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Physics @ CLIC

Albert De Roeck CERNand University of Antwerp and the IPPP Durham

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Linear e+e- Colliders

Since end of 2001 there seems to be a worldwide consensus (ECFA/HEPAP/Snowmass 2001…)

The machine which will complement and extend the LHCbest, and is closest to be realized is a Linear e+e- Colliderwith a collision energy of at least 500 GeV

PROJECTS: TeV Colliders (cms energy up to 1 TeV) Technology ~ready August’04 ITRP: NLC/GLC/TESLA ILC superconducting cavities Multi-TeV Collider (cms energies in multi-TeV range) R&D CLIC (CERN + collaborators) Two Beam Acceleration

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A LC is a Precision Instrument• Clean e+e- (polarized intial state, controllable s for

hard scattering)• Detailed study of the properties of Higgs particles mass to 0.03%, couplings to 1-3%, spin & CP structure,

total width (6%) factor 2-5 better than LHC/measure couplings in model indep. way

• Precision measurements of SUSY particles properties, i.e. slepton masses to better than 1%, if within reach

• Precision measurements a la LEP (TGC’s, Top and W mass)

• Large indirect sensitivity to new phenomena (eg WLWL scattering)

LC will very likely play important role to disentangle the underlying new theory

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LC: Few More Examples Understanding SUSY High accuracy of sparticle mass measurements relevant for reconstruction of SUSY

breaking mechanism Dark Matter LC will accurately measure m and couplings, i.e. Higgsino/Wino/Bino content Essential input to cosmology & searches LC will make a prediction of DMh²~ 3%

(SPS1a) A mismatch with WMAP/Planck would reveal extra sources of DM (Axions, heavy objects) Quantum level consistency: MH(direct)=

MH(indirect)?

sin2W~10-5 (GigaZ), MW ~ 6 MeV(?) (+theory progress) MH (indirect) ~ 5%

1/M GeV-1

G. Blair et al

‘WMAP’ 7 %

LHC ~15 %

‘Planck’

~2 %

LC ~3 %F. Richard/SPS1a

Gaugino mass parameters

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CTF2: CLIC Test Facility 2

Demonstrated that 2 beam acceleration worksReached up to 190 MV/m for short pulses (16ns)

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Building CLIC at CERN?

It is possible!

Geological analyses show that there is a contineous stretch of 40 km parallel to the Jura and the lake,with good geologicalconditions.

Reminder

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Cross Sections at CLIC

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Experimental Issues: Backgrounds CLIC 3 TeV e+e- collider with a luminosity ~ 1035cm-2s-1 (1 ab-1/year)

To reach this high luminosity: CLIChas to operate in a regime of high beamstrahlung

Expect large backgrounds# of photons/beam particle e+e- pair production events Muon backgrounds Neutrons Synchrotron radiationExpect distorted lumi spectrumReport

Old Values

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Experimental issues: Luminosity Spectrum

Luminosity spectrum not assharply peaked as e.g. at LEPor TESLA/NLC

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e+e- Pair Production

Coherent pair production number/BX 4.6 109

energy/BX 3.9 108 TeV

Can be suppressed by strong magneticfield in of the detector

Disappear in the beampipe

Incoherent pair production: number/BX 4.6 105

energy/BX 3.9 104 TeV

4T field

hits/mm2/bunch train

Can backscatter on machine elementsNeed to protect detector with mask

30mm O(1) hit/mm2/bunch train

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Background

Neutral and charged energy as function of cos per bx

Particles acceptedwithin > 120mrad

hadrons: 4 interactions/bx with WHAD>5 GeV

For studies: take 20 bx and overlay events

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Muon BackgroundMuon pairs produced in electromagnetic interactionsupstream of the IP e.g beam halo scraping on the collimators

GEANT3 simulation, taking intoaccount the full CLIC beam delivery system

# of muons expected in the detector ~ few thousand/bunchtrain (150-300 bunches/100-150ns)

OK for (silicon like) tracker Calorimeter?

1 shower >100 GeV/5 bx

~20 muons per bx

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Studies include background, spectra,…

Detector simulation (2004) SIMDET (fast simulation) GEANT3 based programStudies of the benchmark processes include backgrounds,effects of lumi spectrum etc.

Physics generators (COMPHEPPYTHIA6,… )+ CLIC lumi spectrum (CALYPSO)

+ hadrons backgrounde.g. overlay 20 bunch crossings(+ e+e- pair background files…)

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Detector:Active (small) group at CERN now: backgrounds, calorimetry,Time stamping, forward region… Weekly meetings…

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Example B-tagging

B-Decay length is long!

Define Area of Interest by 0.04 rad cone around the jet axis Count hit multiplicity (or pulse height) in Vertex Track layers Tag heavy hadron decay by step in detected multiplicity Can reach 50% eff./~80% purity

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Calorimetry

Importance of good energy resolution (e.g via energy flow)Interesting developments in TeV-class LC working groupse.g. compact 3D EM calorimeters, or “digital” hadronic calorimeters Detailed simulation studies of key processes requiredR&D accordingly afterwards/Join ILC detector efforts

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General Physics Context

• New physics expected in TeV energy range– Higgs, supersymmetry, extra dimensions, …?

• LHC will indicate what physics, and at which energy scale

• Two scenarios:– New physics at a low energy scale

• But perhaps more particles/phenomena at higher energies (e.g., supersymmetry)

– New physics threshold at higher energy scale• In many scenarios, e.g., SUSY, LHC will soon tell us the threshold

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Example: Resonance ProductionResonance scans, e.g. a Z’

Degenerate resonancese.g. D-BESS model

1 ab-1 M/M ~ 10-4 & / = 3.10-3

Can measure M down to 13 GeV

Smeared lumi spectrum allowsstill for precision measurements

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Physics Case: A light Higgs

Large cross sections Large CLIC luminosity Large events statistics Keep large statistics also for highest Higgs masses

O(500 K) Higgses/yearAllows to study the decaymodes with BRs ~ 10-4 suchas H and Hbb (>180 GeV) Eg: determine gH to ~4%

Low mass Higgs:400 000 Higgses/

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Physics case: Higgs potential

Reconstruct shape of the Higgs potential to complete the study of the Higgs profile and to obtain a direct proof of the EW symmetry breaking mechanism

Measure the triple (quartic) couplings

process

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Physics case: the Higgs Potential

Reconstruct shape of the Higgs potential to complete the study of the Higgs profile and to obtain a direct proof of the EW symmetry breaking mechanism

Can measure the Higgs potential for Higgs even for masses up to 300 GeVwith precision up to 5-10% (using polarization/weighting)

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Physics case: Heavy Higgs (MSSM)LHC: Plot for 5 discovery

3 TeV CLIC H, A detectable up to ~ 1.2 TeV

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Physics case: SUSY measurements

Benchmark Scenarios: CMSSMAllowed by present data constraintsADR,F., Gianotti,JE,F. Moortgat, K. Olive, L. Papehep-ph/0508198

LC/LHC complementarityPrecision measurements at ILC/CLICEg. 1150 GeV smuon mass to O(1%)Will a 0.5-1 TeV collider be enough?

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Susy Mass Measurements

Momentum resolutionpt/pt

2 ~ 10-4 GeV-1

adequate for thismeasurement

Mass measurementsto O(1%)

Momentum resolution (G3)

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Physics Case: Extra Dimensions

Universal extra dimensions: Measure all (pair produced) newparticles and see the higher level excitations

RS KK resonances…Scan the different states

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Precision Measurements

E.g.: Contact interactions:Sensitivity to scales up to 100-400 TeV

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Indicative Physics Reach

Approximate mass reach machines: s = 14 TeV, L=1034 (LHC) : up to 6.5 TeV s = 14 TeV, L=1035 (SLHC) : up to 8 TeV s = 28 TeV, L=1034 : up to 10 TeV

Units are TeV (except WLWL reach) Ldt correspond to 1 year of running at nominal luminosity for 1 experiment

† indirect reach (from precision measurements)

PROCESS LHC SLHC DLHC VLHC VLHC ILC CLIC 14 TeV 14 TeV 28 TeV 40 TeV 200 TeV 0.8 TeV 5 TeV 100 fb-1 1000 fb-1 100 fb-1 100 fb-1 100 fb-1 500 fb-1 1000 fb-1

Squarks 2.5 3 4 5 20 0.4 2.5 WLWL 2 4 4.5 7 18 6 90Z’ 5 6 8 11 35 8† 30† Extra-dim (=2) 9 12 15 25 65 5-8.5† 30-55†

q* 6.5 7.5 9.5 13 75 0.8 5compositeness 30 40 40 50 100 100 400TGC () 0.0014 0.0006 0.0008 0.0003 0.0004 0.00008

Ellis, Gianotti, ADRhep-ex/0112004+ few updates

Extend this table

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Summary: Physics at CLIC

Experimental conditions at CLIC are more challenging than at LEP, or ILC

Physics studies for CLIC have included the effects of the detector, and backgrounds e.g e+e- pairs and events.

Benchmark studies show that CLIC will allow for precision measurements in the TeV range

CLIC has a very large physics potential, reach beyond that of the LHC.

Ongoing now: Detector studies and R&D -Tracking with good time stamping, - - - improved calorimetry, pflow, mask area,…

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Summary: Scenarios with early LHC data…

• New physics shows up at the LHC CLIC will – Complete the particle spectra, with a very high reach– Measure accurately parameters of the model (LC quality)

• Only a light Higgs at the LHC CLIC will – Measure its properties very accurately, like ILC and more..

– Extend the LHC direct search reach for non-colored particles

– Extend the indirect search reach to a scale of 500 (1000?) TeV via precision measurements

• No signs of new physics or a Higgs at the LHC CLIC can – Study WW scattering in the 1-2 TeV range in detail– Extend the LHC direct search reach for non-colored particles

– Extend the indirect search reach to a scale of 500 (1000?) TeV via precision measurements

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