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Search for MSSM A/H  2   2 jets at CMS.

Search for MSSM A/H  2   2 jets at CMS. M H ≈ M A CMS Physics TDR focused on production associated with b quarks gg  bbH - using b tagging in analysis. Now try with MET - bring in additional production mechanism. gg  H . May be important at low masses. Event selection.

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Search for MSSM A/H  2   2 jets at CMS.

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  1. Search for MSSM A/H  2 2 jets at CMS.

  2. MH ≈ MA CMS Physics TDR focused on production associated with b quarks gg bbH - using b tagging in analysis. Now try with MET - bring in additional production mechanism. ggH. May be important at low masses. Event selection

  3. Single or double  triggering.  jet defined as narrow, isolated standard jet. Single  ET threshold 93 GeV. Double  ET threshold 66 GeV. L1  trigger Puritiy defined as R(L1 - MC) < 0.4.

  4. Useful  properties: 65% hadronic decays. Narrow jets with 1,3,5 charged particles + neutrals. 2 main tagging methods Calorimeter and tracker isolation. ECAL isolation: Localized / isolated ECAL deposit. Tracker isolation: 1,3,5 charged particles in signal cone. 0 charged particles in isolation cone.  tagging methods

  5. Combine both methods: First perform ECAL isolation Pisol < 5 GeV. Tracker isolation using only Pixels (inner tracker layers). No ET jet threshold. Signal  ~ 0.3 QCD background ~ 10-3. HLT  tagging CMS Physics TDR - volume I

  6. 2  jets ET > 60 GeV. Lead track PT > 35 GeV. 1 prong  decay.  charge correlation. Offline selection cuts

  7. Is MET a useful cut? What about MET resolution? MET I

  8. Need to correct MET. Replace ECAL + HCAL cluster energy with jet energy. Jet energy calibrated for calorimeter response, magnetic field, particle showers and pile up. Set cut to 75 GeV. MET II

  9. Assume  collinear with  jet, M << PT. Require E > 0. (< 0 from miss-measurement). Require non - back to back tau jets.  < 175o Higgs mass reconstruction Emiss tjet1 tjet2 n1 n2 MH = [ 2 E1 E2∙ (1 – cos θ) ]½ With Et = Etjet + En CMS NOTE 2006/xx

  10. Higgs mass

  11. Replacing b-tagging with a MET cut in this channel does give a detectable signal. Still to do: Investigate higher mass regions. Optimise cuts. Compare this study with previous b-tagging ones. Systematics etc… Conclusion and status

  12. Backup slides

  13.  branching ratio

  14. Cut table gg->bbH (200GeV) Three group of cuts:GROUP1, GROUP2andGROUP3. GROUP2andGROUP3 are not correlated cuts and applied independently after GROUP1.

  15. Cut table gg->bbH (200GeV)

  16. Cut table QCD > 170 GeV

  17. Cut table QCD > 170 GeV

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