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Tevatron Searches for Higgs and SUSY

Tevatron Searches for Higgs and SUSY. Dan Claes. for the. and. collaborations. Hadronic Structure 2007 September 3-7 Comenius University Study and Congress Center Modra-Harmónia, Slovakia. Searches for contributions to observed events by Higgs decays as well as

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Tevatron Searches for Higgs and SUSY

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  1. Tevatron Searches for Higgs and SUSY Dan Claes for the and collaborations Hadronic Structure 2007 September 3-7 Comenius University Study and Congress Center Modra-Harmónia, Slovakia

  2. Searches for contributions to observed events by Higgs decays as well as new phenomena beyond the Standard Model are intensifying as the Tevatron data set grows. Chicago  p p 1.96 TeV Booster p CDF DØ Tevatron p p source Main Injector & Recycler CDF Proton-antiproton collider operating at COM energy of 1.96 TeV

  3. Collider Run II Integrated Luminosity ~3 fb-1 recorded! All the results shown today are based on analysis of 1+ fb-1 Collider Run II Peak Luminosity 4-8 fb-1 by 2009 • Will run for at least two more years!

  4. Higgs production at the Tevatron t H g t g t have seen evidence for single top! one in ~1012 events could be a Higgs boson! q W/Z W/Z q H

  5. Nature appears to respect gauge invariance masslessness Through electroweak symmetry breaking within the complex scalar field, V(), of the Higgs the gauge bosons W,Z acquire mass and a spin-0 Higgs boson appears, its own mass unspecified though theoretical considerations do constrain it. Higgs self-coupling diverges Allowed unstable vacuum

  6. mH>114.4 GeV/c2 at 95% confidence Direct searches reveal The latest LEP Electroweak Working Group fit yields a preferred value of: A Standard Model Higgs should be LIGHT! A light Higgs might be around the corner (if the SM is correct) mH < 144 GeV at 95% confidence limit

  7. H->WW Excluded at LEP Most sensitive searches: bb mH<135 GeV/c2 • produced with W or Z boson • decay to b quark pair mH>135 GeV/c2 Analysis Strategy mH < 135 GeV WH/ZH + H bb mH > 135 GeVGluon fusion + HWW Background top, Wbb, Zbb WW, DY, WZ • direct ggH production • decays to W boson pair

  8. electron/muon neutrino Selection - one or two tagged b-jets - e or m with pT > 15 GeV - ET > 20 GeV DØ: 4 non-overlapping samples - e or m with - 1 “tight” or 2 “loose” b-tags CDF: 2 exclusive samples using different b-tagging algorithms

  9. Limits set cutting on NN output: DØ exp, obs CDF exp, obs 95/SM = 9.05, 11.19.95, 10.1

  10. ZH bb b jet Selection: - two acoplanar jets (exactly 2 – CDF) - ≥ 1 tagged b-jets (CDF) 2 tagged b-jets (DØ) - ET > 55 GeV (CDF) 50 GeV (DØ) b jet

  11. ZH bb Backgrounds : - W+heavy flavour jets - Z +heavy flavour jets - top pairs

  12. Look for enhanced production of Zs: e, e, • Selection: • require two isolated muons or • electrons in Z mass window • -one or two tagged b-jets CDF - corrects its b-jets with ET projections

  13. Separate NN trained to reject two main background processes: 2 ‘loose’ b-tags 1 ‘tight’ b-tag Z + jets top pairs 95/SM at MH = 115 GeV 20.4 exp 16 17.8 obs 16

  14. → hadrons → e or  → e or  ee same charge di-lepton mass Selection: - 2 isolated leptons (pT > 15 GeV) (electrons and/or muons)‏ - kinematic likelihood selection e like-sign!  , m , ET or  min T “flips”: charge mis-identification estimated from data: : solenoid vs toroid e: solenoid vs (track,calorimeter) 

  15. L = 1 fb-1 95/SM ~ 18 for MH = 160 GeV

  16. Selection: - two isolated leptons - large ETmiss - Less than 2 jets (>15 GeV) CDF leptons will tend to align If WW comes from a spin-0 Higgs Higgs: small( ) WW: large( )

  17. Matrix Element Technique most sensitive at high masses

  18. SUMMER 2006 • Combines sixteenmutually exclusive final states for WH, ZH, WW - 10.4  SM at mH=115 GeV - 3.8  SM at mH=160 GeV • Today I’ll report on recent progress • updated CDF & DZero low & high mass 1+ fb-1 analyses

  19. Combines sixteen mutually exclusive final states for WH, ZH, WW 7.7  SM at mH=115 GeV 1.4  SM at mH=160 GeV

  20. Higgs Bosons Beyond the Standard Model The Standard Model assumes a single complex Higgs doublet generates W/Z masses and a massive chargeless spin-0 boson, the Higgs, H • Hu/Hd couple to up- and down- type quarks • tanβ is the ratio of their vev’s tanβ= <Hu>/<Hd> • EWSB results in 4 massive scalar (h, H, H±) and one massive pseudoscalar (A) Higgs bosons () 2HDM: 2 Higgs Doublet Models • fully parameterized • (at tree level) by tanβ, mA • with radiative corrections • that depend on stop mixing Minimal Supersymmetric Model At large tan enhanced f0bb and f0tt couplings mean large Higgs production rates at hadron colliders!

  21. Fermiophobic Higgs Decaying to 3g A production mechanism unique to hadron colliders is accessible to the Tevatron provided mH is not too large! For tan b> 1, mH < 200 GeV and mh< 90 GeV B(h )  1 and B( HhW )  1 • Background rates in 3g final state are very low • measured fake rates for Zg or Wgg • tri-photon production extrapolated from di-photon sample No obvious structure in diphoton mass spectrum Optimizing selection on 3s ET >30, 25, 25GeV 0events observed 1.1  0.2expected background

  22. Fermiophobic Higgs Decaying to 3g Optimizing final selection on 3s ET >30, 20, 25GeV and pT > 25 GeV rejects background LEP2 limits of 108 GeV/c2 assumed SM coupling hf VV

  23. Fermiophobic Higgs in 2g+ X 1.1 fb-1 Selection: 2 photons (pT > 25 GeV) Background: , +jet and jet+jet mh>92GeV at 95% CL

  24.  b (b) bb b(b) Search At high tan Br(H/Abb)  90%, but swamped by QCD background  0 b Look for associated production with bs. b g Selection: - 3 b-tagged jets‏ - look for a signal in the invariant mass of two leading jets g b  0 b g The shape from double–tagged events ( mis-tagged rate) Normalized to the 3b-tagged sample outside the signal mass window. ALPGEN MC

  25.  b (b) bb b(b) Search • CDF found two useful discriminators • m12 (invariant mass, 2 leading jets) • mdiff = mass of the tracks assigned to jet from the displaced vertex 0.980 fb-1 0.90 fb-1

  26. Neutral MSSM Higgs  had Main backgrounds: Z (irreducible), W+jets, Zee,, mulijet, di-boson DØ: -channel only CDF: e, , e+ channels • 1 isolated  • separated from • opposite sign • hadronic  • isolated e or  • separated from • opposite sign • hadronic  • set of 3 NNs discri- • minate  from jets • variable-size cone algorithm for  > 55 GeV • mvis < 20 GeV removes • remaining W background • Ws removed by a cut on the MET • projected on the bisector between s.

  27. Neutral MSSM Higgs  had Small excess in CDF’s e+ channel • but < 2 effect • not observed in CDF e channel While DØ is in good agreement with SM

  28. Neutral MSSM Higgs  had Both experiments give similar results: in the 90<mA<200 GeV region tan> ~40-60 excluded for the no-mixing and mhmax benchmarks

  29. SUPERSYMMETRY Particle Name Symbol Spartner Name Symbol gluon g gluino g charged Higgs H+ chargino 1,2 charged weak boson light Higgs h neutralino 1,2,3,4 heavy Higgs Hpseudoscalar Higgs Aneutral weak boson Z photon  quark q squark qR,L lepton l slepton lR,L ~ ~ 0 ~  ~ ~ • The LightestSupersymmetricParticleprovides • ET if the LSP is stable and R-parity is conserved • photons and ET if the LSP is a gravitino and NLSP a neutralino • long-lived particles if the LSP decays weakly • SUSY particles are heavy • high pT final state objects

  30. Minimal Supersymmetric SM Extension adding the fewest new particles • 2 Higgs doublet h0 H0 A0 H+ • and described by 4 parameters M1U(1) M2U(2) gaugino mass parameter at EW scale mhiggsino mass parameter tanb ratio of VEV of Higgs doublets • scalar sector described by MANYmass parameters • different SUSY breaking different class of models SUSY Symmetry Breaking SUGRA( ~ 10 11 GeV) MSSM Assumptions: • 5 free parameters mocommon scalar mass m1/2common squark mass Ao trilinear coupling tanb sign(m) • SUSY particles are pair produced • Lightest SUSY particle (LSP) is stable • Lightest SUSY particle is

  31. Stop  charm + ET ~ with 0 as LightestSupersymmetricParticle and and pair production R-parity Search for: 2 charm jets plus Missing ET Pre-selection: 2 jets, pT > 40(20) GeV Lepton, track vetos δφ(jj) < 165o δφmax- δφmin < 120o δφ(j,ET) > 50o A=(ET-HT)/(ET+HT)>-0.05 ET> 60 GeV then flavor tag (>= 1 jet)

  32. Stop  charm + ET Finally optimize mass-dependent cuts on HT and P = max + min For HT>140 P<320 SM process Number of events Wl+jets 20.62  2.34 Z+jets * 13.23  1.76 Wl +HF (bb, cc) 11.94  1.06 Z+HF (bb, cc) 11.60  0.78 WW,WZ,ZZ 2.70  0.27 tt 2.17  0.07 Single top 1.76  0.05 Zll(e,,)+jets 0.12  0.09 Zll(e,,)+ HF (bb, cc) 0.09  0.04 Total BKG 64.213.22 Data 66 *use Zee+jets to normalize Zvv+jets

  33. Search for Long-lived Stop CDF Electromagnetic Calorimeter (EM) Some models predict long-lived massive particles due to: – weak coupling (e.g., NLSP in SUSY models with GMSB) – Kinematic constraints (chargino in SUSY with AMSB) – New symmetry (gluino in split-SUSY, LSP stop in ED models) A long-lived, charged massive particle (CHAMP) appears as a “slow” muon. TOF Hadronic Calorimeter Tracking Chamber Muon Detector – High PT, low velocity, highly ionizing “muon” – Measure velocity () via TOF detector + timing from tracking detector – Calculate mass from momentum and  Control Region dominated byW Data Signal Region

  34. Search for Long-lived Stop • Signal region: no candidates with m>120 • consistent with expected background Prospino2 Exclude stable stop with m<250 GeV/c2 at 95%CL

  35. Squarks/Gluinos  jets + ET Assuming R-partity is conserved, squarks and gluinos can decay directly into the LSP (01). or cascade down to the LSP The dominant signature for ppqq, qg, gg + Xisjets+ET    Separate 2-jet, 3-jet and >3-jet analysis. At least 3 jets ET > 25 GeV and ET > 25 GeV

  36. Squarks/Gluinos  jets + ET 1.4 fb-1 Mgluino < 290 for any Mq ~ Mgluino < 380 excluded for Mg ~ Mq A0=0 tan = 5 <0 ~ ~

  37. Squarks/Gluinos  jets + ET 0.96 fb-1 ~ ~ Mgluino < 402 excluded for Mg~Mq Mgluino < 309 excluded – any Mq A0=0 tan = 3 <0 ~

  38. Squarks  had + jets + ET τ- A0 = -2m0 tan = 15  < 0 enhanced  decay • Selection: • 2 or more jets ET > 35 GeV • ET > 75 GeV • at least one hadronic  • Optimization: • ET > 175 GeV • > 325 GeV

  39. Squarks  had + jets + ET Predicted Yields Signal (m0,m½) ( 80,160) 4.70.4 (100,150) 7.10.6 Background 1.7 Data 2 LEP2 slepton searches LEP2 chargino searches Translating to

  40. Chargino/NeutralinoTrileptons Production of 1 02 will lead to trileptonfinal stateswithET perhaps thecleanestsignature of supersymmetry. Dominant backgrounds: Dibosons and Drell-Yan with converting bremsstrahlung photon • Limits set on Br as a • function of  mass • Results interpretted within • select mSUGRA scenarios ~ ee+track Large  and Br Maximal 3 ~

  41. Chargino/NeutralinoTrileptons Final Selection Signal: 1-2 events Background: 1  0.3 Data: 0 DØee+track: DØ Combined Limit (5 analysis) : DØ Combined Limit (14 analysis) :

  42. Conclusions

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