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Strong EWSB in Top Quark Production

Praha, Nov 3, 2005. Strong EWSB in Top Quark Production. Ivan Melo. M. Gintner, I. Melo, B. Trpi š ov á (University of Ž ilina). Outline. Motivation for new vector ( ρ ) resonances: Strong EW Symmetry Breaking (SEWSB) Vector resonance model

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Strong EWSB in Top Quark Production

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  1. Praha, Nov 3, 2005 Strong EWSB in Top Quark Production Ivan Melo M. Gintner, I. Melo, B. Trpišová (University of Žilina)

  2. Outline • Motivation for new vector (ρ) resonances: Strong EW Symmetry Breaking (SEWSB) • Vector resonance model • ρ signal at LHCpp → ρtt→ WWtt + X ρtt → tttt + X • ρ signal at future e+e- colliders e+e- → ννtt e+e- → tt

  3. EWSB: SU(2)L x U(1)Y→ U(1)Q Weakly interacting models: - SUSY - Little Higgs Strongly interacting models: - Technicolor

  4. 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

  5. WL WL→ WL WLWLWL → t tt t → t t t t t π = WL L = i gπMρ/v (π- ∂μπ+ - π+ ∂μπ-)ρ0μ + gt t γμ t ρ0μ+ gt t γμ γ5 t ρ0μ

  6. International Linear Collider: e+e- at 1 TeV ee ―› ρtt ―›WW tt ee ―› ρtt ―›tt tt ee ―› WW ee ―› tt ee ―› ννWW ee ―›ννtt Large Hadron Collider: pp at 14 TeV pp ―› ρtt ―›WW tt pp ―› ρtt ―›tt tt pp ―› WW pp ―› tt pp ―› jj WW pp ―› jj tt

  7. Chiral effective Lagrangian 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+ρμ+ u+ i g’/6 Yμ) u ψL + b2ψRPb i γμ (u ∂μ – u ρμ+ u i g’/6 Yμ) u+PbψR + λ1ψL i γμ u+ Aμγ5 u ψL +λ2ψR Pλ i γμ u Aμγ5 u+PλψR BESS Our model Standard Model with Higgs replaced with ρ gπ= Mρ /(2 v gv) gt=gv b2/4+ … Mρ≈ √a v gv/2 t

  8. Low energy constraints Unitarity constraints WLWL → WLWL , WLWL → t t,t t → t t gv≥ 10 → gπ ≤ 0.2 Mρ(TeV) |b2 – λ2| ≤ 0.04 → gt≈ gv b2 / 4 |b1 – λ1| ≤ 0.01 → b1 = 0 gπ ≤ 1.75 (Mρ= 700 GeV) gt ≤ 1.7 (Mρ= 700 GeV)

  9. Partial (Γ―›WW) andtotal width Γtot of ρ

  10. Search at LHC: pp → W W t t + X J. Leveque et al. ATL-PHYS-2002-019: pp -> Htt -> WWtt MH =[120-240] GeV ρ • BRA: pp → ρtt→WWtt • σ(WWtt) = σ(ρtt) x BR(ρ->WW) • 2) Full calculation: pp → WWtt

  11. pp → W W t t + X (full calculation) 39 diagrams in gg channel No resonance background ρ ρ ρ

  12. CompHEP results: pp → W W t t + X ρ: Mρ=700 GeV, Γρ=4 GeV, b2=0.08, gv=10 SM: MH = 700 GeV ΓH = 184 GeV MWW(GeV) MWW(GeV) σ(gg) = 10.2 fb ―› 1.0 fb σ(gg) = 11.3 fb ―› 0.20 fb No resonance background: σ(gg) = 0.037 fb Cuts: 700-3Γρ < mWW < 700 +3Γρ (GeV) pT > 100 GeV, |y| < 2

  13. Total cross sections for ρtt and WWtt BRA: σ(WWtt) = σ(ρtt) x BR(ρ->WW)

  14. |N(ρ) – N(no res.)| √(N(no res.)) R = ≈ S/√B > 5 BRA Full calc.

  15. Search at LHC: tttt vs WWtt BRA BRA

  16. Search at Hadron Colliders: p+p(p) ―› t + t Tevatron: p + p ―› t + t σS= 1.2 fb σB = 8 306 fb LHC: p + p ―› t + t σS = 22.7 fb σB = 752 000 fb Mρ=700 GeV Γρ=12.5 GeV No cuts

  17. Subset of fusion diagrams + approximations (Pythia) Full calculation of 66 diagrams at tree level (CompHEP)

  18. Pythia vs CompHEP ρ (M = 700 GeV, Γ = 12.5 GeV, g’’ = 20, b2 = 0.08) Before cuts √s (GeV) 800 1000 1500 Pythia (fb) 0.35 0.95 3.27 CompHEP (fb) 0.66 1.16 3.33

  19. Backgrounds (Pythia) e+e- → tt γ e+e- → e+e- tt σ(0.8 TeV) = 300.3 + 1.3 fb → 0.13 fb(0.20 fb) σ(1.0 TeV) = 204.9 + 2.4 fb → 0.035 fb (0.16 fb)

  20. e- e+→ t t ρ different from Higgs ! x+y=560 nm z=0.40 mm n=2x1010 ρ (M= 700 GeV, b2=0.08, g’’=20)

  21. Conclusions • New strong ρ-resonance model • pp → W W t t + Xpp → t t t t + X at LHC • R values up to a few 100 (before t,W decays and detector effects), L = 100 fb-1 • Backgrounds pp → tt, W + jets, Z + jets, … ? • e+e- → ννtt R ≤ 26 at CM energy = 1 TeV, L = 200 fb-1 e+e- → tt Lscan = 1 fb-1 Similar work on pp → t t t t + X : T.Han et al, hep-ph/0405055

  22. WWtt reconstruction • WWtt →lν jj jjb jjb • b tagging …… 50 % • l detection …. 90 % • one trigger lepton pT > 30 (20) GeV e (μ) • jets pT > 30 GeV • kinematical cuts for 6 jets …….. ≈ 20 % • BR: W → e(μ)ν ….. 21.3 % … Pl W → hadrons …68 % …. Ph ε = εcutsεb2εl 4 Pl Ph = 1.2 %

  23. Search at Hadron Colliders Mρ=700 GeV, Γρ=12.5 GeV Tevatron: p + p ―› t + t σS= 1.2 fb σB = 8 306 fb LHC: p + p ―› t + t σS = 22.7 fb σB = 752 000 fb

  24. pp → ρt t + X(8 diagrams in gg channel) BRA: σ(WWtt) = σ(ρtt) x BR(ρ->WW)

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