Light higgs decay in susy cascade
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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

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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


Light higgs decay in susy cascade

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


Light higgs decay in susy cascade

MET

Alain Romeyer - January 2005


Light higgs decay in susy cascade

dRbb

Alain Romeyer - January 2005


Light higgs decay in susy cascade

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


Light higgs decay in susy cascade

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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