Physics at LHC Prague, 6-12 July, 2003 R. Kinnunen Helsinki Institute of Physics A/H ->  and H + ->  in CMS R. Kinnunen Physics at LHC Prague July , 2003 Helsinki Institute of Physics Helsinki, Finland

Physics at LHC Prague, 6-12 July, 2003 R. Kinnunen Helsinki Institute of Physics Contents H/A ->  Cross sections and branching fractions Hadronic  trigger  -jet identification and hadronic jet suppression  tagging with impact parameter measurement b-jet tagging in bbH/A Signal to background ratios and expected discovery reaches, tan  mesurement from event rates H + ->  Cross sections and branching fractions Trigger for H + ->  in fully hadronic events  polarization in H + ->  and W + ->  Signal to background ratios and expected discovery reaches, tan  mesurement from event rates

Physics at LHC Prague, 6-12 July, 2003 R. Kinnunen Helsinki Institute of Physics - Efficient background reduction with b tagging in bbH/A Relative to SM, H/A -> ZZ, WW are strongly suppressed but - Higgs boson mass reconstruction for H,A ->  Hbb, H , H  couplings are enhanced at high tan  How to search for heavy neutral MSSM Higgs bosons use bbH for production with H/A ->  decay channels - 3 final states for H/A ->  (jet+jet, lepton+jet, lepton+lepton) - H/A -> bb may be also viable (under study)

Physics at LHC Prague, 6-12 July, 2003 R. Kinnunen Helsinki Institute of Physics Production and decay of H, A Production through gg -> H/A and gg -> bbH/A gg->bbH/A dominates the production at large tan  ~90% of the total production cros section BR(H ->  ) ~ 10% for tan  > 10 For large m A, enhancement of BR(H->  ) for larger |  | parameter due suppression of H,A ->  decays HIGLU,HQQ from of M. Spira et al. Pole mass for Yukawa coupling g g g g H H b b 

Physics at LHC Prague, 6-12 July, 2003 R. Kinnunen Helsinki Institute of Physics Final states investigated for H, A ->  H -> -> 2  jets BR ~ 42.0% Backgrounds from QCD multijet events, Z,  * -> , tt, Wt, W+jets H, A ->  -> lepton +  jet BR ~ 45.6% H, A ->  ->2 leptons BR ~ 12.4% Backgrounds from Z,  * -> , tt, bb, Wt, WW, W+jets Simulation tools PYTHIA for event generation HDECAY for normalization of cross sections and branching fractions for two-  jet and two-lepton channels Full simulation for trigger,  selection, b tagging, mass reconstruction Fast simulation for signal to background ratios

Physics at LHC Prague, 6-12 July, 2003 R. Kinnunen Helsinki Institute of Physics Hadronic Tau trigger Level-1 output rate of 1-Tau and 2-Tau triggers: 3 kHz at low luminosity 6 kHz at high luminosity HLT output rate on tape for  ’s: 4 (10) Hz at low (high) luminosity 93 (112) GeV for 1-Tau for low (high) luminosity 66 (76) GeV for 2-Tau for low (high) luminosity Trigger requirements: Efficiency: 78 (54)% for H-> , m H = 200 GeV, 1 or 2 Tau 81 (72)% for H+-> , m H+ = 200 GeV, 1 Tau Level-1 1-Tau and 2-Tau triggers on the calorimeter jet reconstructed in 12x12 trigger towers with maximum E t in the central 4x4 towers and no significant activity in the neighbouring towers (trigger tower = HCAL cell + 5x5 ECAL cells,  x  = 0.087x0.087 in the barrel) The required Level-1 rate can be achieved with the thresholds of

Physics at LHC Prague, 6-12 July, 2003 R. Kinnunen Helsinki Institute of Physics Level-2 Tau trigger Reconstruction of a jet centered at the hardest Level-1  jet Isolation in the EM calorimeter: Suppression of 3 for QCD background with  E t em < 5.6 GeV Signal efficiency ~ 85% same for m H = 200 and 500 GeV Efficiency (QCD vs H->  1/3 prong jets) as a function of E t cut-off - sum of the E t deposits in ECAL within 0.13 <  R(jet direction, cell) < 0.4   jet definition:  E t em < E t cut- off

Physics at LHC Prague, 6-12 July, 2003 R. Kinnunen Helsinki Institute of Physics Level-3 Pixel Tau trigger 1. Reconstruction of tracks around the Level-1 jet direction 2. Small signal cone (  R S = 0.07) around the hardest track 3. Larger isolation cone around jet direction Accept tracks only in the signal cone HLT efficiency for 1 or 3 tracks in the signal cone and for  R = 0.35: QCD suppression ~ 10 3 signal efficiency ~ 40% using track counting in the Pixel (vertexing) detector: - good efficiency required, high p t accuracy not needed Efficiency (QCD vs H->  1/3 prong jets) as a function of the isolation cone size

Physics at LHC Prague, 6-12 July, 2003 R. Kinnunen Helsinki Institute of Physics Off-line  jet identification Exploits further the narrowness and the isolation of the  jet in the full tracker Define a narrow signal cone  r = 0.03 (0.07 for HLT) around the leading track direction 1. Leading track cut: Find the leading track in the L1  jet, set a cut p t > 40 GeV  jet isolation: No track, p t > 1 GeV, allowed within 0.03 <  R < Number of tracks in the signal cone: 1 or 3 tracks in the signal cone (p t leading > 40 GeV) 4. Further reduction of hard QCD jets: Very hard QCD jets can be further suppressed with a cut in p t leading / E t jet

Physics at LHC Prague, 6-12 July, 2003 R. Kinnunen Helsinki Institute of Physics Simulation of the QCD di-jet background using (for the moment) a rejection factor as a function of E t jet (initial QCD di-jet rate ~10 12 events for 60 fb -1 ) efficiency verified with full simulation and complet reconstruction for p t gen < 170 GeV Suppression of ~ 1000 per jet can be obtained Signal efficiency (per event) including Level-1 and HLT trigger from full simulation: m H = 200 GeV 0.8% m H = 500 GeV 8.9%  selection efficiency for hadronic QCD jets from fast simulation

Physics at LHC Prague, 6-12 July, 2003 R. Kinnunen Helsinki Institute of Physics  impact parameter tagging in H ->  The  lifetime is small, c  ~ 90  m, but can be still used to further supress the fake  ’s from Z -> ll and from QCD multi-jet events using impact parameter measurement (1 or 3 prong  ’s) and vertex reconstruction (3 prong  ’s) S. Lehti CMS full simulation and reconstruction Best separation combining the measurements in the two  jets into one variable sqrt(  ip (  1 ) 2 +  ip (   ) 2 ) where  ip (  1 ) and  ip (   ) are significansies of the impact parameter measurements of the leading tracks in jets 1 and 2 Signal efficisiency ~ 60% QCD suppression factor of ~ 9

Physics at LHC Prague, 6-12 July, 2003 R. Kinnunen Helsinki Institute of Physics B jet tagging in gg -> bbH/A Tagging of the associated b jets is the most efficient way to reduce the Z,  * ->  (bbZ ~ 1-2 %)  and to further reduce the QCD multijet events Associated b jets in gg -> bbH/A are soft and uniformly distributed over |  | < 2.5: Efficiencies (E t threshold + tagging propability) relatively low Significance of the signed transverse impact parameter CMS full simulation and complete reconstruction Tagging algorithm: at least 2 tracks, p t > 1 GeV,  ip > 2, inside the jet cone Efficiency per jet: 32% non-  jets in bbH ~ 2 % light quark and gluon jets non-  jets in gg -> bbH/A jets in QCD di-jet events

Physics at LHC Prague, 6-12 July, 2003 R. Kinnunen Helsinki Institute of Physics Higgs boson mass reconstruction in H ->  The neutrinos from H ->  (  -> hadrons+,  -> l+ ) are emitted close to the directions of the visible  ’s (jets or leptons): neutrino reconstruction possible using the E t miss measurement in events with      0) m H = sqrt(2 E  E  (1-cos  jj  Higgs boson mass from full simulation for H ->  -> two jets, m H = 500 GeV, tan  = 20, with  jet   jet   < 175 o Efficiency (  cut  E  E  >0) 36%  fit 14.9% Efficiency and resolution sensitive to the E t miss measurement and to the      cut  jet, e,  jet E t miss  jj

Physics at LHC Prague, 6-12 July, 2003 R. Kinnunen Helsinki Institute of Physics Event selection for A,H->  -> 2  jets Basic event selection: - 2  jets passing the Level-1 and HLT triggers and the off-line  selection (1 or 3 hard tracks, isolation) -  tagging with impact parameters - Higgs boson mass reconstruction (      cut, E , E  > 0) i) Further selection with E t miss : - E t miss > 40 GeV -central jet veto beyond 30 GeV ii) Further selection with b-jet tagging: - one b-tagged jet, E t > 20 GeV - central jet veto beyond 30 GeV Two alternatives for further reduction: larger staistics but poor S/B much improved S/B but lower statistics Total background

Physics at LHC Prague, 6-12 July, 2003 R. Kinnunen Helsinki Institute of Physics Leptonic final states, H/A ->  -> e , ll Event selection: - 2 isolated leptons, p t > 20 GeV - one tagged b jet, veto on second central jet beyond 30 GeV - impact parameter  tagging lepton+lepton final states can be used to double the statistics lepton +  jet final states, H/A ->  -> l +  jet Event selection: - one isolated lepton (p t > 20 GeV), one  jet (E t > 40 GeV) - one tagged b jet, second jet veto - Higgs boson mass reconstruction Reach not yet optimized for large m A (> 200 GeV) in CMS H/A ->  -> e  m A = 200 GeV tan  = 20 H/A ->  -> ll - Higgs boson mass reconstruction

Physics at LHC Prague, 6-12 July, 2003 R. Kinnunen Helsinki Institute of Physics Expected 5  -discovery reach for H/A ->  Results for H/A ->  from full simulation and complete reconstruction Variation of BR(H ->  ) due to H ->  i  j decay modes ~ 40% at m H =500 GeV, tan  =20, for -200 GeV <  < 500 GeV Higgs boson mass resolution ~ 2%

Physics at LHC Prague, 6-12 July, 2003 R. Kinnunen Helsinki Institute of Physics Measurement of tan  in H ->  from event rates using the tan  dependence  BR ~ tan 2  * x - Luminosity uncertainty  L/L ~ 5% - Theoretical uncertainty on the cross section for gg -> bbH: dx/x ~ 30% - The gg -> bbH component is selected by b jet tagging: 1b or 2b tagging, less theoretical uncertainty and higher experimental purity with 2b tagging  tan  /tan  = ½ * sqrt((N S +N B ) / N S 2 + (  L/L) 2 + (  x/x) 2 )  tan  /tan  1b tagging 2b tagging H/A ->  -> 2  jets, m A = 500 GeV, tan  = 40, 60 fb -1 16% 19% H/A ->  -> lepton +  jets, m A = 200 GeV, tan  = 20, 30 fb -1 16% H/A ->  -> e , m A = 140 GeV, tan  = 14, 30 fb -1 18% dominated by rate uncertainty up to tan  ~ 30 Precision of Higgs boson mass measurement in H/A ->  -> 2  jets m A = 500 GeV, tan  = 40, 60 fb -1  m H /m H = 1.5% m A = 200 GeV, tan  = 40, 60 fb -1  m H /m H = 1. 2%

Physics at LHC Prague, 6-12 July, 2003 R. Kinnunen Helsinki Institute of Physics How to search for charged Higgs bosons at LHC If m H+ < m top : Production through tt events, t -> bH +  accessible through the H + ->  t 2 -> lepton+qq final state If m H+ > m top : Production through gg -> tbH +, gb -> tH +, qq’ -> H +, gg -> H + H -, gg -> W + H - -gg -> tbH +, gb -> tH + most promising processes, cross sections large enough and the associated top and b jets can be used for background reduction H+H+ H+H+ - gg -> H + H -, gg -> W + H - have small production cross sections -Event rate sufficient for qq’ -> H + ->  but suppression of the qq’ -> W->  background is difficult tg b g g t b

Physics at LHC Prague, 6-12 July, 2003 R. Kinnunen Helsinki Institute of Physics One tagged b jet enough to suppress the backgrounds, use gb -> tH + Event generation with PYTHIA Normalization of the production cross sections to T. Plehn, MADPH T. Plehn Normalization of branching fractions to HDECAY HDECAY tan  = 30 H + -> 

Physics at LHC Prague, 6-12 July, 2003 R. Kinnunen Helsinki Institute of Physics Trigger for H + -> ,  -> jet +  -Cut on the leading track and isolation needed Level-1: single Tau trigger (E t > 93 GeV, low luminosity) High Level Trigger: cut on E t miss in the calorimetry (possible due to off-line E t miss > 100 GeV) Level-3 Single Tau: - Reconstruction of tracks in the full tracker within the L1  jet Efficiency for p t leading track > 20 GeV and isolation in <  R < 0.4: QCD rejection ~ 30 Signal efficiency ~ 58% QCD rejection ~ 100 for E t miss > 65 GeV Efficiency (QCD vs H->  1/3 prong jets) as a function of p t cut for the leading track

Physics at LHC Prague, 6-12 July, 2003 R. Kinnunen Helsinki Institute of Physics  polarization in H + ->  and W + ->  H+H+ ++ ++ ++ H + ->   leads to harder pions from   and from the longidutinal components of  and a 1 than the corresponding decays in W + ->   W+W+ ++ ++ ++ TAUOLA interfaced to PYTHIA  ->   LL  ,a 1 T  L,a 1 L Large suppression of W ->  in tt, Wt, W+jet using the cut: p leading track / E  jet > 0.8: Signal, m H+ = 400 GeV 46% Signal, m H+ = 200 GeV 22% tt background 1.8%  jet = calorimeter jet from  -> hadrons + tt background Signal

Physics at LHC Prague, 6-12 July, 2003 R. Kinnunen Helsinki Institute of Physics Event selection for gb -> tH ±, H ± ->  Quasi two-body decay between the  jet and E t miss in fully hadronic events -> almost background-free situation in m T (  -jet,E t miss ) - E t  jet > 80 – 100 GeV, containing a hard track with p t track /E t  jet > E t miss > 100 GeV - Veto on 5 th jet, veto on second top quark Cut on  (  jet, E t miss ) -> low mass background can be suppressed  (  jet, E t miss ) > 20 o m T (  jet, E t miss ) - Reconstruction of associated hadronic top from two jetand one b-tagged jet  (  jet, E t miss ) tt background Signal background 30 fb -1

Physics at LHC Prague, 6-12 July, 2003 R. Kinnunen Helsinki Institute of Physics Expected 5  -discovery reach for charged Higgs boson H + -> tb and qq’ -> H + ->  are also promising good background knowledge needed Excess of  ’s can be measured in tt, t -> bH +, H + ->  for m H+ < m top No sensitivity for intermediate tan  with gb -> tH + (with SM decay channels): H + -> Wh, h -> bb accessible (in MSSM) only at small tan  tan  measurement from event rates using  ~ tan 2  at high tan  Expected uncertainty for tan  >30 with 20% theoretical uncertainty :  tan  /tan  < 14% for m H+ = 200 GeV  tan  /tan  < 20% for m H+ = 400 GeV

Physics at LHC Prague, 6-12 July, 2003 R. Kinnunen Helsinki Institute of Physics Conclusions H/A ->  accessible for 30 fb -1 with e  and ll final states for tan  > 14 at m A = 140 GeV jet+ lepton final states for tan  > 10 at m A = 200 GeV and for 60 fb -1 with 2  jet final states for tan  > 18 at m A = 200 GeV tan  > 25 at m A = 500 GeV tan  determination with event rates:  tan  /tan  = 16% for H/A ->  -> 2 jets, m A = 500 GeV, tan  = 40  16% for H/A ->  -> lepton+jet, m A = 200 GeV, tan  = 20 18% for H/A ->  -> e , m A = 140 GeV, tan  = 14 14% for gb -> tH +,H + -> , m A = 200 GeV, tan  = 30 H + ->  accessible in gb -> tH + in fully hadronic final states with 30 fb -1 for tan  > 20 at m A = 200 GeV tan  > 32 at m A = 400 GeV Search for H/A and H + can start early, with < 10 fb -1 With ~ 60 fb -1 masses in the 500 – 800 GeV range accessible more specifically :  m H /m H in H/A ->  -> 2  jets, tan  = 40, 60 fb -1 : 1.2% for m A = 200 GeV 1.5% for m A = 500 GeV