Effect of the beam-beam interactions on the dynamic aperture 
and amplitude growth in the LHC


The dynamic aperture at collision energy is determined 
primarily by the nonlinear fields
of the IR quadrupoles but is also influenced by the 
beam-beam interactions. We revisit the choice of the 
crossing angle that maximizes the dynamic aperture 
with an accurate modeling of the long-range interactions 
and use the present values of the IR quadrupole field 
harmonics.  A separate but related issue we address is 
the amplitude growth of particles in the beam halo
due to the long-range interactions.