Acceptance calculations methods for low-beta* optics

We report about two methods to estimate the RP acceptance at low beta* optics. The first approach parametrizes the proton coordinates as a function of the optical functions which depends on the transverse position, on the scattering angle and on the momentum loss of the proton at the interaction point. A complete parametrization has been performed and we conclude that it works only for momentum loss less than 1 percent. The second approach is based on the tracking of the proton through the LHC lattice using MAD: look-up tables in different kinematical variables intervals are created.