1. 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)

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

5. 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

6. WL WL → t t

7. 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.

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

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

11. Pythia vs CompHEP ρ (M = 700 GeV, Γ = 12.5 GeV, g’’ = 20, b2 = 0.08)
Before cuts
√s (GeV)
Pythia (fb)
CompHEP (fb)

12. Backgrounds (Pythia) e+e- → e+e- tt e+e- → tt γ
σ(0.8 TeV) = fb → 0.13 fb (0.20 fb)
σ(1.0 TeV) = fb → fb (0.16 fb)

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