Study of beam-beam effects in HERA with self-consistent beam-beam simulation

The beam-beam effect in HERA was studied with a self-consistent beam-beam simulation by using the particle-in-cell method. A remarkable agreement between the experimental measurement and the simulation result was observed on the emittance growth, luminosity reduction, and coherent tune shifts. The simulation study also showed that the chaotic coherent beam-beam instability could occur in HERA and this collective beam-beam instability could be avoided with a slightly different working point.