Anomalous W couplings to V0 Z0 or

1
Anomalous W couplings to V0 ( Z0 or ?)
Can write the Lagrangian for the triple gauge
coupling sector as
where gWW? e, gWWZ e cot ?W in SM
, with all other coefficients
0. Anomalous terms will show up in single and
double W production (except ? exchange). (N.B.
Compton collider accesses a different set of
channels in ?? or e?).
2
Total and differential cross sections ALR
Forward peak dominated by uninteresting ?
exchange can be turned off by choice of
polarisation.
Polarisation also gives sensitivity to anomalous
??V via ALR in WW production.
3
Anomalous WW couplings
Best sensitivity is in semileptonic WW events.
Charge can be identified, and angular
distributions fitted. Lots of tricks learned
from LEP.
Fits to one anomalous moment at a time.

Expected SUSY scale
4
Other possible effects from high scales
Sensitivity to Z in a variety of E6 and
L-R symmetric models, 1000fb-1. Linear Collider
indirect reach is much further than LHC direct.
(Cases A and B are different assumed precisions
see next slide)
5
High Scales, continued
Limits on the scale parameter of Contact
Interactions, from study of polarised ee- to
hadrons (left) or to ?? (right) 500 GeV,
1000fb-1.
Note sensitivity to polarisation precision, and
to positron polarisation
6
Large Extra Dimensions
Lots of new theoretical and detection ideas.
E.G. Search for ee-? ? G, where the
Graviton gets lost in the bulk (A-H,D,D).
Signal is a soft gamma missing
energy. Background inescapable ee-? ?? ?
a) no polarisation
b) e- polarised c) both
polarised

background a)
background b)
background c)
No. of Extra Dimns
c.f. pp ? jet G at LHC. Linear Collider
comparable for ? lt 5, LHC cannot do ? 5 or 6
7
Precision Measurements at the GigaZ important in
all non-SUSY scenarios (and SUSY eventually ?)
L 5?1033 close to pole ? 109 Z0 in lt100 days
From ALR, both beams polarised
Better statistics give better systematics
From lineshape fit
Better statistics vertex resolution
5 point scan of WW threshold. 100 fb-1 in 1
year, ?s 161 GeV
8
Benefits from GigaZ
Redo the SM fit. Confront with what we know
about Higgs.
Mh1 TeV
SM fit with GigaZ MW input
?1 a T, ?2 a U, ?3 a S
Todays blue band
Mh70 GeV
Will this agree with measured mh?
(Dmt100 width of green line)
9
Cheating Invisibility - an example of where
precision is better than energy

• Assume
• 2 HDM with SM-coupled Higgs
• just above machine threshold ?s.
• Light Higgses (h or A) not coupled
• to ZZ
• All other Higgses above threshold
• Scan allowed masses for the above-
• threshold Higgses gives blue dots
• (tiny scatterplots).
• Outer ellipses, current limits
• Inner ellipses, 90 and 99
• at GigaZ
• Red stars, SM prediction if
• mh ?s-100

10
Checklist of ?? and ?e processes
Most need more study!
EWSB
QCD
11
Direct Higgs production in ??
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MOST cross sections are bigger in ??
Pair production of charged Scalars, Fermions or
Ws at sW2
13
The EWSB Labyrinth what the Linear Collider
needs to do
(After Francois Richard)
Y
SUSY?
Explore
SSB mechanism
N
N
SM?
Higgs properties
Y
New Signals?
Explore
Y
Y

N
Quantum Level including GigaZ mt,
Mh, sin2?W, ???
Higgs at LHC or TeV?
N

N
NO Higgs! Confirmed at Linear Coll.?
NDgt4?
Y
Instead of SUSY WHAT?
Explore
TC?
No new physics (yet)
no way out without a Linear Collider
14
What next? Political postlude. The Linear
Collider is an expensive programme 7B for 500
GeV, more to reach 800 GeV to 1 TeV. It will
take 8 years to build, after a decision to go
ahead.

• Physicists need to agree
• that it is the right next step. (Snowmass
  thought so. Do you?)
• the best technology X-band or Superconducting
  (maybe even C-band?)
• where to build it, and how to involve as many
  Labs as possible
• to persuade governments to support it, even if
  not in their own country
• We want to be driven by physics, not expediency!
• In my opinion
• Whatever the cause of EWSB, the Linear Collider
  is essential to study it.
• We do not need to wait for results from LHC
  before going ahead

Attend your local work- Shops LCWS02