Calculations on depolarization in HERA due to beam-beam effects

Polarized beams will play an important role in the HERA physics program in the next few years. First, the HERMES experiment will use longitudinally polarized electrons (or positrons) for collisions with a polarized gas target while at the detectors H1 and ZEUS these particles undergo collisions with the proton beam in a transversely polarized state. Later, spin rotators will be installed around the H1 and ZEUS experimental regions, allowing for collisions of longitudinally polarized electrons/positrons with the proton beam. Measurements show that for present HERA beam intensities the beam-beam effect does not reduce polarization by more than 5%. We present calculations using the spin tracking code SITROS which explore depolarization due to beam-beam effects towards higher beam intensities and luminosity