Identifying Universal Extra Dimensions at CLIC

1. Identifying Universal Extra Dimensions at CLIC M. Battaglia, A Datta, A. De Roeck, K. Kong, K. Matchev Minimal UED model  CLIC experimentation  UED signals & Measurements Paris 22/4 UED Albert De Roeck (CERN)

2. Cheng, Schmaltz and Matchev hep/ph0205314 KK partners for all particles R size of extra dim. Paris 22/4 UED Albert De Roeck (CERN)

3. MUED Phenomenology  All particles get partners with SAME spin  Particles are pair produced (KK number conservation) Radiatively corrected mass spectrum Hadron collider searches may be problematic soft decay products Paris 22/4 UED Albert De Roeck (CERN)

4. Detecting MUEDs at pp colliders hep/ph0205314 R-1 = 20 Discovery reach for MUEDs using the 4lepton+ missing ET channel Good discovery potential at the LHC Paris 22/4 UED Albert De Roeck (CERN)

5. 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 Paris 22/4 UED Albert De Roeck (CERN)

6. 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=20 Match SUSY parameters to get same spectrum Paris 22/4 UED Albert De Roeck (CERN)

7. CLIC Simulation Realistic luminosity Spectrum s = 3 TeV ~ 4  evts/bx SIMDET for detector response Reconstruct muons Paris 22/4 UED Albert De Roeck (CERN)

8. 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 Paris 22/4 UED Albert De Roeck (CERN)

9. Comparison: angular distributions of muons Production polar angle  of the decay muons If mass difference M1 -M1 small  correlation between muons & parents total signal Theoretical prediction After detector simulation 2 fit: can distinguish UED from SUSY at 5 with 350 fb-1 at s= 3 TeV Paris 22/4 UED Albert De Roeck (CERN)

10. Different Cross Section T. Tait LHCLC document •  Different rate •  Different onset • Difference due to • Both left & right handed • Doublets in MUED • Fermions  Bosons    3 Paris 22/4 UED Albert De Roeck (CERN)

11. Threshold scan Sensitivity to the mass 1D 1S Standard curve Move 1S by -2.5 GeV with beamstrahlung Move 1D by -2.5 GeV M = ±0.11 GeV for 1S and ±0.23 GeV for 1D Paris 22/4 UED Albert De Roeck (CERN)

12. Muon Energy Spectrum Inclusive muon energy spectrum determined by two body kinematics Measure endpoints after detector simulation 1D and 1S masses from threshold scan M1 ~ 0.25 GeV for 1 ab-1 Paris 22/4 UED Albert De Roeck (CERN)

13. Radiative return Radiative return to the Z2 Peak in the photon spectrum Not present for SUSY Paris 22/4 UED Albert De Roeck (CERN)

14. 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 Paris 22/4 UED Albert De Roeck (CERN)