Lattice function perturbations caused by the beam-beam interaction

A model of the beam-beam interaction has been used to explain the discrepancy between the luminosity as derived from experimental counting rates versus the luminosity derived from beam measurements. The physical picture is that the beam-beam interaction distorts the lattice functions of the machine. These distortions change the real luminosity by altering the beam size at the IR. The calculated luminosity is also affected in that the lattice distortions cause beam parameters to be incorrectly determined. >