NUHM, CMSSM, VCMSSM, m. SUGRA but need other strategies for other models