1. LPSC - GrenobleJulien MOREL 1 Z'  e + e - discovery potential computation Julien MOREL ATLAS Exotics group IN2P3 – CNRS - LPSC - Grenoble 18 / 09 / 2007 – CSC dilepton/diphoton

2. LPSC - GrenobleJulien MOREL 2 Z'  e + e - discovery potential computation CSC full simulated Z’…  Z’ χ  e + e - a 1 TeV  7250 Z’ with M Z’ = 1 TeV et M ll >500GeV  DataSet = 5605 Généré Reconstruit Mll (GeV) Invariante mass spectrum Electron energy spectrum

3. LPSC - GrenobleJulien MOREL 3 Z'  e + e - discovery potential computation di-electron invariant mass spectrum modelisation Background modelisation (DY) # Event/ 10 GeV Normalisation 1 fb -1  G pdf depand on the pdf  Fit with a 6 parameters ad-hoc function ( Χ 2 /ndf = 726/557)  Good modelisation between 300 GeV et 6 TeV -DY Pythia -DY (modelisation)

4. LPSC - GrenobleJulien MOREL 4 Z'  e + e - discovery potential computation # Evénements / 10 GeV Normalisation 1 fb -1 -Z’ χ généré officiel -Modélisation du Z’χ di-electron invariant mass spectrum modelisation Signal modelisation (DY + Z’)  Only 4 experimental parameters : The mass The total decay width A Z’ amplitude An interference amplitude  Model independent parameterization # Evénements / 10 GeV Normalisation 1 fb -1 -DY Pythia -Modélisation DY -Modélisation Z’ (M=3 TeV, Γ=20 GeV) Modelisation of a big interference:

5. LPSC - GrenobleJulien MOREL 5 Z'  e + e - discovery potential computation Z’ performences Gaussian part  ~83 % of events  σ~8.5 GeV  μ~-2.4 GeV Negative tail  ~0.4 % of events  May be a DY systematic (M gene – M reco )/ M gene for 1 TeV Z’ Positive tail  ~ 17 % of events  Include crack events  Non negligible contribution

6. LPSC - GrenobleJulien MOREL 6 Z'  e + e - discovery potential computation di-electron invariant mass spectrum modelisation Cross check with full simulated 1 TeV Z’ Normalisation 1 fb -1 # Evénements / 1 GeV -Z’ χ reco (CSC simulation) -DY reco (modelisation) -Z’ χ reco (modelisation) Taking into account the resolution and efficiency

7. LPSC - GrenobleJulien MOREL 7 Z'  e + e - discovery potential computation di-electron invariant mass spectrum modelisation Cross check with full simulated 7 TeV Z’ (private production) -Z’ χ Reco (full simulation) -Z’ χ Reco (modelisation) # Event/ 10 GeV -Z’ χ Gene (CSC simulation) -Z’ χ Gene (modelisation) Fit of generation Reco modelisation from gene fit

8. LPSC - GrenobleJulien MOREL 8 Z'  e + e - discovery potential computation di-electron invariant mass spectrum modelisation We can modelise many Z’ at different mass -Z’ χ Gene  Efficiency -Z’ χ Reco (modelisation)  Generation with pythia  Fit the generated shape with our parameterization  Include the resolution and efficiency

9. LPSC - GrenobleJulien MOREL 9 Z'  e + e - discovery potential computation ZEUS NLO + NLO MRST NLO + NLO CTEQ NLO + NLO CTEQ LO + LO Systematic incertainties LHAPDF/CTEQ error sets  NLO calculation Effect : Cross section + 20 to 34 % Mclimit implementation  -0%, + 20%  PDF incertainties  4 à 8 % Mclimit implementation   5% F.Heinemann

10. LPSC - GrenobleJulien MOREL 10 Z'  e + e - discovery potential computation Using MCLimit for 2 TeV Z’ example Les résultats de MCLimit H0 = DY, H1 = 2 TeV Z’ Mass = 2 TeV Width = 24.3 GeV Ampl. Z’ = 499 Ampl. Interference = -793 Normalisation 1 fb -1 # Event/ 10 GeV -Z’ reco (modelisation) -DY reco (modelisation) -Pseudo data Few events Hypo DY Hypo Z’ 5000 pseudo exp. Lumi = 1 fb -1 Using Lumi5s() : Using Lumi5s() : We need 0.37 fb -1 are enought to discover this Z’. With 5000 pseudo exp. results may fluctuate a bit. Need more calculation -2lnQ fit from generation

11. LPSC - GrenobleJulien MOREL 11 Z'  e + e - discovery potential computation Discovery potentiel CMS Result Etude de la découverte du Z’ via :  6 models: SSM, LRM, ALRM, χ, ψ, η  3 differentes masses : 1, 3, 5 TeV Preliminary discovery limit For Z’ Chi Z’ mass (TeV) Int lumi (fb -1 ) ATLAS preliminary ~5 fb-1 for 3 TeV

12. LPSC - GrenobleJulien MOREL 12 Z'  e + e - discovery potential computation Luis result on 4 decembre 2007 fit based approche