Suppression of Beam-Beam Interaction in a Muon Collider

In a recent paper G.V. Stupakov and P. Chen[1] have advanced the possibility of beam-beam interaction suppression in circular colliders for heavy particles such as muons and protons, by introducing a plasma at the interaction point. More recently and independently, A. Skrinsky [2] has suggested to use flowing liquid Li for the same purpose in a muon collider. This is an alternative that is only plausible for muons and indeed is used in the present cooling scenario [3]. The electromagnetic interaction between the colliding beams results in perturbation of the individual particle motion, which leads to unstable motion and loss of the beam. This effect is quantified with the single parameter beam-beam tune shift [4]. For a round beam = rcN 4 N , where N is the number of particles in the bunch, rc is the classical radius of the particle in the beam and N is the normalized emittance. 0:044 for a muon collider. Recalling the definition of luminosity