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R. Sekhar ChivukulaMichigan State University
November 13, 2012
Vector Boson Signalsof Electroweak
Symmetry Breaking
Monday, November 12, 12
A New Boson
Monday, November 12, 12
ATLAS
CERN-PH-EP-2012-218arxiv:1207.7214
Monday, November 12, 12
CERN-PH-EP-2012-220arxiv:1207.7235
CMS
Monday, November 12, 12
Is the New Boson THE HIGGS Boson?
Symmetry Magazine, Oct 30, 2012
Monday, November 12, 12
Loss of Unitarity in
Electroweak Symmetry Breaking
Monday, November 12, 12
Sum 0
SU(2) x U(1) @ E4
Monday, November 12, 12
including (d+e)
SU(2) x U(1) @ E2 & The Higgs
Lee, Quigg, Thacker
Monday, November 12, 12
including (d+e)
SU(2) x U(1) @ E2 & The Higgs
Lee, Quigg, Thacker
gHWW
Monday, November 12, 12
Alternatives?“Higgsless” Models
Monday, November 12, 12
Expand 5-D gauge bosons in eigenmodes: e.g. for S1/Z2:
Extra-D
KK mode
4-D gauge kinetic term contains1
2
!!
n=1
"
M2
n(Aan
µ )2 ! 2MnAan
µ !µA
an
5 + (!µAan
5 )2# i.e., A
anL ! A
an5
Mn =
n
R
Flat Space:
Massive Vector Bosons from 5-D
Monday, November 12, 12
g4 =
g5!
!RMn =
n
R!UV !
1
g25
4D EFT
5D EFT
???
1/R
�UV
Energy Scales and Couplings
Monday, November 12, 12
Cancellation of bad high-energy behavior through
exchange of massive vector particles
RSC, H.J. He, D. Dicus (2002)Csaki, Grojean, Murayama, Pilo, Terning (2004)
4-D KK Mode Scattering
Monday, November 12, 12
Higgsless models are low-energy effective theories of Dynamical Electroweak Symmetry Breaking with. They include:
• massive 4-d gauge bosons arise in the context of a 5-d gauge theory with appropriate boundary conditions
• WW scattering is unitarized through exchange of KK modes (instead of scalar bosons)
• the language of Deconstruction allows a 4-d “Moose” representation of the model
Chivukula & He hep-ph/0201164Csaki, Grojean, Murayama, Pilo, Terning hep-ph/0305237
General Principles
Monday, November 12, 12
A Simple Realizaton:The Three-Site Model
Monday, November 12, 12
g0 g1f2f1
g2L
R
SU(2) ! SU(2) ! U(1) g0, g2 ! g1
Gauge boson spectrum: photon, Z, Z’, W, W’ (as in BESS)
Fermion spectrum: t, T, b, B ( is an SU(2) doublet)
and also c,C, s,S, u,U, d,D plus the leptons
pR1
!L1!L0
!R1 tR2, bR2
!
RSC, Coleppa, DiChiara, He, Kurachi, EHS, Tanabashi hep-ph/0607124
3-Site Model: Basic Structure
Monday, November 12, 12
g0 g1f2f1
g2L
RSU(2) ! SU(2) ! U(1)
g0, g2 ! g1
“Bulk Fermion” RH Boundary FermionLH Boundary Fermion
degree of delocalization
3-Site Fermion masses
each ordinary fermion mass value is tied to ordinary fermion masses are of the form mf ⇡M✏L✏fR
heavy “KK” fermion masses are ~ M
flavor structure same as in standard model
M
✏L L0⌃01 R1 + R1 L1 + L1⌃12
✓✏uR 00 ✏dR
◆ ✓uR2
dR2
◆�
✏fR
Monday, November 12, 12
S = T = W = 0
Y = M2
W (!W ! !Z)
Use WW scattering to see W’: Birkedal, Matchev, Perelstein hep-ph/0412278
General ideal delocalization condition gi(!fi )2 = gW vw
i
is realized as in 3-site model
From the W, fermion eigenvectors, one solves for
For all but top quark, !fR ! 1 so the choice
g0(!fL0
)2
g1(!fL1
)2=
v0W
v1W
�2L ⇤ (1 + �2fR)2⇤
x2
2+
�18�
�2fR
2
⇥x4 + · · ·
⌅x2 �
�g0
g1
⇥2
⇥ 4�
MW
M �W
⇥2
3-Site Ideal Delocalization
makes W’ fermiophobic and Z’ nearly so
✏2L ⇡ 2✓
M2W
M2W 0
◆
Monday, November 12, 12
1-loop fermionic EW precision corrections too large
Allowed Region
MW’
M
10000
20000
25000
400 600 800 1000 1200 0
5000
15000
T,B
KK fermion mass (GeV)
W’ mass (GeV)
Unitarity violated
WWZ vertexvisibly altered
Chivukula et al. hep-ph/0607124
3-Site Parameter Space
�⇢ =M2 ✏4tR16 ⇡2 v2
MW 0 << MT,B
Monday, November 12, 12
But What About the New Boson?
Hong-Jian He, Ning Chen, Tomohiro Abe: Arxiv 1207.4103
Monday, November 12, 12
Linear Scalar Link Fields: ϕ1 & ϕ2
Leads to two-Higgs particles: h, H
pR1
He, Chen, Abe: arxiv 1207.4103
Linear 3-Site Model
Monday, November 12, 12
WW Unitarization
H,hγ,Z,Z’
+
Unitarize jointly by scalar and vector exchange!Leads to sum rule:
See next talk...Monday, November 12, 12
LHC Phenomenologyof Vector Bosons
RSC, EHS, H.-J. He, Y.-P. Kuang, et. al., Phys. Rev. D78 (2008) 031701& arxiv:1206.6022 and PRD in press
Monday, November 12, 12
References
LHC Signatures:
W’,Z’ Production and Decay at LHC
⌫⌫
Monday, November 12, 12
Two processes with large rates and clear signatures!
W’ production at LHC
Vector Boson Fusion
Associated Production
LHC @14 TeV
Monday, November 12, 12
References
500 GeV W’ boson
Associated Production (WZZ channel)
Monday, November 12, 12
Background is 10x larger than
estimated in Birkedal, Matchev
& Perelstein (2005)
forward jet tag removes WZ background
500 GeV W’ boson
Vector Boson Fusion (WZjj channel)
Monday, November 12, 12
Fusion
Associated
Integrated Luminosity for W’ Discovery
LHC at 14 TeV
Monday, November 12, 12
W’ Discovery at 8 TeV
Associated Production
Monday, November 12, 12
arxiv:1206.6022, PRD in press
W’ Production at 8 TeV
Monday, November 12, 12
• ATLAS/CMS has discovered a new boson.
• Measure properties: is it the Higgs?
• If it isn’t, there are potential new signatures in multi-gauge boson signals.
Conclusion
Monday, November 12, 12
• C.-P. Yuan met Prof. Kuang at CCAST Workshop, Beijing in 1993.
• E. Simmons invited by Prof. Kuang to speak at ITP in Beijing in 1995.
• NSF USA-China International Program, Qing Wang and Yi Liao visited MSU, Carl Schmidt visited Tsinghua U, 1997-99.
• Hong-Jian He was a postdoc at MSU, 1997-2000.
• Chivukula, Dicus, & He on unitarity, 2001.
• Kuang et. al., LHC signature paper 2007...
MSU, Tsinghua, and Prof. Kuang
Monday, November 12, 12
生日快乐!
Monday, November 12, 12
Backup Slides
Monday, November 12, 12
Discussion Question
N. Arkani-Hamed, SavasFest 2012
?
Monday, November 12, 12
Ohl & Speckner arXiv:0809.0023
Z’ Search at LHC
Ohl & Speckner predict that the 3-site Z’ boson (at or near ideal delocalization) should be visible in 100 fb-1 of LHC data
pT � 50 GeV
| cos �| � 0.95
75 GeV mjj 85 GeV
MW 0 = 500 GeV
Monday, November 12, 12
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