1 / 30

Satyaki Bhattacharya

Higgs Search with the CMS detector at LHC. Satyaki Bhattacharya. data taking starts 2007. Startup Luminosity 2X10 33 cm -2 /s. that is: 20 fb -1 per year. Silicon Tracker. PbWO 4 ECAL. sampling brass HCAL. solenoid 4Tesla field. MUON Chambers. numbers are for barrel.

nell-long
Download Presentation

Satyaki Bhattacharya

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 Search with the CMS detector at LHC Satyaki Bhattacharya S. Bhattacharya

  2. data taking starts 2007 Startup Luminosity 2X1033 cm-2/s that is: 20 fb-1 per year Silicon Tracker PbWO4 ECAL sampling brass HCAL solenoid 4Tesla field MUON Chambers numbers are for barrel S. Bhattacharya

  3. Standard Model Higgs S. Bhattacharya

  4. Higgs production at LHC ggH High gluon flux – dominant although loop process Vector Boson Fusion (VBF) 10% at MH=100GeV Comparable to gg->H at MH=1 TeV ttH, bbH,HW,HZ S. Bhattacharya

  5. Decays and Search Strategy MH < ~140 GeV Hbbdominant ggHbb : background too large ttHttbb possible Hgg –small BR but very clean MH < ~500 GeV 120-200 GeV HWW*/WWlnln (serious tt,Wtb background) 200-500 GeV HZZ4l gives highest sensitivity between 200-500 GeV MH > ~500 GeV GH large, use channels with large BR, HZZ/WW VBF x-sec large and can be used search channels S. Bhattacharya

  6. Low mass(<140 GeV): H gg Two clean electromagnetic clusters For unconverted photons Backgrounds: gg,qqgg,qgqg sgg=646MeV 5s discovery in ~15 fb-1 events/50MeV mgg for 130 GeV Higgs S. Bhattacharya

  7. H  ZZ  4 Clean, resolution better than 1GeV Discovery Luminosity: S. Bhattacharya

  8. Discovery reach of CMS • CMS can probe the entire “allowed” mass range • 5s discovery possible in few months in many channels Total HZZl+l-l+l- HWWllnn Hgg S. Bhattacharya

  9. Higgs in MSSM S. Bhattacharya

  10. MSSM Higgs sector Two Higgs doublets pseudoscalar Higgs 3 fields are gauged away 8 real Higgs fields ( 4 complex fields) charged Higgs heavy Higgs light Higgs All masses, x-sections,BRs and mixing angle a are determined by two parameters tanb– ratio of vacuum expectation values of the two doublets MA– mass of pseudoscalar Higgs A S. Bhattacharya

  11. h discovery @ 30fb-1 Decay BRs and searches for h are like SM Higgs S. Bhattacharya

  12. H±discovery @ 30 fb-1 For charged higgs associated production with top is dominant S. Bhattacharya

  13. A/H discovery @ 30 fb-1 At large tanb A/H coupling to down type fermion is strong and H production with bb and H decay to t become important S. Bhattacharya

  14. A/H t+t- jets + X Higgs signal over total background Signal: gg  bbH/A and ggH/A H/A  t+t - MA 500GeV s.Br=0.188pb MA 200GeV s.Br=9.53pb full simulation + NLO x-section backgrounds: Z/g*2t, multijets faking t tt and W+jet with Wtn reduce background by requiring: narrow t jet, b-tag,central jet veto. t impact parameter,vertexing ~15% mass resolution S. Bhattacharya

  15. Summary • CMS is capable of searching SM Higgs over the entire allowed mass range between LEP MH limit and ~ TeV (unitarity bound) • Atleast one MSSM Higgs will be found in entire MA-tanb plane • 5s discovery possible in few months • Few hundred MeV mass resolution from Hgg, HZZ4l for low-intermediate mass Higgs • Also • CP and spin of Higgs can be measured with 100fb-1 S. Bhattacharya

  16. Extras S. Bhattacharya

  17. Interm. Mass: H  WW  ll'X Isolated leptons + ETmiss tt serious background  Require central jet veto S. Bhattacharya

  18. High Mass: ZZ lljj HZZ lljj has large branching fraction at higher masses. Mass reconstruction possible but GH is large S. Bhattacharya

  19. ttH, H bb Preselection: 1 isolated lepton + atleast 6 jets Likelihood based analysis: L_event = Anti b-tag prob. of W jets X b-tag prob of other jets X Mass prob. of W,t,t X sorting of b-jet energies Pick jet combinations with highest L_event. Select event based on 3 likelihood functions, then count Events around mass window. Efficiencies: 115 GeV H = 1.3% ttbb = 0.4%, ttZ = 0.2% (full dettector simulation done) Reconstructed masses of H,W,t,t S. Bhattacharya

  20. VBF : New channel H decay H decay Features: Forward tagged jets Relatively high pT Higgs Important at very high mass (10% at low mass, total at very high mass) Very useful for WW*, also used for gg,t+t- at lower mass S. Bhattacharya

  21. MSSM Higgs Production ggH most important at low mass and low tanb light higgs production x-sections similar to SM higgs at high tanb gg/qqHbb dominant for heavy Higgs for H± tttH-b is most important S. Bhattacharya

  22. MSSM Higgs Production (ii) S. Bhattacharya

  23. Higgs Production in MSSM(details) • H/A production • ggH/A, gg/qqbbH/A • g(AVV)=0  no VBF • At large tanβ • VBF suppressed for H • g(A/Hbb) enhanced  ~90% bbH/A for tanβ>10 and MA>300 GeV • H SM-like near lower mass limit ( high tanβ, small MA)VBF significant • h production • h SM-like for MA>mhmax Higgs couplings with up(u) down(d) fermions and vector bosons (v) • H± production For MH±<Mt :tttH±b For MH±>Mt: • ggtbH±,H+H-,W±H± • gbtH± • qqH± S. Bhattacharya

  24. channels considered for a SUSY Higgs • H/h gg, bb • H->bb in WH,ttH • h->gg in Wh, tth->lgg • H/hZZ*/ZZ4l • h/H/At+t-  (e/m)jET, emET,jjET • Including qqH,ttH,WH • H+t+n from tt • H+t+n, H+tb for MH+>Mt • AZh with hbb • Agg • H/A c02c02, c0ic0j, c+1c-2 • H±c+2c02 ~ ~ ~ ~ ~ ~ ~ ~ S. Bhattacharya

  25. A/H t+t- jets + X (detailed efficiency) S. Bhattacharya

  26. Httleptons Signal: ggH or ggbbH, H t t, t  leptons s.Br is ~ 100 – 900 fb at high tanb bbH strongly dominant. Background: leptonic final states of Z/g*,tt,bb,WW,WZ require isolated leptons, pt>20GeV (isolated=no tracks with pt> 2GeV in DR=0.3) eliminates bb background ct of t ~90mm. Use impact parameter of leptons to identify t reduces Z/g*,tt backgrounds require 1 jet with pt>20 GeV and b-tag kills Drell Yan This channel should be useful even if sparticles are light S. Bhattacharya

  27. H/A  m+m- • ppbbH/A + X with H/A  m+m- 2soft(ET< 50GeV) b jets • Use b-tag against Z/g* background • Use central jet veto against tt Mass resolution 1%, |mH-mA| ~ 2 GeVH/A peaks superimposed (mass difference can be upto ~ 5.5 GeV) S. Bhattacharya

  28. MSSM Discovery reach Ref: Paris Sphicas, Physics at LHC,Vienna,2004 S. Bhattacharya

  29. MSSM discovery reach (ii) S. Bhattacharya

  30. CMS Trigger Rates CMS total level1 rate is 16 kHz at startup Total High Level Trigger (HLT) is 100 Hz. S. Bhattacharya

More Related