Strong EWSB in Top Quark Production

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Strong EWSB in Top Quark Production
Praha, Nov 3, 2005

• Ivan Melo

M. Gintner, I. Melo, B. Trpišová
(University of Žilina)
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Outline

• Motivation for new vector (?) resonances
• Strong EW Symmetry Breaking (SEWSB)
• Vector resonance model
• ? signal at LHC pp ? ?tt ? WWtt X
• ?tt ? tttt X
• ? signal at future ee- colliders
• ee- ? ??tt
• ee- ? tt

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EWSB SU(2)L x U(1)Y ? U(1)Q

• Weakly interacting models
• - SUSY
• - Little Higgs
• Strongly interacting models
• - Technicolor

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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
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WL WL ? WL WL WL WL ? t t t t ? t t
t
t
t
p WL
L i gp M? /v (p- ?µ p - p ?µ p-) ?0µ
gt t ?µ t ?0µ gt t ?µ ?5 t ?0µ
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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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Chiral effective Lagrangian 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 ?µ
u i g/6 Yµ) u ?L b2 ?R Pb i ?µ
(u ?µ u ?µ u i g/6 Yµ) u Pb ?R
?1 ?L i ?µ u Aµ ?5 u ?L ?2 ?R
P? i ?µ u Aµ ?5 u P? ?R
BESS
Our model
Standard Model with Higgs replaced
with ?
gp M? /(2 v gv) gt gv b2 /4
M? va v gv /2
t
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Unitarity constraints
Low energy constraints
gv 10 ? gp 0.2 M?
(TeV) b2 ?2 0.04 ? gt gv b2 /
4 b1 ?1 0.01 ? b1 0

• WL WL ? WL WL , WL WL ? t t, t t ? t t

gp 1.75 (M? 700 GeV) gt 1.7 (M?
700 GeV)
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Partial (G?WW) andtotal width Gtot of ?
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Search at LHC pp ? W W t t X
J. Leveque et al. ATL-PHYS-2002-019 pp -gt Htt
-gt WWtt MH 120-240
GeV
?

• BRA pp ? ?tt ?WWtt
• s(WWtt) s(?tt) x BR(?-gtWW)
• 2) Full calculation pp ? WWtt

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pp ? W W t t X (full calculation) 39 diagrams
in gg channel
No resonance background
?
?
?
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CompHEP results pp ? W W t t X
? 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 gt 100 GeV, y lt 2
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Total cross sections for ?tt and WWtt
BRA s(WWtt) s(?tt) x BR(?-gtWW)
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N(?) N(no res.)
v(N(no res.))
R
S/vB gt 5
BRA
Full calc.
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Search at LHC tttt vs WWtt
BRA
BRA
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Search at Hadron Colliders pp(p) ? t t
Tevatron p p ? t t sS 1.2 fb
sB 8 306 fb LHC p p ? t t
sS 22.7 fb sB 752 000 fb
M?700 GeV G?12.5 GeV No cuts
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Subset of fusion diagrams approximations
(Pythia)
Full calculation of 66 diagrams at tree level
(CompHEP)
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Pythia vs CompHEP

• ? (M 700 GeV, G 12.5 GeV, g
  20, b2 0.08)
• Before cuts
• vs (GeV) 800
  1000 1500
• Pythia (fb) 0.35
  0.95 3.27
• CompHEP (fb) 0.66
  1.16 3.33

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Backgrounds (Pythia)

• ee- ? tt ?
• ee- ? ee- tt
• s(0.8 TeV) 300.3 1.3 fb ? 0.13 fb
  (0.20 fb)
• s(1.0 TeV) 204.9 2.4 fb ? 0.035 fb
  (0.16 fb)

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e- e ? t t
?
different from Higgs !
xy560 nm z0.40 mm n2x1010
? (M 700 GeV, b20.08, g20)
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Conclusions

• New strong ?-resonance model
• pp ? W W t t Xpp ? t t t t X at
  LHC
• R values up to a few 100 (before t,W decays and
  detector effects), L 100 fb-1
• Backgrounds pp ? tt, W jets, Z jets, ?
• ee- ? ??tt R 26 at CM energy 1 TeV, L
  200 fb-1
• ee- ? tt Lscan 1 fb-1

Similar work on pp ? t t t t X T.Han et
al, hep-ph/0405055
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WWtt reconstruction

• WWtt ?l? jj jjb jjb
• b tagging 50
• l detection . 90
• one trigger lepton pT gt 30 (20) GeV e (µ)
• jets pT gt 30 GeV
• kinematical cuts for 6 jets .. 20
• BR W ? e(µ)? .. 21.3 Pl
• W ? hadrons 68 . Ph
• e ecutseb2el 4 Pl Ph 1.2

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Search at Hadron Colliders
M?700 GeV, G?12.5 GeV
Tevatron p p ? t t sS 1.2 fb
sB 8 306 fb LHC p p ? t t
sS 22.7 fb sB 752 000 fb
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pp ? ? t t X(8 diagrams in gg channel)
BRA s(WWtt) s(?tt) x BR(?-gtWW)