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CMS search plans for dijet resonances

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CMS search plans for dijet resonances Powered By Docstoc
					Searches for Extra Dimensions
 and Comopsiteness in CMS


                     Guinyun Kim
          Kyungpook National University, Korea
            On behalf of CMS collaboration


     The 16th International Conference on Supersymmetry
       and the Unification of Fundamental Interactions
                      June 16 – 21, 2008
                      Seoul, Korea                        1
                                     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
            CMS: Compact Muon Solenoid
                  SUPERCONDUCTING                           CALORIMETERS
                  COIL                                       ECAL              HCAL
                                                           Scintillating
                                                                              Plastic scintillator/brass
                                                          PbWO4 crystals      sandwich



                                                                                             IRON YOKE




                    TRACKER
                    Silicon Microstrips
                    Pixels


               Total weight : 12,500 t                                                      MUON
               Overall diameter : 15 m
                                                MUON BARREL                                 ENDCAPS
               Overall length : 21.6 m
               Magnetic field : 4 Tesla                                      Cathode Strip Chambers (CSC )
                                          Drift Tube      Resistive Plate
Muons:                                    Chambers ( DT ) Chambers ( RPC )   Resistive Plate Chambers (RPC)

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                                                             3
                       Searches for Extra Dimensions

 Large ED (ADD): Arkani-Hamed, Dimopoulos, Dvali      Virtual or Resonance
 ● Graviton in bulk
                    Phys Lett B429 (98)                     exchange
                                                                         ll
 ● DY interference, or missing E
                                 T
                                                                         qq
TeV-1  ED
                Dienes, Dudas, Gherghetta
         (DDG): Nucl Phys B537 (99)
                                                                         
● Gauge Bosons and Higgs in bulk
                                                                         ZZ
● spin-1 KK resonances

● DY interference



Warped ED
                 Randall, Sundrum
            (RS):Phys Rev Lett 83 (99)                                            jet+MET
● Graviton as narrow spin-2
                                                               emission           +MET
resonances
                                                               Searches Concentrated on
Universal ED (UED): Appelquist, Cheng, Dobrescu         • High mass dijet final states
● spin-1 KK resonances
                       Phys. Rev. D 64 (01)
                                                        • High mass dilepton final states
                                            SUSY08, G.N. Kim                             4
               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
                                                                         Dijet Resonance
       New Interactions
                                                              q, q, g                           q, q, g
  2. Dijet Resonances: LHC is a parton-parton                                     X
    resonance factory in a previously unexplored
    region                                                    q, q, g                           q, q, g
                                                                            s - channel
    Model Name        X     Color     JP   G / (2M)   Chan.
    E6 Diquark        D     Triplet   0+   0.004      ud           Present limit (95%CL)
    Excited Quark     q*    Triplet   ½+ 0.02         qg           Mq*>775 GeV (D0)
                                                                   MW’>800, MZ’>640 GeV (D0)
    Axigluon          A     Octet     1+   0.05       qq
                                                                   MD>420 GeV (CDF)
    Coloron           C     Octet     1-   0.05       qq           MrT8>480 GeV (CDF)
    Octet Technirho   rT8   Octet     1-   0.01       qq,gg        MA(C)>980 GeV (CDF)
    R S Graviton      G     Singlet   2-   0.01       qq,gg         D0: PRD 69 (2004) R111101
                                                                    CDF: PRD55 (1997) R5263
    Heavy W           W„    Singlet   1-   0.01       q1q2
                                                                                                5
    Heavy Z           Z„    Singlet   1- SUSY08, G.N.qq
                                           0.01       Kim
                         Observation of Dijet in CMS
                                                       h=1               h=0                  h=-1

                                                                     Jet 1
    Jet Reconstruction                                                                        Transverse


   Standard jet reconstruction                                                                           f
                                                                                  q
                                                   proton                                         proton
        Cone algorithm R  h 2  f 2  0.5
             Midpoint & iterative cone
                                                                                  Jet 2
              indistinguishable at high PT.
                                                                                      Jet 2
                                                                 Jet 1                               ET
        Standard jet kinematics
              Jet E = SEi, Jet p=Spi                                                          h
          
                                                                                                       f
             q = tan-1(py/px)                                               -1
             ET = Esinq, pT=√px2+py2                                0
                                                                 1


   Dijet is two leading jets.
        Invariant mass
                                
         m  ( E1  E2 ) 2 - ( p1  p2 ) 2
                                                                                       Dijet Mass = 900 GeV
                                                                                                     6
                                              SUSY08, G.N. Kim
                    Jet Response and Corrections
   Jets in Barrel have uniform response                 Jet Response vs h relative to Barrel
    in h and are sensitive to new physics                                |h|<1.3
        Jet response changes smoothly and                                |h|<1
         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.                                       CMS Preliminary



   Measured jet pT in the calorimeter is                    Jet Response vs pT in Barrel
    less than true jet pT (particles in cone)

   Measured jets are corrected so pT is
    the same as true jet pT                                                   Jets we use
        Scales Jet (E,px,py,pz) by
             ~1.5 at pT = 70 GeV
             ~1.1 at pT = 3 TeV
             for jets in barrel region
                                                                                                (GeV)
                                          SUSY08, G.N. Kim                                  7
                 Dijet Rates and Cross Sections
                                     Jet 1
                     s
                                                         QCD dijet cross section is large.
     PDF(xa)
                      ˆ                                       ^ from color force is large
                                                               s
Proton                                   Proton
                                 PDF(xb)                                            | jet h | < 1
    Jet 2
   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 quarks u and d have large
             PDFs at high x (high dijet mass).               Many signals are also large
         Parton scattering cross section s    ^                                        ^
    
                                                                 Either large PDFs or s or both.

                                        SUSY08, G.N. Kim                                     8
              Search for Contact Interactions with Dijet
   New physics at large scale                           Composite Quarks              New Interactions
                                                         q                 q
       Composite Quarks                                       M~
       New Interactions                                                                             M~

 Modeled by contact interaction
     Intermediate state collapses to a point for            q                  q
      dijet mass << .
     For example, the standard contact                                      Dijet Mass << 
      interaction among left-handed quarks                           Quark Contact Interaction
      introduced by Eichten, Lane and Peskin                             q              q
      (PRL50,811)                                                                   
        • Excluded for + < 2.7 TeV (D0:PRL82, 2457)
                                                                         q                    q
   Observable Signatures
                                                                 L = ± [2p / 2] (q m q) (q m q)
       Effects at high pT and dijet mass.
         Rate:   Higher rate than QCD                                        QCD Background
        ds                                      g 2 (1)
             s SM  s Int.   s NewPhs. ( 
                                2
                                                         )
        d                                      4p 2                                       Signal
         Angle: Angular distributions can be very
          different from QCD.                                    0                      1      cos q*
                                                                                                    9
                                              SUSY08, G.N. Kim
           Inclusive Jet PT and Contact Interactions
   Contact interactions create large rate at high PT and immediate discovery possible
        Error dominated by jet energy scale (~10%) in early running (10 pb-1)
             E~ 10% not as big an effect as = 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  < 2.7 TeV.
         Rate of QCD and Contact Interactions                       Sensitivity with 10 pb-1




                                            SUSY08, G.N. Kim            PAS: CMS PAS SBM_07_001   10
                  Dijet Ratio: Simple Angular Measure
   Dijet angular distributions are sensitive to
    new physics.                                                          QCD Background

 Dijet   Ratio = N(|h|<0.7) / N(0.7<|h|<1.3)                                          Signal
       Number of events in which each leading jet
        has |h|<0.7, divided by the number in which            0                      1     cos q*
        each leading jet has 0.7<|h|<1.3
 Simplest   measurement of angular distribution                        Jet 1               Numerator
                                                                                            Sensitive
       Most sensitive part for new physics
                                                                                             to New
       It was first introduced by D0 (PRL82, 2457).                             z
                                                                                             Physics

                                                                                            |cos q*| ~ 0
                                                                        Jet 2

                                                                    Jet 1
                                                                                          Denominator
                                                                                  z       Dominated by
                                                                                          QCD
                                                       Jet 2                    Jet 2 |cos q*| ~ 0.6,
                                                                   or
                                                                                 (rare)
                                                                                        usually
               L + > 2.7 TeV , L - > 2.4 TeV      h = -1.3 -0.7            0.7        1.3       11
                                         SUSY08, G.N. Kim
                                 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




                                       SUSY08, G.N. Kim                                 12
         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  we can discover is increased by 2 TeV for 100 pb-1
           From  ≈ 5 TeV with old dijet ratio (PTDR) to  ≈ 7 TeV with new dijet ratio.
          Old Dijet Ratio (PTDR)                                   New Dijet Ratio

                        + (TeV)                                            + (TeV)
                              3                                                   3
                                   5                                                     5

                                       10
     QCD                                                   QCD                                10




                                        SUSY08, G.N. Kim                                 13
            Search for New Particles with Dijet Resonance
New particles, X, produced in parton-parton                                 Signature: dijet resonances
annihilation will decay to 2 partons (dijets).                                       → mass bumps.




                                                             Rate
          q, q, g                           q, q, g
  space




                              X

          q, q, g                            q, q, g                                M
                                                          time                                            Mass
           Model Name                      X          Color         JP        G / (2M)          Channel
           E6 Diquark                      D          Triplet       0+        0.004             ud
           Excited Quark                   q*         Triplet       ½+        0.02              qg
           Axigluon                        A          Octet         1+        0.05              qq
           Coloron                         C          Octet         1-        0.05              qq
           Octet Technirho                 rT8        Octet         1 -       0.01              qq, gg
           R S Graviton                    G          Singlet       2-        0.01              qq, gg
           Heavy W                         W'         Singlet       1-        0.01              q 1q 2
           Heavy Z                         Z'         Singlet       1-        0.01              qq
                             Tevatron has searched but not found any dijet resonances so far.
                             Best limits on dijet resonances by CDF RUN II (CDF note 9246).
                               Model      Excluded (GeV)            Model     Excluded (GeV)
                              A or C         260 - 1250              D           290 - 630
                                rT8          260 - 1110       W'                 280 - 840                14
                                                SUSY08, G.N. Kim
                                  q*         260 - 870        Z'                 320 - 740
                            Dijet Mass Resolution
From the study of Dijet mass resolution:
   Gaussian core of resolution for |h|<1 and
    |h|<1.3 is similar.                                           2 TeV Z’
   Resolution for corrected calorimeter jets                     |η| < 1.3
    (CaloJets) is follows:
        9 % at 0.7 TeV
        5.7% at 2 TeV
        4.5 % at 5 TeV
     Dijet Mass Resolution


                                                                    5.7%


                          Corrected CaloJets

                               GenJets
                            Natural Width

                                               SUSY08, G.N. Kim        15
                       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
                                        p1

                     ds
                        =
                             (
                          p0 1- m / s   )        p0, p1, p2 : arbitrary parameters
                     dm        m p2
      QCD Backgound




                                                                                     Dijet Mass (TeV)
         PAS: CMS PAS SBM_07_001                                                             16
                                     SUSY08, G.N. Kim
             Searches using Rate of Dijet Resonance

     Fractional difference between new particles and QCD dijets
     Resonances with 100 pb-1                        Resonances with 1 fb-1




   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).         17
                                  SUSY08, G.N. Kim
                             Systematic Uncertainties
   Jet Energy Scale
                                                                             Energy scale
        CMS estimates +/- 5 % is
         achievable by 1 fb-1
        Changes dijet cross
                                                                    PDF
         section between 30% and
         70%                                                    Resolution


   Parton Distributions
        CTEQ 6.1 uncertainty


   Resolution
        Bounded by difference
         between particle level jets
         and calorimeter level jets.


   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                                   18
         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.

                                   SUSY08, G.N. Kim                 19
                   Discovery Sensitivity for Models
   Resonances produced by the valence
    quarks of each proton
        Large cross section from higher                5s Sensitivity to Dijet Resonances
                                                                  CMS           CMS           CMS
         probability of quarks in the initial state              100 pb-1       1 fb-1       10 fb-1
         at high x.
                                                       E6
        E6 diquarks (ud g D g ud) can be              Diquark
         discovered up to 3.7 TeV for 1 fb-1
                                                       Excited
                                                       Quark
   Resonances produced by color force
        Large cross sections from strong force        Axigluon
                                                       or Coloron
        With just 1 fb-1 CMS can discover
             Excited Quarks up to 3.4 TeV             Color Octet
             Axigluons or Colorons up to 3.3 TeV      Technirho
             Color Octet Technirhos up to 2.2 TeV.                  0      1      2     3        4     5
                                                                                              Mass (TeV)
   Discoveries possible with only 100 pb-1
        Large discovery potential with 10 fb-1


                                          SUSY08, G.N. Kim                                         20
                   Exclusion Sensitivity to Models
   Resonances produced via                        95% CL Sensitivity to Dijet Resonances
    color interaction or valence                        Tevatron              CMS       CMS             CMS
                                                    Exclusion (Dijets)       100 pb-1   1 fb-1         10 fb-1
    quarks.
        Wide exclusion possibility               E6
                                                  Diquark
         connecting up with many
         exclusions at Tevatron                   Excited
                                                  Quark

                                                  Axigluon
                                                  or Coloron
   Resonances produced weakly
    are harder.                                   Color Octet
                                                  Technirho
        But CMS has some sensitivity
         to each model with sufficient            W’
         luminosity.
        Z‟ is particularly hard.                 RS
                                                  Graviton
             Weak coupling and requires
              an anti-quark in the proton at      Z’
              high x.                                           0        1        2     3        4     5         6
                                                                                                     Mass (TeV)

                                          SUSY08, G.N. Kim                                             21
         Search for New Particles with High Mass
                   Dilepton final states
Heavy resonances with mass above 1 TeV/c2 decaying into a lepton pair

           /Z/Z'/KKZ/G      e-,m-
  q(g)
                                                       Standard Model
                                       1.   Drell-Yan Process
   q (g)                     e+,m +
                                                Beyond Standard Model
                              1. Z’ boson predicted by Grand Unified Theories (GUT):
                                     • ZSSM within the Sequential Standard Model (SSM)
   Total Cross-section for           • Z Zh and Z : E6 and SO(10) GUT group
     Drell-Yan process
                                     • ZLR :left-right symmetry model
   LHC 1 fb-1                        • ZALR: alternative left-right symmetry model
                              2. Kaluza-Klein (KK) excitations of Z, KKZ: TeV-1 model
                              3. KK excitations of a graviton, G: Randall-Sundrum model

                                 SUSY08, G.N. Kim                                    22
                     Drell-Yan events based on RS Model
      Cross-section for Drell-Yan production at Drell-Yan line-shape vs mll at LHC for MG=1.5 TeV
      LHC of the first two KK excitations
                         k / M Pl  0.1                                c  k / M Pl  1
        1.5 TeV
                                                                                    c=0.5
                                                                                      c=0.1

                                                                           c=0.01       c=0.05



                   MG (GeV)           H. Davoudiasl et al., PRD63-075004

Experimental and Theoretical constraints on the RS model                                       LHC
          when the SM lies on the TeV-brane                                                   10 fb-1

       R5  20k 2  M 52  c  k / M Pl  0.1
        p  M Pl e - krcp  10 TeV                                                          LHC
                                                                                            100 fb-1
        The sensitivity reach at LHC by the Drell-Yan events :
                    10 fb-1:             100 fb-1:
                      H. Davoudiasl et al., PRL 84 (2000) 2080
                                              SUSY08, G.N. Kim                                    23
                                                                           MG (GeV)
                 High mass Di-electron final states in CMS


1. Selection of Di-electron events
    • EHCAL/EECAL < 10 %
    • Isolation cut : 0.1<R<0.5 ( R  h  f )
                                               2        2




    • A track is requested to be associated for each electron candidate

2. Correction                                Ratio Mee/Mtrue before and after corrections
    • Saturation correction
    • Energy correction
    • z-vertex distribution
    • Final State Radiation Recovery



                                     SUSY08, G.N. Kim                             24
                   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=4.0 TeV/c2                      M=3.0 TeV/c2            M=1.5 TeV/c2, c=0.01




                                        Drell-Yan
                                       background                     Drell-Yan
                                                                     background




           Table




                                       SUSY08, G.N. Kim                                25
Discovery potential of CMS




           5s discovery limit on the resonance mass (TeV/c2)




       SUSY08, G.N. Kim                                26
             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: S PT < 3 GeV/c in a cone of R < 0.3

                Trigger Efficiency                           Invariant mass resolution




                                     SUSY08, G.N. Kim                                    27
                                             CMS Note 2006/123
                 Discovery potential in Z'→m+m- channel

                                                          Integral Luminosity needed to reach
                                                                 5s significance (S=5)
Summary of the signal significance expected
         for different Z’ models



                                              L




         SL =    2ln (L s+ b / L b )

                                       SUSY08, G.N. Kim                              28
                     Discovery potential in GADD→m+m- channel

qq   / Z / G  m m                    - I.Belotelov, I.Golotvin, A.Lanyov, E.Rogalev, M.Savina, S.Shmatov,
                                            D.Bourikov, CMS-NOTE 2006/076
                                                                                               Backgrounds:
  Leading Order DY cross section (in fb) for ADD graviton with      1+ n / 2       n/2
               n=3 and 6 and MS=3,4,5,7 TeV/c2            M Pl =   MS          R               For M(μμ)inv>1TeV
                                                                                               ZZ/WZ/WW:
                                                                                               σ = 2.59x10-4 fb-1
                                                                                               tt:
                                                                                                σ = 2.88x10-4 fb-1
            Landsberg code + STAGEN + PHYTIA + ORCA + OSCAR                              From bottom to top:SM, n=6,5,4,3.

Trigger:
Single muon & dimuon (L1+HLT)
pT>7 GeV(μμ), 19 GeV(single μ)
Efficiency > %98
Event selection:
M(μμ)inv > Mcut
Different Mcut for different MS:
Mcut = 1TeV for MS = 3TeV
Mcut = 1.5TeV for MS =4 and 5TeV
Mcut = 2.0TeV for MS =7 and 10TeV                SUSY08, G.N. Kim                                                    29
                           Discovery potential in GADD→m+m- channel

         Significance values for ScL for the ideal detector




                                                             5s limit on MS
ScL =   2 { N S + N B )ln (1 + N S / N B )- N S }
           (




                                                    SUSY08, G.N. Kim          30
Discovery potential in RS graviton GKK→m+m- channel

                                       I.Belotelov, I.Golotvin, V. Palichik,
                                       A.Lanyov, E.Rogalev, M.Savina, S.Shmatov,
                                       CMS-NOTE 2006/104




                    SUSY08, G.N. Kim                                  31
Discovery potential in RS graviton GKK→m+m- channel

                                                      C=0.02
                                             C=0.01
                                                           C=0.05
                                                                C=0.1




     s NLO
K=         =1
     s LO


                         Systematic
                     uncertainties due to
                        s
                     K = NLO = 1.30 ± 0.05
                         s LO
                        EW correction,
                        Hard-scale and
                       PDF uncertainties

                    SUSY08, G.N. Kim                                    32
                                      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  + = 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  + = 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                                 33
Backup Slides
The CMS Detector
                      Calorimeters
                            Hadronic

                            Electro-
                            magnetic




   SUSY08, G.N. Kim           35
                    CMS Barrel & Endcap Calorimeters
                                  (r-z view, top half)
                                        |h|1

        h  -1.0          h  - 0.5        h0            h  0.5         h  1.0
        q  130 o         q  118 o        q  90 o       q  62 o        q  40 o


                                        HCAL OUTER

h  -1.5                                                                             h  1.5
                                       SOLENOID                                      q  26 o
q  154 o
                                      HCAL BARREL
                 HCAL                                                  HCAL
        3m
                 END                  ECAL BARREL                      END
                        ECAL                                    ECAL
h-3             CAP    END                                     END    CAP           h3
q  174 o               CAP                                     CAP                  q6o

                                                                                     Z
 HCAL > 10 l I
 ECAL > 26 l 0                                                                   36
                                       SUSY08, G.N. Kim
                           Trigger and Luminosity
   Collision rate at LHC is expected to be 40 MHz                      Event Selection
        40 million events every second !
        CMS cannot read out and save that many.
                                                                        CMS Detector

   Trigger chooses which events to save
                                                                                4 x 107 Hz

   Two levels of trigger are used to reduce rate in steps
        Level 1 (L1) reduces rate by a factor of 400.                   L1 Trigger
        High Level Trigger (HLT) reduces rate by a factor of 700.
                                                                                1 x 105 Hz
   Trigger tables are intended for specific luminosities
        We‟ve specificied a jet trigger table for three luminosities    HLT Trigger
        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.                     1.5 x 102 Hz
             LHC schedule projects these after ~ 1 year of running.
        L = 1034 cm-2 s-1. Integrated luminosity ~ 10 fb-1.              Saved for
             One months running at design luminosity.                     Analysis
            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.
                              L1                   HLT           ANA        Mass values
             Path      ET  Pre-      Rate     ET  Rate         Dijet Mass   are efficient for
                                                                            each trigger,
                     (GeV) scale     (Hz)   (GeV) (Hz)          (GeV)
L = 1032                                                                    measured with
             Low      25     2000     146     60         2.8                prior trigger
100 pb-1
             Med      60      40      97     120         2.4      330
             High     140      1      44     250         2.8      670       As luminosity
                                                                            increases new
              Add New Threshold (Ultra).    Increase Prescales by 10.       trigger paths
L = 1033
 1 fb-1                                                                     are added
             Ultra    270      1      19     400         2.6     1130
                                                                            Each with new
              Add New Threshold (Super).    Increase Prescales by 10.
                                                                            unprescaled
L = 1034
             Super    450      1      14     600         2.8     1800       threshold.
 10 fb-1
                                       Jet h Region
   Barrel jets have uniform response & sensitive to new physics                         Dijet Balance
        Jet response changes smoothly and slowly up to | jet h | = 1.3                      Barrel Jet
             CaloTowers with |h|<1.3 are in barrel with uniform construction.                (|h|<1.3)
             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         Probe Jet
                                                                                                (any h)
   Measure relative response vs. jet h in data with dijet balance
        Data will tell us what is the region of response we can trust.
    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
                   CMS Preliminary                                  Region
                          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 cross section                       h cut and sensitivity




                                      SUSY08, G.N. Kim                             40
                            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.
         MET / SET for QCD Dijets and Cut             99% Efficiency Cut & Chosen Cut

				
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