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Gravitons

Gravitons. A first look into. RS. at ATLAS. Tracey Berry Royal Holloway. Branching Fraction. 10 -2 10 -4 10 –6 10 -8. g. W. u. Z. RS model. t. Dilepton Channel. Z / . l -. l +. l +. l +. l -. l -. l -. Dilepton channel. H. Tevatron 700 GeV G KK.

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Gravitons

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  1. Gravitons A first look into RS at ATLAS Tracey Berry Royal Holloway UK SUSY/Exotics Meeting 1st March 2007

  2. Branching Fraction 10-2 10-4 10–6 10-8 g W u Z RS model t Dilepton Channel Z/ l- l+ l+ l+ l- l- l- Dilepton channel H Tevatron 700 GeV GKK andall undrum Model R S Randall, Sundrum,Phys Rev Lett 83 (99) 5D curve space with AdS5 slice: two 3(brane)+1(extra)+time! Coupling proportional to p-1 for KK levels above the fundamental level (n>=1) for n=0 graviton couples with the gravitational strenght Signature:Narrow, high-mass resonance states in dilepton/dijet/diboson channels • Couplings of each individual KK excitation are determined by the scale, = Mple-kRc ~ TeV massesmn = kxne-krc (J1(xn)=0) 1 highly curved/warped extra dimension (ED) Gravity localised in the ED Diphoton Channel SM ED UK SUSY/Exotics Meeting 1st March 2007

  3. Branching Fraction 10-2 10-4 10–6 10-8 g W u Z RS model t = Mple-kRc Dilepton channel H Tevatron 700 GeV GKK andall undrum Model R S Randall, Sundrum,Phys Rev Lett 83 (99) 5D curve space with AdS5 slice: two 3(brane)+1(extra)+time! Signature: Narrow, high-mass resonance states in dilepton/dijet/diboson channels Coupling proportional to p-1 for KK levels above the fundamental level (n>=1) for n=0 graviton couples with the gravitational strenght • Couplings of each individual KK excitation are determined by the scale, = Mple-kRc ~ TeV massesmn = kxne-krc (J1(xn)=0) K/MPl Mll (GeV) 10-2 10-4 10-6 10-8 10-10 d/dM (pb/GeV) KK excitations can be excited individually on resonance • Model parameters: • Gravity Scale: • 1st graviton excitation mass: m1 • = m1Mpl/kx1, & mn=kxnekrc(J1(xn)=0) • Coupling constant: c= k/MPl • 1 = m1 x12 (k/Mpl)2 700 GeV KK Graviton at the Tevatron k/MPl = 1,0.7,0.5,0.3,0.2,0.1 from top to bottom Resonance 1 0.5 0.1 0.05 0.01 position LHC 1500 GeV GKK and subsequent tower states width 1000 3000 5000 k = curvature, R = compactification radius Mll (GeV) Davoudiasl, Hewett, Rizzo hep-ph0006041 UK SUSY/Exotics Meeting 1st March 2007

  4. RS1 Discovery Limit 400 600 800 1000 Davoudiasl, Hewett, Rizzo hep-ph0006041 K/MPl Mll (GeV) At the LHC only the 1st excitations are likely to be seen at the LHC, since the other modes are suppressed by the falling parton distribution functions. d/dM (pb/GeV) 10-2 10-4 10-6 10-8 10-10 KK excitations can be excited individually on resonance • Best channels to search in are G(1)e+e- and G(1)gg due to the energy and angular resolutions of the LHC detectors • G(1)e+e- best chance of discovery due to relatively small bkdg, from Drell-Yan* 700 GeV KK Graviton at the Tevatron k/MPl = 1,0.7,0.5,0.3,0.2,0.1 from top to bottom 1 0.5 0.1 0.05 0.01 Allenach et al, JHEP 9 19 (2000), JHEP 0212 39 (2002) LHC 1500 GeV GKK and subsequent tower states 1000 3000 5000 Mll (GeV) Allenach et al, hep-ph0006114 Allenach et al, hep-ph0211205 * UK SUSY/Exotics Meeting 1st March 2007

  5. Present RS Constraints D0 performed combined ee+gg (diem search) CDF performed ee & gg search, then combine Present Experimental Limits Theoretical Constraints • c>0.1 disfavoured as bulk curvature becomes to large (larger than the 5-dim Planck scale) • Theoretically preferred Lp<10TeV assures no new hierarchy appears between mEW and Lp UK SUSY/Exotics Meeting 1st March 2007 • Theoretically preferred Lp<10TeV, otherwise the model would no longer be interesting for solving the hierarchy problem – assures no new hierarchy appears between mEW and Lp

  6. RS1 Discovery Limit Di-electron 100 fb-1 MG=1.5 TeV 100 fb-1 • HERWIG • Main Bkdg: Drell-Yan • Model-independent analysis • RS model with k/MPl=0.01 as a reference (pessimisitc scenario) • Fast Simulation *Reach goes up to 3.5 TeV for c=0.1 for a 20% measurement of the coupling. Sensitive at 5s up to 2080 GeV Allenach et al, hep-ph0006114 Allenach et al, hep-ph0211205 * UK SUSY/Exotics Meeting 1st March 2007

  7. CMS RS Discovery Limits G1μ+μ- G1 c>0.1 disfavoured as bulk curvature becomes to large (larger than the 5-dim Planck scale) Theoretically preferred Lp<10TeV G1e+e- LHC completely covers the region of interest UK SUSY/Exotics Meeting 1st March 2007

  8. Angular distributions RS1 Model Determination How could a RS G resonance be distinguished from a Z’ resonance? Potentially using Spin information: G has spin 2: ppGee has 2 components: ggGee & qqGee: each with different angular distributions: MG=1.5 TeV 100 fb-1 e+e- MC = 1.5 TeV LHC Spin-2 could be determined (spin-1 ruled out) with 90% C.L. up to MG = 1720 GeV with 100 fb-1 Note: acceptance at large pseudo-rapidities is essential for spin discrimination (1.5<|eta|<2.5) UK SUSY/Exotics Meeting 1st March 2007 Allanach et al, hep-ph 0006114 Stacked histograms Spin-2 nature of the G(1) can be measured : For masses up to 2.3 TeV (c=0.1) there is a 90 % chance that the spin-2 nature of the graviton can be determined with a 95 % C.L.

  9. RS Gravitons Datasets MC Dataset • 3400 Ggg and 10200 Gee Events: • Generated with Mass = 1000 GeV k/Mpl=0.1 • Code version 11.0.42 and reconstructed with FullSim • Limited reconstruction information available. - can't trace mother/daughter - so just use the highest 2 Et e/photons in the event for now to lookat distributions. More detailed investigations to follow in future…. Thanks to Barry King at Liverpool for generating the samples and producing ntuples. UK SUSY/Exotics Meeting 1st March 2007

  10. ee Invariant Mass 10190 5323 Generator level invariant mass: first two e+/- with opposite charge and with E>100 GeV Reconstructed mass:highest energy 2 Et’s in the eventwhich pass the selection criteria No +/- requirement here UK SUSY/Exotics Meeting 1st March 2007

  11. Reconstructed e/g Selection Criteria Electron:Has a TrackIsEMel==0Pt > 5.0|Eta|<2.5E/P>0.5WeightRatio>0.6NBel + NPixel>0NHitsel    = NBel + NPixel + ElecNSCTHits[i-1] + ElecNTRTHits[i-1]> 5 Photon:isEMphot==0Etphot>5.0|Eta|<2.5Charge photon==0 UK SUSY/Exotics Meeting 1st March 2007

  12. Reconstructed e variables 5323 For G=1000 GeV Interested in reconstructing e+/- with E above 200 GeV And up to ~1.5-2 TeV GeV GeV GeV GeV UK SUSY/Exotics Meeting 1st March 2007

  13. Reconstructed e variables 5323 For MG=1 TeV Graviton production is mainly gg initiated MG=1 TeV LHC e+e- In G rest-frame UK SUSY/Exotics Meeting 1st March 2007

  14. Reconstructed e variables e+e- ~ uniformly distributed in phi UK SUSY/Exotics Meeting 1st March 2007

  15. Gee Distributions peaks at p implies e’s back-to-back Expect the ee to be back-to-back in the G rest frame UK SUSY/Exotics Meeting 1st March 2007

  16. Charge Reconstruction When more generator information available will match generated and reconstructed electrons Reconstructed mass:highest energy 2 e’s in the event which pass the selection criteria 5.1% 94.9% UK SUSY/Exotics Meeting 1st March 2007

  17. Gee Events Most events have 1 or 2 “good” reconstructed electrons UK SUSY/Exotics Meeting 1st March 2007

  18. Ggg Reconstructed mass:highest Et 2 g’s in the event which pass the selection criteria UK SUSY/Exotics Meeting 1st March 2007

  19. Future Plans • Look at new samples which have more generator level information available. • Look into reconstruction efficiency • Investigate e/g selection criteria • Look into backgrounds UK SUSY/Exotics Meeting 1st March 2007

  20. BACKUP…. UK SUSY/Exotics Meeting 1st March 2007

  21. Branching Fraction 10-2 10-4 10–6 10-8 g W u Z RS model t = Mple-kRc Dilepton channel H Tevatron 700 GeV GKK Experimental Signature for Model RS • Model parameters: • Gravity Scale: • 1st graviton excitation mass: m1 • = m1Mpl/kx1, & mn=kxnekrc(J1(xn)=0) • Coupling constant: c= k/MPl • 1 = m1 x12 (k/Mpl)2 5D curve space with AdS5 slice: two 3(brane)+1(extra)+time! Resonance position Coupling proportional to p-1 for KK levels above the fundamental level (n>=1) for n=0 graviton couples with the gravitational strenght 1 extra warped dimension • Couplings of each individual KK excitation are determined by the scale, = Mple-kRc ~ TeV massesmn = kxne-krc (J1(xn)=0) width Signature:Narrow, high-mass resonance states in dilepton/dijet/diboson channels k = curvature, R = compactification radius 400 600 800 1000 K/MPl Mll (GeV) d/dM (pb/GeV) 10-2 10-4 10-6 10-8 10-10 KK excitations can be excited individually on resonance 700 GeV KK Graviton at the Tevatron k/MPl = 1,0.7,0.5,0.3,0.2,0.1 from top to bottom 1 0.5 0.1 0.05 0.01 LHC 1500 GeV GKK and subsequent tower states 1000 3000 5000 Mll (GeV) Davoudiasl, Hewett, Rizzo hep-ph0006041 UK SUSY/Exotics Meeting 1st March 2007

  22. RS1 Discovery Limit I. Belotelov et al. CMS NOTE 2006/104 CMS PTDR 2006 Di-lepton states G1μ+μ- c=0.01 100 fb-1 c=0.1 100 fb-1 Solid lines = 5s discovery Dashed = 1s uncert. on L • Two muons/electrons in the final state • Bckg: Drell-Yan/ZZ/WW/ZW/ttbar • PYTHIA/CTEQ6L • LO + K=1.30 both for signal and DY • Full (GEANT-4) and fast simulation/reco • Viable L1 + HLT(rigger) cuts • Theoretical uncert. • Misalignment, trigger and off-line reco • inefficiency, pile-up Misalignment during 1st period when the momentum resolution will be reduced from 1-2% to 4-5%. G1e+e- B. Clerbaux et al. CMS NOTE 2006/083 CMS PTDR 2006 UK SUSY/Exotics Meeting 1st March 2007 Likelihood estimator based on event counting suited for small event samples: S=√(2[(S+B)log(1+S/B)-S])>5

  23. RS1 Discovery Limit Di-photon states G1 • Two photons in the final state • Bckg: prompt di-photons, QCD hadronic jets • and gamma+jet events, Drell-Yan e+e- • PYTHIA/CTEQ5L • LO for signal, LO + K-factors for bckg. • Fast simulation/reco + a few points with • full GEANT-4 MC • Viable L1 + HLT(rigger) cuts • Theoretical uncert. • Preselection inefficiency M.-C. Lemaire et al. CMS NOTE 2006/051 CMS PTDR 2006 c=0.1 Di-jet states K. Gumus et al. CMS NOTE 2006/070 CMS PTDR 2006 • Bckg: QCD hadronic jets • L1 + HLT(rigger) cuts 5 Discovered Mass: 0.7-0.8 TeV/c2 UK SUSY/Exotics Meeting 1st March 2007

  24. RS1 Model Parameters A resonance could be seen in many other channels: mm, gg, jj, bbbar, ttbar, WW, ZZ, hence allowing to check universality of its couplings:  e Relative precision achievable (in %) for measurements of s.B in each channel for fixed points in the MG,Lp plane. Points with errors above 100% are not shown. Also the size (R) of the ED could also be estimated from mass and cross-section measurements. Allenach et al, hep-ph0211205 Allenach et al, JHEP 9 19 (2000), JHEP 0212 39 (2002) UK SUSY/Exotics Meeting 1st March 2007 BR(G→) = 2 * BR(G→ee)

  25. Extra Dimensions: Motivations MEW (1 TeV) << MPlanck (1019 GeV)? Randall, Sundrum,Phys Rev Lett 83 (99) RS 1 highly curved ED Gravity localised in the ED Planck TeV brane = Mple-kRc ~ TeV if warp factorkRc ~11-12 Some of these models can be/have been experimentally tested at high energy colliders UK SUSY/Exotics Meeting 1st March 2007

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