by the Snowmass Physics Groups
new discoveries in particle physics and cosmology have vastly
improved our understanding of the universe. Recent experimental
results and theoretical developments strongly suggest that even
greater discoveries are close at hand.
- Among the outstanding issues
to be addressed are:
origin of electroweak symmetry breaking
- the potential unification of
the fundamental forces, including gravity
- the elucidation of neutrino
masses and mixing
- the origin of CP-violation
and the nature of flavor
- the physics of quark and
gluon production and confinement, and the phases of QCD
- the nature of dark matter and
dark energy, and the cosmology of the early universe.
- No single type of facility
can illuminate all of these fundamental issues. Maintaining a
diverse program is crucial for deciphering the basic laws of
- Strong support for existing
experimental research, including the Tevatron, the B-factories,
and the Large Hadron Collider programs, particle astrophysics and
cosmology, and the physics of heavy flavors, neutrinos and rare
decays, is critical for the continuing success of
particle physics. Theoretical
research in support of these experimental programs is essential.
- There are fundamental
questions concerning electroweak symmetry breaking and physics
beyond the Standard Model that cannot be answered without a
physics program at a Linear Collider overlapping that of the Large
Hadron Collider. We therefore strongly recommend the expeditious
construction of a Linear Collider as the next major international
High Energy Physics project.
- Forthcoming discoveries will
point the way for future exploration of new frontiers.
It is therefore essential that an aggressive R&D program
be pursued to develop the needed facilities and associated
technologies. These include new energy-frontier hadron and lepton
colliders and detectors, neutrino superbeams and factories, large
underground detectors, and space- and ground-based astrophysical
experiments. Future large-scale projects should involve extensive
partnerships of the international community.