Phenomenology of Vector Resonances from SEWSB at Future e+e- Colliders 14th KSF, Smolenice Oct 13, 2004 Phenomenology of Vector Resonances from SEWSB at Future e+e- Colliders Ivan Melo D. Bruncko (IEP SAS Kosice) M. Gintner (University of Zilina) I. Melo (University of Zilina)

Outline Motivation for new vector (ρ) resonances Vector resonance models ρ signals in e+e- → ννtt

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 → t t

Chiral effective Lagrangian A simple Lagrangian L = i gπ Mρ/v (π- ∂μ π+ - π+ ∂μ π- )ρ0μ + gV t γμ t ρ0μ + gA t γμ γ5 t ρ0μ (1) Chiral effective Lagrangian L = - v2 Tr [ Aμ Aμ] - a v2 /4 Tr[(ωμ + i g'' ρμ . τ/2 )2] + b1 IbL + b2 IbR + ... (2) gπ = Mρ /(2 v g''), gV ≈ g'' b2 /[4(1+b2)], Mρ ≈ √a v g''/2.

Unitarity constraints WL WL → WL WL , WL WL → t t, t t → t t gπ ≤ 1.75 (Mρ= 700 GeV) gV ≤ 1.7 (Mρ= 700 GeV) Low energy constraints g’’ ≥ 10 |b2| ≤ 0.08

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

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

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)

Conclusions ρ in e+e- → ννtt – sensitive probe of mt physics σ(1 TeV) = 0.16 (0.035) fb R values up to 8