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

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

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

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

WL WL → WL WL WL WL → t t t t → t t L = i gπ Mρ /v (π- ∂μ π+ - π+ ∂μ π-) ρ0μ + gt t γμ t ρ0μ + gt t γμ γ5 t ρ0μ

International Linear Collider: e+e- at 1 TeV ee ―› ρtt ―› WW tt ee ―› ρtt ―› tt tt ee ―› WW ee ―› tt ee ―› νν WW ee ―› νν tt 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

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 gv ρμ . τ/2 )2] + Lmass + LSM(W,Z) + b1 ψL i γμ (u+∂μ – u+ ρμ + u+ i g’/6 Yμ) u ψL + b2 ψR Pb i γμ (u ∂μ – u ρμ + u i g’/6 Yμ) u+ Pb ψR + λ1 ψL i γμ u+ Aμ γ5 u ψL + λ2 ψR Pλ i γμ u Aμ γ5 u+ Pλ ψR 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

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

Partial (Γ―›WW) and total width Γtot of ρ

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

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

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

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

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

Search at LHC: tttt vs WWtt BRA BRA

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

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

Pythia vs CompHEP Before cuts √s (GeV) 800 1000 1500 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

Backgrounds (Pythia) e+e- → e+e- tt e+e- → tt γ 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)

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)

Conclusions New strong ρ-resonance model pp → W W t t + X pp → 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

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 %

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

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