1 / 57

Outline

Outline. Higgs SUSY Exotics. W CANDIDATE. TOP CANDIDATE. top mass reconstruction. Gold-plated channel: tt  bW bW  bl bjj Isolated lepton (e, ) p T > 20 GeV exactly 4 jets p T > 40 GeV no kinematic fit in pessimistic case without b-tagging. Hadronic top:

kamin
Download Presentation

Outline

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. Outline • Higgs • SUSY • Exotics A.Rozanov ITEP Winter School of Physics February 2006

  2. W CANDIDATE TOP CANDIDATE top mass reconstruction • Gold-plated channel: tt  bW bW  bl bjj • Isolated lepton (e,) pT > 20 GeV • exactly 4 jets pT > 40 GeV • no kinematic fit • in pessimistic case without b-tagging Hadronic top: 3 jets with highest vector sum W boson: Two jets in hadronic top with highest momentum sum injjj C.M. frame. A.Rozanov ITEP Winter School of Physics February 2006

  3. Hadron top, no b-tag L=300 pb-1 S B mW mtop mtop top mass reconstruction A.Rozanov ITEP Winter School of Physics February 2006

  4. First top reconstruction • Top signal visible in few days (even with simple selection and no b-tagging) • Cross-sections accuracy up to 20% • top mass up to 7 GeV for (b-jet scale ~ 10%) • feedback on detector performance (b-tagging, jet scale) • important as tt is backgrounf for many searches A.Rozanov ITEP Winter School of Physics February 2006

  5. Single top production Tevatron: Wg fusion: 2.1 pb  5% Wt: 0.1 pb  10% W*: 0.9 pb  5% Measure Vtb Deviations means new physics: anomalous couplings, FCNC, extra charged higgs with s-resonance in tb system, new gauge boson W’ etc A.Rozanov ITEP Winter School of Physics February 2006

  6. LHC goals after 10 fb-1 : • Top mass with ~1 GeV precision • Cross-section ~ 10% • W-polarization 2 % • top spin correlations 4% • Single top cross-sections Top measurements at LHC At nominal luminosity – top pair every second: LHC will be top factory A.Rozanov ITEP Winter School of Physics February 2006

  7. Higgs • Higgs production at LHC • see lecture V.Novikov this school A.Rozanov ITEP Winter School of Physics February 2006

  8. Higgs branching ratios SM Higgs xsections and branching ratios A.Rozanov ITEP Winter School of Physics February 2006

  9. SM Higgs with mH > 130 GeV • Events observed with 4e, 4 and 2e2 final states • Clear mass peak with S/B >> 1 • 30 fb-1 enough for 5  discovery A.Rozanov ITEP Winter School of Physics February 2006

  10. ATLAS SM Higgs, H->ZZ->4l • Very clean signature • Narrow resonance • Small background contribution • Main experimental issues • Lepton isolation • Zbb and ttbb rejection • Good for discovery in wide Higgs mass range • 130 < MH < 600 GeV A.Rozanov ITEP Winter School of Physics February 2006

  11. SM Higgs with mH = 160-175 GeV • H W W* dominates • need H W W* l  l  and H W W* qq l  • no peak, shape close to background A.Rozanov ITEP Winter School of Physics February 2006

  12. SM Higgs with mH = 160-175 GeV • ATLAS H W W* l  l  • 30 fb-1 enough for 5  discovery A.Rozanov ITEP Winter School of Physics February 2006

  13. intro Motivations for low mass Higgs (LEP) et (WW scattering unitarity) (electroweak fits) mH < 186 GeV at 95% CL mh < 90 GeV in MSSM without radiative corrections mh < 130 GeV in MSSM with radiative corrections Aleph LEP Higgs candidate mH=115 GeV A.Rozanov ITEP Winter School of Physics February 2006

  14. Difficult case 115GeV Higgs (10fb-1) No K-factors=NLO/LO~2 Total S/ B : ~ 4  • 3/4 channels with less than 3 A.Rozanov ITEP Winter School of Physics February 2006

  15. 130GeV Higgs: first year (10fb-1) Total S/ B : ~ 6  • H->4l small signal but small background • 3/4 channels with less than 3 • qqH->qqWW counting channel (no clear peak); relies on knowledge of background A.Rozanov ITEP Winter School of Physics February 2006

  16. More optimistic view on H • Actual K-factor bigger for signal, significance up by 30-40% • Addition of H + 1jet enhance significance by at least 30% H+1j H+0j A.Rozanov ITEP Winter School of Physics February 2006

  17. Jet Jet SM Higgs + 2jets at the LHC Tagging Jets   Central Jet Veto Higgs Decay Products A.Rozanov ITEP Winter School of Physics February 2006

  18. VBF channels • qqH->qqWW* - most powerful channel for 125<MH<180 GeV • Background: pp->WW+X and tt production MH=160 GeV e A.Rozanov ITEP Winter School of Physics February 2006

  19. SM Higgs via ttH • Complex channel (Hbb): • One lepton (trigger) • 4 b-jets + 2 jets • b-tagging essential • Need to know well background (ttbb+ttjj) • Good for discovery and Yukawa coupling determination • 80 < MH < 120 GeV • high performance b-tagging improves significance ATLAS 30 fb-1 A.Rozanov ITEP Winter School of Physics February 2006

  20. Higgs Improvements of ttH->bb A.Rozanov ITEP Winter School of Physics February 2006

  21. MSSM Higgs • Minimal super-symmetric extension of Higgs sector • Five Higgs: h, H (CP-even), A (CP-odd), H • Parameter space reduced to two: MA,tan • Theoretical limit on light MSSM Higgs: h<135 GeV T A.Rozanov ITEP Winter School of Physics February 2006

  22. MSSM Higgs • Large multiplicity of discovery modes: • SUSY particles heavy: • SM-like: h,bb,,WW; H4l • MSSM-specific: A/H,,tt; Hhh, AZh; H • SUSY accessible: • H/A  02 02, 02  h 01 • Small impact on Higgs branching ratio to SM particles • Consider different MSSM scenarios • Different upper limits to light MSSM Higgs (h) A.Rozanov ITEP Winter School of Physics February 2006

  23. 4 Higgs observable 3 Higgs observable 2 Higgs observable 1 Higgs observable MSSM Higgs Discovery Potential • Most of plane explored with 10 fb-1 • >1 MSSM Higgs observable: • Disentangle SM and MSSM directly • VBF not used yet! 5s Contours A.Rozanov ITEP Winter School of Physics February 2006

  24. MSSM Higgs and VBF • The addition of VBF modes in MSSM searches enhances sensitivity to low mass Higgs • One experiment with 10 fb-1 covers almost entirely MSSM plane • Only light Higgs (h) A.Rozanov ITEP Winter School of Physics February 2006

  25. Early LHC SUSY search SUSY stabilizes mH  SUSY at TeV scale  spectacular signatures at LHC • SUSY best candidate for early discovery • Gluino ans Squark strongly produced • QCD comparable cross-section – 100 events/day at L=1033 and m(gluino)~ 1 TeV • ETmiss from LSP escaping detection • High ET jets if unification of gaugino mass assumed • Spherical events: Tevatron - Mg,q > 400 GeV • Multiple leptons: decay of charginos/neutralinos • see lecture of D.Kazakov “SUSY at LHC” A.Rozanov ITEP Winter School of Physics February 2006

  26. Inclusive SUSY signatures • A typical SUSY event at LHC will contain hard jets + n leptons and large missing transverse energy, ET . • The SUSY mass scale: • The effective Mass gives a handle on the SUSY mass scale • Cuts to reject SM background • 4 jets with PT > 50GeV • 2 jets with PT > 100GeV • ET > max(0.2Meff,100GeV) • no lepton p q q h,Z ATLAS 20.6fb−1 SUSY signal (full sim.) SM background A.Rozanov ITEP Winter School of Physics February 2006

  27. MSUSY vs. Effective mass • Plot MSUSY vs. the peak value of the Meff (from full simulation). • Repeat this for different mSUGRA models. • Correlation line from fast simulation • Meff can be used over a broad range of mSUGRA models. ATLAS Meff is a good variable for the estimation of the SUSY mass scale A.Rozanov ITEP Winter School of Physics February 2006

  28. q q 02 Z 01 SUSY A.Rozanov ITEP Winter School of Physics February 2006

  29. Backgrounds for ETmiss • Real ETmiss from neutrino in W, Z+jets,tt • Instrumental ETmiss from mismeasured multi-jets (dead/hot cells, non-gaussian tails, gaps in acceptance etc) • Reject events with fake ETmiss : beam-gas, displaced vertexes, hot cells, ETmiss along jets, jets in gaps. • All detector and machine garbage end up in ETmiss trigger A.Rozanov ITEP Winter School of Physics February 2006

  30. SM background no lepton ATLAS TDR Dominant SM background processes: • Z+N jets • W+N jets • tt+N jets • multijets (QCD) • sum of all BG ATLAS based on Parton Shower model. • New background estimation using Matrix Element generator ALPGEN 1.33 • W/Z + N jets, tt + N jets are generated • and processed with the fast ATLAS • simulation • Collinear and soft kinematic regions • are assessed with PS (PYTHIA). • ME-PS matching. A.Rozanov ITEP Winter School of Physics February 2006

  31. SM background – 1 lepton p • Signal reduced to 20-40% of no lepton mode • S/B better than in 0-lepton mode. Clean discovery mode • QCD-multijets suppressed with fake leptons • tt- dominant, but more predictable q l q l SM cuts+1lepton A.Rozanov ITEP Winter School of Physics February 2006

  32. 5 discovery curves ~ one year at 1034 cm-2s-1 up to ~2.5 TeV ~ one year at 1033 cm-2s-1 up to ~2 TeV ~ one month at 1033 cm-2s-1 up to ~1.5 TeV Early LHC SUSY search • For L=1033 cm-2 s-1 • 1000 GeV in 1 week • 1500 GeV in one month • 2000 GeV in one year • Main limitation from understanding detector performance • Need large amount of W, Z, tt for background studies A.Rozanov ITEP Winter School of Physics February 2006

  33. mSUGRA framework mSUGRA framework (m0, m1/2, A0, tanβ=v1/v2, sgn(μ)). Gluino mass correlated with m1/2 , slepton mass with m0 • Selected mSUGRA points chosen according to recent experimental data (WMAP,LEP limits,CLEO,BELLE). • Do not take too seriously A.Rozanov ITEP Winter School of Physics February 2006

  34. Excluded by b s (CLEO,BELLE) Favored by gμ−2 at the 2σ level Muon g−2 coll. Focus point WMAP: 0.094<Ωχh2<0.129 Stau1=LSP Funnel region s-channel Higgs-exchange. Stau coannihilation The (m0,m1/2) - mSUGRA plane Bulk region t-channel slepton exchange. (ATL-PHYS-2004-011) (Ellis et al., Phys. B565 (2003) 176) A.Rozanov ITEP Winter School of Physics February 2006

  35. p p Exclusive signatures • Two invisible LSP per event, no direct sparticle mass measurement • kinematics edges from invariant mass of OppositeSign/SameFlavour dilepton mll. • Remove SUSY/SM BG using OppositeFlavor/OppositeSign Bulk region 4.20fb−1 ATLAS mllmax ~ m20 - m10 = 219-118 =101 GeV if m ~  m10 m20 m = 155 GeV • only SUSY signal (full sim.) • select events with 2 leptons A.Rozanov ITEP Winter School of Physics February 2006

  36. p p ~ c01 ~ ~ ~ ~ b c02 g lR b b l l Sbottom/Gluino Mass • Jet or b-tagged jet in addition to dileptons. • sensitivity to sbottom and gluino masses. ~ ~ ~ ~ ~ A.Rozanov ITEP Winter School of Physics February 2006

  37. ~ qL ~ ~ c02 c01 q h b b b-tagging in SUSY • S-quark - Two b-jets in the final state with h bbq edge 1% error (100 fb-1) ATLAS A.Rozanov ITEP Winter School of Physics February 2006

  38. What LHC can do for SUSY • discover SUSY up to mSUSY ~ 2 TeV • discover and measure mass of at least lightest Higgs h • measure sparticles masses by kinematical edges • constrain theory by fitting a model to the data A.Rozanov ITEP Winter School of Physics February 2006

  39. Heavy Majorana Neutrinos • m(NR)=500 GeV m(WR)=2000 GeV • appears in Left-Right Symmetric Model • Connection with Leptogenesis (talk V.Rubakov this school) • Production qq  WR or qq  Z’ • Decays: WR  l NR , Z’  N’ N’, N’  lqq • Backgrounds: tt and Drell-Yan • ATLAS full simulation for L=500 pb-1 A.Rozanov ITEP Winter School of Physics February 2006

  40. Heavy Majorana Neutrinos • Signal : 11 events • tt background: 0.6 events A.Rozanov ITEP Winter School of Physics February 2006

  41. Graviton resonance m= 1 TeV • Ge+e- branching ~ 2% • predicted in Randall-Sundrum extra-dimensions • large enough signal for discovery with L < 10 fb-1 for m < 1.3 TeV • similar signature from Z’ e+e- A.Rozanov ITEP Winter School of Physics February 2006

  42. Graviton versus Z’ • similar signature from Z’ e+e- • for standard couplings Z’ seen at L=30 fb-1 up to 3-4 TeV • distinguish Graviton (s=2) from Z’(s=1) by angular distributions Higher luminosity ~ 100 fb-1 needed A.Rozanov ITEP Winter School of Physics February 2006

  43. Rs Black Holes At The LHC If Mpl ~ O(1 TeV)  Black Hole Production possible at LHC N.Arkani-Hamed, S. Dimopoulos and G.R.Dvali [hep-ph/9803315] S.Dimopoulos and G. Landsberg [hep-ph/0106295] • σ ~ πRS2 ~ O(100)pb • LHC  Black Hole Factory • BH lifetime ~ 10-27 – 10-25 seconds • Decays with equal probability to all particles via Hawking Radiation MBH = √S Parton Parton MBH~MPL: Study Quantum Gravity at the LHC Rs = Schwarzschild radius A.Rozanov ITEP Winter School of Physics February 2006

  44. Black Hole Event in ATLAS BH evaporates into (q and g : leptons : Z and W : n and G : H) = (72%:11%:8%:6%:2%:1%) (hadron : lepton) is (5 : 1) accounting for t, W, Z and H decays S.B. Giddings, S. Thomas, Phys.Rev.D65(2002)056010 gamma Decay of 6.1 TeV Black Hole High multiplicity events Muon A.Rozanov ITEP Winter School of Physics February 2006

  45. Number of Extra dimensions 2 4 6 Event Multiplicity A.Rozanov ITEP Winter School of Physics February 2006

  46. Reconstructed BH Mass • BH will be produced with a range of masses at LHC • Mass reconstruction by Σ P of all decay products A.Rozanov ITEP Winter School of Physics February 2006

  47. Conclusion A lot of physics can done in the first two years of LHC (2008-2009) • Studies of properties of the events at an order of magnitude higher centre-of-mass energy than at existing machine • Studies of Standard Model processes • Jet production, minimum bias, underlying event • Inclusive W and Z production (also with jets) • Top production • B-physics (in ATLAS and CMS, as specially in LHCb) • Discovery of SM Higgs m=114-1000 GeV • Search for SUSY particles up to 2 TeV and SUSY h • Search for extra generations of fermions • Search for new gauge bosons • Start searches for exotics • Predicted or unpredicted! A.Rozanov ITEP Winter School of Physics February 2006

  48. Additional material A.Rozanov ITEP Winter School of Physics February 2006

  49. A.Rozanov ITEP Winter School of Physics February 2006

  50. b-jet efficiency light-jet pT (GeV/c) A.Rozanov ITEP Winter School of Physics February 2006

More Related