Bobby Scurlock

1
Preparations for Inclusive Searches for
Supersymmetry in the Leptons Jets MET
Topology at CMS

• Bobby Scurlock
• Darin Acosta
• Paolo Bartalini
• Richard Cavanaugh
• Alexey Drozdetskiy
• Guenakh Mitselmakher
• Yuriy Pakhotin

2
Outline

• The Large Hadron Collider
• The Compact Muon Solenoid
• Triggers at CMS
• SuperSymmetry
• Signatures
• Fast CMS Simulation results
• New Study using full CMS detector simulation
• Study systematic effects and ways to deal with
  them
• Establish new reach scenarios
• Develop tools for analysis with real data
• Conclusions

3
The Large Hadron Collider

• Two proton rings housed in same tunnel as LEP
• Design luminosity L 1034 cm2s1 100
  fb-1/year (Pile up 20 collisions/crossing)
• Start-up luminosity L 1033 cm2s1 10
  fb-1/year
• Completion mid 2007

R 4.5 kmE 7 TeV
CMS
4
The Compact Muon Solenoid
5
SuperSymmetry

• Minimal Gravity Mediated Supersymmetry (mSUGRA)
• Universal gravitational interactions break SUSY
  at scale F (1011 GeV)2
• Reduces number of free parameters from 105 to 5
• m0 Common scalar mass
• m1/2 Common gaugino mass
• A0 Common scalar trilinear coupling
• tan ? Ratio of v.e.v. of Higgs doublets
• Sign(?) sign of Higgsino mixing parameter

6
SUSY Event Rates and Cross-sections
Rates at full design Luminosity 100 fb-1/year
SUSY Production

• Sparticle Production 102-108 events/year
• Low mass SUSY few Hz ? Should be observable in
  early LHC running

7
Jet and Lepton Triggers
Jet Trigger If Single Jet Trigger Budget is few
Hz implies an inclusive single jet threshold of
400600 GeV
Single Jet HLT Rate vs JetET Cut
Inclusive Jet Rate (cone algorithm, R0.5)
High lumi
Low lumi
NB May be more advantageous to use Lepton
Triggers because they are less systematically
challenging than JetMET Triggers
Muon Trigger If Muon Trigger Budget is 30 Hz
implies 1? PT gt 20 GeV 2? PT gt 10 GeV
Decreasing Rate
See K. Kotovs Talk
8
SUSY Signature

• Squark/gluino production dominates the total
  cross-section for low energy SUSY
• Complex squark/gluino decay chains
• Many high-ET jets
• Heavy-flavor (? and b, especially at large tan?)
• Leptons
• From sleptons, charginos, W/Z, and b-jets
• Missing transverse energy (MET)
• From LSP and neutrinos from taus, sneutrinos

• We are conducting a reach study for a few bench
  mark points in mSUGRA space using full detector
  simulation e.g. LM1
• Includes systematic effects
• Other points in parameter space will be probed
  using fast simulation
• Results will be published in CMS Physics
  Technical Design Report next year

See Y. Pakhotins Talk

• LM1 mSUGRA Parameters
• mo 60 GeV
• m1/2 250 GeV
• tanb 10
• sign(m) 1
• Ao 0
• s 50 pb (NLO)

9
SUSY Study using Full Detector Simulation

• Previous study used fast CMS detector simulation
  CMSJET
• No systematic uncertainties were included
• Now including systematic effects on reach
• JetMET energy scale and resolution, Muon fake
  rates and ID, trigger efficiencies, etc

Examplesystematic effects due to Calorimeter
Calibration Uncertainty
See M. Schmitts Talk
SM Background LM1 Signal
L10 fb-1
Number of Background events passing a MET cut
will be very sensitive to shifts in MET
Steeply falling BG
S/v(SB) S/v(SB s(Systematici)2)
Flatter Signal
Example
Raw MET from Full Simulation
METcut (GeV)
10
JetsMET Reach vs. Luminosity (Fast Simulation)
1 year _at_ L1034
1 year _at_ L1033
Results using old fast simulation. No systematic
effects included
1 month _at_L1033
Tevatron reach lt 0.5 TeV

• Squarks/gluinos probed to 1.5 TeV with 1 fb-1
• Up to 2.5 TeV at design luminosity (100 fb-1)

11
Conclusions

• Discovery of SUSY, if it exists, is almost
  assured at the LHC
• Inclusive mSUGRA squark/gluino discovery reach to
  1.5 TeV with 1 fb1, 2.5 TeV with 100 fb1
• Conducting a careful study of SUSY using full CMS
  detector simulation
• Including potential systematic effects

12

• Backup slides start here

13
Example High Level Trigger Table

• Using Lepton Triggers for SUSY may be
  systematically less challenging than calorimeter
  based triggers
• ? May be useful to use lepton triggers for early
  physics at CMS

14
Minimal SuperSymmetry

• SUSY
• Symmetry between bosons and fermions
• Squarks/sleptons scalar counterparts to the
  fermions
• Charginos/neutralinos/gluinos fermion
  counterparts to SM gauge bosons
• At least two Higgs doublets (5 scalars)
• Avoids fine-tuning of SM, can lead to GUTs
• Minimal Supersymmetric Standard Model (MSSM)
• Usually consider RP ? (-1)3(B-L)2S conserved ?
  LSP is stable
• 105 new parameters
• Minimal Gravity Mediated Supersymmetry (mSUGRA)
• Require SUSY to be a local symmetry
• Universal gravitational interactions break SUSY
  at scale F (1011 GeV)2
• 5 free parameters
• m0 Common scalar mass
• m1/2 Common gaugino mass
• A0 Common scalar trilinear coupling
• tan ? Ratio of v.e.v. of Higgs doublets
• Sign(?) sign of Higgsino mixing parameter
• Typically

15
mSUGRA Cross-section

• LM1 mSUGRA Parameters
• mo 60 GeV
• m1/2 250 GeV
• tanb 10
• sign(m) 1
• Ao 0
• s 50 pb (NLO)

• Some Branching Ratios
• dominate x-section

• Squark/gluino production dominates the total
  cross-section for low energy SUSY
• Cross sections dont vary much with ?, tan?

16
SUSY Signatures

• Complex squark/gluino decay chains
• Many high-ET jets
• Heavy-flavor (? and b, especially at large tan?)
• Leptons
• From sleptons, charginos, W/Z, and b-jets
• Missing transverse energy (MET)
• From LSP and neutrinos from taus, sneutrinos

LM1

• One might expect
• 3-4 Hard Jets
• Leading Jet ET ? 250 GeV
• MET ? 200 GeV

17
Fast CMS Detector Simulation SUSY Study

• Counting excess events over SM background
• Discovery mode SUSY search at LHC
• Explicit sparticle reconstruction not done
• 6 Analyses
• ETmiss jetsMET, no lepton requirements
• Ol no leptons
• 1l 1 lepton
• 2lOS 2 leptons, opposite sign
• 2lSS 2 leptons, same sign
• 3l 3 leptons
• Plot 5? sensitivity contours

18
Fast CMS Detector Simulation SUSY Study

• Highest mass scale achieved using jetsMET with
  no explicit lepton requirement
• Current study requires lepton trigger ? Reach
  about 2 TeV
• Systematic effects expected to shift 5s contours
  lower

• ETmiss jetsMET, no lepton requirements
• Ol no leptons
• 1l 1 lepton
• 2lOS 2 leptons, opposite sign
• 2lSS 2 leptons, same sign
• 3l 3 leptons

19
(No Transcript)