1. Alain Romeyer - January 20051 Light higgs decay in SUSY cascade - Status report Introduction Trigger efficiency B tagging Jet calibration Invariant mass reconstruction Likelihood fit Conclusion Filip Moortgat (CERN) Alain Romeyer (Mons - Belgium)

2. Alain Romeyer - January 20052 Introduction Signature : h0h0 LSP MET b B tagging Benchmark point LM5 Tan  = 10 A O = 0 µ > 0 M 1/2 = 360 GeV M 0 = 230 GeV MSUGRA 5 parameters : m 0, m 1/2, A, tan , sign(µ) S. Abdullin – L. Pape Update II of the new MSUGRA test points proposal

3. Alain Romeyer - January 20053 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 CERN available our reconstruction strategy launched on digis First results Isajet 7.69 + Pythia 6220 + CMKIN OSCAR 2_4_6 ORCA 7_6_1 generator simulation digitisation FULL SIMULATION CHAIN

4. Alain Romeyer - January 20054 « Reconstruction » strategy ORCA_8_6_1 Simulated events I – L1 +HLT Reconstruction II - Jet Reconstruction : Iterative Cone Algo. cone size : 0.5 tower Et thr. : 0.5 GeV seed Et thr. : 1 GeV III - B tagging : By Track Counting Number of tracks above minimum significance : 2 MET : MET from EcalHcalTower Analysis event selection IV - b  ̅b inv mass reco. Efficiency ? Jet sel. Pt > 10 GeV

5. Alain Romeyer - January 20055 Trigger efficiency GeneratedHLT 100 00096 462 (19 338) L1 : 99.9 % - HLT : 96 % ~ all events !!! TriggerCondition (GeV)% of evts 1 jetEt > 57123.5 3 jetsEt > 20921.7 4 jetsEt > 12232.7 B jet1 Jet Et > 23777.4 MET calo 1 jet > 180 GeV + MET > 12379.5 MET jets 1 jet > 180 GeV + MET > 12379.8 Low Lumi. Caveat : ~ same efficiency for SUSY bkg. Non cumulative Trigger !!!

6. Alain Romeyer - January 20056 Btagging Number of jetsNumber of tagged jets Efficiency / Inefficicenc y (%) b955934731049.5 u123 80794087.6 d9740979578.2 c50728910317.9 Global efficiency : 49.5 % Global inefficiency : 9.4 % Nhiggs = Nhiggs after HLT * ( Btag Eff. )² ~ 4700 evts Track Counting Algo. (default setting) Need to be optimised Filip

7. Alain Romeyer - January 20057 Efficiency / inefficiency

8. Alain Romeyer - January 20058 Efficiency / inefficiency…

9. Alain Romeyer - January 20059 Select b jets from h 0 Select only b jets coming from h 0 decay No jet energy calibration (from parton content in a 0.3 cone)

10. Alain Romeyer - January 200510 Jet reconstruction accuracy

11. Alain Romeyer - January 200511 Jet calibration Jet calibration method following CMS-note 1999/066 Association between rec. Jets and generated partons before hadro. (cone < 0.3) 2 types of jets : b jets and other E true jet = sum(E quarks,gluons ) Correction Factor C = E true jets / E rec jets Fit of the correction factor surface in the E vs |  | plane :

12. Alain Romeyer - January 200512 E correction for b jets

13. Alain Romeyer - January 200513 E correction for non b jets Same operation is done with the jet momentum

14. Alain Romeyer - January 200514 Impact on Minv Select only b jets coming from h 0 decay Calibrated jets

15. Alain Romeyer - January 200515 Impact on jet reco. accuracy

16. Alain Romeyer - January 200516 Invariant mass (no cuts)

17. Alain Romeyer - January 200517 Likelihood fit Follow the Z’  µµ strategy (CMS AN 2004/018) Unbinned method No constraints on the absolute background level only on the background shape 3 parameters : m h,  and Fraction of signal Normalised Gaussian Extract from background fit

18. Alain Romeyer - January 200518 Fit result (full stat) Unbinned fit Binned only when plotted

19. Alain Romeyer - January 200519 Various running time 50 000 evts – S = 10.9 25 000 evts – S = 7.95 15 000 evts – S = 5.8 100 000 evts – S = 14.1

20. Alain Romeyer - January 200520 Conclusion For the first time the full analysis chain is working higgs peak visible with significance above 5 ~15000 evts (~ 40 days of understood data) Future : Include SM background 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