Lucie Linssen, BSM, BNL-Snowmass, 5 April 2013 1
Potential for New Physics searchesin e+e- collisions at CLIC
Lucie Linssen, CERNon behalf of the CLIC detector and physics study
Lucie Linssen, BSM, BNL-Snowmass, 5 April 2013 2
Outline, referencesOutline• CLIC machine, physics, energy staging• Top• SM Higgs, Higgs multiplet, Higgs compositeness• SUSY• Z’, contact interactions and other physics reach• Summary and outlook
References• CLIC CDR (#1), A Multi-TeV Linear Collider based on CLIC Technology,
https://edms.cern.ch/document/1234244/• CLIC CDR (#2), Physics and Detectors at CLIC, arXiv:1202.5904• CLIC CDR (#3), The CLIC Programme: towards a staged e+e- Linear Collider
exploring the Terascale, arXiv:1209.2543• Brau et al., the physics case for an e+e- linear collider, arXiv:1210.0202• D. Dannheim et al., CLIC e+e- linear collider studies, Input to the Snowmass
process 2013 (submitted to the accelerator WG for Snowmass)
CLIC in just a few words
Lucie Linssen, BSM, BNL-Snowmass, 5 April 2013 3
• 2-beam acceleration scheme at room temperature• Gradient 100 MV/m => √s up to 3 TeV • Staging scenario ~350 GeV to 3 TeV• High luminosity (a few 1034 cm-2s-1)
focus is on energy frontier reach !
CLIC is the most mature option for a multi-TeV scale future e+e- collider
hadron vs. lepton colliders
Lucie Linssen, BSM, BNL-Snowmass, 5 April 2013 4
p-p collisions e+e- collisions
Proton is compound object Initial state not known event-by-event Limits achievable precision
e+/e- are point-like Initial state well defined (√s / polarization) High-precision measurements
Circular colliders feasible Linear Colliders (avoid synchrotron rad.)
High rates of QCD backgrounds Complex triggering schemes High levels of radiation
Cleaner experimental environment trigger-less readout Low radiation levels
√s constrained by design √s can be tuned Threshold scans
High cross-sections for colored-states Superior sensitivity for electro-weak states
Physics potential of LHC/HL-LHC and high-energy e+e- collider are complementary !
Lucie Linssen, BSM, BNL-Snowmass, 5 April 2013 5
In particular, e+e- collisions at CLIC bring:• Precision Higgs physics (SM and BSM), precision top physics• Other precision measurements, like WW scattering, single W production• Direct searches to weakly coupled BSM states, e.g. sleptons, gauginos• ….
Physics highlights include• Higgs• Top• SUSY• Z’• Contact interactions• Extra dimensions• ….
Experimental sensitivities are now well understood, most studies based on• Full GEANT4 simulation/reconstruction• Including pile-up of background
CLIC physics potential
physics at CLIC
Lucie Linssen, BSM, BNL-Snowmass, 5 April 2013 6
• Precision SM measurements: Higgs, top √s 350 GeV, and up to 3 TeV⪅
• Discovery of new physics at TeV scale, unique sensitivity to particles with electroweak charge
• New Physics model discrimination, e.g. SUSY up to √s ~ 3 TeV
sparticles in SUSY example scenario(not excluded by LHC results)
physics at CLIC
Lucie Linssen, BSM, BNL-Snowmass, 5 April 2013 7
• Precision SM measurements: Higgs, top √s 350 GeV, and up to 3 TeV⪅
• Discovery of new physics at TeV scale, unique sensitivity to particles with electroweak charge
• New Physics model discrimination, e.g. SUSY up to √s ~ 3 TeV
sparticles in SUSY example scenario(not excluded by LHC results)
Example of energy staging
Lucie Linssen, BSM, BNL-Snowmass, 5 April 2013 8
integrated luminosity
Based on 200 days/year at 50% efficiency (accelerator + data taking combined)
Lucie Linssen, BSM, BNL-Snowmass, 5 April 2013 9
CLIC_ILD and CLIC_SiD
CLIC_ILD CLIC_SiD
7 m
Two general-purpose CLIC detector conceptsBased on initial ILC concepts (ILD and SiD), adapted to CLIC conditions
Most physics studies in this talk => full detector simulation + background overlays
Lucie Linssen, Ljubljana, Nov 2012 10
Precision top physics 350, 500 GeV• e+e- collisions at and above the ttbar threshold provide two complementary ways of measuring the top quark mass:
• Direct reconstruction (<= studied for CLIC at 500 GeV)• Threshold scan (<= studied for CLIC around 350 GeV)
• For both, total uncertainties on the level of 100 MeV are within reach with 100 fb-1, highest precision (theoretically clean) with threshold scan
threshold scanCLIC ~350 GeV
2D fit withMtop, αs
See: arXiv:1303.3758
Other options for top physics at CLIC include: top couplings, LR asymmetries, boosted tops…
Lucie Linssen, BSM, BNL-Snowmass, 5 April 2013 11
Higgs physics at CLIC (1)Dominant processes:
Available luminosity increases with √s !
Higgsstrahlungdecreases with √s
W(Z) - fusionincreases with √s
Mh = 125 GeV 350 GeV 1.5 TeV 3 TeV
σ(e+e-=> ZH) 129 fb 6 fb 1 fb
σ(e+e-=> Hνν) 30 fb 309 fb 484 fb
Int L (4-5 yrs) 500 fb-1 1.5 ab-1 2 ab-1
# ZH events 65000 7500 2000
# Hνν events 15000 460000 970000
Lucie Linssen, BSM, BNL-Snowmass, 5 April 2013 12
Higgs physics at CLIC (2)
350 GeV
500 GeV
1.4 TeV
3 TeV
Benchmarking results obtained so far:
<= estimate based on 1 TeV ILC result
All based on full detector simulation with beam-induced background and physics backgroundsNo polarisation assumed (80% electron polarisation will enhance Hνν/HHνν signals by 80%)
Complete set of Higgs will be ready for Minneapolis meeting(Incl. couplings to Z, bb, cc, gg, W*W, γγ, γZ, ττ, μμ and ttH and self-coupling)
Lucie Linssen, BSM, BNL-Snowmass, 5 April 2013 13
heavy Higgs, non-SMHiggs multiplet BSM searches accessible up to √s/2
Example MSSM benchmark study at 3 TeV
3 TeV 3 TeV
HA H±
Multi-jet final statesFull simulation studies with background overlay
Lucie Linssen, BSM, BNL-Snowmass, 5 April 2013 14
heavy Higgs searchesCLIC access to SUSY heavy Higgs searches
Lucie Linssen, BSM, BNL-Snowmass, 5 April 2013 15
Higgs compositenessLHC: WW scattering and strong double Higgs production
LHC: single Higgs processes
CLIC: double Higgs production via vector boson fusion
Allows to probe Higgs compositeness at the 30 TeV scale for 1 ab-1 at 3 TeV(60 TeV scale if combined with single Higgs production)
Vector resonance mass
LHC: direct search WZ =>3 leptons
dimensionless scale parameter
allowed regionEW precision tests
Lucie Linssen, BSM, BNL-Snowmass, 5 April 2013 16
SUSY => slepton study, 3 TeVSlepton production at CLIC very cleanSUSY “model II”: slepton masses ~ 1 TeVChannels studied include
Leptons and missing energy Masses from analysis of endpoints of energy spectra
All channels combined
smuon
Lucie Linssen, BSM, BNL-Snowmass, 5 April 2013 17
gaugino pair production, 3 TeVSUSY “model II”:
Pair production and decay:
82 %
17 %
Separation using di-jet
invariant masses (test of PFA)
use slepton study result
Lucie Linssen, BSM, BNL-Snowmass, 5 April 2013 18
results of SUSY benchmarks, 1.4 TeV
CLIC CDR Vol. 3
all results with
L => 1.5 ab-1
Large part of the SUSY spectrum measured at <1% level
Lucie Linssen, BSM, BNL-Snowmass, 5 April 2013 19
results of SUSY benchmarks, 3 TeV
all results with
L => 2 ab-1
CLIC CDR Vol. 2
Large part of the SUSY spectrum measured at <1% level
Lucie Linssen, BSM, BNL-Snowmass, 5 April 2013 20
resolving new physics modelsPrecision measurements at CLIC allow to distinguish between models of new physics, e.g. following first observations at LHC
e.g. CLIC 3 TeV example, resolving power for SUSY breaking models
Lucie Linssen, BSM, BNL-Snowmass, 5 April 2013 21
sensitivity to Z’Example: neutral gauge boson (Z’) in minimal anomaly-free Z’ model (AFZ’)
Study of Z’ 5σ discovery potential in at 1.4 TeV and 3 TeV, for different coupling values
Dimuon events3 TeV
1.4 TeV
Lucie Linssen, BSM, BNL-Snowmass, 5 April 2013 22
contact interactionse+e- μ+μ- e+e- bb
Limits on the scale (Λ/g) of contact interactions
3 TeV1 ab-1
Lucie Linssen, BSM, BNL-Snowmass, 5 April 2013 23
CLIC physics reach, short overviewHave just scratched the surface of CLIC physics• more details given in Vol. 2 & 3 of CLIC CDRChallenge the Standard Model with direct measurements and at the loop level• Challenge SM up to the 60 TeV scale
CLIC3 TeV
Direct observation
Loop / effective operator
Lucie Linssen, BSM, BNL-Snowmass, 5 April 2013 24
CLIC detector and physics studyorganisation
Pre-collaboration structure, based on a “Memorandum on Cooperation”http://lcd.web.cern.ch/LCD/Home/MoC.html
Australia: ACAS; Belarus: NC PHEP Minsk; Czech Republic: Academy of Sciences Prague; Denmark: Aarhus Univ.; Germany: MPI Munich; Israel: Tel Aviv Univ.; Norway: Bergen Univ.; Poland: Cracow AGH + Cracow Niewodniczanski Inst.; Romania: Inst. of Space Science; Serbia: Vinca Inst. Belgrade; Spain: Spanish LC network; UK: Birmingham Univ. + Cambridge Univ. + Oxford Univ.; USA: Argonne lab; + CERN
17 participating institutes
Lucie Linssen, BSM, BNL-Snowmass, 5 April 2013 25
summary and outlook
CLIC is an exciting and realistic option fora future machine at the energy frontier
Welcome to join !
lcd.web.cern.ch/lcd/
CLIC Physics:• Complementary to the LHC• Focus on high precision measurements• Physics reach demonstrated (full simulation with pile-up)• Staged approach => large potential for SM and BSM physics
~350 – 375 GeV : precision Higgs and top physics ~1.5 TeV : Higgs (including ttH and self-coupling), BSM ~3 TeV : Higgs, Higgs self-coupling, BSM, …
Ongoing CLIC physics potential studies• current focus on detailed Higgs studies• more on BSM on a ≥1 year timescale
Lucie Linssen, BSM, BNL-Snowmass, 5 April 2013 26
SPARESLIDES
Lucie Linssen, BSM, BNL-Snowmass, 5 April 2013 27
CLIC strategy and objectives
Faster implementation possible, (e.g. for lower-energy Higgs factory): klystron-based initial stage
Lucie Linssen, BSM, BNL-Snowmass, 5 April 2013 28
plans for the phase 2013-2016
Further exploration of the physics potential• Complete picture of Higgs prospects at ~350 GeV, ~1.4 TeV, ~3 TeV• Discovery reach for BSM physics• Sensitivity to BSM through high-precision measurements
Detector Optimisation studies• Optimisation studies linked to physics (e.g aspect ratio, forward region coverage);• Interplay between occupancies and reconstruction;• Interplay between technology R&D and simulation models.
Technology demonstrators• Many common developments with ILC• Complemented with CLIC requirements
cf. LHCresults
Drives the CLIC staging strategy
Lucie Linssen, BSM, BNL-Snowmass, 5 April 2013 29
CLIC two-beam acceleration schemeTwo Beam Scheme:
Drive Beam supplies RF power• 12 GHz bunch structure• low energy (2.4 GeV - 240 MeV)• high current (100A)
Main beam for physics• high energy (9 GeV – 1.5 TeV)• current 1.2 A
Accelerating gradient: 100 MV/m
Lucie Linssen, BSM, BNL-Snowmass, 5 April 2013 30
CLIC layout at 3 TeV
Lucie Linssen, BSM, BNL-Snowmass, 5 April 2013 31
motivation for energy stagingCLIC physics potential:• Good physics at various CM energies• Most studies require high luminosity
At each energy stage, the centre-of-mass energy can be tuned downby a factor ~3 with limited luminosity loss(e.g. for threshold scans)
Making optimal use of the capacities (luminosity) of CLIC, this is best studied with a collider built in a few successive energy stages.
The optimal choice of the actual energy stages will depend on the physics scenario, driven by 8 TeV + 14 TeV LHC results.
The scenarios “A” and “B” are therefore “just examples”
Lucie Linssen, BSM, BNL-Snowmass, 5 April 2013 32
Parameters, scenario A
Lucie Linssen, BSM, BNL-Snowmass, 5 April 2013 33
Parameters, scenario B
SUSY model for 1.4 TeV studies
Lucie Linssen, BSM, BNL-Snowmass, 5 April 2013 34
sparticles in SUSY example scenario(not excluded by LHC results)
masses(GeV)
modelparameters
Lucie Linssen, BSM, BNL-Snowmass, 5 April 2013 35
physics aims => detector needs
impact parameter resolution: e.g. c/b-tagging, Higgs BR
jet energy resolution: e.g. W/Z/h di-jet mass separation
angular coverage, very forward electron tagging
momentum resolution: e.g. Smuon endpoint
Higgs recoil mass, Higgs coupling to muons
W-Zjet reco
smuonend point
(for high-E jets)
Lucie Linssen, BSM, BNL-Snowmass, 5 April 2013 36
CLIC detector concepts
ultra low-massvertex detectorwith ~25 μm pixels
main trackers:TPC+silicon (CLIC_ILD)all-silicon (CLIC_SiD)
fine grained (PFA) calorimetry, 1 + 7.5 Λi,
strong solenoids4 T and 5 T
return yoke withInstrumentationfor muon ID
complex forward region with final beam focusing
6.5 m
… in a few words …
e-
e+
Lucie Linssen, BSM, BNL-Snowmass, 5 April 2013 37
calorimetry and PFAJet energy resolution and background rejection drive the overall detector design
=> => fine-grained calorimetry + Particle Flow Analysis (PFA)
Typical jet composition:60% charged particles 30% photons10% neutrons
Always use the best info you have:60% => tracker30% => ECAL10% => HCAL
What is PFA?
Hardware + software !
Lucie Linssen, BSM, BNL-Snowmass, 5 April 2013 38
calorimetry and PFA
Lucie Linssen, BSM, BNL-Snowmass, 5 April 2013 39
CLIC machine environmentCLIC machine environment (1)
Drives timingrequirementsfor CLIC detector
CLIC at 3 TeV
L (cm-2s-1) 5.9×1034
BX separation 0.5 ns
#BX / train 312
Train duration (ns) 156
Rep. rate 50 Hz
σx / σy (nm) ≈ 45 / 1
σz (μm) 44
Beam related background: Small beam profile at IP leads very high E-field
Beamstrahlung Pair-background γγ to hadrons
very small beam size
Lucie Linssen, BSM, BNL-Snowmass, 5 April 2013 40
Beamstrahlung important energy lossesright at the interaction point
E.g. full luminosity at 3 TeV: 5.9 × 1034 cm-2s-1
Of which in the 1% most energetic part:2.0 × 1034 cm-2s-1
Most physics processes are studied well above production threshold => profit from full luminosity
3 TeV√senergy spectrum
CLIC machine environment (2)Coherent e+e- pairs
7 x 108 per BX, very forwardIncoherent e+e- pairs
3 x 105 per BX, rather forward gg→ hadrons
3.2 events per BX main background in calorimeters
~19 TeV in HCAL per bunch train
Simplified view:Pair background• Design issue (high occupancies)gg → hadrons• Impacts on the physics• Needs suppression in data
Lucie Linssen, BSM, BNL-Snowmass, 5 April 2013 41
background suppression at CLIC
• Full event reconstruction + PFA analysis with background overlaid• => physics objects with precise pT and cluster time information
• Then apply cluster-based timing cuts tCluster
Triggerless readout of full train
t0 physics event (offline)
Lucie Linssen, BSM, BNL-Snowmass, 5 April 2013 42
time window / time resolution
Translates in precise timing requirements of the sub-detectors
The event reconstruction software uses:
t0 physics event (offline)
Lucie Linssen, BSM, BNL-Snowmass, 5 April 2013 43
PFO-based timing cutsExample: SelectedPandoraNewPFAs