The transverse beam spin induced asymmetry is calculated for the scattering of transversally polarized
electrons on a proton target within a realistic model. Such asymmetry is due to the interference between
the Born amplitude and the imaginary part of two photon exchange amplitude. In particular, the contribution
of non-excited hadron state (elastic) to the two photon amplitude is calculated. The elastic contribution
requires infrared divergences regularization and can be expressed in terms of numerical integrals of the
target form factor. The inelastic channel corresponding to the one pion hadronic state contribution is
enhanced by squared logarithmic terms. We show that the ratio of elastic over inelastic channel is of
the order of 0.3 and cannot be ignored. Enhancement effects due to the decreasing of form factors bring
the transverse beam asymmetry to values as large as $10^{-4}$ for particular kinematical conditions. |
