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Disentangling the Origins of New Gauge Bosons at the ILC

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Disentangling the Origins of New Gauge Bosons at the ILC S. Godfrey, Carleton University Workshop on Possible Parity Restoration at High Energy – PowerPoint PPT presentation

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Title: Disentangling the Origins of New Gauge Bosons at the ILC


1
Disentangling the Origins of New Gauge Bosons at
the ILC
S. Godfrey, Carleton University Workshop on
Possible Parity Restoration at High Energy  Jun.
11-12,   2007,  IHEP,  Beijing
2
Outline
  • Models of new physics
  • Discovery and Identification at the LHC
  • Z Discovery and identification at the ILC
  • W Discovery and identification at the ILC
  • Final Comments

References G. Weiglein et al. LHC/LC Study
Group Phys. Rept. 426, 47 (2006)
hep-ph/0410364 TESLA TDR hep-ph/0106315 A.
Leike, Phys. Rept. 317, 143 (1999)
hep-ph/9805494 M. Cvetic and S. Godfrey,
hep-ph/9504216
3
Many Models of New Physics
  • Extended gauge sectors
  • Extra U(1) factors
  • Left-Right symmetric model
  • Un-unified Model
  • Little Higgs
  • Topcolour
  • Extra dimensions (ADD, RS, UED) KK excitations
  • ADD Graviton tower exchange effective operators
  • Randall-Sundrum Gravitons Discrete KK graviton
    spectrum
  • Ununified Extra Dimensions (UED)
  • Many, many models

4
see  Mohapatra Raychaudhuri Martins
Simoes Wu
Left Right Symmetric Models
  • Expect
  • Higgs Multiplets with an
  • expanded Higgs sector, eg
  • Extra Gauge Bosons
  • r depends on Higgs content of the model
    with
  • r 1 for Higgs doublets and r2 for Higgs
    triplets
  • Will focus on phenomenology of gauge bosons

5
Little Higgs
Arkani-Hamed et al hep-ph/0206021
  • The little Higgs models are a new approach to
    stabilize the
  • weak scale against radiative corrections

New Strong Dynamics Global Symmetry Symmetries
Broken Pseudo-Goldstone Scalars New Gauge Bosons
related to SU(2) New Heavy Top cancels quadratic
divergences Light Higgs SM vector bosons
fermions
  • Need to experimentally identify the little Higgs
    Mechanism
  • Also need to identify the particular little Higgs
    model
  • Study properties of

Han, Logan, McElrath, Wang, Phys.Rev.D67095004,20
03. hep-ph/0301040 Han, Logan, Wang, JHEP
0601099,2006. hep-ph/0506313
6
Many Other Models
Un-Unified Model
  • Left handed Quarks and Leptons transform as
    doublets
  • under separate SU(2) groups
  • qR and lR are singlets under both SU(2)q and
    SU(2)l
  • Parametrize by f - the mixing angle of charged
    gauge bosons

Georgi, Jenkins, Simmons, PRL 62, 2789
(1989) Barger, Rizzo PL B206, 133 (1988)
3rd Family Model
  • Quarks and Leptons of 3rd family transform as
    doublets
  • under a separate SU(2)h group

Effective Rank 5 E6 Model
7
What do these models have in common?
They all have new s-channel structure at TeV
scale
  • Spin 1 appear in many models
  • Z in string inspired models
  • Z, W in extended gauge sectors
  • ZR, WR in left-right symmetric models
  • ZKK, gKK, WKK, in theories with extra dimensions
  • ZH, WH in Little Higgs Models
  • Also possible higher spin states
  • Gravitons in theories with extra dimensions
  • String resonances
  • And scalar states
  • Radions
  • Graviscalars

8
  • How do we discover the new physics?
  • How do we identify the new physics?
  • Likely that discoveries at the LHC will get us
    started
  • But will need the ILC to discriminate between
    models
  • Possible Routes
  • Direct Discovery
  • Indirect discovery assuming specific models
  • Indirect tests of New Physics via Leff
  • Tools
  • Di-fermion channel
  • Anomalous gauge boson couplings
  • Anomalous fermion couplings
  • Higgs couplings

9
New Z Gauge Bosons at the LHC
Di-lepton Resonance Search
Z??? production
  • Select 2 opposite sign high pT
  • isolated leptons and examine
  • invariant mass distribution
  • If you find a peak
  • quantify its significance
  • Measure its s x BR

T. Martin
10
Di-lepton Resonance Search
  • If you dont
  • Derive upper limit on s x BR
  • Constrain models

11
Discovery Limits for Z Gauge Bosons at the LHC
Z??? production
SLH
KK
LH
c
y
h
12
LHC Discovers dilepton s-channel Resonance !!
See Brooijmans
May be seen very early first weeks
What is it? Many possibilities for s-channel
resonance
13
How do we distinguish them?
  • Assume the LHC discovers a single heavy
    resonance
  • Tools to determine what it is
  • Cross sections Widths
  • Angular Distributions
  • Couplings (decays, polarization)

14
LHC can give some information
Invariant Mass Distributions
Z??? production
Rizzo, hep-ph/0305077
Z
Azuelos et al, hep-ph/0402037
15
Forward Backward Asymmetries
Dittmar, Nicollerat, Djouadi, hep-ph/0307020
Han, Logan, Wang, JHEP 0601099,2006.
hep-ph/0506313
LHC can resolve to some extent
16
What about the ILC?
  • Advantages of ILC
  • Precision
  • well defined energy
  • well known initial state
  • High luminosity
  • Excellent particle ID
  • Clear event signatures
  • Polarization of e-, e gives helicity information
  • eg and gg options also being considered
  • New resonances lead to new s- and t-channel
    contributions
  • ILC is the ideal facility to measure this

17
ee-ff
-ef
MZ750 GeV Zc ZLR ZALR
18
Many observables
  • Sensitive to flavour
  • Sensitive to helicity

19
Numerous difermion observables
18 di-fermion observables
20
Discovery vs Exclusion
2s Exclusion Limits (95 C.L.)
21
Dependence on measurement precision
From TESLA TDR
22
Z Identification
Extraction of Z couplings assuming MZ is known
from LHC
95 C.L. bounds L1 ab-1 DL0.2, P-0.8,
P0.6, DP0.5
Note sign ambiguity
S. Riemann TESLA TDR LHC/LC Study
23
What else can we learn?
Godfrey, Kalyniak, Tomkins hep-ph/0511335
24
The Importance of Polarization
  • No polarization
  • Only electron
  • electron positron

25
What happens for higher mass?
26
How does it change with more observables?
27
What happens with higher energy?
28
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29
What happens if Z not detected at LHC?
  • If the Z is too heavy
  • Or if couplings to quarks small
  • The distance from the SM
  • helps determine the model
  • and the mass
  • Measurement at several Ös to
  • disentangle mass and couplings

L1ab-1
L50fb-1
S. Riemann
30
Indirect Signatures for Gravitons
Off Resonance Interference of exchange of
virtual graviton KK states with SM
amplitudes Leads to deviations in
dependent on both l and s/MH
SM
Hewett, hep-ph/9811356
Hewett, hep-ph/9811356
Can use multipole moments to distinguish spin 2
from spin 1
Rizzo hep-ph/0208027
31
Search and Identification of W
  • Limits from LHC up to 5.9 TeV assuming
  • SM strength couplings
  • But very model dependent

In ee- consider two processes
32
Search and Identification of W
Left-Right Symmetric Model
Un-Unified
33
Search and Identification of W
In ee-
SG, Kalyniak, Kamal, Leike, PR D61, 113009 (2000)
Kinematic cuts to reflect detector
acceptance Radiative Bhabba-scatter with e
lost down beam Where mrad is minimum
angle for veto detector
34
Sensitive to W but also to Z

Peaks are due to Z
35
ds/dEg depends on W model sensitivity to W
eR
eL
LRM
SSM(WZ)
KK
36
  • Limits not competitive with LHC
  • But if LHC discovers them can measure their
    couplings

37
Constraints on Couplings Z nn
Includes systematic errors
38
Constraints on Couplings Wen
39
Varying MW
40
  • No Z in process to complicate picture
  • Sensitive to both q and l couplings
  • Can enhance t-channel exchange by imposing cut
    that q is
  • collinear to beam
  • Can then approximate with simpler process
  • Results are consistent with exact calculation
  • Convolute with either WW or backscattered laser
    spectrum

SG, Kalyniak, Kamal, Doncheski, PR D63, 053005
(2001)
41
Backgrounds 2 jets with one lost down the beam
SM
Can be eliminated with
42
Exclusion Limits for W using egnqq
  • At Ös500 GeV, in general not competitive with
    LHC
  • LR model already ruled out by Tevatron
  • Higher limits from eg mode argument for eg
    collider
  • At Ös1 TeV KK, UUM, and SSM competitive or
    surpass LHC

43
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44
Constraints on W couplings from egnqq
  • Assume W discovered at LHC
  • Results for backscattered laser mode
  • 95 C.L. contours

LR
LR
SSM
SSM
SM
KK
KK
45
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46
Summary
  • Extra gauge bosons are a feature of many theories
  • of physics Beyond the Standard Model
  • If the LHC discoveries such a state the ILC
  • will be an extremely powerful tool for
  • disentangling its origins
  • Depending on MZ the ILC would be able to
  • determine the origins of the Z and determine
  • if it arose from Parity Restoration at high
    energy
  • Precision measurements of ILC crucial for this
  • Many independent observables give high resolving
    power
  • Polarization to study different helicities

47
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48
Measuring Little Higgs Parameters
J. Conley, M.P. Le, J. Hewett
MH not known from LHC
s fixed
49
Follows del Aguila, Cvetic and Langacker, PR D48
R969 (1993) Godfrey Cvetic, hep-ph/9504216
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