Working Group Convenors: Vernon
Barger (Wisconsin), Deborah Harris
(Fermilab), Yoshi Kuno
(Osaka); Michael Zeller (Yale)
If muon colliders can be realized, they offer a path to high-energy
lepton collisions for the study of electroweak symmetry breaking and new
phenomena. The large Yukawa coupling of the muon to Higgs bosons and similar
objects, coupled with the naturally small beam-momentum spread, raises
intriguing possibilities for formation experiments. The idea that a millimole
of muons might be collected over the course of a year opens new opportunities
for neutrino factories based on muon storage rings.
This working group is to consider the physics potential of accelerator
complexes that produce very intense muon and neutrino beams. Any such
facility will require a very-high-intensity proton source, and could also
include conventional neutrino beams, a muon-storage-ring neutrino source
or a muon collider. Many of the scientific goals to be explored here overlap
with the interests of P2: Flavor Physics, P5: QCD, E3: Linear
Colliders, E4: Hadron Colliders, E5: Fixed-Target Experiments,
and the underground laboratory aspects of E6: Astro/Cosmo/Particle
Experiments. This group will work in close collaboration with working
groups M1: Muon Storage Rings and Colliders, and M6: Intense
A general goal is to describe a roadmap for the development and productive
exploitation of intense muon and neutrino sources over the next 20-30
years. Are there synergies between underground neutrino detectors, high-intensity
neutrino sources based on pion "superbeams," muon storage rings, and muon
colliders? Does a staged construction program for a multi-TeV muon collider
promise a strong physics program at each stage? What is the scientific
imperative for a lepton collider at tens or hundreds of TeV per beam?
For the different aspects of the physics program:
How rich is the program of neutrino oscillation measurements
that a neutrino factory would make possible? Will the questions
still be interesting when a neutrino factory operates?
What is the optimal machine energy, baseline and flux for measurements
of neutrino mixing angles, matter effects, and CP violation? Is
more than one baseline necessary?
What results from ongoing experiments might materially change
the targets for oscillation studies at a neutrino factory?
What is the role of very low energy experiments that might be
done using a neutrino beam created at the Spallation Neutron Source?
How many of the pressing questions could be answered using super-intense
muon-neutrino and muon-antineutrino beams generated by pion beams?
Are mixed beams of muon neutrinos and electron antineutrinos
(or vice versa) a benefit or a curse? How important is
Can one envisage a practical, large-volume detector that will
identify electrons, muons, and taus, and measure their charges?
If such a detector could be constructed, what advantages would
it bring to experiments?
Nonoscillation neutrino physics. Consider the scientific potential
of neutrino beams from muon storage rings and pion superbeams.
What is the potential for conventional neutrino measurements
at short baselines at a low-energy neutrino factory or at a high-energy
muon storage ring? Specifically, what are the prospects for (i)
extracting parton distributions from hydrogen targets? (ii) measuring
neutrino cross sections? (iii) determining the weak mixing parameter
and the strong coupling constant?
Can a neutrino program based on intense pion beams share detector
facilities with a neutrino factory?
What novel experiments could be carried out using polarized targets
or silicon targets? What is their scientific importance? Are there
other ways to obtain equivalent information?
Intense muon sources. Consider the scientific program that
could be developed using intense sources of low-energy muons. How
do the requirements on beam properties differ from those appropriate
to neutrino factories or muon colliders?
How can intense muon sources advance the study of lepton flavor
violation? What are the relative capabilities of muon decay or
muon conversion experiments and the study of rare kaon decays?
How could the availability of intense muon sources improve the
precision of measurements of fundamental static properties of
the muon, including the anomalous magnetic moment and a permanent
electric dipole moment?
Are there important applications of copious supplies of low-energy
muons beyond particle physics?
Muon colliders. This group should consider the physics potential
of muon colliders as Higgs factories, and at center of mass energies
of 500 GeV, 1 TeV, and several TeV.
For a Higgs factory, what is the program of measurements a muon
collider could accomplish? What luminosity and energy spread are
required for incisive studies of the Higgs boson's properties.
Other than precise determinations of mass and width, what measurements
would establish the nature of the Higgs boson?
For a modest-energy muon collider, can the luminosity be competitive
with a linear collider? How great a disadvantage is the less-flexible
polarization of the muon beams?
Define a program of experimentation for a 4-TeV muon collider.
What are the principal scientific goals? What luminosity is required
to carry them out?
Consider the novel experimental environment at a muon collider:
evaluate the effects of the different background environment at
a muon collider relative to electron and hadron colliders.
For all energies, what compromises must be made for a detector
to operate gracefully in the environment? Will detectors at a
muon collider need new or different technologies than those at
electron or proton machines?
What are the eventual limitations on beam energy and luminosity?
How can full international collaboration on a muon storage ring
or muon collider project be realized? Is it feasible to assign full
responsibility for design, construction, commissioning, test and operation
of major subsystems to different portions of the world community while
maintaining effective overall project management?
Organizing Committee Contacts:
Working Group Convenors: Ian Shipsey (Purdue), Hitoshi Yamamoto (Hawaii), Gustavo
Burdman (Boston); Joel Butler
Asymmetric electron-positron colliders have become highly productive
b factories, and it is natural to consider luminosity improvement
programs or new machines with greatly enhanced luminosity. Phi factories
offer special conditions for the study of kaon decays, quantum entanglements,
and other issues. Tau / charm factories hold promise for detailed measurements
at unprecedented sensitivities. The task of this working group is to consider
the future of low-energy electron-positron colliders and to evaluate developments
needed to make incisive instruments practical.
Electron-positron colliders at energies below the Z mass should
be evaluated in terms of the physics potential that they offer and the
characteristics required to realize that potential. Specific issues that
this group should consider include:
This group should coordinate with the physics issues working groups
to help compile the scientific cases for electron-positron colliders
as b factories (including "giga-Z" machines as b
factories), charm factories, phi factories, and tau factories. What
are the outstanding questions that heavy-flavor factories could address?
For each physics topic, consider the contributions from existing and
potential experiments using other instruments, and give a critical
assessment of the competitive advantages and disadvantages of electron-positron
colliders. Working group P2: Flavor physics is a natural forum
for laying out the comparisons.
What is a reasonable goal for the desired luminosity at the various
cm energies? For each kind of instrument, outline a comprehensive
experimental program and estimate the integrated luminosity required
to carry it out.
Quantify the physics gained at each machine as a function of the
Are there additional energy scales that could yield important results?
What special detector capabilities are required to achieve the scientific
goals of each of the machines? Do any detector R&D issues arise?
This group should interact regularly with working group M2: Electron-Positron
Circular Colliders, to exchange information on the desirable machine
properties and help define accelerator R&D issues for each type of machine.
Organizing Committee Contacts:
Working Group Convenors: Marco
Battaglia (CERN), John Jaros
(SLAC), Jim Wells (UC
Davis); Ian Hinchliffe (LBNL)
Electron-positron linear colliders (and options using gamma gamma, e-gamma,
e-e-) should be evaluated in terms of the physics potential that they
offer, and in terms of the accelerator issues that will guide their evolution.
This group should work in close collaboration with its counterpart, M3:
Linear Colliders, and should examine the impact of a very large
circular electron-positron collider discussed in M2: Electron-Positron
The eeLC group should coordinate with the physics groups to help
compile and critically examine the case for an initial phase of the
ee collider at a cm energy of up to about 500 GeV, depending on the
results from prior experiments at the Tevatron and LHC. For some representative
physics scenarios, what is a reasonable goal for integrated luminosity
at various cm energies, beam polarizations and beam particles? is
there a compelling initial physics program at a luminosity of a few
x 1033 cm-2s-1? Are there particular
advantages or challenges to experimentation raised by the different
running conditions in the TESLA and NLC/JLC designs?
The eeLC group should review the case for and feasibility of special
options for LC operations:
Catalogue the physics needs that may require positron polarization,
gamma gamma collisions or e-e- collisions. Compare the capabilities
of an electron-positron collider and a gamma-gamma collider for
making detailed measurements of the properties of Higgs bosons,
and for discovering Higgs bosons. What are the R&D issues remaining
for each option? What are the requirements on the initial design
to allow any of these to be added after the initial phase?
Examine the case for high-luminosity operation at the Z
pole. What are the benefits and drawbacks from the design of a
special beam delivery system for low energy collisions? Should
there be a special detector devoted to operating below 500 GeV?
What special requirements are imposed if a free electron laser
program is added to the high energy physics facility? What should
the HEP community do to facilitate the potential for a FEL program?
Evaluate the scientific case for an initial-phase "Higgs factory"
at an energy of about 300 GeV.
What new physics landmarks come into view as the energy of a linear
collider is raised to 1 TeV; to 1.5 TeV; to 2 TeV;
to 5 TeV? What luminosity and other performance characteristics
would be required to maximize the scientific output?
Are there particular issues that detector R&D must address to guarantee
the productivity of a linear collider?
What are the beam physics limits and accelerator limits imposed on
LC performance, and what are the primary outstanding R&D issues that
are critical to study in the next several years?
The eeLC group should assume that a technical review panel will likely
be established within the next year to evaluate the superconducting
L-band and warm rf X- or C-band accelerator proposals. That review,
conducted under the auspices of some worldwide body, would examine
the performance parameters of the machines, the technical risks, needed
R&D, comparative costs and upgradability. Without undertaking the
work that such a panel would do, the eeLC group should work to sharpen
the questions that this review panel should examine, and consider
the way in which the panel should operate.
What are the paths for upgrade of an initial LC, both in energy and
in luminosity? What extensions in energy using the original TESLA
or X-band LC designs are feasible? What R&D issues should be given
priority? What is the possibility of upgrading either TESLA or X-band
LC using two-beam drive power sources? What are the critical R&D issues?
What constraints on the initial phase would ultimate conversion to
two-beam drive impose?
How can full international collaboration on a LC project be realized?
Is it feasible to assign full responsibility for design, construction,
commissioning, test and operation of major subsystems to different
portions of the world community while maintaining effective overall
Organizing Committee Contacts:
Working Group Convenors: Krishna Kumar (UMass), Ron
Ray (Fermilab), Paul Reimer (Argonne);
Mark Strovink (Berkeley).
Fixed-target experiments offer a great diversity of beams for use in
experiments of high sensitivity over a wide range of topics in particle
physics. Decay, formation, and scattering experiments (including scattering
on polarized or nuclear targets) all hold important potential. The study
of subtle effects and rare processes offers a virtual window on very high
energy scales. New kinds of experiments may reveal the structure of hadrons
at an unprecedented level of detail. The task of this working group is
to consider the future of fixed-target experimentation (other than experimentation
using muon and neutrino beams, which are the province of working group
E1: Neutrino Factories and Muon Colliders). The group should work
closely with working groups M6: Intense Proton Sources, and M3:
Linear Colliders, and with P2: Flavor Physics, and P4: QCD
and Strong Interactions, as well as P1: Electroweak Symmetry Breaking
and P3: Scales beyond 1 TeV.
This working group is to consider the scientific opportunities for fixed-target
studies in light of the capabilities of existing and planned accelerator
complexes. The group should also call attention to the case for beams
of novel character that might require research and development to be realized.
Provide an inventory of existing and planned accelerators and the
fixed-target beams they supply.
What are the scientific imperatives for the study of rare kaon decays,
and what requirements do they place on detectors and accelerators?
What are the needs for the study of charmed particles? Give a critical
assessment of the comparative advantages and disadvantages of fixed-target
experiments. Working group P2: Flavor Physics is a natural
forum for laying out the comparisons with electron-positron colliders
discussed in working group E2: Electron-positron Colliders below
What are the most important issues in hadron spectroscopy, and how
can they best be addressed?
What questions drive new experiments using pion, kaon, and proton
beams? What beam characteristics do the physics issues demand?
What questions drive new experiments using hyperon beams? What beam
characteristics do the physics issues demand?
What questions drive new experiments using electron beams and photon
beams such as derived from backscattering lasers from electron beams?
What beam characteristics do the physics issues demand?
What opportunities arise from copious sources of antiprotons? What
characteristics of the antiproton beams are required for the key applications?
What would be the goals and attributes of an "antimatter factory"?
What are the prospects for new studies of neutron properties, including
the persistent electric dipole moment, using accelerator sources?
Consider the case of fixed-target beams of higher energy than will
be available over the next decade. What are the most compelling scientific
goals, and what would it take to address them?
What would be the utility of fixed-target beams derived from a linear
collider? What beam characteristics do the physics opportunities demand?
In cooperation with working groups E1 -- E4, survey the needs for
test beams over the next decade and beyond and compare those needs
with the available inventory.
Organizing Committee Contacts:
Working Group Convenors: Kevin Lesko
(LBNL), Tim McKay (Michigan), Suzanne
Staggs (Princeton); Harry
Nelson (Santa Barbara)
Experimental research in Astro/Cosmo/Particle Physics is being carried
out by detectors underground, undersea, in ice, on the surface of the
Earth, and in the sky. In the last decade, remarkable discoveries have
been made by instruments of each flavor, including
the evidence for neutrino oscillations from underground atmospheric
and solar neutrino experiments,
the detection of cosmic-ray particles above the GZK cutoff by ground-based
air shower experiments,
the evidence for the acceleration of the expansion of the universe
from supernovae observations made by ground-based telescopes,
the spatial and temporal mapping of the distribution of gamma-ray
bursts by satellite instruments, and
the detection of anisotropy in the cosmic microwave background radiation
from satellite, balloon, and ground-based detectors
Such results have galvanized interest in astro/cosmo/particle physics,
and there has been an explosion of experimental activity. New instruments
are now coming on line (including SNO, Fly's Eye, AMS, Chandra, XMM, LIGO,
etc.) or are currently under construction (including CDMS-II, Axion, Auger,
ICECUBE, ANTARES, NESTOR, INTEGRAL, VERITAS, HESS, MAP, PLANCK, GLAST,
LIGO-II, etc.). Even larger and more ambitious experiments are being seriously
considered (including UNO, SNAP, DEEP, OWL, LISA, etc.).
The next decade and beyond promise to be very exciting for experimentalists
working in these areas. Not only can we expect new and exciting results
from experiments that are an order of magnitude (or several orders of
magnitude) more sensitive than earlier ones, but the use of new technology
and instrumentation in all areas will lead to important breakthroughs
in capability. Experiments in astro/cosmo/particle physics have a strong
intellectual and technological overlap with those in accelerator-based
particle physics and astronomy, and thus it will be important to carry
out cohesive development of instrumentation across the various fields.
Experimentalists in this area have a broad base of backgrounds including
particle physics, nuclear physics, cosmology/astrophysics, and astronomy.
This working group will be most closely connected with working groups
P2: Flavor Physics and P4: Astro/Cosmo/Particle Physics.
In the area of neutrino oscillations, the group should coordinate its
work with working group E1: Neutrino Factories and Muon Colliders.
The main goals for this working group are to sketch, in broad terms, the
experimental program in astro/cosmo/particle physics, to examine the rationale
for future large-scale experiments, and to understand how experimentation
in this field will benefit from developments in other fields, and vice-versa.
We also need to identify the unique opportunities for experimentation
required to move beyond the current generation of detectors.
Along with the new detectors come challenges that also need to be considered
by this working group. Among other things, we should consider the issues
of coordination between experiments, the need for permanent infrastructure
in the field, the mechanisms of project review and funding, and the way
in which collected data will be made available to the community at large.
Review the current status of experimentation in the following areas:
nonaccelerator particle physics carried out underground, including
solar neutrino, atmospheric neutrino, proton decay, double beta
decay, and supernovae neutrino experiments,
high-energy particle (gamma-ray, cosmic rays, and neutrino) detectors,
dark energy and dark matter experiments,
cosmology experiments, and
detectors of gravitational waves.
The emphasis here should be on existing experiments, or those already
In the various areas of experimentation, examine the generic detector
capabilities needed to carry out the desired scientific program during
the next decade and beyond. For example, among other things, how will
we be able to:
detect the polarization of the CMBR?
carry out photometric and spectroscopic measurements of many
supernovae out to redshifts of 1.5?
detect pp solar neutrinos in real time?
detect WIMPs or axions, or rule them out as interesting dark
make very sensitive wide-field observations of the high energy
gamma-ray and neutrino skies?
search for proton decay at sensitivities exceeding 10^35 years?
search for cosmic ray particles with energies exceeding 10^21
The future scientific program will reflect strong input from working
groups P2 and P4. In conjunction with these generic capabilities,
determine what new advances in technology/ instrumentation will be
critically needed, and outline the prospects for developing these
Identify the major new facilities that are being considered. Enumerate
their quoted performance (sensitivity, resolutions, etc.) and examine
their technical feasibility. What new technologies will be required?
An important infrastructure issue concerns a national underground
laboratory. Taking as a starting point the Underground Science
(Bahcall) report, consider the scientific programs that motivate an
underground laboratory and enumerate the desirable characteristics
of an underground laboratory. Are the requirements of different experiments
compatible with a single site? Taking into account underground laboratory
space around the world, consider whether the U.S. needs such a facility.
What advantages and challenge would the creation of a new national
underground laboratory entail?
The development of experiments in this area has proceeded in a somewhat
random fashion. Instrumentation development has not been supported
vigorously enough, there has been insufficient communication between
the experimental groups, and duplication of experiments with similar
scientific goals. How can some of these issues be better handled in
the next decade? What mechanisms can be used to coordinate worldwide
experimental effort in this field?
Experiments in astro/cosmo/particle physics are being built by people
with a variety of backgrounds (nuclear physics, particle physics,
astrophysics/astronomy, etc.). Funding comes from a variety of agencies
(including NSF, DOE, NASA, Smithsonian, and private sources). Often,
cultural differences lead to problems that should be avoidable in
obtaining funding or developing efficiently organized collaborations.
For example, the astronomical and particle physics communities have
different outlooks on the public availability of gathered data. Another
example is the project review and funding procedures. Different agencies
have different procedures, and this often leads to a lengthy funding
process. Examine some of these cultural differences, seeking community
and agency input. What mechanisms are working and what are not? How
can the community and the agencies work together more effectively?
Organizing Committee Contacts:
Working Group Convenors: Stephan
Lammel (Fermilab), Wesley
Smith (Wisconsin), …, …
Particle physics has often been the driver of progress in technologies
that are the key to advances in other scientific fields, in industry and
eventually commerce. Examples of past decades range from cryogenic vacuum
systems and superconducting wire and magnet technology to the invention
of the World Wide Web. At other times, although not directly the generator
of new technologies, our field has sparked progress by pushing new technologies
to meet the needs of our next-generation experiments or numerically intensive
theoretical investigations. Recent examples include high-precision radiation-tolerant
particle detectors like silicon pixels that are now finding applications
in the field of medical imaging as fast, low-exposure alternatives to
x-ray films; compact high-speed electronics capable of acquiring and processing
vast floods of data; high-gradient linear accelerators for electron-positron
colliders that may form the basis for the future development of x-ray
free electron lasers of super-high instantaneous brilliance; petabyte-scale
analysis challenges of current and next generation collider experiments
and the plans to meet these needs through the development of "Data Grids."
Astrophysics has joined particle physics in this role through new programs
such as large-scale sky surveys, precise measurements of cosmological
parameters, and simulation of astrophysical processes. The scale, complexity
and duration of ongoing and future programs have forced new approaches
to the development of software by large and distributed collaborations,
and have benefitted from the application of new statistical and algorithmic
approaches from applied mathematics. These changes have resulted in the
adoption of new programming models and tools and have led to a major role
by computing professionals (software engineers) in experiments and advanced
This working group should review leading-edge technologies recently
developed (or in need of development) for new experiments and theoretical
or computational investigations. Developments related to particle detectors,
accelerators, online data acquisition systems, offline data analysis systems
and networked "Grid" systems, or other areas, should be examined for their
impact on experimental, theoretical, and computational investigations
in particle physics. Technologies developed, or to be developed, within
particle physics should be examined for their potential impact on society.
The group should also review the demands for computer science expertise
and software engineering in the current and future programs. It should
The technology advances developed or enhanced by research in particle
physics over the past 20 -- 30 years.
Key problems and areas in particle detection technology, accelerator
technology, information technology, and advanced algorithms for further
developments that are vital for progress in our field.
Areas of opportunity in the above fields where particle physics may
play a principal role in fostering progress in key technologies important
to scientific research and/or society at large.
Areas where new developments in other fields may directly benefit
particle physics over the next several years.
Promising areas for common developments among experiments, and between
particle physics and other fields, that could be of great mutual benefit.
The changing role of computing professionals in our field and the
need of physicists to enhance their knowledge of modern computing
approaches and tools.
The working group should aim at formulating a plan for further development
and improved exploitation of such technologies, to the mutual benefit
of our field and society at large. It should estimate the scope, structure,
manpower and other resources that will be required to make such a plan
Organizing Committee Contacts: