Phenomenology of New Vector Resonances from SEWSB at

Future e+e- Colliders

Ivan Melo

M. Gintner, I. Melo, B. Trpisova (University of Zilina)

IEP SAS, Kosice, May 13, 2005

• Motivation for new vector (ρ) resonances: Strong EW Symmetry Breaking (SEWSB)

• Vector resonance model

• ρ signals in e+ e- → ννtt, e+ e- → tt• ρ signal in pp → ρtt → WWtt

Outline

Higgs bosonHiggs boson

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 SU(2)L x SU(2)R → SU(2)V , vev ~ 90 MeV

EWSBSU(2)L x SU(2)R → SU(2)V , vev ~ 246 GeV

LEP: e+e-, Ecm = 209 GeVTevatron: pp, Ecm = 2 000 GeV, L = 1 fb-1

LHC: pp, Ecm = 14 000 GeV, L = 100 fb-1

ILC: e+e-, Ecm = 1 000 GeV, L = 200 fb-1

CLIC: e+e-, Ecm = 3-5 000 GeV, L = 200 fb-1

WL WL → WL WL WL WL → t t t t → t t

L = i gπ Mρ /v (π- ∂μ π+ - π+ ∂μ π-) ρ0μ

+ gV t γμ t ρ0μ + gA t γμ γ5 t ρ0

μ

International Linear Collider: e+e- at 1 TeV

ee ―› νν WW ee ―› νν tt ee ―› ρtt ―› WW ttee ―› ρtt ―› tt tt

ee ―› WWee ―› tt

Large Hadron Collider: pp at 14 TeV

pp ―› jj WW pp ―› jj tt pp ―› ρtt ―› WW ttpp ―› ρtt ―› tt tt

pp ―› WWpp ―› tt

Chiral effective LagrangianSU(2)L x SU(2)R global, SU(2)L x U(1)Y localL = Lkin - v2 Tr [ Aμ Aμ] - a v2 /4 Tr[(ωμ + i g'' ρμ . τ/2 )2] - ψL u+ u+ M ψR – h.c. + ψL i γμ (∂μ + Wμ + i g’/6 Yμ) ψL

+ ψR i γμ (∂μ + Yμ + i g’/6 Yμ) ψR

+ 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

+ κ2 ψR Pκ i γμ u (ωμ + ρμ) u+ Pκ ψR

Minimal model Standard Model with Higgs replaced with ρ

BESS

Our model

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 ρ0

μ

Chiral effective Lagrangian

L = - v2 Tr [ Aμ Aμ] - a v2 /4 Tr[(ωμ + i g'' ρμ . τ/2 )2] + b1 Ib

L + b2 IbR + ...

gπ = Mρ /(2 v g'') gV ≈ g'' b2 /4 = gA (b1 = 0) Mρ ≈ √a v g''/2

Unitarity constraints

WL WL → WL WL , WL WL → t t, t t → t t

Low energy constraints

gπ ≤ 1.75 (Mρ= 700 GeV)gV ≤ 1.7 (Mρ= 700 GeV)

g’’ ≥ 10 → gπ ≤ 0.2 Mρ (TeV)|b2 – λ2| ≤ 0.04 → gV ≈ g’’ b2 / 4

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- → 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)

≈ S/√B

e- e+ → t t

different from Higgs !

ρ (M= 700 GeV, b2=0.08, g’’=20)

ρ

Search at Hadron Colliders

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

Search at LHC: pp → W W t t

Cuts: 650 < mWW < 750 GeV pT > 100 GeV |y| < 2

g g ―› WW tt 39 diagramsu u ―› WW tt 131 diagramsd d ―› WW tt 131 diagrams

Signal: σ(gg) = 10.2 fb ―› 1.0 fb

Background: σ(gg) = 10.6 fb ―› 0.6 fb σ(uu) = 2.4 fb ―› 0.1 fb

R > 5

Conclusions

• New strong ρ-resonance model

• ρ in e+e- → ννtt R values up to 8

• e+e- → tt – sensitive probe of mt physics,

Lscan = 1 fb-1 (preliminary)

• pp → W W t t R > 5 (preliminary !)