1 / 46

Higgs to 2 t , 2b and BSM Higgs searches in CMS

Higgs to 2 t , 2b and BSM Higgs searches in CMS. Nikitenko (IC), Split, October 2012. Introduction. access to Higgs couplings y t , y b to down type fermions through measurement of s xBr ( f -> tt , bb). Standard Model MSSM.

adeola
Download Presentation

Higgs to 2 t , 2b and BSM Higgs searches in CMS

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript


  1. Higgs to 2t, 2b and BSM Higgs searches in CMS Nikitenko (IC), Split, October 2012

  2. Introduction • access to Higgs couplings yt, yb to down type fermions through measurement of • s xBr(f->tt, bb) Standard Model MSSM

  3. Tools for searches with ts and bs

  4. t tagging performance of HPS algorithm t ID uncertainty – 6 % t jet energy scale unc. < 3 %

  5. b tagging performance • Identification using track impact parameter • TC, JP, JPB • Identification using secondary vertex • SSV • Identification using both track ip and secondary vertex • CSV

  6. tt and bb mass resolution • tt ~ 20 % • bb: ~ 10 %

  7. Search for SM H->ttin gg->H and VBF H production

  8. Event categories • VBF category is most sensitive at mH=125 GeV pTt

  9. results VBF 0 jet 1 jet

  10. Search for SM H->bb in VH production

  11. VH analysis strategy • 5 topologies: ZH (Z->ee,mm,nn), WH (W->ee,mm) • select events with high pTV and high pTH • normalize backgrounds (V+udscg, V+bb, tt) on the data in control regions from simultaneous fit in each mode • propagate to signal region using MC • Extract signal from the fit of BDT output

  12. Results

  13. Search for SM H->bb in ttH production To be completed

  14. Analysis and result in one slide l+jets • l+jets and di-lepton analyses • Divide events in categories of (Njet, Nb-tag-jet) • Extract signal from fit of ANN outputs ll+jets

  15. CMS prospects for SM Higgs searches with 30 fb-1

  16. BSM CMS searches • MSSM charged Higgs in t->H+b decays • H+->tn • MSSM neutral f->tt, bb, mm • NMSSM a1->mm • double charged Higgs bosons

  17. Searches for t->H+b (mH+ < mt) T. Plehn et al., hep-ph/0312286 • Study decay mode H+->tn assuming BR(H+->tn)=1 m H+ < mtm H+ > mt pp->tbH+ is in MC@NLO (T.Plehn et al) recipie for m H+ ~ mt: add tt and tbH+ 4FS and 5FS NLO calculations exist

  18. CMS H+->tn. Topologies considered: NttSUSY> NttSM NttSUSY> NttSM NttSUSY< NttSM

  19. Results of H+->tn analysis with 2.3 fb-1 Access or deficit of events in data is related to the difference between MSSM and SM tt~ event yields: th+jets x=Br(t->H+b) th+jets channel is most sensitive, since most of the tt~->WbWb background is measured from the data and mT shape is used

  20. MSSM neutral f->tt • gfbbMSSM= gfbbSMx tanb (f=A) at tree level • sSM(gg->H) ~ 20-10 pb at mH = 115-140 GeV • Br (f->tt) ~ 10 %

  21. Off-line Selections • e/m th - |he/m|<2.1, pTe>20 GeV, pTm>17 GeV, pTt>20 GeV, |ht|<2.3, second lepton veto • em - |he(m)|<2.3(2.1), pTl1,l2>20,10 GeV • cut on “CDF variable” Pzis used against W+jets • separation on b-tag and non-b-tag event categories Final states used: tmth teth tetm f->tt mass resolution ~ 20 %

  22. tt: allowed region in mA-tanb • What theorists need to re-evalulatemA-tanb limits in any other scenario ? • sgg->hx egg->hb + sbbh x ebbhb < Nevb b-tag analysis • sgg->h x egg->hno-b + sbbh x ebbhno-b < Nevno-b 0-b-tag analysis Phys. Lett. B 713 (2012) 68

  23. f->mm analysis • Two isolated muonspT > 30, 20 GeV, |h|<2.1 • ETmiss < 30 GeV (against tt~) • Three event category combined • at least one b-tag jet, pT > 20 GeV, |h|<2.4 • 3rdmuon (from b’s) pT > 3 GeV, |h|<2.4 • Other events CMS PAS HIG-12-011

  24. bf, f->bb analysis (7 TeV) • Triple b-tagging; multijet background from data Fully hadronic analysis CMS PAS HIG-12-026 Leptonic analysis CMS PAS HIG-12-027

  25. NMSSM a1->mm and F++F-(-)searhes gg->a1->mm qq->F++F-(-) 4 lept. CMS PAS HIG-12-004

  26. Conclusions • SM H->tt and bb are very important for coupling measurement • expect good sensitivity with 30 fb-1 • Hunting for BSM Higgs boson(s) in new territory • no BSM Higgs boson(s) found yet • important to continue searches and extract model “independent” cross-sections in SUSY f->tt, mm, bb analyses

  27. Background evaluation methods • eth, mth, em and mm final states are included in analysis DY->tt from data DY->mm with m-> MC t replacement DY->ll from MC corrected for l->t fake rate W from high mT control data region Multijet from SS data events

  28. Results

  29. Background scaling factors and shapes

  30. Event selections and input variables for BDT • BDT output for WH (W->mn) high pT analysis at 8 TeV

  31. MSSM Higgs bosons • Five Higgs bosons: h, H, A, H+/- • Higgs sector is defined at tree level by MA, tanb • rad. corrections introduce dependence on other model parameters • Upper limit on mh ~ 135 GeV

  32. Search for NMSSM Higgs boson a1->mm • NMSSM solves MSSM ”m-term problem” by introducing additional complex singlet scalar field S • neutral Higgs boson sector expands to three CP-even scalars (h1,h2,h3), two CP-odd scalars (a1,a2) • “Ideal”- NMSSM Higgs scenarios” : 2mt < ma1 < 2mb (prefers ma1 close to 2mb) Dermisek, Gunion 2010 • s(gg->a1) x BR(a1->mm) is defined by tanb and qA • a1 =cosqAaMSSM + sinqAaS At cosqA=1; s(gg->a1) ~ cos2qA Dermisek, Gunion 2009

  33. t and b tagging is the tool for searches

  34. Event selection and results • Selections • two isolated muonspT > 5.5 GeV, |h|<2.4 • two intervals in mmm ; h: barrel, endcapmm pairs • mmm background shape from fit of the data Background model from fit of data two mass intervals for signal search Signal mass resolution 50 – 120 MeV for barrel

  35. Search for double charged Higgs • Higgs boson triplet F0, F+, F++ is predicted in little Higgs models, the minimal seesaw model of type II. • F++ Yukawa coupling matrix YFlilj is proportional to the light neutrino mass matrix and allows to test the neutrino masses by measuring BR(F++->lilj) • A.Hektor, M. Kadastik, M. Muntel et al., Nucl.Phys. B787 (2007) 198-210 Both pair production and associated production are studied NLO cross-sections: M. Muhlleitner M. Spira Phys. Rev. D68 (2003) 117701

  36. Results 3 lept. pre-select. 4 lept. lept.=e, m, t CMS PAS HIG-12-005 3 lept.

  37. t tagging performance t ID uncertainty – 6 % t jet energy scale unc. < 3 %

  38. CMS Z->tt measurement

  39. b tagging performance Efficiency High efficiency High purity Fake rate High efficiency High purity

  40. 4FS vs 5FS in b(b)f cross-section “Santander matching” • by R. Harlander, M. Kramer, M. Schumacher CERN-PH-TH/2011-134. Presently used in SUSY H->tt ATLAS and CMS analyses 5FS 4FS

  41. Signal generation issues (see details in LHC Higgs Xsection WG, YR2) • gg->h: presence of b-loop in gg->h has no effect on acceptance for the current analysis • PYTHIA gg->bbhvs bb->h at NLO • there is some discrepancy in pTb, hb at high mA. R. Harlander, M. Wiesemann, M. Cutajar, A. Nikitenko in YR2

  42. CMS SUSY f->tt analysis combines b-tagged and non-b-tagged events • |hb-jet| < 2.4, |hjet| < 5.0 Efficiency of the signal selections is provided in the paper mth, mA=120 GeV

  43. Results of H+->tn analysis with 2.3 fb-1 JHEP 1207 (2012) 143 ~ 8 At tanb ~ 8 Br(t->H+b) has a minimum in MSSM at a given m In the next iteration of analysis with whole 2011 dataset it might be possible to exclude mH+ < ~ 130 GeV, since for this mass region exp. exclusion limits on Br(t->H+b) might be smaller than minimal possible values in MSSM mhmax

  44. f->mm analysis CMS PAS HIG-12-011 • Two isolated muonspT > 30, 20 GeV, |h|<2.1 • ETmiss < 30 GeV (against tt~) • Three event category combined • at least one b-tag jet, pT > 20 GeV, |h|<2.4 • 3rdmuon (from b’s) pT > 3 GeV, |h|<2.4 • Other events

  45. bf, f->bb analysis (fully hadronic) CMS PAS HIG-12-026 • HLT: two b-tagged jets • Three jets |h|<2.2 • mf<180 GeV : pT> 46, 28, 20 GeV • Mf>180 GeV : pT>60, 53, 20 GeV • Multijet background: • from double-b-tag data h->bb mass resolution ~ 10 %

  46. CMS PAS HIG-12-027 bf, f->bb analysis (leptonic) • HLT: m + 1 or 2 b-tagged jets • MuonpT > 15 GeV, no isol. applied • >= 3 jets, pT> 30, 30, 20 GeV with muon inside one of two leading jets • Triple b tagging • Multijet background from data

More Related