From the Tevatron to the LHCCosener’s House, April 24-25, 2004

Morning PrayerJohn 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 ~ 1016 GeV?probe directly via neutrino physics, indirectly via masses, couplings

• Quantum theory of gravity?extra space-time dimensions?

All these issues tackledby the LHC (Tevatron)

Electroweak Symmetry Breaking

The Electroweak Vacuum

• Generating particle masses requires breaking gauge symmetry:

mW,Z =/= 0 <0|XI|0> =/= 0

mW2 = mZ

2 cos2 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

• Top-antitop condensate? needed mt > 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 mt = 160 – 180 GeV

• Sensitive to massof Higgs boson

mH < 200 GeV ?

• Direct:• LEP Searches for

e+ e- -> Z + H• Hint seen in late 2000

now < 2 σ

Current Limit:

mH > 114.4 GeV

Waiting for the Higgs boson

Higgs probability distribution:

combining direct,

indirect information

mH > 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 modelsextra `Top’, gauge bosons, `Higgses’

• Higgsless modelsstrong 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, NuTeV?

What mostof us think

Higgs + Higher-Order Operators

Precision EW data suggest they are small: why?

But conspiraciesare possible: mH

could be large, even if believeEW data …?

Do not discard possibility of heavy Higgs

Corridor toheavy 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

MT < 2 TeV (mh / 200 GeV)2

MW’ < 6 TeV (mh / 200 GeV)2

MH++ < 10 TeV

Generic LittleHiggs Spectrum

Loop cancellation mechanisms

Supersymmetry Little 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: mKK > 300 GeV?

compatibility with precision data?

• Warped extra dimension + brane kinetic terms?

Lightest KK mode @ 300 GeV, strong WW @ 6-7 TeV

Tevatron & LHC

Updated Estimate of Tevatron Higgs Reach (June 2003)

Updated Tevatron Luminosity Projections

The Large Hadron Collider (LHC)

Proton- Proton Collider

7 TeV + 7 TeV

Luminosity = 1034cm-2sec-1

Primary targets: •Origin of mass•Nature of Dark Matter•Primordial Plasma•Matter vs Antimatter

LHC Progress `Dashboard’

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 matterg – 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

Some Sample Higgs Signals

ttH

bbH

γγZZ* -> llll

Measuring Higgs Self-Coupling

Heavier Higgs possible @ SLHCLight Higgs @ low-energy LC

LHC-LC report

Sensitivity to Strong WW scattering

@ LHC @ 800 GeV LC

LHC-LC report

Measuring WW Resonance

Form factor measurements@ 500 GeV LC

Resonance parameters@ LHC

Resonance parameters @ 500 GeV LCLHC-LC report

Constraining Triple-Gauge Coupling

Other Physics @ EW Scale

Why Supersymmetry (Susy)?

• Hierarchy problem: why is mW << mP ?

(mP ~ 1019 GeV is scale of gravity)• Alternatively, why is

GF = 1/ mW2 >> GN = 1/mP

2 ?• Or, why is

VCoulomb >> VNewton ? e2 >> G m2 = m2 / mP2

• Set by hand? What about loop corrections?

δmH,W2 = O(α/π) Λ2

• Cancel boson loops fermions• Need | mB

2 – mF2| < 1 TeV2

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 < Ωχh2 < 0.124

gμ - 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 mt = 178 GeV

JE, Olive, Santoso, Spanos

Current Constraints

on CMSSM

Impact ofHiggsconstraintreducedif larger mt

Focus-pointregion far up

Differenttan βsign of μ

JE, Olive, Santoso, Spanos

Density belowWMAP limit

Decays do not affectBBN/CMB agreement

DifferentRegions of

SparticleParameterSpace if

Gravitino LSP

DifferentGravitinomasses

JE, Olive, Santoso, Spanos

CMSSM

Up to 10 TeV

massesarbitrary

Gravitino LSP

Coverage in Different Supersymmetric Models

500 (1000)GeV LCcovers partof space

Supersymmetry Searches at LHC

`Typical’ supersymmetric

Event at the LHC

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

LHC-LC report

CP Violation in the MSSM?

• Assuming universality for the soft susy-breaking 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

Carena, JE, Mrenna, Pilaftsis, Wagner

Assuming common value of φA, φ3

Cross Sections across Mixed Higgs Peaks

JE, Lee, Pilaftsis

φA = 90,φ3 = -90, -10Diagrams

Kinematics

CP-Violating Asymmetries

Rather small Could 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 LCScapabilities

LC obervescomplementarysparticles

Battaglia, De Roeck, JE, Gianotti, Olive, Pape

Example of Benchmark Point

Spectrum ofBenchmark SPS1a~ Point B ofBattaglia et al

Several sparticlesat 500 GeV LC,more at 1000 GeV,some need higher E

LHC-LC report

Examples of Sparticle Measurements

Spectrum edges@ LHC

Thresholdexcitation@ LC

Spectra@ LC

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 scale Fine-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 >> lP

- Could be origin of supersymmetry breaking

- Enable reformulation of the

hierarchy problem

Reformulated

Sequence of KK Resonances?In Randall-Sundrum model

S1/Z2 orbifold version @ LC

Possible spectrum @ LHC

Sensitivity incontact-interaction regime

LHC-LC report

Scenario with Universal Extra D

Spectrum like supersymmetry:More degenerate

Lightest KK particle stable: dark matter?

Distinguish from susyvia 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:

mH = 130 GeV, 1/R ~ 400 GeV

• Relaxed if top quark

partially

localizedLSP 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

The Reach of the LHC for New High-Mass Physics