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Randall Sundrum KK Graviton at CMS

Randall Sundrum KK Graviton at CMS. Caroline Collard, LLR, Ecole Polytechnique, France Work in collaboration with M.-C. Lemaire, P. Traczyk and G. Wrochna. Overview. Extra Dimensions & Randall Sundrum Model Search for RS graviton in the CMS detector The CMS detector Signal & Background

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Randall Sundrum KK Graviton at CMS

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  1. Randall Sundrum KK Graviton at CMS Caroline Collard, LLR, Ecole Polytechnique, France Work in collaboration with M.-C. Lemaire, P. Traczyk and G. Wrochna Exotic Signals at Hadron Colliders

  2. Overview • Extra Dimensions & Randall Sundrum Model • Search for RS graviton in the CMS detector • The CMS detector • Signal & Background • First Analysis: 5  discovery limit • The photon radiation with PHOTOS • If no signal? 95% CL signal exclusion • If a signal? Spin-2 analysis • Conclusions Exotic Signals at Hadron Colliders

  3. Extra Dimensions • Why? • Unification of gravitation with other forces. • Hierarchy problem : MEW and MPL Different models of ED Exotic Signals at Hadron Colliders

  4. Warped ED The Randall-Sundrum Model: • only one extra dimension  5D Anti-de-Sitter Spacetime • metric: e-2kr  dx dx + r2 d2 • k (~ MPL): AdS5 curvature, r: compactification radius, r : new coordinate and x: traditional 4D coordinates • GravityScale: =MPL e-kr no hierarchy if kr≈12 SM brane Planck brane bulk r  r  = 0 r  = r  Exotic Signals at Hadron Colliders

  5. Warped ED The Randall-Sundrum Model: • Two parameters in the model:e-kr and k/MPL • Graviton in 5D  KK graviton excitations in 4D Experimental measurement of the 1st KK graviton M1 [Mn = k xn e-kr with J1(xn)=0] 1 [n =  Mn xn2 (k/MPL)2 with (open decay mode)] • Other parameter choice: M1 and c= k/MPL c is related to 1 and also to the coupling Exotic Signals at Hadron Colliders

  6. Variation of c 0.01 ≤ c ≤ 0.1 c = 0.1 c = 0.05 c = 0.02 c = 0.01 d/dM MG Exotic Signals at Hadron Colliders

  7. The CMS detector • pp collider: 14 TeV in cms • Start in 2007 • 1 year @ low lumi: 10 fb-1 • 1 year @ high lumi: 100 fb-1 Higgs Discovery and Search for New Physics Exotic Signals at Hadron Colliders

  8. Analysis • Signal: • ffbar, gg  G   (B.R.= 4 %) • ffbar, gg  G  e+e-, +- (B.R.= 2 %) Generation with PYTHIA Photon Radiation with PYTHIA or PHOTOS Detector response with CMSJET (Fast Simulation) Exotic Signals at Hadron Colliders

  9. CMS Performance in CMSJET • ECAL:For electron and  detection Barrel (||<1.56) E/E = 3% /√E + 0.2/E + 0.55% Endcap (1.65<| |< 3) E/E = 6% /√E + 0.9/E + 0.55% • Tracker:For muon detection p/p = 4% √p Exotic Signals at Hadron Colliders

  10. Analysis CMSJET • Backgrounds: • For  : ffbar, gg   (+ photon-jet: ffbar  g, fg f, gg  g + dijet: ff  ff, ffbar  ffbar, ffbar  gg, fg  fg, gg  ffbar, gg  gg) No K factor for . • For e+e-, +-: pp  Z/  l+l- (Drell Yan) K factor =1.38 from comparison between PYTHIA MC and CDF data # Events M(GeV) Exotic Signals at Hadron Colliders

  11. MG= 1500 GeV, c=0.01,Lumi=100 fb-1 CMSJET G   # Events M (GeV) Exotic Signals at Hadron Colliders

  12. 5  Discovery Limit CMSJET 100 fb-1 G   c =0.01 .B (fb) MG(GeV) Exotic Signals at Hadron Colliders

  13. MG= 1000 GeV, c=0.01,Lumi=100 fb-1 CMSJET Difference in resolution for e (Energy in calo) and  (Momentum in tracker) => Different mass windows Exotic Signals at Hadron Colliders

  14. 5  Discovery Limit CMSJET G  e+e- c =0.01 .B (fb) MG(GeV) Exotic Signals at Hadron Colliders

  15.  Radiation with PHOTOS Use of PHOTOS to generate  radiation, in place of PYTHIA Dependence on the input parameters used in PHOTOS: E fraction, Double Bremsstrahlung flag, Interference flag With E fraction= 0.01, Double Bremsstrahlung flag = T, Interference flag=F, Mass Limits for 5  Discovery: => Results in agreement! Exotic Signals at Hadron Colliders

  16. Use of PHOTOS Impact of input parameters: CMSJET RMS= 42.44 RMS= 40.01 PHOTOS (0.01, F, F) PHOTOS (0.02, T, T) # Entries RMS= 39.92 RMS= 41.32 PYTHIA PHOTOS (0.01, T, F) Mee(GeV) Exotic Signals at Hadron Colliders

  17. 5  Discovery Limit with PHOTOS Theoretical constraint on curvature c G  e+e- Theroretical constraint for no new hierarchy CMSJET MG(GeV) Exotic Signals at Hadron Colliders

  18. If there is no signal … • NS: number of expected signal events • NB: number of background events • Nobs:number of “observed” events • 95% CL Exclusion Limit Exotic Signals at Hadron Colliders

  19. 95% CL Exclusion Limit CMSJET Excluded Signal Exclusion at 95% CL c |R5| < M52  = 10 TeV Region of interest Photons MG(GeV) Muons Electrons Exotic Signals at Hadron Colliders

  20. If there is a signal … • How to be sure it is a RS Graviton? • Graviton? not a Z’? • RS model? CMSJET MG=2000 GeV, c=0.01 Exotic Signals at Hadron Colliders

  21. Angular Distribution • Graviton = spin 2 CMSJET pp  G  +- MG=1000 GeV c=0.1 After  cut: ( |  | < 3.0 for e |  | < 2.4 for  ) gg  G  ll: 1-cos4 qqbar  G  ll: 1-3cos2+4cos4 Cos Exotic Signals at Hadron Colliders

  22. How different from Z’? • Kolmogorov-Smirnov Test • Rem: No  mode for Z’ CMSJET M= 2000 GeV Z’ 1+ cos2 G For G: number of events corresponding to Lumi, randomly chosen Cos Exotic Signals at Hadron Colliders

  23. 95% CL Exclusion Limit Spin 1 rejection with 90% probability at 95% CL Excluded CMSJET Electrons Leptons c |R5| < M52  = 10 TeV Region of interest MG(GeV) Exotic Signals at Hadron Colliders

  24. Detector acceptance || < 2.4 CMSJET || < 1.5 Cos Importance of the pattern recognition in the endcap regions! Exotic Signals at Hadron Colliders

  25. RS model? Davoudiasl, Hewett, Rizzo hep-ph/0006041 c=1. c=0.5 c=0.1 c=0.05 c=0.01 d/dM Mll(GeV) If the 1st graviton is found, there is a prediction where to find the next resonances for c not too big. Exotic Signals at Hadron Colliders

  26. Conclusions • Signal? Test of Randall Sundrum model after 1 year data taking at the high luminosity design • Graviton?  channel or angular distributions of lepton decay products • Next Step: Full simulation-reconstruction chain Exotic Signals at Hadron Colliders

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