Post on 24-Jan-2016
Paris 22/4 UED Albert De Roeck (CERN) 1
Identifying Universal Extra Dimensions at CLIC
Minimal UED model CLIC experimentation
UED signals & Measurements
M. Battaglia, A Datta, A. De Roeck, K. Kong, K. Matchev
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Cheng, Schmaltz and Matchev hep/ph0205314
R size of extra dim.
KK partners for all particles
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MUED Phenomenology
Hadron collider searches may be problematic soft decay products
All particles get partners with SAME spin Particles are pair produced (KK number conservation)
Radiatively corrected mass spectrum
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Detecting MUEDs at pp colliders
Discovery reach for MUEDs using the 4lepton+ missing ET channel
R-1 = 20
Good discovery potential at the LHC
hep/ph0205314
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MUED signals
Experimental Signatures almost identical to Supersymmetry• Partners for all particles with identical interactions
• Lightest KK state (1) is stable like LSP
– Also a dark matter candidate
Differences• Cross sections• Spin of the partner (Same for KK, differ by ½ for SUSY)
– Different dependence of the threshold behaviour of KK pair or SUSY pair production
• No a priori extended Higgs sector – No A,H,H±, less gauginos
• The KK spectrum repeats n times (higher levels)• Not obvious if these can be used at LHC (under study)
LC for proper interpretation of the signal. CLIC as a case study
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Study (s)muon production
Study the processes
MUED n=1 KK modes and n=2 2 and Z2
included in CompHEP (41.10)
Fix R-1 = 500 GeV, R=20Match SUSY parameters to get same spectrum
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CLIC Simulation
SIMDET for detectorresponseReconstruct muons
Realistic luminosity Spectrums = 3 TeV
~ 4 evts/bx
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Analysis
• Signal (14 fb) • background (20 fb)
Event selection Reconstruct 2 muons Missing energy > 2.5 TeV Transverse energy below 150 GeV Sphericity larger than 0.05 MZ filter Reduces background with a factor ~5-10
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Comparison: angular distributions of muons
Production polar angle of the decay muonsIf mass difference M1 -M1 small correlation between muons & parents
Theoretical prediction After detector simulation2 fit: can distinguish UED from SUSY at 5 with 350 fb-1 at s= 3 TeV
signal
total
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Different Cross Section
Different rate
Different onset
Difference due to-Both left & right handed Doublets in MUED-Fermions Bosons
T. Tait LHCLC document
3
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Threshold scan
Sensitivity to the mass
1S
1D
with beamstrahlung
Standard curve
Move 1S by -2.5 GeV
Move 1D by -2.5 GeV
M = ±0.11 GeV for 1S and ±0.23 GeV for 1
D
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Muon Energy Spectrum
Inclusive muon energy spectrum determined by two body kinematics
Measure endpoints
1D and 1
S masses from threshold scan M1 ~ 0.25 GeV for 1 ab-1
after detectorsimulation
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Radiative return
Radiative return to the Z2
Peak in the photon spectrumNot present for SUSY
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Conclusions
MUED and SUSY signals at the LHC may look very similar at LHC• Not yet clear if LHC can distinguish between both cases
– E.g if H,A expected to be at high mass or level 2 KK out of reach
• A linear collider can provide decisive information
• Here a case study with ~ 500 GeV KK muons (smuons) at CLIC including detector & beam smearing effects and backgrounds
– Cross sections– Spin analysis of the new particles– Threshold measurements– Radiative returns This scenario: 350 fb-1 sufficient for separation
• Mass determination of the KK-muons and LKP, including all effects, amounts to M/M of better than 0.1% with 1 ab-1 (= 1 CLIC year) each for threshold scans and inclusive muon spectra