Understanding Matter, Energy, Space and Time:

1
Understanding Matter, Energy, Space and Time The
Case for the ee- Linear Collider

• Document produced at the instigation of the
  World Wide Study of Physics and Detectors in its
  meeting in Jeju Korea , August 2002. The writing
  group consisted of Takayuki Matsui, Sachio
  Komamiya, Francois Richard and Paul Grannis.

2
Preliminary versions of the document were made
available to the worldwide linear collider
community, and were discussed in regional
meetings in Prague Arlington TX. Numerous
comments were received from the community and
were incorporated into the current draft.
Comments and responses by the writing committee
are found on the web page
http//sbhep1.physics.sunysb.edu/grannis/wwlc_rep
ort.html
3
What is this report intended to do? The hardest
task was to come to some common understanding on
who the document is aimed at. The audiences
could be (a) HEP community (b) scientists outside
high energy, (c) officials/staff of
governments. Choose to make it a vehicle for HE
physicists defining the case for the LC, in
language comprehensible to scientists in allied
disciplines. succinctly stated and without
specialized jargon, but not wholly
oversimplified. At twelve pages of reasonably
dense argument, it is inappropriate for use as a
primary document for government officials. It
could be of use as a supplementary document
outlining the science goals and demonstrating
worldwide support of HE community.
4

• The WW Physics and Detector group believed that
  having a single document, subscribed to by a
  large number of physicists from around the world,
  would have the benefits
• A first coordinated attempt to state the case for
  the LC by individuals in all regions, and thus
  provide tangible evidence of the
  single-mindedness of the international community.
  
• Provide the case for the LC from which simpler
  documents aimed at governments, the public, or
  other audiences could be drawn.
• Outline the set of options that could be
  implemented, with the nature of the arguments
  that should shape the 'scope document' to follow.
  (This document does not attempt to define the
  priorities for the scope definition, but gives
  some guidance on how scenarios of emerging
  physics might shape the choice.)
• Give the nature of LC detector requirements
• Provide a basis for arguing the need for a LC
  that operates during the LHC era.

5

• The premise is given in the introduction
• A worldwide consensus has formed for a baseline
  LC with collision energies up to 500 GeV,
  luminosity above 1034cm-2s-1, and electron
  polarization (gt80). We know enough to predict
  that this baseline LC will make key discoveries
  and measurements illuminating the nature of EWSB.
• Outline
• The scientific case for the Linear Collider
• The Linear Collider facility
• Linear Collider detectors
• The international character of LC research
• Conclusions

• Where we stand today
• Understanding the Higgs boson
• New discoveries beyond the Standard Model
• Benefit of precision measurements and interplay
  between LC and LHC
• Cross connections (n quark flavor, cosmology,
  astroparticle, RHI physics)

6

• Key scientific points
• We know enough now to predict with great
  certainty that fundamental new understanding of
  how forces are related, and the way that mass is
  given to all particles, will be found with a
  linear collider operating at an energy of at
  least 500 GeV.
• We are confident that the new physics that we
  expect beyond the standard model will be
  illuminated by measurements at both the LHC and
  the LC, through an intimate interplay of results
  from the two accelerators.
• The physics investigations envisioned at the LC
  are very broad and fundamental, and will require
  a leading edge program of research for many years.

7
Figure intended to illustrate the ability of
precision measurements to illuminate physics at a
much higher scale many found it either
confusing or unnecessary. Eliminated in the
present version.
8

• Concluding bullets
• Scientific case rests on recent experiments we
  are confident of discoveries at the LC
• Concurrent LHC and LC operation needed to
  maximize discovery
• Energy above 500 GeV will be needed ultimately
• Two viable technological approaches exist
• Several options (e-e-, gg, eg, positron
  polarization) would be beneficial, depending on
  physics. Retain flexibility to add.
• State of the art detectors needed. RD needed
  now
• Inter-regional cooperation mechanisms now
  established. LC can be template for world
  collaborative projects

9

• Next steps
• ILCSC endorsement (or recommendation to modify)
  this document.
• Assemble names of signatories through the
  regional Physics and Detector Working Groups
  (list on the WW group web page referenced in
  document).
• Proceed to a scope document using this as the
  basis for possible options.
• Produce materials for governments, outreach
  etc. Should these be unified or
  regional/national?