Alain Romeyer - Sept 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)

Alain Romeyer - Sept 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

Alain Romeyer - Sept 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

Alain Romeyer - Sept 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  evts/year Low Lumi.

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

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

Alain Romeyer - Sept 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

Alain Romeyer - Sept Jet reconstruction Test jet reconstruction and calibration with a Z  b  b sample (production of 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

Alain Romeyer - Sept 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 !!!

Alain Romeyer - Sept Conclusion Full simulation of signal (and SUSY bkg) done for SUSY LM5 using : ISAJET 7.69 Pythia 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

Alain Romeyer - Sept 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.