A New Vector Resonance Production at LHC

Παρουσίαση με θέμα: "A New Vector Resonance Production at LHC"— Μεταγράφημα παρουσίασης:

1 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)

2 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

3 EWSB: SU(2)L x U(1)Y → U(1)Q
Weakly interacting models: - SUSY - Little Higgs Strongly interacting models: - Technicolor

4 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

5 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

6 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

7 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

8 Unitarity constraints
Low energy constraints gv ≥ → gπ ≤ 0.2 Mρ (TeV) |b2 – λ2| ≤ → gt ≈ gv b2 / 4 Unitarity constraints WL WL → WL WL , WL WL → t t, t t → t t gπ ≤ (Mρ= 700 GeV) gt ≤ (Mρ= 700 GeV)

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

10 Search at LHC: pp → W W t t + X pp → t t t t + X
pp -> g g ―› WW tt diagrams u u ―› WW tt diagrams d d ―› WW tt diagrams Two approaches: 1) BRA: pp → ρtt →WWtt,tttt 2) Full calculation

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

12 (39 diagrams in gg channel)
pp → W W t t + X (39 diagrams in gg channel) Full calculation

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

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

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

16 tttt vs WWtt BRA BRA

17 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)

18 Search at Hadron Colliders
Mρ=700 GeV, Γρ=12.5 GeV Tevatron: p + p ―› t + t σS = 1.2 fb σB = fb LHC: p + p ―› t + t σS = fb σB = fb

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