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Searches for Extra Dimensions and Comopsiteness in CMS

Searches for Extra Dimensions and Comopsiteness in CMS

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Searches for Extra Dimensions and Comopsiteness in CMS

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  1. Searches for Extra Dimensions and Comopsiteness in CMS Guinyun Kim Kyungpook National University, Korea On behalf of CMS collaboration The 16th International Conference on Supersymmetryand the Unification of Fundamental Interactions June 16 – 21, 2008 Seoul, Korea 1

  2. Contents • Introduction • CMS Experiments • Searches for Extra Dimensions • Search for New Particles/Physics with High Mass Dijet final states • Search for Contact Interactions with Dijet • Search for New Particles with Dijet Resonances • Search for New Particles/Physics with High Mass Dilepton final states • High mass Di-electron final states in CMS • High mass Di-muon final states in CMS • Conclusions

  3. SUPERCONDUCTING CALORIMETERS COIL ECAL HCAL Scintillating PbWO4 crystals Plastic scintillator/brass sandwich Total weight : 12,500 t IRON YOKE Overall diameter : 15 m Overall length : 21.6 m Magnetic field : 4 Tesla TRACKER MUON ENDCAPS Silicon Microstrips Pixels MUON BARREL Cathode Strip Chambers (CSC ) Drift Tube Resistive Plate Chambers ( DT ) Chambers ( RPC ) Resistive Plate Chambers (RPC) CMS: Compact Muon Solenoid • Muons: • muon system acceptance: |η|<2.4 • muons momentum resolution: σ(1/pT)~10-2 (pT~10 GeV) • Calorimetry: • HCAL |η|<5, δE/E ~ 120% / √E + 5% • ECAL |η|<3, δE/E ~ 1.5% / √E + 0.5% + 0.15% / E SUSY08, G.N. Kim

  4. Searches for Extra Dimensions Virtual or Resonance exchange Large ED (ADD): • Graviton in bulk • DY interference, or missing ET Arkani-Hamed, Dimopoulos, Dvali Phys Lett B429 (98) ll qq  ZZ Dienes, Dudas, Gherghetta Nucl Phys B537 (99) TeV-1 ED (DDG): • Gauge Bosons and Higgs in bulk • spin-1 KK resonances • DY interference jet+MET +MET Randall, Sundrum Phys Rev Lett 83 (99) Warped ED (RS): • Graviton as narrow spin-2 resonances emission • Searches Concentrated on • High mass dijet final states • High mass dilepton final states Universal ED (UED): • spin-1 KK resonances Appelquist, Cheng, Dobrescu Phys. Rev. D 64 (01) SUSY08, G.N. Kim

  5. Model Name X Color J P G / (2M) Chan. E6 Diquark D Triplet 0+ 0.004 ud Excited Quark q* Triplet ½+ 0.02 qg q, q, g q, q, g Axigluon A Octet 1+ 0.05 qq X Dijet Resonance Coloron C Octet 1- 0.05 qq q, q, g q, q, g Octet Technirho rT8 Octet 1- 0.01 qq,gg R S Graviton G Singlet 2- 0.01 qq,gg s - channel Heavy W W ‘ Singlet 1- 0.01 q1q2 Heavy Z Z ‘ Singlet 1- 0.01 qq Search for New Particles/Physics with High Mass Dijet final states Contact Interaction • Motivation :New Physics Signals 1. Contact Interaction: Indirect observation of an energy scale () of new physics. • Composite Quarks • New Interactions 2. Dijet Resonances: LHC is a parton-parton resonance factory in a previously unexplored region Present limit (95%CL) Mq*>775 GeV (D0) MW’>800, MZ’>640 GeV (D0) MD>420 GeV (CDF) MT8>480 GeV (CDF) MA(C)>980 GeV (CDF) D0: PRD 69 (2004) R111101 CDF: PRD55 (1997) R5263 SUSY08, G.N. Kim

  6. h=0 h=1 h=-1 Jet 1 Transverse f q proton proton Jet 2 ET Jet 1 h Jet 2 f -1 0 1 Observation of Dijet in CMS Jet Reconstruction • Standard jet reconstruction • Cone algorithm • Midpoint & iterative cone indistinguishable at high PT. • Standard jet kinematics • Jet E = SEi, Jet p=Spi • q = tan-1(py/px) • ET = Esinq, pT=√px2+py2 • Dijet is two leading jets. • Invariant mass Dijet Mass = 900 GeV SUSY08, G.N. Kim

  7. Jet Response vs pT in Barrel Jets we use (GeV) Jet Response and Corrections Jet Response vs h relative to Barrel • Jets in Barrel have uniform response inh and are sensitive to new physics • Jet response changes smoothly and slowly up to | jet h | = 1.3 • Measure relative response vs. jet h in data with dijet balance • Data will tell us what is the region of response we can trust. • Measured jet pT in the calorimeter is less than true jet pT (particles in cone) • Measured jets are corrected so pT is the same as true jet pT • Scales Jet (E,px,py,pz) by • ~1.5 at pT = 70 GeV • ~1.1 at pT = 3 TeV • for jets in barrel region |h|<1.3 |h|<1 CMS Preliminary 7 SUSY08, G.N. Kim

  8. Jet 1 PDF(xa) Proton Proton | jet h | < 1 PDF(xb) Jet 2 Dijet Rates and Cross Sections • QCD dijet cross section is large. • s from color force is large ^ • Rate = Cross Section x Luminosity • Luminosity (L) is rate of protons / area supplied by the LHC. • Design L=1034 cm-2 s-1 ~ 10 fb-1/month • Cross section from two factors • Parton distributions functions (PDFs) • Probability of finding partons in proton with fractional momentum x • Valence quarksu and d have large PDFs at high x (high dijet mass). • Parton scattering cross section s • Many signals are also large • Either large PDFs or s or both. ^ ^ SUSY08, G.N. Kim

  9. Composite Quarks New Interactions q q M ~ L M ~ L q q Dijet Mass << L Quark Contact Interaction q q L q q QCD Background L = ± [2p / L2] (q gm q) (q gm q) dN/ dcos q* Signal 0 1 cos q* Search for Contact Interactions with Dijet • New physics at large scale L • Composite Quarks • New Interactions • Modeled by contact interaction • Intermediate state collapses to a point for dijet mass << L. • For example, the standard contact interaction among left-handed quarks introduced by Eichten, Lane and Peskin (PRL50,811) • Excluded for L+ < 2.7 TeV (D0:PRL82, 2457) • Observable Signatures • Effects at high pT and dijet mass. • Rate: Higher rate than QCD • Angle: Angular distributions can be very different from QCD. SUSY08, G.N. Kim

  10. Inclusive Jet PT and Contact Interactions • Contact interactions create large rate at high PTand immediate discovery possible • Error dominated by jet energy scale (~10%) in early running (10 pb-1) • DE~ 10% not as big an effect as L+= 3 TeV for PT>1 TeV. • PDF “errors” and statistical errors (10 pb-1) are smaller than E scale error • With 10 pb-1 we can see new physics beyond Tevatron exclusion of L+ < 2.7 TeV. Rate of QCD and Contact Interactions Sensitivity with 10 pb-1 P A S P A S SUSY08, G.N. Kim PAS: CMS PAS SBM_07_001

  11. QCD Background dN/ dcos q* Signal 0 1 cos q* Dijet Ratio: Simple Angular Measure • Dijet angular distributions are sensitive to new physics. • Dijet Ratio =N(|h|<0.7) / N(0.7<|h|<1.3) • Number of events in which each leading jet has |h|<0.7, divided by the number in which each leading jethas 0.7<|h|<1.3 • Simplest measurement of angular distribution • Most sensitive part for new physics • It was first introduced by D0 (PRL82, 2457). Numerator Sensitive to New Physics |cos q*| ~ 0 Jet 1 z Jet 2 Jet 1 Denominator Dominated by QCD |cos q*| ~ 0.6, usually z Jet 2 Jet 2 or (rare) SUSY08, G.N. Kim h = -1.3 -0.7 0.7 1.3

  12. Dijet Ratio from QCD • We have optimized the dijet ratio for a contact interaction search in barrel • Old dijet ratio used by D0 and PTDR was N(|h|<0.5) / N(0.5<|h|<1.0) • New dijet ratio is N(|h|<0.7) / N(0.7<|h|<1.3) • Dijet ratio from QCD agrees for GenJets and Corrected CaloJets • Flat at 0.6 for old ratio, and flat at 0.5 for new ratio up to around 6 TeV. Old Dijet Ratio New Dijet Ratio P A S PTDR SUSY08, G.N. Kim

  13. CMS Sensitivity to Contact Interactions from Dijet Ratio • Optimization dramatically increases sensitivity to contact interactions. • Raising the signal and decreasing the QCD error bars. • Value of L+ we can discover is increased by 2 TeV for 100 pb-1 • From L+≈ 5 TeV with old dijet ratio (PTDR) to L+ ≈ 7 TeV with new dijet ratio. New Dijet Ratio Old Dijet Ratio (PTDR) L+ (TeV) L+ (TeV) 3 3 5 5 P A S 10 10 QCD QCD SUSY08, G.N. Kim

  14. Model Name X Color J P G / (2M) Channel Rate E6 Diquark D Triplet 0+ 0.004 ud space Excited Quark q* Triplet ½+ 0.02 qg M Axigluon A Octet 1+ 0.05 qq Mass time Coloron C Octet 1- 0.05 qq Octet Technirho rT8 Octet 1- 0.01 qq, gg q, q, g q, q, g X R S Graviton G Singlet 2- 0.01 qq, gg Heavy W W' Singlet 1- 0.01 q1q2 q, q, g q, q, g Heavy Z Z' Singlet 1- 0.01 qq Search for New Particles with Dijet Resonance New particles, X, produced in parton-parton annihilation will decay to 2 partons (dijets). Signature: dijet resonances → mass bumps. Tevatron has searched but not found any dijet resonances so far. Best limits on dijet resonances by CDF RUN II (CDF note 9246). SUSY08, G.N. Kim

  15. Dijet Mass Resolution • From the study of Dijet mass resolution: • Gaussian core of resolution for |h|<1 and |h|<1.3 is similar. • Resolution for corrected calorimeter jets (CaloJets) is follows: • 9 % at 0.7 TeV • 5.7% at2 TeV • 4.5 % at 5 TeV P A S 2 TeV Z’ |η| < 1.3 Dijet Mass Resolution P A S P A S 5.7% Corrected CaloJets GenJets Natural Width SUSY08, G.N. Kim

  16. Rate of Dijet Resonances • Measure rate as a function of corrected dijet mass and look for resonances. • Use a smooth parameterized fit or QCD prediction to model background p0, p1, p2 : arbitrary parameters QCD Backgound PTDR P A S Dijet Mass (TeV) PAS: CMS PAS SBM_07_001 SUSY08, G.N. Kim

  17. Searches using Rate of Dijet Resonance Fractional difference between new particles and QCD dijets Resonances with 100 pb-1 Resonances with 1 fb-1 PTDR P A S • Strongly produced resonances can be seen • Convincing signal for a 2 TeV excited quark (q*) in 100 pb-1 • Tevatron excluded up to 0.775 TeV (D0) and 0.87 TeV (CDF). SUSY08, G.N. Kim

  18. Systematic Uncertainties • Jet Energy Scale • CMS estimates +/- 5 % is achievable by 1 fb-1 • Changes dijet cross section between 30% and 70% • Parton Distributions • CTEQ 6.1 uncertainty • Resolution • Bounded by difference between particle level jets and calorimeter level jets. Energy scale PDF Resolution PTDR • Systematic uncertainties on the cross section as a function of dijet mass are large. • But they are correlated vs. mass. The distribution changes smoothly. SUSY08, G.N. Kim

  19. Sensitivity to Resonance Cross Sections of New Particles • Cross Section for Discovery or Exclusion • Shown here for 1 fb-1 • Compared to cross section for 8 models • CMS expects to have sufficient sensitivity to • Discover with 5s significance any model above solid black curve • Exclude with 95% CL any model above the dashed black curve. P T D R SUSY08, G.N. Kim

  20. 5s Sensitivity to Dijet Resonances CMS 100 pb-1 CMS 1 fb-1 CMS 10 fb-1 E6 Diquark Excited Quark Axigluon or Coloron Color Octet Technirho 0 1 2 3 4 5 Mass (TeV) Discovery Sensitivity for Models • Resonances produced by the valence quarks of each proton • Large cross section from higher probability of quarks in the initial state at high x. • E6 diquarks (ud g D g ud) can be discovered up to 3.7 TeV for 1 fb-1 • Resonances produced by color force • Large cross sections from strong force • With just 1 fb-1 CMS can discover • Excited Quarks up to 3.4 TeV • Axigluons or Colorons up to 3.3 TeV • Color Octet Technirhos up to 2.2 TeV. • Discoveries possible with only 100 pb-1 • Large discovery potential with 10 fb-1 P T D R SUSY08, G.N. Kim

  21. Exclusion Sensitivity to Models 95% CL Sensitivity to Dijet Resonances • Resonances produced via color interaction or valence quarks. • Wide exclusion possibility connecting up with many exclusions at Tevatron • Resonances produced weakly are harder. • But CMS has some sensitivity to each model with sufficient luminosity. • Z’ is particularly hard. • Weak coupling and requires an anti-quark in the proton at high x. Tevatron Exclusion (Dijets) CMS 100 pb-1 CMS 1 fb-1 CMS 10 fb-1 E6 Diquark Excited Quark Axigluon or Coloron Color Octet Technirho W ’ R S Graviton Z ’ 0 1 2 3 4 5 6 P T D R Mass (TeV) SUSY08, G.N. Kim

  22. /Z/Z'/KKZ/G e, q(g) q e+, + (g) LHC 1 fb-1 Search for New Particles with High Mass Dilepton final states Heavy resonances with mass above 1 TeV/c2 decaying into a lepton pair • Standard Model • Drell-Yan Process • Beyond Standard Model • Z’ boson predicted by Grand Unified Theories (GUT): • ZSSM within the Sequential Standard Model (SSM) • Z Z and Z : E6 and SO(10) GUT group • ZLR :left-right symmetry model • ZALR: alternative left-right symmetry model • Kaluza-Klein (KK) excitations of Z, KKZ: TeV-1 model • KK excitations of a graviton, G: Randall-Sundrum model Total Cross-section for Drell-Yan process SUSY08, G.N. Kim

  23. Drell-Yan events based on RS Model Cross-section for Drell-Yan production at LHC of the first two KK excitations Drell-Yan line-shape vs mll at LHC for MG=1.5 TeV 1.5 TeV c=0.5 c=0.1 c=0.05 c=0.01 MG (GeV) H. Davoudiaslet al., PRD63-075004 Experimental and Theoretical constraints on the RS model when the SM lies on the TeV-brane LHC 10 fb-1 LHC 100 fb-1 The sensitivity reach at LHC by the Drell-Yan events : 10 fb-1: 100 fb-1: H. Davoudiaslet al., PRL 84 (2000) 2080 SUSY08, G.N. Kim MG (GeV)

  24. High mass Di-electron final states in CMS • Selection of Di-electron events • EHCAL/EECAL < 10 % • Isolation cut : 0.1<R<0.5 ( ) • A track is requested to be associated for each electron candidate • Correction • Saturation correction • Energy correction • z-vertex distribution • Final State Radiation Recovery Ratio Mee/Mtrue before and after corrections P T D R SUSY08, G.N. Kim

  25. High mass Di-electron final states in CMS Invariant Mass Distribution for (a) KK Z boson, (b) SSM Z’ boson and (c) Graviton production for an integrated luminosity of 30 fb-1 M=3.0 TeV/c2 M=1.5 TeV/c2, c=0.01 M=4.0 TeV/c2 P T D R Drell-Yan background Drell-Yan background Table SUSY08, G.N. Kim

  26. Discovery potential of CMS P T D R P T D R 5s discovery limit on the resonance mass (TeV/c2) P T D R SUSY08, G.N. Kim

  27. High mass Di-muon final states in CMS Selection of Di-muon events: • Level-1 trigger: • Two muons with PT> 3 GeV or one inclusive muon with P> 14 GeV. • HLT: single-muon OR di-muon (non-isolation) • Two muons of opposite sign reconstructed by the Global Muon Reco algorithm • Acceptance | h | < 2.4 • PT >20 GeV/c for each muon • Isolation:SPT < 3 GeV/c in a cone ofDR< 0.3 Trigger Efficiency Invariant mass resolution SUSY08, G.N. Kim CMS Note 2006/123

  28. Discovery potential in Z'→+- channel Integral Luminosity needed to reach 5s significance (SL=5) Summary of the signal significance expected for different Z’ models P T D R SUSY08, G.N. Kim

  29. Discovery potential in GADD→+- channel I.Belotelov, I.Golotvin, A.Lanyov, E.Rogalev, M.Savina, S.Shmatov, D.Bourikov, CMS-NOTE 2006/076 Backgrounds: For M(μμ)inv>1TeV ZZ/WZ/WW:σ= 2.59x10-4 fb-1tt:σ = 2.88x10-4 fb-1 Leading Order DY cross section (in fb) for ADD graviton with n=3 and 6 and MS=3,4,5,7 TeV/c2 Landsberg code + STAGEN + PHYTIA + ORCA + OSCAR From bottom to top:SM, n=6,5,4,3. Trigger: Single muon & dimuon (L1+HLT)pT>7GeV(μμ), 19GeV(single μ)Efficiency > %98 Event selection: M(μμ)inv > McutDifferent Mcut for different MS:Mcut = 1TeV for MS = 3TeVMcut = 1.5TeV for MS =4 and 5TeV Mcut = 2.0TeV for MS =7 and10TeV SUSY08, G.N. Kim

  30. Discovery potential in GADD→+- channel Significance values for ScL for the ideal detector 5s limit on MS SUSY08, G.N. Kim

  31. Discovery potential in RS graviton GKK→+- channel I.Belotelov, I.Golotvin, V. Palichik, A.Lanyov, E.Rogalev, M.Savina, S.Shmatov, CMS-NOTE 2006/104 SUSY08, G.N. Kim

  32. Discovery potential in RS graviton GKK→+- channel C=0.02 C=0.01 C=0.05 C=0.1 P T D R Systematic uncertainties due to EW correction, Hard-scale and PDF uncertainties P T D R P T D R SUSY08, G.N. Kim

  33. Conclusions • Discussed CMS search plans for new particles with Dijet and Dilepton. • New Particles/Physics with Dijet : • Rate of high pT jet could give a convincing contact interaction signal: • Can discover L+ = 3 TeV in 10 pb-1 even if jet energy errors are 10%. • Dijet ratio will probe contact interactions in dijet angular distributions : • Can discover L+ = 4, 7, 10 TeV in 10, 100, 1000 pb-1 with small systematics. • Ratio of high dijet mass can be used to discover new particles up to several TeV: • Axigluon, Coloron, Excited Quark, Color Octet Technirho, Graviton, or E6 Diquark • New Particles/Physics with Dilepton: • Gives a convincing signal for various new particles (hevay gauge bosons, Extra dimensions) with luminosity more than 10 fb-1. • CMS is preparing to discover new particles/physics at the TeV scale using Dijet and Dilepton. SUSY08, G.N. Kim

  34. Backup Slides

  35. The CMS Detector Calorimeters Hadronic Electro- magnetic Protons Protons SUSY08, G.N. Kim

  36. CMS Barrel & Endcap Calorimeters(r-z view, top half) | h | < 1 h = 0.5 q = 62 o h = 1.0 q = 40 o h = - 0.5 q = 118 o h = 0 q = 90 o h = -1.0 q = 130o HCAL OUTER h = 1.5 q = 26 o h = -1.5 q = 154 o SOLENOID HCAL BARREL HCAL END CAP HCAL END CAP ECAL BARREL 3 m ECAL END CAP ECAL END CAP h = 3 q = 6 o h = - 3 q = 174 o Z HCAL > 10 l I ECAL > 26 l0 SUSY08, G.N. Kim

  37. Event Selection CMS Detector 4 x 107 Hz L1 Trigger 1 x 105 Hz HLT Trigger 1.5 x 102 Hz Saved for Analysis Trigger and Luminosity • Collision rate at LHC is expected to be 40 MHz • 40 million events every second ! • CMS cannot read out and save that many. • Trigger chooses which events to save • Two levels of trigger are used to reduce rate in steps • Level 1 (L1) reduces rate by a factor of 400. • High Level Trigger (HLT) reduces rate by a factor of 700. • Trigger tables are intended for specific luminosities • We’ve specificied a jet trigger table for three luminosities • L = 1032 cm-2 s-1. Integrated luminosity ~ 100 pb-1. • LHC schedule projects this after ~1 months running. • L = 1033 cm-2 s-1. Integrated luminosity ~ 1 fb-1. • LHC schedule projects these after ~ 1 year of running. • L = 1034 cm-2 s-1. Integrated luminosity ~ 10 fb-1. • One months running at design luminosity.

  38. Add New Threshold (Ultra). Increase Prescales by 10. L = 1033 1 fb-1 Add New Threshold (Super). Increase Prescales by 10. L = 1034 10 fb-1 Jet Trigger Table and Dijet Mass Analysis • CMS jet trigger saves all high ET jets & pre-scales the lower ET jets. • Prescale means to save 1 event out of every N events. Mass values are efficient for each trigger, measured with prior trigger L = 1032 100 pb-1 As luminosity increases new trigger paths are added Each with new unprescaled threshold.

  39. Dijet Balance Barrel Jet (|h|<1.3) Probe Jet (any h) Jet response vs h relative to |h|<1.3 Hcal towers and h cuts h = 1 h = 1.3 |h|<1.3 |h|<1 HB HE Transition Region CMS Preliminary Jet h Region • Barrel jets have uniform response & sensitive to new physics • Jet response changes smoothly and slowly up to | jet h | = 1.3 • CaloTowers with |h|<1.3 are in barrel with uniform construction. • CaloTowers with 1.3<|h|<1.5 are in barrel / endcap transition region • Some of our analyses use | jet h |<1.3, others still use | jet h |<1 • All are migrating to | jet h |<1.3 which is optimal for dijet resonances • Measure relative response vs. jet h in data with dijet balance • Data will tell us what is the region of response we can trust.

  40. Optimization of h cut • QCD cross section rises dramatically with |h| cut due to t-channel pole. • Z’ signal only gradually increases with |h| cut g optimal value at low |h|. • Optimal cut is at |h| < 1.3 for a 2 TeV dijet resonance. • Optimization uses Pythia Z’ angular distribution for the resonance. h cut and sensitivity h cut and cross section P A S P A S 40 SUSY08, G.N. Kim

  41. Dijet Event Cleanup • Dijet events do not usually contain large missing ET • A cut at MET / SET < 0.3 is >99% efficient for PT > 100 GeV • Won’t change the QCD background to new physics. • Most unphysical background contain large missing ET • Catastrophic detector noise, cosmic ray air showers, beam-halo backgrounds • A simple cut at MET / SET < 0.3 should remove most of these at high jet PT. • This cut is our first defense, simpler and safer than cutting on jet characteristics. 99% Efficiency Cut & Chosen Cut MET / SET for QCD Dijets and Cut