1. FIMCMS, 26 May, 2008 S. Lehti HIP Charged Higgs Project Preparative Analysis for Background Measurements with Data R.Kinnunen, M. Kortelainen, S. Lehti, L. Wendland Helsinki Institute of Physics, Helsinki FINCMS meeting Kumpula, May 26, 2008

2. FIMCMS, 26 May, 2008 S. Lehti Heavy charged Higgs production gg->tbH ±, H ± ->  in fully hadronic final state was studied in CMS Physics TDR by the HIP group Good prospects of finding charged Higgs boson in tau decay modes at large tan  might be the only possible channel for finding the heavy charged MSSM Higgs boson at the LHC Discovery of charged Higgs bosons in gg->tbH ±, H ± ->  requires integrated luminosity > 30 fb -1 in most of the parameter space Backgrounds should be measured from data, if possible Motivation of this study: Background measurements with low LHC luminosities Introduction

3. FIMCMS, 26 May, 2008 S. Lehti Event selection Trigger: Level-1:  jet, E T > 80 GeV HLT: Missing E T > 65 GeV, primary vertex reconstruction with pixel lines, regional reconstruction in  the full tracker around the Level-1  jet p T > 20 GeV for the leading track, isolation in a cone around the leading track Offline analysis: Veto on isolated leptons from W-> l  to ensure missing E T from H ± ->  Identification of one energetic hadronic  jet Veto on additional  jets Missing E T > 100 GeV W and top mass reconstruction tagging of one b jet transverse mass reconstruction from the  jet and Missing E T

4. FIMCMS, 26 May, 2008 S. Lehti Software tools and resources - - Analysis software is being developed - compiled ROOT analysis - Possibility to use PROOF under investigation - Grid job submission support - Visualization - Multivariate analysis - dCache server(s) successfully in use - 100 TB disk space to be shared with production, analysis groups and users - Connection 1 Gb/s FUNET/Nordunet - Connection 9 Gb/s to sepeli - World readable with xrootd - Local computing resources: ametisti and sepeli clusters. The analysis package can be compiled and used also from one’s laptop/desktop machines

5. FIMCMS, 26 May, 2008 S. Lehti Software version and data samples - CMSSW version CMSSW_1_6_11 used Helicity correlations are important for background suppression (Semi)-private event generation and simulation in progress with TAUOLA polarization effects switched ON - Simulation of signal samples ready for m H+ = 200, 300, 400 GeV - Background generation with ALPGEN - Simulation of tt and W+3jets backgrounds in progress with TAUOLA - W+3jet background in 2 W-mass bins - Background samples and cross sections (  polarization not included) : tt: tt0j_mT_70-alpgen,  = 627.9 pb W+3 jets: W3jet_0ptw100-alpgen, 0 < p T W < 100 GeV,  = 590 pb W+4 jets: W4jet_0ptw100-alpgen, 0 < p T W < 100 GeV,  = 125 pb QCD: QCD_Pt_80_120, 80 < p T jet < 120 GeV,  = 3.08  b QCD_Pt_120_170, 120 < p T jet < 170 GeV,  = 494 nb QCD_Pt_170_230, 170 < p T jet < 230 GeV,  = 101 nb QCD_Pt_230_300, 230 < p T jet < 300 GeV,  = 24.5 nb

6. FIMCMS, 26 May, 2008 S. Lehti Trigger simulation for gg->tbH ±, H ± ->  Level 1: Single tau, E T > 80 GeV Level 2: MET > 65 GeV, ECAL isolation of tau candidates - Sum of ECAL transverse deposits in 0.13<  R < 0.4 smaller than 5 GeV Level 2.5 : Signal vertex from pixel reconstruction Regional track reconstruction with maximum 7 hits Reconstruction region in  : 0.1x0.1 Isolation in 0.065 20 GeV, isolation tracks p T >5 GeV Level 3: As for Level2.5 but with wider reconstruction region in  : 0.5x0.5 and isolation tracks p T > 1 GeV m H+ = 200 GeVm H+ = 300 GeVm H+ = 400 GeV Level 170% (34%)73% (39%)75% (39%) Level 2 MET cut63% (60%)74% (77%)82% (84%) Level 2 Jet Reco74% (89%)81% (89%)80% (89%) Level 2 ECAL Isolation74% (89%)81% (89%)80% (89%) Level 2.5 SiStrip Isolation61% (67%)69% (78%)72% (81%) Level 3 SiStrip Isolation67% (74%)68% (74%)69% (74%) Global HLT19% (27%)28% (40%)32% (45%) Preliminary trigger (and MC matched) efficiencies

7. FIMCMS, 26 May, 2008 S. Lehti Definition of  identification variables: - Matching cone R m around the jet direction for searching the leading track - Signal cone R s around the leading track, important for  →  X - Isolation cone R i around the signal cone For 1-prong  ’s (separate study for  →  ) : R m = 0.1, R i = 0.45 with veto on tracks with p T > 0.5 GeV in the isolation cone  ECAL isolation for  jet:  E T cell (0.1 <  R < 0.45) < 1 GeV,  R defined around the track impact point in ECAL Rejection of electrons and hadronic jets (neutral hadrons) with the HCAL cluster: -0.98 < (E T HCAL cell – p T track )/ p T track < 0.2 within  R(HCAL cell,track impact point) < 0.45 p leading track / E  > 0.8, to exploit the opposite  helicity correlations in in the H ± ->  and W ± ->  decays, leading to harder pions from H ± ->  Identification starts from  -like jets in events passing the L1+HLT trigger Off-line  identification

8. FIMCMS, 26 May, 2008 S. Lehti  -jet reconstruction and corrections Methods tested for  jet reconstruction: Particle Flow  jets (CMS PF project) Calorimeter  jets Calorimeter  jets corrected combining tracker, ECAL and HCAL measurements for 1-prong  ’s (HardTauAlgo, HIP project) Improvement of energy scale and resolution with PF and HardTauAlgo Tails due to difficulty of separating the ECAL clusters from the charged pion and from  0 ’s in    n     candidates before  -selection (including  )

9. FIMCMS, 26 May, 2008 S. Lehti PF  jet reco::CaloTauHardTauAlgorithm  candidates 1) 54.7 (fb)50.1 (fb)43.8 (fb) E T >100 GeV19.7 (36.0%)17.1 (34.1%)13.7 (31.3)%  < 2 18.6 (94.4%)16.3 (93.3%)13.0 (93.8%) track, p T >20 GeV11.2 (60.2%)13.9 (85.3%)12.2 (31.3)% charged isolation4.80 (42.9%)5.42 (40.3%)5.13 (53.1%) elm isolation3.96 (82.5%)3.90 (72.0%)3.74 (58.9%) neutral hadron rejection3.00 (75.8%)3.76 (96.4%)3.57 (86.5%) electron rejection-3.43 (92.6%)3.47 (96.0%) R  > 0.81.58 (52.7%)1.86 (53.5%)2.03 (60.3%) Efficiency / jet2.9%3.3%4.6% Efficiency / event10.5%11.0%13.0% Matching  from H->  98.1%98.4%98.5 % Preliminary  selection efficiency for signal with m H+ = 300 GeV Cut optimization and study of the track parameter dependence in progress with possible use of TMVA methods

10. FIMCMS, 26 May, 2008 S. Lehti PF reconstructionreco:CaloTauHardTauAlgo all  canditates 9.81 x 10 5 (pb)9.05 x 10 5 (pb)7.42 x 10 5 (pb) E T >100 GeV9.50 x 10 5 (60.1%)3.09 x 10 5 (34.1%)1.71 x 10 5 (24.1%)  < 2 5.10 x 10 5 (86.4%)2.61 x 10 5 (84.5%)1.47 x 10 5 (84.9%) charged isolation1061 (2.1 x 10 -3 )199.8 (7.7 x 10 -4 )122.5 (8.4 x 10 -4 ) elm isolation206.2 (19.4%)47.7 (23.9%)31.0 (25.3%) neutral hadron rejection55.6 (27.0%)26.1 (54.7%)26.1 (84.2%) electron rejection-26.1 (100%) R  > 0.8 13.3 (23.9%)9.4 (36.0%)12.3 (47.1%) Efficiency / jet1.35 x 10 -5 1.03 x 10 -5 1.66 x 10 -5 Efficiency / event2.86 x 10 -5 2.01 x 10 -5 2.65 x 10 -5 Preliminary  selection efficiency for QCD jets, 120 < p T < 170 GeV/c TDR study: Efficiency/event 9.2 x 10 -5 for 170 < p T < 380 GeV/c

11. FIMCMS, 26 May, 2008 S. Lehti Main background processes: tt, W+3jet/4jet and QCD multi-jet events Background sources in the signal area: MET uncertainty fake  ’s (mainly in QCD multi-jet events) Methods to measure backgrounds from data tt and W+jets: measure background from MET uncertainty using precise muon momentum measurement from W->  decay in tt and W+3jet events QCD background: using QCD multi-jet events and fake  probability from  +jet events Preparative study of background measurements

12. FIMCMS, 26 May, 2008 S. Lehti Isolated electron veto to suppress W->e  jet veto to suppress W->  One isolated muon with p T  > 100 GeV No other muons E T miss > 100 GeV 3 jets, E T > 20 GeV tt selection: 2 b jets, suppression of W+3jets W and top reconstruction m T ( ,MET) reconstruction W+3jet selection: no b jets, suppression of tt m T ( ,MET) reconstruction Background analysis for with muons in tt and W+3jet events Event selection: 1.Single muon trigger 2.Off-line selection cuts:

13. FIMCMS, 26 May, 2008 S. Lehti Minimization of   = ((m jj –m W )/  W ) 2 + ((m jjj –m top )/  top ) 2 +  ((E i m –E i )/  i ) 2 with constraints m W 2 - (p 1 + p 2 ) 2 = 0, m top 2 - (p 1 + p 2 + p 3 ) 2 = 0 One jet (p 3 ) b tagged Top mass reconstruction and b tagging Cut optimization and variable selection with TMVA methods in progress

14. FIMCMS, 26 May, 2008 S. Lehti Obtaining clean MET in the signal and tt events difficult due to associated  jets from W →  Origin of the remaining large mass tail, decay mode of second W Very large masses : W->e and W->  hadrons  Close to m T ,MET)~ 100 GeV : W->cs, ud W->  W->e W->cs W->ud Transverse mass m T ,MET) in tt background

15. FIMCMS, 26 May, 2008 S. Lehti Transverse mass in W+3jet events  (W+3jet) = 590 pb, events at large m T ( ,MET) : 27 fb - W+jets events generated in 2 m W -bins (including Tauola) Events at large m T ( ,MET) originate from the BW tail of W MET cleaning not a problem, but signal-type events from W mass tail

16. FIMCMS, 26 May, 2008 S. Lehti Event selection: Events from tau + MET trigger At least one jet with p T jet > 100 GeV One of the jets with p T jet > 100 GeV taken randomly as  candidate 3 jets, E T > 20 GeV one ”b” jet top mass reconstruction E T miss > 100 GeV m T (  candidate,MET) reconstruction Method to measure the QCD background from data Events in the signal area: N QCD (  -sel)  N QCD (QCD-sel) *  miss-id)  miss-id) is planned to be measured in  +jet events (study in progress) Hadronic jets can lead to background due to bad  identification (fake  jets) mainly in the QCD multi-jet events Background also due to MET fluctuations from bad jet measurement - need to identify the bad jets to eliminate this source

17. FIMCMS, 26 May, 2008 S. Lehti Conclusions and outlook  in For H ± ->  in the fully hadronic channel at m H+ > m top suppression of fake  signals in the backgrounds, including the QCD multi-jet production, requires - strong  isolation - high quality measurement for the leading track - large MET cut even for the low mass range (due to QCD multi-jet background), clean MET measurement With real data one needs first to understand the backgrounds. Trying to measure the backgrounds from data.   Background events found in signal area, m T  m T  candidate  GeV were observed  - tt: mainly due to W->  decays - W+jets: due to natural W width - QCD: due problems with MET Ongoing work, development of the search strategies continues Short term plan: writing a CMS note