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Signatures of a new vector resonance from strongly interacting electroweak symmetry breaking

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Signatures of a new vector resonance from strongly interacting ... pp ?0 tt bb t t X bb l?lb jjb (43.5%) reconstruction (CompHEP, Pythia, Atlfast, Root) ... – PowerPoint PPT presentation

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Title: Signatures of a new vector resonance from strongly interacting electroweak symmetry breaking


1
Signatures of a new vector resonance from
strongly interacting electroweak symmetry breaking
Exotics meeting, CERN Oct 10, 2007
  • M. Gintner, I. Melo, B. Trpiová
  • University of ilina

2
Outline BESS Model Vector
Resonance ? pp processes sensitive to ?, cross
sections (CompHEP
calculation)
Reconstruction of pp ? W W- t t
X and pp ? b b t t X
(CompHEP, Pythia, Atlfast, Root)
3
Chiral SB in QCD
  • SU(2)L x SU(2)R ? SU(2)V , vev 90
    MeV

EWSB
SU(2)L x SU(2)R ? SU(2)V , vev 246
GeV
4
,b
,b
,b
,b
t
t
t
1,2
1,2
1,2
p WL
are BESS coupling constants
is the SU(2)L coupling constant
v is EW scale (246 GeV)
R.Casalbuoni et al. Phys.Lett. B155 (1985) 95
M.Gintner, I.Melo, B.Trpisova, Acta Phys.
Slovaca, 56(2006)1
5
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
R.Casalbuoni et al. Phys.Lett. B155 (1985) 95
M.Gintner, I.Melo, B.Trpisova, Acta Phys.
Slovaca, 56(2006)1
6
Large Hadron Collider pp at 14 TeV
pp ? ?tt ? WW tt pp ? ?tt ? tt tt pp ? ?tt
? bb tt pp ? ?bb ? bb tt
pp ? WW pp ? tt
pp ? jj tt
pp ? jj WW
M? 1 000 GeV G? 42.3 GeV
7
CompHEP pp ? bb ? tt X
sS 174 fb
Signal 6 diagrams
Background G G ? t t 3 diagrams
sB 25 605 fb
8
CompHEP pp ? bb ? WW- X
sB 450 fb
sS 15.4 fb
Signal 4 diagrams
mWW
sB ? 100 fb
Background
uu ? WW- dd ? WW- 4 diagrams
sS ? 14.0 fb
pTW
9
CompHEP pp ? tt?0 X ? bb t t X
sB 17 fb
QCD
sS 3.7 fb
Signal
mbb
Signal 8 diagrams
QCD bottom
QCD background 35 diagrams
Signal bottom
pTb
10
CompHEP pp ? bb?0 X ? bb t t X
sB 833 fb
QCD
Signal
G?127 GeV s 337 fb
sS 134 fb
mtt
Signal 8 diagrams
QCD top
QCD background 35 diagrams
Signal top
pTt
11
CompHEP pp ? tb? X ? bb t t X
sB 332 fb
QCD
sS 86 fb
Signal
mtb
Signal 8 diagrams
QCD top
bottom
QCD background 35 diagrams
Signal top
bottom
pTq
12
CompHEP results pp ? W W- t t X
? M?700 GeV, G?4 GeV, b20.08,
gv10 39 diagrams
Irreducible background
sS 1.0 fb
8 diagrams
MWW(GeV)
Cuts 700-3G? lt mWW lt 700 3G? (GeV)
pT (t) gt 100 GeV, y(t) lt 2
sB 0.037 fb
13
39/8 diagrams in the dominant gg channel
CompHEP results pp ? W W t t X (continued)
?
No-resonance background
?
?
14
Cross sections in the peak region in fb
sS 174 sB 25 605 sS 14 sB
100 sS 3.7 sB 17 sS 134 sB
833 sS 86 sB 332 sS 1 sB
0.037
  • pp ? bb ? tt X
  • pp ? bb ? WW- X
  • pp ? tt?0 X ? bb t t X
  • pp ? bb?0 X ? bb t t X
  • pp ? tb? X ? bb t t X
  • pp ? ?0 tt ? W W t t X

15
pp ? W W t t X l jjbjjbjj
reconstruction (CompHEP, Pythia, Atlfast, Root)
One charged lepton channel
40 of events
electron gt 30 GeV
GeV
muon gt 20 GeV
mass of the W
Cuts
of
jets gt 25 GeV
50
b-tagging efficiency
Reconstruction criterion
16
CompHEP
? M?1000 GeV G?26 GeV
Reconstruction
number of events/32 GeV
Lum 100 fb-1 12.8 events
17
pp ? ?0 tt ? bb t t X ? bb l?lb jjb (43.5)
reconstruction
(CompHEP, Pythia, Atlfast, Root)
e gt 30 GeV
µ gt 20 GeV
of
Cuts
L 100 fb-1
j gt 25 GeV
GeV
NS0.8
L 100 fb-1
NB8
18
Conclusions
sS 174 sB 25 605 sS 14 sB
100 sS 3.7 sB 17 sS 134 sB
833 sS 86 sB 332 sS 1 sB
0.037
  • pp ? bb ? tt X
  • pp ? bb ? WW- X
  • pp ? tt?0 X ? bb t t X
  • pp ? bb?0 X ? bb t t X
  • pp ? tb? X ? bb t t X
  • pp ? ?0 tt ? W W t t X

Thanks to Jonathan Ferland for his great help
with reconstruction !
19
Backup
20
Distribution in invariant mass of WW pair (? ?WW)
? M?700 GeV, G?4 GeV, b20.08,
gv10
Pz(?) chosen correctly in 61.5 of events
number of events/17 GeV
21
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
22
1. Can we improve WWtt reconstruction ?
L 100/fb 2.4 events 8 diagrams
versus
2.
8 diagrams
23
Total width Gtot of ?
24
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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