From the Tevatron to the LHC Cosener s House

From the Tevatron to the LHC Cosener’s House, April 24 -25, 2004 Morning Prayer John Ellis

Open Questions beyond the Standard Model • What is the origin of particle masses? due to a Higgs boson? + other physics? solution at energy < 1 Te. V (1000 Ge. V) • Why so many types of matter particles? matter-antimatter difference? • Unification of the fundamental forces? at very high energy ~ 1016 Ge. V? probe directly via neutrino physics, indirectly via masses, couplings • Quantum theory of gravity? All these issues tackled extra space-time dimensions? by the LHC (Tevatron)

Electroweak Symmetry Breaking

The Electroweak Vacuum • Generating particle masses requires breaking gauge symmetry: m. W, Z =/= 0 <0|XI|0> =/= 0 m. W 2 = m. Z 2 cos 2 θW => I = ½ • I = ½ also needed for fermion masses • What is X? Elementary or Composite?

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

Searches for the Higgs Boson Indirect: • Direct: • Precision electroweak measurements at LEP, SLC, etc • Predicted successfully mt = 160 – 180 Ge. V • Sensitive to mass of Higgs boson m. H < 200 Ge. V ? • LEP Searches for e+ e- -> Z + H • Hint seen in late 2000 now < 2 σ Current Limit: m. H > 114. 4 Ge. V

Waiting for the Higgs boson m. H > 114. 4 Ge. V Higgs probability distribution: combining direct, indirect information How soon will the Higgs be found? …

Theorists getting Cold Feet • 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?

Heretical Interpretation of EW Data Do all the data tell the same story? e. g. , AL vs AH 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 …? Do not discard possibility of heavy Higgs Corridor to heavy Higgs?

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)2 • Higgs light, other new MH++ < 10 Te. V physics heavy Not as complete as susy: more physics > 10 Te. V

Generic Little Higgs Spectrum Loop cancellation mechanisms Supersymmetry Little Higgs

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 @ 300 Ge. V, strong WW @ 6 -7 Te. V

Tevatron & LHC

Updated Estimate of Tevatron Higgs Reach (June 2003)

Updated Tevatron Luminosity Projections

The Large Hadron Collider (LHC) Proton- Proton Collider 7 Te. V + 7 Te. V Luminosity = 1034 cm-2 sec-1 Primary targets: • Origin of mass • Nature of Dark Matter • Primordial Plasma • Matter vs Antimatter

LHC Progress `Dashboard’

The First Direct Exploration of the Te. V Scale … • Why is this interesting? Any new energy range takes us deeper inside matter, but also … • Several reasons to expect new physics: Origin of particle masses Stabilization of gauge hierarchy Unification of couplings Dark matter g – 2 of muon

The Physics Scope of the LHC Interesting cross sections Bread-and-butter physics W Δm = 15 Me. V Susy Higgs top Δm = 1 Ge. V

A la recherche du Higgs perdu … Higgs Production at the LHC … not far away? Combining direct, Indirect information

Some Sample Higgs Signals γγ ZZ* -> llll tt. H bb. H

Measuring Higgs Self-Coupling Light Higgs @ low-energy LC Heavier Higgs possible @ SLHC LHC-LC report

Sensitivity to Strong WW scattering @ LHC @ 800 Ge. V LC LHC-LC report

Measuring WW Resonance Form factor measurements @ 500 Ge. V LC LHC-LC report Resonance parameters @ LHC Resonance parameters @ 500 Ge. V LC

Constraining Triple-Gauge Coupling

Other Physics @ EW Scale

Why Supersymmetry (Susy)? • Hierarchy problem: why is m. W << m. P ? (m. P ~ 1019 Ge. V is scale of gravity) • Alternatively, why is GF = 1/ m. W 2 >> GN = 1/m. P 2 ? • Or, why is VCoulomb >> VNewton ? e 2 >> G m 2 = m 2 / m. P 2 • Set by hand? What about loop corrections? δm. H, W 2 = O(α/π) Λ 2 • Cancel boson loops fermions • Need | m. B 2 – m. F 2| < 1 Te. V 2

Other Reasons to like Susy It enables the gauge couplings to unify It stabilizes the Higgs potential for low masses Approved by Fabiola Gianotti

Constraints on Supersymmetry • Absence of sparticles at LEP, Tevatron selectron, chargino > 100 Ge. V squarks, gluino > 250 Ge. V • Indirect constraints Higgs > 114 Ge. V, b -> s γ • Density of dark matter lightest sparticle χ: WMAP: 0. 094 < Ωχh 2 < 0. 124 gμ - 2

Current Constraints on CMSSM Focus-point region above 7 Te. V for mt = 178 Ge. V Excluded because stau LSP Excluded by b s gamma WMAP constraint on relic density Excluded (? ) by latest g - 2 Latest CDF/D 0 top mass JE, Olive, Santoso, Spanos

Current Constraints on CMSSM Different tan β sign of μ Impact of Higgs constraint reduced if larger mt Focus-point region far up JE, Olive, Santoso, Spanos

Different Regions of Sparticle Parameter Space if Gravitino LSP Different Gravitino masses Density below WMAP limit Decays do not affect BBN/CMB agreement JE, Olive, Santoso, Spanos

500 (1000) Ge. V LC covers part of space

Supersymmetry Searches at LHC `Typical’ supersymmetric Event at the LHC reach in supersymmetric parameter space

Observability of Lightest CMSSM Higgs Boson Cross section comparable to SM Higgs JE, Heinemeyer, Olive, Weiglein

Heavier MSSM Higgs Bosons Observability @ LHC-LC report

CP Violation in the MSSM? • Assuming universality for the soft susybreaking parameters • Two possible sources: Phase in trilinear term A: φA Phase in gluino mass: φ3 • Loop effects on MSSM Higgs bosons • CP-violating mixing: h, H A

Observability @ LEP & LHC Some uncovered regions of parameter space Assuming common value of φA, φ3 Carena, JE, Mrenna, Pilaftsis, Wagner

Cross Sections across Mixed Higgs Peaks Diagrams φA = 90, φ3 = -90, -10 Kinematics JE, Lee, Pilaftsis

CP-Violating Asymmetries Rather small Could be large! JE, Lee, Pilaftsis

Examples of Integrated Asymmetries Could be large! JE, Lee, Pilaftsis

Supersymmetric Benchmark Studies Lines in susy space allowed by accelerators, WMAP data Sparticle Detectability @ LHC along one WMAP line Battaglia, De Roeck, JE, Gianotti, Olive, Pape Specific benchmark Points along WMAP lines LHC enables calculation of relic density at a benchmark point

LHC and LC Scapabilities LHC almost `guaranteed’ to discover supersymmetry if it is relevant to the mass problem LC oberves complementary sparticles Battaglia, De Roeck, JE, Gianotti, Olive, Pape

Example of Benchmark Point Spectrum of Benchmark SPS 1 a ~ Point B of Battaglia et al Several sparticles at 500 Ge. V LC, more at 1000 Ge. V, some need higher E LHC-LC report

Examples of Sparticle Measurements Threshold excitation @ LC Spectrum edges @ LHC Spectra @ LC LHC-LC report

Mass Measurements @ Benchmark B = SPS 1 a Fit to CMSSM parameters LHC-LC report

Supersymmetric Benchmark Studies Lines in susy space allowed by accelerators, WMAP data Sparticle detectability Along one WMAP line Battaglia, De Roeck, JE, Gianotti, Olive, Pape Specific benchmark Points along WMAP lines Calculation of relic density at a benchmark point

How `Likely’ are Large Sparticle Masses? Fine-tuning of EW scale Fine-tuning of relic density Larger masses require more fine-tuning: but how much is too much? JE, Olive, Santoso

If not supersymmetry, what ? Extra Dimensions ? - Suggested by Kaluza and Klein to unify gravity and electromagnetism Reformulated - Required for consistency of string theory - Could help unify strong, weak and electromagnetic forces with gravity if >> l. P - Could be origin of supersymmetry breaking - Enable reformulation of the hierarchy problem

Sequence of KK Resonances? In Randall-Sundrum model Possible spectrum @ LHC Sensitivity in contact-interaction regime S 1/Z 2 orbifold version @ LC LHC-LC report

Scenario with Universal Extra D Spectrum like supersymmetry: More degenerate Distinguish from susy via LC cross sections Lightest KK particle stable: dark matter? LHC-LC report

`Constrained Standard Model’ • Break supersymmetry by boundary conditions in extra dimension • If top quark not localized, 1 -parameter potential: m. H = 130 Ge. V, 1/R ~ 400 Ge. V • Relaxed if top quark partially localized LSP is stop Barbieri

And if there are large extra dimensions & gravity becomes strong at the Te. V scale Black Hole Production at LHC? Multiple jets, Leptons from Hawking Radiation

The Reach of the LHC for New High -Mass Physics