1. Alain Romeyer - Sept. 20041 Light Higgs search in SUSY cascades Introduction (Previous studies) Plans for this analysis Simulation chain Reconstruction and analysis framework Conclusion Alain Romeyer (Mons - Belgium) Filip Moortgat (CERN)

2. Alain Romeyer - Sept. 20042 Introduction It has been shown in CMS-note 1997/070 : signal can be seen with only few months of data main bkg : SUSY SM bkg very low discrimination between SUSY signal and SUSY bkg is difficult Signature : h0h0 LSP MET b B tagging

3. Alain Romeyer - Sept. 20043 Plans for this analysis Using the Full simulation and reconstruction On one particular MSUGRA point (LM5) Background study : SUSY and SM (t, W, Z + jets…) Optimise the reconstruction : Trigger efficiency study Jet reconstruction and calibration B tagging efficiency Reconstruct the b َ b invariant mass and then… If visible : using end-points try to estimate the squark masses Using the Fast simulation study the CMS reach Scan the MSUGRA parameter phase space Provide a sensitivity region in the (m 0,m 1/2 ) plane for several luminosities

4. Alain Romeyer - Sept. 20044 MSUGRA Point 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 All SUSY channel : 4.9 pb  150 000 evts/year Low Lumi.

5. Alain Romeyer - Sept. 20045 Masses and Branching ratios Branching ratio ~ 20% of SUSY events contain our decay chain (~ 30 000 evts/year) From Isajet

6. Alain Romeyer - Sept. 20046 Simulated events Production of signal events and pile-up Signal events : all SUSY channel (easier for later event reweighting) Private production of 10 000 evts @ Mons (~25 days) ~20% contains our decay chain Digitisation : merge pile-up and signal 100 000 evts production ready using Digis waiting for DST Isajet 7.69 + Pythia 6220 + CMKIN OSCAR 2_4_6 ORCA 7_6_1 generator simulation digitisation Low statistic -> only a first try FULL SIMULATION CHAIN

7. Alain Romeyer - Sept. 20047 Signal Background : SUSY SM : top, QCD… « Reconstruction » strategy Simulated events I – L1 +HLT Reconstruction II - Jet Reconstruction : optimisation (large jet multiplicity) calibration Energy resolution … III - B tagging : B tagging efficiency mistagging rate test of different algorithms optimise for SUSY cascade (plenty of bs comming from tops and sbottom) IV - MET important for event selection Efficiency tables

8. Alain Romeyer - Sept. 20048 Jet reconstruction Test jet reconstruction and calibration with a Z  b  b sample (production of 50 000 events already asked) Position of the peak Energy resolution Iterative Cone Algorithm perhaps not adapted to our problems Splitting and merging of jets is not implemented Midpoint Cone Algorithm could be an interesting solution

9. Alain Romeyer - Sept. 20049 Physics analysis VII - Analysis b  ̅b inv mass reco.  select the 2 b jets coming from the higgs decay  reliable fit strategy  higgs mass CMS reach  CMS sensitivity VI - Event selection Reject SM and SUSY bkg  MET  Number of jets  … Optimisation !!!

10. Alain Romeyer - Sept. 200410 Conclusion Full simulation of signal (and SUSY bkg) done for SUSY LM5 using : ISAJET 7.69 Pythia 6.220 OSCAR_2_4_6 ORCA_7_6_1 Plans : First step : full higgs analysis chain on LM5 Study trigger efficicency (~95%) Study jet reconstruction in SUSY cascade environment (calibration !!!) B tagging efficiency (~50 – 60%) Study background : SUSY and SM (top, Z+jets…) Optimize selection criteria (MET, number of jets…) Fit higgs mass

11. Alain Romeyer - Sept. 200411 Conclusion… Second step : Try to reconstruct masses of sparticles in the cascade decay chain using endpoints Third step : CMS reach Scan the MSUGRA parameter phase space with fast simulation (FAMOS) For the moment we have used 10k events, now starting to run on 100k events We have already some first results !!! will be shown in november SUSY BSM meeting.