1. Search for a New Vector Resonance in the pp WWtt+X Channel at LHC
September 2006
Search for a New Vector Resonance in the pp WWtt+X Channel at LHC
M. Gintner, I. Melo, B. Trpišová
University of Žilina

2. Motivation An alternative to the SM Higgs boson:
Strong Electroweak Symmetry Breaking
A new strong vector resonance as an isospin triplet ( )

3. The Model Modified BESS model -- the only non SM particle
Respects the symmetries of the SM Higgs sector:
local,
global
> 10
<
0.1
… coupling constants of the original BESS ~ ~
… coupling constant
GeV … electroweak scale

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

5. 39(8) diagrams in the dominant gg channel
No resonance
background ρ ρ ρ

6. CompHEP Results Cuts: GeV 0.96 fb … 39 diagrams
ρ: Mρ=700 GeV,
Γρ=4 GeV,
b2=0.08, g =10 “
Cuts:
GeV
0.96 fb … diagrams
0.037 fb … No diagrams R ~ ~
46 … diagrams

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

8. Invariant mass of the WW pair …
Mass of the ρ-resonance
number of events/17 GeV
8 diagrams
39 diagrams
Lum=100/fb
2.4 events
12.2 events
number of events/17 GeV

9. 8 diagrams 39 diagrams Mass of the W boson Mass of the top quark
Lum=100/fb
Lum=100/fb
12.2 events
2.4 events
number of events/0.6 GeV
number of events/0.6 GeV
Mass of the top quark
Lum=100/fb
Lum=100/fb
2.4 events
12.2 events
number of events/2.5 GeV
number of events/2.5 GeV

10. Conclusions For the resonance with GeV, g”=10, =0.08: 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

11. versus