A New Vector Resonance Production at LHC 15th CCSP, Kosice, Sep 6, 2005 A New Vector Resonance Production at LHC Ivan Melo M. Gintner, I. Melo, B. Trpisova (University of Zilina)

Outline ρtt → tttt Motivation for new vector (ρ) resonances: Strong EW Symmetry Breaking (SEWSB) Vector resonance model ρ signal in pp → ρtt → WWtt ρtt → tttt

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 ρ ρ ρ ρ 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 ρ ρ ρ ρ 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 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 pp → t t t t + X pp -> g g ―› WW tt 39 diagrams u u ―› WW tt 131 diagrams d d ―› WW tt 131 diagrams Two approaches: 1) BRA: pp → ρtt →WWtt,tttt 2) Full calculation

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

(39 diagrams in gg channel) pp → W W t t + X (39 diagrams in gg channel) Full calculation

CompHEP results Cuts: 700-3Γ < mWW < 700 +3Γ (GeV) pT > 100 GeV |y| < 2 S: σ(gg) = 10.2 fb ―› 1.0 fb Mρ=700 GeV, Γρ=4 GeV, b2=0.08, gv=10 No ρ Background: σ(gg) = 0.037 fb σ(uu) = 0.013 fb MWW(GeV)

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

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

tttt vs WWtt BRA BRA

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)

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