  I investigate the difference between the quasiparticle properties in two
dimensional(2D)and three dimensional(3D) s-wave superconductors. Using the
original BCS model for the pairing interaction and direct Coulomb interaction I
show that quasiparticle interactions lead to a stronger energy dependence in
the single-particle self-energies in 2D than in 3D superconductors. This
difference arises from the presence of the low lying collective mode of the
order parameter in the 2D case which ensures that oscillator strength in the
response function is at low frequencies, $\sim \Delta$. This strong
quantitative difference between 2D and 3D superconductors points to the
importance of treating quasiparticle interactions in low dimensional
superconductors rather than assuming that renormalizations remain unchanged
from the normal state.
