1. Search for Charged Higgs bosons with H ± ->  -> hadrons  decay mode in fully hadronic final state Ritva Kinnunen Matti Kortelainen, Sami Lehti and Lauri Wendland Helsinki Institute of Physics Alexandre Nikitenko Imperial College, UK Monoranjan Guchait Tata Institute, Mumbai Tiit Sepp Tarto, Estonia Alexandros Attikis Nicosia, Cypros

2. Outline Introduction Signal and background processes Short term goals for H ± searches Research highligts from 2008/2009  -jet identification for H ± searches Muon replacement method Tau-trigger efficiency measurement Status and Plans for analysis with data Analysis methods Background measurements from data

3. Signal and background processes tbgb -> tgg(qq) -> Production through tt -> tbH ±, gb -> tH ±, gg(qq) -> tbH ± processes Background processes for fully hadronic final states: tt, W 1 ->  W 2 ->qq’ ’ tt, W 1 ->  W 2 ->e/  /  + ’ W+3/4jets, W->  QCD multi-jet events, fake  ’s, fake MET

4. Simulated event display of tbH +  bW(  cs) + b +  with radiative gluon in r,  projection

5. Short term goals for H ± searches The focus of the HIP group has been so far the search of the heavy charged Higgs bosons with m H+ > m top In view of the LHC low luminosity runs emphasis has been moved towards lower Higgs boson masses, m H+ ≤ m top New process included tb tt -> tbH ± ->  jet + 2 b jets + 2 jets + missing E T with fully hadronic final state tb Reach of H ± discovery and exclusion in tt -> tbH ± production is expected to superseed that of Tevatron already with 200 fb -1 Backgrounds und analysis methods similar to the searches of heavy Charged Higgs bosons Responsability of this channel on the HIP group

6. Light charged Higgs bosons from tt->WbH + b Tevatron and LEP limits

7. Andrey Korytov (UF) Physics Week, May 14, 2009 7 Current list of “must-do” analyses –all analyses going beyond this list are always welcome—bring it on! –A few analyses not listed above are being evaluated for their competitiveness: BSM double- charged Higgs, VBF H  WW, MSSM heavy charged Higgs, MSSM H 

8. Research highlights from 2008/2009 1.  -jet identification for H± searches 2. Implementation of a new method to replace muons with MC  ’s for for background measurement from data 3. Tau  trigger efficiency measurement from data

9.  -jet identification for H+ searches l Cuts were reoptimized for best separation against QCD multi-jet events - correlations between the selections taken into account - cuts can still be tightened, if necessary l Standard  -jet identification cuts were used with high E T cut - Jet E T > 119 GeV, leading track p T > 20 GeV/c - Charged track isolation and isolation of electromagnetic energy deposition - Matching of track p to hadronic energy deposition to reject electrons l Helicity correlations were used to suppress taus from W   decays - R  =p track /E vis.  jet > 0.8 - suppresses also further hadronic jets with neutral particles l Results for 1-prong  decays with trigger excluding missing E T - Signal efficiency 2-5 % with high purity - QCD background suppressed by a factor of 10 5 or better - ttbar and W+3/4 jets backgounds suppressed by a factor of 10 4 or better l Also 3-prong  decays are promising l Improvement expected from particle flow jets - Better energy resolution of  jets, etc. Cross-section, fb Results for 1-prong tau identification signal QCD ttbar W+3/4 jets

10. R. Kinnunen Helsinki Institute of Physics FinnCMS meeting, December 19, 2008 Muon replacement method A method for replacing a muon with MC tau is being developed as a tool in CMSSW For each selected muon a tau with the same momentum is generated with correct polarization state Full detector simulation for taus Muons are removed from the event, and the new taus are merged with the rest of the event at DIGI level Event is finally reconstructed with the standard CMSSW algorithms and used for analysis

11. R. Kinnunen Helsinki Institute of Physics FinnCMS meeting, December 19, 2008 Muon replacement validation First testing and validation with Z - >μμ data by replacing the muon with higher p T with a muon –We were able to identify a few problems which have been fixed –The figures on the right show that the replacement is technically working well Physics validation with tt and W+jets data samples by replacing a muon with a tau

12. Tau Trigger Efficiency Measurement Matti Kortelainen and Sami Lehti Helsinki Institute of Physics Chi-Nhan Nguyen Texas University Michail Bachtis University of Wisconsin Andres Florez, Eric Brownson, Edouardo Luiggi Vanderbilt University Simone Gennai Pisa

13. Goals Develop methods and tools for measuring the tau trigger efficiency Starting the development and testing with simulated Monte- Carlo data Preparing for the real data o Planning a study with the first data and aiming for one of the early publications in CMS

14. Methods Start with fake taus, since there won’t be enough genuine taus for some time Selection o Muon triggers to avoid bias on jets - W+jets as fake tau source - Z->  with one tau decaying into a muon as the signal Parameterization o Usually a lot of fake taus with soft Calo deposits pass tau identification o Efficiency obtained from the fake tau methods give usually lower efficiencies than real taus (CDF experience) o Use parametrization to take that into account

15. Jet reconstruction efficiencies 1 jet reco eff Z->  QCD L2 jet reco eff Z->  QCD Level-1 efficiencies Level-2 efficiency

16. R. Kinnunen Helsinki Institute of Physics Staus and Plans Status and Plans for analysis with data

17. The group will work in the following sectors with the 2009/2010 data 1. Measurement of tau-trigger efficiencies 1.Testing of analysis methods for H ± searches 3.Measurement of backgrounds for H ± searches 4.Search of the light charged Higgs bosons with tt -> tbH ± ->  jet + 2 b jets + 2 jets + missing E T Publication expected with 200 fb -1

18. R. Kinnunen Helsinki Institute of Physics FinnCMS meeting, December 19, 2008 Analysis methods Selection of fully hadronic events - Veto on associated electrons and muon (from W->e  ) to be performed with standard e,  -identification methods: optimization in progress - Veto on associated  jets (from W->  ) challenging: work for a new method in progress Identification of one energetic hadronic  jet, E T > 100 GeV: -optimization already performed with calorimeter  jets -optimization with Pflow method in progress Missing E T > 100 GeV: tests of the new methods tcMET, PFMET in progress B tagging: standard methods for b-tagging in tt events W and top mass reconstruction: application of kinematic fit methods of the Top group in progress Transverse mass reconstruction from the  jet and Missing E T - backgrounds: m T (  jet, MET) < m W

19. R. Kinnunen Helsinki Institute of Physics FinnCMS meeting, December 19, 2008 Measurement of tt and W+jet backgrounds from data Motivation: tt and W+3/4jet events can lead to background in signal area (large m T (  jet, MET))‏ due to MET uncertainty tt events can lead to background in signal area also due to leptonic decays of the associated W The W->  decays in muonic multi-jet events can be used to measure these backgrounds from data Method: Replace exatly one isolated muon with a  with the same energy and decay the  with correct polarization state -> muon replacement method Select and replace two isolated muons to estimate the background from recidual associated W->  decays Perform the  identification and run the standard signal selection No separation of tt and and W+jet backgrounds Status: - MC studies in progress - Preparation for transfering the muon data (muon trigger + muon skimms)‏ to Helsinki T2 center

20. R. Kinnunen Helsinki Institute of Physics FinnCMS meeting, December 19, 2008 Method: Select QCD multi-jet events taking randomly one jet with E T jet > 100 GeV as the  – jet candidate Perform the standard event selection Scale the selected events with  -jet mis-identification efficiency  miss-id) to be measured with QCD di-jet events from pre-scaled jet triggers with the early LHC data (the  +jet and Z+jet event rates are too low for E T > 100 GeV)‏ Measurement of QCD multi-jet background from data Motivation: The QCD multi-jet background can lead to background in the signal area due to fake MET This background can be measured exploiting the hadronic multi-jet data Status: Preparive studies in progress Apply and optimize methods of the the ongoing  -fake rate studies for other physics channels