BESS Model Resonance in the pp W W tt X Channel at LHC

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BESS Model Resonance in the pp WW tt X
Channel at LHC
Herlany, September 2006

• M. Gintner, I. Melo, B. Trpišová
• University of Žilina

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Outline BESS Model Vector
Resonance ? Cross sections for pp ?WWtt X

reconstruction
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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 ? as an isospin
triplet ( ) ? BESS
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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. s model - a v2 /4 Tr(?µ
i gv ?µ . t/2 )2 Lmass
LSM(W,Z) b1 ?L i ?µ (u?µ u i
gv ?µ . t/2 u i g/6 Yµ) u ?L
b2 ?R Pb i ?µ (u ?µ u i gv ?µ . t/2 u i g/6
Yµ) u Pb ?R ?1 ?L i ?µ u Aµ ?5 u
?L ?2 ?R Pb i ?µ u Aµ ?5 u Pb
?R
Our model
Standard Model with Higgs replaced
with ?
?µ u(?µ i g/2 Yµt3)u u(?µ i g Wµ .
t/2)u/2 Aµ u(?µ i g/2 Yµt3)u - u(?µ i g
Wµ . t/2)u/2 u exp(i p . t /2v) ?L
(tL,bL) Pb diag(1,p)
M? va v gv /2
v 246 GeV EW scale
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t
t
t
p WL
are BESS coupling constants
is the SU(2)L coupling constant
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• International Linear Collider ee- at 1 TeV

ee ? ?tt ? WW tt ee ? ?tt ? tt tt
ee ? WW ee ? tt
ee ? ?? WW
ee ? ?? tt
Large Hadron Collider pp at 14 TeV
pp ? ?tt ? WW tt pp ? ?tt ? tt tt
pp ? WW pp ? tt
pp ? jj WW
pp ? jj tt
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Partial (G?WW) andtotal width Gtot of ?
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Analysis of pp
For the dominant gg channel

• cross-sections and statistical
  significance
• (CompHEP calculation)
• reconstruction
• CompHEP events generation
• Pythia decay and hadronization
• Atlfast detector effects and
  reconstruction of the jets
• ROOT, C -- event reconstruction

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39/8 diagrams in the dominant gg channel
No-resonance background
?
?
?
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CompHEP results pp ? W W t t X (39 diag.)
? M?700 GeV, G?4 GeV, b20.08,
gv10
SM MH 700 GeV GH 184 GeV
MWW(GeV)
MWW(GeV)
s(gg) 10.2 fb ? 1.0 fb
s(gg) 11.3 fb ? 0.20 fb
No resonance background s(gg)
0.037 fb
Cuts 700-3G? lt mWW lt 700 3G? (GeV)
pT (t) gt 100 GeV, y(t) lt 2
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Total cross sections for ?tt and WWtt
8 diagrams s(WWtt) s(?tt) x BR(?-gtWW)
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N(?) N(no res.)
v(N(no res.))
R
S/vB gt 5
8 diagr.
39 diagr.
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Search at LHC tttt vs WWtt
8 diagrams
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l jjbjjbjj Reconstruction
32 68
One charged lepton channel
40 of events
electron gt 30 GeV
muon gt 20 GeV
of
Cuts
GeV
mass of the W
jets gt 25 GeV
50
b-tagging efficiency
Reconstruction criterion
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Invariant mass of WW pair (? ?WW)
number of events/17 GeV
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39 diagrams
8 diagrams
Mass of the W boson
Lum100/fb
Lum100/fb
12.2 events
2.4 events
number of events/0.6 GeV
number of events/0.6 GeV
Mass of the top quark
Lum100/fb
Lum100/fb
12.2 events
2.4 events
number of events/2.5 GeV
number of events/2.5 GeV
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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 ?
reconstruction 40 of events fall into the ?
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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versus