BESS Model Resonance in the pp W + W tt + X Channel at LHC M. Gintner, I. Melo, B. Trpišová University of Žilina Herlany, September 2006

Outline BESS Model Vector Resonance ρ Cross sections for pp → WWtt + X reconstruction

EWSB: SU(2) L x U(1) Y → U(1) Q Weakly interacting models: - SUSY - SM (light) Higgs Strongly interacting models: - Technicolor A new strong vector resonance ρ as an isospin triplet ( ) → BESS

BESS (Breaking EW Symmetry Strongly) Model SU(2) L x SU(2) R global, SU(2) L x U(1) Y local L = L kin + L non.lin. σ model - a v 2 /4 Tr[(ω μ + i g v ρ μ. τ/2 ) 2 ] + L mass + L SM (W,Z) + b 1 ψ L i γ μ (u + ∂ μ – u + i g v ρ μ. τ/2 + u + i g’/6 Y μ ) u ψ L + b 2 ψ R P b i γ μ (u ∂ μ – u i g v ρ μ. τ/2 + u i g’/6 Y μ ) u + P b ψ R + λ 1 ψ L i γ μ u + A μ γ 5 u ψ L + λ 2 ψ R P b i γ μ u A μ γ 5 u + P b ψ R Standard Model with Higgs replaced with ρ Our model ω μ = [u + (∂ μ + i g’/2 Y μ τ 3 )u + u(∂ μ + i g W μ. τ/2)u + ]/2 A μ = [u + (∂ μ + i g’/2 Y μ τ 3 )u - u(∂ μ + i g W μ. τ/2)u + ]/2 u = exp( i π. τ /2v) ψ L = (t L,b L ) P b = diag(1,p) M ρ ≈ √a v g v /2 v ≈ 246 GeV … EW scale

t t t π = W L are BESS coupling constants is the SU(2) L coupling constant

International Linear Collider: e+e- at 1 TeV ee ―› νν WWee ―› νν tt ee ―› ρ tt ―› WW tt ee ―› ρ tt ―› tt tt ee ―› WW ee ―› tt Large Hadron Collider: pp at 14 TeV pp ―› jj WWpp ―› jj tt pp ―› ρ tt ―› WW tt pp ―› ρ tt ―› tt tt pp ―› WW pp ―› tt

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

Analysis of pp I. cross-sections and statistical significance (CompHEP calculation) II. reconstruction CompHEP – events generation Pythia – decay and hadronization Atlfast – detector effects and reconstruction of the jets ROOT, C++ -- event reconstruction For the dominant gg channel:

39/8 diagrams in the dominant gg channel No-resonance background ρ ρ ρ

Cuts: 700-3Γρ < m WW < Γρ (GeV) p T (t) > 100 GeV, |y(t)| < 2 σ(gg) = 10.2 fb ―› 1.0 fb No resonance background: σ(gg) = fb M WW (GeV) CompHEP results: pp → W W t t + X (39 diag.) ρ: Mρ=700 GeV, Γρ=4 GeV, b 2 =0.08, g v =10 SM: M H = 700 GeV Γ H = 184 GeV σ(gg) = 11.3 fb ―› 0.20 fb M WW (GeV)

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

|N(ρ) – N(no res.)| √(N(no res.)) R =≈ S/√B > 5 8 diagr. 39 diagr.

Search at LHC: tttt vs WW tt 8 diagrams

l jjbjjbjj Reconstruction One charged lepton channel: Cuts: electron > 30 GeV muon > 20 GeV jets > 25 GeV Reconstruction criterion 40% of events mass of the W: GeV b-tagging efficiency 50% of 32 % 68 %

number of events/17 GeV 8 diagrams 39 diagrams Lum=100/fb 2.4 events Lum=100/fb 12.2 events Invariant mass of WW pair (ρ →WW)

8 diagrams 39 diagrams number of events/0.6 GeV number of events/2.5 GeV Mass of the W boson Mass of the top quark Lum=100/fb 2.4 events 12.2 events

Conclusions I. in the final state – maximum values of R at around 100 II. reconstruction The top quark and the W reconstruction O.K. The ρ reconstruction – 40% of events fall into the ρ peak  need to improve the reconstruction algorithm III. Future work much larger cross-section compared to, i.e. larger numbers of events

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