Title: μ+-μ− colliders: possibilities and challenges
Abstract: The current status of the μ+-μ− collider concept is reviewed and discussed. In a reference scenario, a high-intensity pulsed proton accelerator (of K-factory class) produces large numbers of secondary π's in a nuclear target, which produce muons by decay. The muons are collected and cooled (by “ionization cooling”) to form high-intensity bunches that are accelerated to high-energy collisions. High-luminosity μ+-μ− and μ−-p colliders at TeV or higher energy scales may be possible. Challenges in implementing the scenario are described. Possible variations in muon production, accumulation, and collisions are discussed; further innovations and improvements are encouraged.