Presentation on theme: "From the Tevatron to the LHC Coseners House, April 24-25, 2004 Morning Prayer John Ellis."— Presentation transcript:
From the Tevatron to the LHC Coseners 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 TeV (1000 GeV) Why so many types of matter particles? matter-antimatter difference? Unification of the fundamental forces? at very high energy ~ 10 16 GeV? probe directly via neutrino physics, indirectly via masses, couplings Quantum theory of gravity? extra space-time dimensions? All these issues tackled by the LHC (Tevatron)
The Electroweak Vacuum Generating particle masses requires breaking gauge symmetry: m W,Z =/= 0 =/= 0 m W 2 = m Z 2 cos 2 θ W => I = ½ I = ½ also needed for fermion masses What is X? Elementary or Composite?
Elementary Higgs or Composite? Higgs field: =/= 0 Problems with loops Fermion-antifermion condensate Just like QCD, BCS superconductivity Top-antitop condensate? needed m t > 200 GeV New technicolour force? inconsistent with precision electroweak data? Cut-off Λ ~ 1 TeV with Supersymmetry? Cutoff Λ = 10 TeV
Searches for the Higgs Boson Indirect: Precision electroweak measurements at LEP, SLC, etc Predicted successfully m t = 160 – 180 GeV Sensitive to mass of Higgs boson m H < 200 GeV ? Direct: LEP Searches for e + e - -> Z + H Hint seen in late 2000 now < 2 σ Current Limit: m H > 114.4 GeV
Waiting for the Higgs boson Higgs probability distribution: combining direct, indirect information m H > 114.4 GeV 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., A L vs A H What attitude towards LEP, NuTeV? 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 Higgs light, other new physics heavy Not as complete as susy: more physics > 10 TeV M T < 2 TeV (m h / 200 GeV) 2 M W < 6 TeV (m h / 200 GeV) 2 M H++ < 10 TeV
Generic Little Higgs Spectrum Loop cancellation mechanisms SupersymmetryLittle Higgs
Higgsless Models Four-dimensional versions: Strong WW scattering @ TeV, incompatible with precision data? Break EW symmetry by boundary conditions in extra dimension: delay strong WW scattering to ~ 10 TeV? Kaluza-Klein modes: m KK > 300 GeV? compatibility with precision data? Warped extra dimension + brane kinetic terms? Lightest KK mode @ 300 GeV, strong WW @ 6-7 TeV
The First Direct Exploration of the TeV 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 Bread-and-butter physics Δm = 15 MeV Δm = 1 GeV Interesting cross sections W top Higgs Susy
Higgs Production at the LHC A la recherche du Higgs perdu … … not far away? Combining direct, Indirect information
Why Supersymmetry (Susy)? Hierarchy problem: why is m W << m P ? (m P ~ 10 19 GeV is scale of gravity) Alternatively, why is G F = 1/ m W 2 >> G N = 1/m P 2 ? Or, why is V Coulomb >> V Newton ? 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 TeV 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 GeV squarks, gluino > 250 GeV Indirect constraints Higgs > 114 GeV, b -> s γ Density of dark matter lightest sparticle χ: WMAP: 0.094 < Ω χ h 2 < 0.124 g μ - 2
Current Constraints on CMSSM WMAP constraint on relic density Excluded because stau LSP Excluded by b s gamma Excluded (?) by latest g - 2 Latest CDF/D0 top mass Focus-point region above 7 TeV for m t = 178 GeV JE, Olive, Santoso, Spanos
Current Constraints on CMSSM Impact of Higgs constraint reduced if larger m t Focus-point region far up Different tan β sign of μ JE, Olive, Santoso, Spanos
Density below WMAP limit Decays do not affect BBN/CMB agreement Different Regions of Sparticle Parameter Space if Gravitino LSP Different Gravitino masses JE, Olive, Santoso, Spanos
CP Violation in the MSSM? Assuming universality for the soft susy- breaking parameters Two possible sources: Phase in trilinear term A: φ A Phase in gluino mass: φ 3 Loop effects on MSSM Higgs bosons CP-violating mixing: h, H A
Observability @ LEP & LHC Some uncovered regions of parameter space Carena, JE, Mrenna, Pilaftsis, Wagner Assuming common value of φ A, φ 3
Cross Sections across Mixed Higgs Peaks JE, Lee, Pilaftsis φ A = 90, φ 3 = -90, -10 Diagrams Kinematics
CP-Violating Asymmetries Rather smallCould be large! JE, Lee, Pilaftsis
Examples of Integrated Asymmetries Could be large! JE, Lee, Pilaftsis
Supersymmetric Benchmark Studies Specific benchmark Points along WMAP lines Lines in susy space allowed by accelerators, WMAP data Sparticle Detectability @ LHC along one WMAP line LHC enables calculation of relic density at a benchmark point Battaglia, De Roeck, JE, Gianotti, Olive, Pape
LHC almost `guaranteed to discover supersymmetry if it is relevant to the mass problem LHC and LC Scapabilities LC oberves complementary sparticles Battaglia, De Roeck, JE, Gianotti, Olive, Pape
Example of Benchmark Point Spectrum of Benchmark SPS1a ~ Point B of Battaglia et al Several sparticles at 500 GeV LC, more at 1000 GeV, some need higher E LHC-LC report
Mass Measurements @ Benchmark B = SPS1a Fit to CMSSM parameters LHC-LC report
Supersymmetric Benchmark Studies Specific benchmark Points along WMAP lines Lines in susy space allowed by accelerators, WMAP data Sparticle detectability Along one WMAP line Calculation of relic density at a benchmark point Battaglia, De Roeck, JE, Gianotti, Olive, Pape
JE, Olive, Santoso How `Likely are Large Sparticle Masses? Fine-tuning of EW scaleFine-tuning of relic density Larger masses require more fine-tuning: but how much is too much?
If not supersymmetry, what ? Extra Dimensions ? - Suggested by Kaluza and Klein to unify gravity and electromagnetism - 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 Reformulated
Sequence of KK Resonances? In Randall-Sundrum model S 1 /Z 2 orbifold version @ LC Possible spectrum @ LHC Sensitivity in contact-interaction regime LHC-LC report
Scenario with Universal Extra D Spectrum like supersymmetry: More degenerate Lightest KK particle stable: dark matter? Distinguish from susy via LC cross sections 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 GeV, 1/R ~ 400 GeV Relaxed if top quark partially localized LSP is stop Barbieri
And if there are large extra dimensions & gravity becomes strong at the TeV scale Black Hole Production at LHC? Multiple jets, Leptons from Hawking Radiation
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