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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