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Light higgs decay in SUSY cascade. Introduction Trigger efficiency B tagging Jet energy resolution Invariant mass reconstruction Endpoints Conclusion . Alain Romeyer (Mons - Belgium). Introduction. Benchmark point LM5 Tan b = 10 A O = 0 µ > 0 M 1/2 = 360 GeV M 0 = 230 GeV.

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light higgs decay in susy cascade
Light higgs decay in SUSY cascade
  • Introduction
  • Trigger efficiency
  • B tagging
  • Jet energy resolution
  • Invariant mass reconstruction
  • Endpoints
  • Conclusion

Alain Romeyer (Mons - Belgium)

Alain Romeyer - January 2005

introduction
Introduction

Benchmark point LM5

Tan b = 10

AO = 0

µ > 0

M1/2 = 360 GeV

M0 = 230 GeV

MSUGRA 5 parameters : m0, m1/2,A, tan b, sign(µ)

S. Abdullin – L. Pape Update II of the new MSUGRA

test points proposal

Alain Romeyer - January 2005

slide3

LSP

MET

p

q

q

b

B tagging

b

p

Same decay chain may appears on the other side…

Alain Romeyer - January 2005

simulated events
Simulated events
  • Production of signal events and pile-up
  • Signal events : all SUSY channel (easier for later event reweighting)
    • ~20% contains our decay chain
  • Digitisation : merge pile-up and signal
  • official 100 000 evts production at CERNavailable
  • our reconstruction strategy launched on digis

Isajet 7.69 + Pythia 6220 + CMKIN

generator

FULL SIMULATION CHAIN

simulation

OSCAR

digitisation

ORCA8_7_4

Alain Romeyer - January 2005

reconstruction strategy
« Reconstruction » strategy
  • ORCA

Reconstruction

Simulatedevents

  • II - Jet Reconstruction :
    • Iterative Cone Algo.
      • cone size : 0.5
      • tower Et thr. : 0.5 GeV
      • seed Et thr. : 1 GeV

I – L1 +HLT

Efficiency ?

Jet sel.

Pt > 30 GeV

  • III - B tagging :
    • Combined B Tagging
    • S > 1.5
  • Analysis
  • event selection
  • IV - b ̅b inv mass reco.
  • MET :
    • MET from EcalHcalTower

Alain Romeyer - January 2005

c code in orca
C++ code in ORCA
  • Chi2chi1hbbAnalysis
    • Several .cc and .h files for each reconstruction module (MET, Trigger, Jets, Btagging, ROOT …)
    • Stored in CVS on ppemons (http://cms.umh.ac.be) :
      • setenv CVSROOT :pserver:[email protected]:/var/www/html/cvsweb/cvs
      • cvs login -> password is n0te
      • Cvs co Chi2Chi1hbbAnalysis
      • Scram b
      • RunAnalysis –c orcarc_example
    • Produce root files for analyses (MC info + Reco objects)

Alain Romeyer - January 2005

trigger efficiency
Trigger efficiency
  • L1 : 99.9 % - HLT : 96 %

Low Lumi.

Non cumulative Trigger !!!

~ all events !!!

Caveat : ~ same efficiency for SUSY bkg.

Alain Romeyer - January 2005

btagging
Btagging

Nhiggs = Nhiggs after HLT * ( Btag Eff. )² ~ 4700 evts

Alain Romeyer - January 2005

jet energy resolution
Jet energy resolution

Alain Romeyer - January 2005

njets
Njets

Alain Romeyer - January 2005

slide11
MET

Alain Romeyer - January 2005

slide12
dRbb

Alain Romeyer - January 2005

slide13
Minv

Alain Romeyer - January 2005

endpoint nikita

LSP

MET

Endpoint -> Nikita

Search for extreme kinematical configuration

q2

q1

gluino

squark

B tagging

h0

b

See Luc Pape private note

-> endpoints gives equations with unknown mass (gluino, squak, neutralinos)

-> system has to be solved numerically

Need to look for Hq1, hq2, hq1q2, q1q2 invariant mass distribution

-> for the moment using MC info only

Alain Romeyer - January 2005

hq1 hq2
Hq1 / hq2

hq2

hq1

Alain Romeyer - January 2005

hq1q2 q1q2
hq1q2 / q1q2

q1q2

hq1q2

Alain Romeyer - January 2005

conclusion
Conclusion
  • Future :
    • Include all SM background (W+jets, Z+jets)
    • Improve S/B ratio (cuts, b tagging optimisation…)
    • Reduce the width of the invariant mass
    • Run the code on the Zbb sample for cross check and optimisation of the reconstruction strategy
    • Fast simulation (FAMOS) in order to explore the SUSY parameter phase space
    • Contour plot for the CMS reach
    • PTDR !!! + Analysis note -> setenv CVSROOT :pserver:[email protected]:/var/www/html/cvsweb/cvscvs login -> password is n0teCvs co Analysis_note

Alain Romeyer - January 2005

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