Luminosity-Limiting Coherent Phenomena in Electron-Positron Colliders

We have developed a new simulation program that correctly models the transverse beam-beam dynamics of beams with arbitrary distribution and ellipticity, in $e^{+}{e}^{-}$ colliders. We find that the dynamics, and hence the achievable luminosity, is limited by two kinds of coherent phenomena—the flip-flop effect and period- $n$ beam-size oscillations. While both solutions coexist, the former are typically stronger and occur at lower currents than the latter. These results are in broad agreement with experimental observations, and suggest that greater care needs to be taken in the choice of operating parameters of the high-luminosity B factories that are presently under construction.