New Vector Resonance as an Alternative to Higgs Boson (Strong EWSB)

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New Vector Resonance as an Alternative to Higgs
Boson(Strong EWSB)
Fyzika za Štandardným modelom klope na dvere
Svit, 9.-16.9. 2007

• Ivan Melo
• University of Zilina

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EWSB - one of Great Mysteries of Particle Physics
Problem !

• SM . 1 Higgs
• Strong EWSB .. no Higgs
• SUSY (MSSM) ..... 5 Higgs
• Large Extra Dimensions
• Little Higgs

Monotheists Atheists Polytheists
Classical
New
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Naturalness problem (Fine-tuning, Gauge Hierarchy
problem)
- (200 GeV)2 for ? 103 GeV
- (200 GeV)2 . 1032 for ? 1019 GeV
mH 100 200 GeV
- (200 GeV)2 . 1032
(200 GeV)2 . 1032
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SM Strong EWSB SUSY (MSSM)
Large Extra Dimensions Little Higgs
0 ? mH 319 GeV
H not elementary, it melts into techniquarks at
?TC 1-3 TeV

t1(2)
? is not 1019 GeV, ? is as low as 103 GeV
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Fundamental energy scales
Greg Anderson, Northwestern University
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• Every fundamental energy scale should have a
  dynamical origin
• 
  K. Lane

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Linear sigma model (model of nuclear forces)
U(s,p)
s
v µ/v? 90 MeV
SU(2)L x SU(2)R ? SU(2)V
s v s (spontaneous chiral symmetry
breaking)
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Standard model Higgs Lagrangian
U(s,p)
s
SU(2)L x SU(2)R ? SU(2)V
v µ/v? 246 GeV
Higgs Lagrangian Linear sigma model
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Where are EW pions ???
ms µ2 mp 0
SU(2)L x SU(2)R ? SU(2)V (global)
massless GB
Higgs mechanism W,Z become massive by eating GB
SU(2)L x U(1)Y ? U(1)Q (local)
EW pions F1,F2,? become WL, ZL
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Where is s ?

• the (linear) s model, although it has some
• agreeable features, is quite artificial. A
  new particle is postulated, for which there is no
  experimental evidence
• M. Gell-Mann, M. Levy, Nuovo Cimento 16 p.705
  (1960)

and they decided to get rid of s particle
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Nonlinear s model (QCD)
v 90 MeV
Effective Lagrangian valid until a few hundred MeV
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Where is Higgs boson ?
Higgs Lagrangian, although it has some
agreeable features, is quite artificial. A new
particle is postulated, for which there is no
experimental evidence
so we get rid of the Higgs boson
Higgs boson is not necessary, Higgs mechanism
works even without Higgs !
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Nonlinear s model (SM Higgs sector)
v 246 GeV
Effective Lagrangian valid until 1-3 TeV
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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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Technicolor

• Technicolor of massless U and D techniquarks
• SU(2)L x SU(2)R invariant
• As a result of dynamics, interactions of
• massless techniquarks, we get
• - SU(2)L x SU(2)R ? SU(2)V
• - v 246 GeV
• - EW pions WL, ZL made of
  U,D techniquarks
• Best explanation of Naturalness Hierarchy
  problems

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Extended Technicolor (ETC)

• ETC was introduced to give masses to fermions
• but introduced also large FCNC and conflict
  with precision EW measurements

U
D
ETC
Walking technicolor
f
f
ETC has also problem to explain large top mass
(mt 174 GeV)
Topcolor assisted technicolor
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WL WL ? WL WL WL WL ? t t t t ? t t
t
t
t
(Equivalence theorem)
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 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 P? i ?µ u Aµ ?5 u P?
?R
BESS
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(p1,p2)
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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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, gv 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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N(?) N(no res.)
vN(tt?eett)(N(no res.))
R
S/vB gt 5
gv
gv
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e- e ? t t
?
different from Higgs !
xy560 nm z0.40 mm n2x1010
? (M 700 GeV, b20.08, gv20)
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39/8 diagrams in the dominant gg channel
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No-resonance background
?
?
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CompHEP results pp ? W W t t X
? M?700 GeV, G?4 GeV, b20.08,
gv10 39 diagrams
8 diagrams
MWW(GeV)
gt1,2 gv b2/4
gpM?/2vgv
s(gg) 10.2 fb ? 1.0 fb
Cuts 700-3G? lt mWW lt 700 3G? (GeV)
pT (t) gt 100 GeV, y(t) lt 2
No resonance background s(gg)
0.037 fb
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l jjbjjbjj reconstruction (CompHEP, Pythia,
Atlfast, Root)
Athena 9.0.3
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
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b-tagging efficiency
Reconstruction criterion
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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
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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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? M?1000 GeV G?26 GeV
Lum 100 fb-1 12.8 events
number of events/32 GeV
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1. Can we improve WWtt reconstruction ?
L 100/fb 2.4 events 8 diagrams
versus
2.
8 diagrams
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Conclusions

• New vector resonance as an alternative to Higgs
  Boson
• Modified BESS model motivated by technicolor
• Rich ee- and pp phenomenology