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M. Gintner, I. Melo, B. Trpi šová University of Žilina

Nuclear Seminar, FMFI UK Bratislava May 21, 200 8. Signatures of a new vector resonance from strongly interacting electroweak symmetry breaking at LHC. M. Gintner, I. Melo, B. Trpi šová University of Žilina. Outline Strong Electroweak Symmetry Breaking

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M. Gintner, I. Melo, B. Trpi šová University of Žilina

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  1. Nuclear Seminar, FMFI UK Bratislava May 21, 2008 Signatures of a new vector resonance from strongly interacting electroweak symmetry breaking at LHC M. Gintner, I. Melo, B. Trpišová University of Žilina

  2. Outline • Strong Electroweak Symmetry Breaking • BESS Model Vector Resonance ρ • LHC processes sensitive to ρ, cross sections • (CompHEP calculation) • Reconstruction of pp → W+ W- t t + X; pp → b b t t + X • (CompHEP, Pythia, Atlfast, Root)

  3. EWSB - one of Great Mysteries of Particle Physics • SM ………………………. 1 Higgs • Strong EWSB …….. no Higgs • SUSY (MSSM) ..... 5 Higgs Problem ! Monotheists Atheists Polytheists Classical

  4. Naturalness problem (Fine-tuning problem) ≈ - (200 GeV)2 . 1032for Λ = 1019 GeV mH≈ 100 – 200 GeV + (200 GeV)2 . 1032 - (200 GeV)2 . 1032

  5. SM SUSY (MSSM) = 0 → mH = 319 GeV ~ t1(2) Strong EWSB H not elementary, melts into techniquarks above ΛTC ≈ 1-3 TeV

  6. Chiral SB in QCD SU(2)L x SU(2)R → SU(2)V , vev ~ 90 MeV EWSB SU(2)L x SU(2)R → SU(2)V , vev ~ 246 GeV

  7. ,b ,b ,b ,b t t t 1,2 1,2 1,2 π = WL (Equivalence theorem) mt = 171 GeV≈ v/√2 v is EW scale (v = vev ~ 246 GeV) R.Casalbuoni et al. Phys.Lett. B155 (1985) 95;M.Gintner, I.Melo, B.Trpisova, Acta Phys. Slovaca, 56(2006)1

  8. Large Hadron Collider: pp at 14 TeV pp ―› ρtt ―›WW tt +X pp ―› ρbb ―›WWbb pp ―› ρtt ―›tt tt pp ―› ρtt ―› bb tt pp ―› ρbb ―› bb tt pp ―› ρ+tb ―› tb tb pp ―› ρ+tb ―› W+Z tb pp ―› WW+X pp ―› tt+X pp ―› jj tt pp ―› jj WW Mρ = 1 000 GeV Γρ = 42.3 GeV

  9. BESS (Breaking EW Symmetry Strongly) Model SU(2)L x SU(2)R global, SU(2)L x U(1)Y local L = Lkin + Lnon.lin. σ model -a v2 /4 Tr[(ωμ + i gvρμ . τ/2 )2] + Lmass+ LSM(W,Z) +b1ψL i γμ (u+∂μ – u+i gvρμ . τ/2+ u+ i g’/6 Yμ) u ψL + b2ψRPb i γμ (u ∂μ – u i gvρμ . τ/2 + u i g’/6 Yμ) u+PbψR + λ1ψL i γμ u+ Aμγ5 u ψL +λ2ψR Pb i γμ u Aμγ5 u+PbψR Our model Standard Model with Higgs replaced with ρ ωμ = [u+(∂μ + i g’/2 Yμτ3)u + u(∂μ+ i g Wμ . τ/2)u+]/2 Aμ = [u+(∂μ + i g’/2 Yμτ3)u - u(∂μ+ i g Wμ . τ/2)u+]/2 u = exp(i π . τ/2v) ψL = (tL,bL) Pb = diag(1,p) Mρ≈ √a v gv/2 (2) t v ≈ 246 GeV 1,2 R.Casalbuoni et al. Phys.Lett. B155 (1985) 95;M.Gintner, I.Melo, B.Trpisova, Acta Phys. Slovaca, 56(2006)1

  10. Low energy constraints Unitarity constraints WLWL → WLWL , WLWL → t t,t t → t t unitary up to 3 TeV gv≥ 10 gπ = Mρ/(2v gv) ≤ 0.2 Mρ(TeV) |b2 – λ2 | ≤ 0.04 gt≈ gv b1(2) / 4 |b1 – λ1 | ≤ 0.01 gπ ≤ 1.4 (Mρ= 1 000 GeV) gt ≤ 2.0 (Mρ= 1 000 GeV) if

  11. Partial (Γ―›WW) andtotal width Γtot of ρ0 Mρ = 1 000 GeV Γρ = 42.3 GeV gv = 20 b1 = 0.08

  12. CompHEP: pp → bb → tt + X σB = 26 617 fb Signal bb → tt 6 diagrams σS = 121 fb Background G G → tt 3 diagrams M±3Γ σB = 6 353 fb Cuts: Mρ-3Γρ < mtt < Mρ+3Γρ (GeV) pT(t), pT(t) > 350 GeV σS = 47 fb

  13. CompHEP: pp → bb → W+W- + X σB = 450 fb σS = 15.4 fb Signal 4 diagrams M±3Γ mWW σB → 100 fb Background uu → W+W- dd → W+W- 4 diagrams σS → 14.0 fb pTW

  14. CompHEP: pp → ttρ0 + X → bb t t + X σB = 17 fb QCD σS = 3.7 fb Signal M±3Γ mbb Signal 8 diagrams QCD bottom QCD background 35 diagrams Signal bottom pTb

  15. CompHEP: pp → bbρ0 + X → bb t t + X σB = 833 fb QCD Signal Γρ=127 GeV σ = 337 fb σS = 134 fb mtt Signal 8 diagrams QCD top QCD background 35 diagrams Signal top pTt

  16. CompHEP: pp → tbρ+ + X → bb t t + X σB = 332 fb QCD σS = 86 fb Signal mtb Signal 8 diagrams QCD top bottom QCD background 35 diagrams Signal top bottom pTq

  17. CompHEP: pp → (W+ W-) t t + X pp → (W+ W-) b b + X 39/8 diagrams in the dominant gg channel ρ No-resonance background ρ signal ρ

  18. CompHEP: pp → (W+ W-) t t + X(continued)pp → (W+ W-) b b + X b, Signal + Background: 39 diagrams b, ,b σS+B = 4 400 fb Signal: 8 diagrams σS+B = 9.4 fb σS = 9.4 fb Cuts: Mρ-3Γρ < mWW < Mρ+3Γρ (GeV) mW+b, mW-b > 200 GeV σS = 6.7 fb

  19. CompHEP: pp → (W+ Z) t b + X Signal + Background: 46 diagrams W+ Z σS+B = 12.7 fb Signal: 8 diagrams σS+B = 2.9 fb σS = 2.9 fb Cuts: Mρ-3Γρ < mWZ < Mρ+3Γρ (GeV) mW+b > 200 GeV σS = 2.5 fb

  20. CompHEP: pp → (tt) tt + X Signal + Background: 54 diagrams t t Signal: 8 diagrams σS+B = 3.7 fb σS = 1.3 fb Cuts: Mρ-3Γρ < mtt < Mρ+3Γρ (GeV)

  21. Cross sections in fb + statistical significance(peak region) significance background signal σB = 6 353 σB = 100 σB = 17 σB = 833 σB = 332 σB = 0.25 σB = 2.7 σB = 0.4 σB = 2.4 σS = 47 σS = 14 σS = 3.7 σS = 134 σS = 86 σS = 0.23 σS = 6.7 σS = 2.5 σS = 1.3 S = 5.9 * S = 14.0 * S = 9.0 S = 46.4 S = 47.2 S = 4.6 S = 40.8 * S = 39.5 * S = 8.4 • pp → bb → tt + X • pp → bb → W+W- + X • pp → (bb) tt + X • pp → bb (tt) + X • pp →b(bt) t + X • pp → (W+W-) t t + X • pp → (W+W-) b b + X • pp → (W+Z) t b + X • pp → (tt) tt + X S = NS/ √(NB)statistical significance NS = L σS , NB = L σB ,withL = 100 fb-1integrated luminosity * More than 1 cut applied

  22. pp → W W t t + Xl jjbjjbjj reconstruction(in collaboration with Jonathan Ferland, University of Montreal) One charged lepton channel: 40% of events (CompHEP, Pythia, Atlfast, Root) electron > 30 GeV GeV muon > 20 GeV mass of the W: Cuts: of jets > 25 GeV 50% b-tagging efficiency Reconstruction criterion

  23. 8 diagrams 39 diagrams Lum=100/fb Lum=100/fb 12.2 events 2.4 events number of events/17 GeV Distribution in invariant mass of WW pair (ρ →WW) ρ: Mρ=700 GeV, Γρ=4 GeV, b2=0.08, gv=10 Pz(ν) chosen correctly in 61.5 % of events number of events/17 GeV

  24. 39 diagrams 8 diagrams Mass of the W boson Lum=100/fb Lum=100/fb 12.2 events 2.4 events number of events/0.6 GeV number of events/0.6 GeV Mass of the top quark Lum=100/fb Lum=100/fb 12.2 events 2.4 events number of events/2.5 GeV number of events/2.5 GeV

  25. CompHEP ρ: Mρ=1000 GeV Γρ=26 GeV Reconstruction number of events/32 GeV Lum = 100 fb-1 12.8 events

  26. pp → ρ0 tt → bb t t + X → bb lνlb jjb (43.5%) reconstruction (in collaboration with J. Ferland) e > 30 GeV μ > 20 GeV of Cuts: L = 100 fb-1 j > 25 GeV GeV NS=0.8 L = 100 fb-1 NB=8

  27. Conclusions • Strong EWSB: an alternative to SUSY • ρ is a general prediction of Strong EWSB • (Modified) BESS model preferentially couples ρ with t,b • Several processes promising at CompHEP level

  28. Backup

  29. EWSB: SU(2)L x U(1)Y→ U(1)Q Weakly interacting models: - SUSY - SM (light) Higgs Strongly interacting models: - Technicolor A new strong vector resonanceρas an isospin triplet ( ) → BESS

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