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.
Charge:
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 beam polarization.
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: