Nonlinear Coupling In The Crossing-Angle Beam-Beam Interaction

The effects of the beam-beam interaction with a small crossing angle on large-amplitude particles in an e+e- collider are studied. An analytical resonance analysis method is developed to understand the nonlinear coupling resonance driving mechanism. The major effect of the crossing angle for large-amplitude particles is to drive the 5Q(x) +/- Q(s) = integer resonance family. The analytic results are consistent with a computer simulation. The resonance is observed in the crossing-angle experiment in the Cornell Electron Storage Ring.