BESS Model Resonance in the pp W+W tt + X Channel

at LHC

M. Gintner, I. Melo, B. Trpišová

University of Žilina

CERN, Nov 1, 2006

Outline

BESS Model Vector Resonance ρ

Cross sections for pp →WWtt + X (CompHEP calculation)

reconstruction

(CompHEP, Pythia, Atlfast, Root)

jjbjjbjjl l

052

01

0)(v

ttgttgM

igL tt

Vg

Mg

v2

t t t

π = WL

2

22

21 4 V

Vtt

g

gO

bggg

2,bgV are BESS coupling constantsg is the SU(2)L coupling constant

10Vg

1.02 bv is EW scale (246 GeV)

1,2 1,2 1,2

R.Casalbuoni et al. Phys.Lett. B155 (1985) 95; M.Gintner, I.Melo, B.Trpisova, Acta Phys. Slovaca, 56(2006)1

Large Hadron Collider: pp at 14 TeV

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

pp ―› WWpp ―› tt

39/8 diagrams in the dominant gg channel

ttWW -

jjbjjbjjl l

No-resonancebackground

ρ

ρ

ρ

XttWW

Cuts: 700-3Γρ < mWW < 700 +3Γρ (GeV) pT (t) > 100 GeV, |y(t)| < 2

σ(gg) = 10.2 fb ―› 1.0 fb

No resonance background: σ(gg) = 0.037 fb

MWW(GeV)

CompHEP results: pp → W W t t + X

ρ: Mρ=700 GeV, Γρ=4 GeV, b2=0.08, gv=10 39 diagrams 8 diagrams

gt1,2

= gv b2/4gπ=Mρ/2vgv

l jjbjjbjj reconstruction (CompHEP, Pythia, Atlfast, Root)

One charged lepton channel:

jjbjjbjjlWbbWWWttWW l

Cuts: Tpelectron > 30 GeV

muon > 20 GeV

jets > 25 GeV

Reconstruction criterion

22

2222

)()(

)()()(

2211

654321

tbWtbW

WjjWjjWjj

mmmm

mmmmmm

l

40% of events

mass of the W: 25Wm GeV

b-tagging efficiency 50%

of

Athena 9.0.3

nu

mb

er o

f ev

ents

/17

GeV

GeV]mWW[

nu

mb

er o

f ev

ents

/17

GeV

GeV]mWW[

39 diagrams 8 diagrams

Lum=100/fb

12.2 events

Lum=100/fb

2.4 events

Distribution in invariant mass of WW pair (ρ →WW)

GeV]mWW[ GeV]mWW[

ρ: Mρ=700 GeV, Γρ=4 GeV, b2=0.08, gv=10

Pz(ν) chosen correctly in 61.5 % of events

8 diagrams 39 diagramsn

um

ber

of

even

ts/0

.6 G

eV

nu

mb

er o

f ev

ents

/0.6

GeV

nu

mb

er o

f ev

ents

/2.5

GeV

nu

mb

er o

f ev

ents

/2.5

GeV

GeV]m jj[ GeV]m jj[

GeV]mWb[ GeV]mWb[

Mass of the W boson

Mass of the top quark

Lum=100/fbLum=100/fb

Lum=100/fbLum=100/fb

2.4 events

2.4 events 12.2 events

12.2 events

GeV]mWW[

GeV]mWW[

nu

mb

er o

f ev

ents

/32

GeV

Lum = 100 fb-1

12.8 events

ρ: Mρ=1000 GeV Γρ=26 GeV

versus

8 diagrams

ttttttWW

1. Can we improve WWtt reconstruction ?

2.

L = 100/fb2.4 events8 diagrams

Appendix

BESS (Breaking EW Symmetry Strongly) Model 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+ i gv ρμ . τ/2 + u+ i g’/6 Yμ) u ψL

+ b2 ψR Pb i γμ (u ∂μ – u i gv ρμ . τ/2 + u i g’/6 Yμ) u+ Pb ψR + λ1 ψL i γμ u+ Aμ γ5 u ψL

+ λ2 ψR Pb i γμ u Aμ γ5 u+ Pb ψR

Standard Model with Higgs replaced with ρ

Our model

ωμ = [u+(∂μ + i g’/2 Yμτ3)u + u(∂μ+ i g Wμ . τ/2)u+]/2Aμ = [u+(∂μ + i g’/2 Yμτ3)u - u(∂μ+ i g Wμ . τ/2)u+]/2u = exp(i π . τ /2v)ψL = (tL,bL)

Pb = diag(1,p)

Mρ ≈ √a v gv /2

v ≈ 246 GeV … EW scale

Total width Γtot of ρ

Vg

Mg

v2

2

22

21 4 V

Vtt

g

gO

bggg

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 ( ) → BESS0,