  We consider a new momentum cut-off scheme for sums over zero-point energies,
containing an arbitrary function f(k) which interpolates smoothly between the
zero-point energies of the modes around the kink and those in flat space. A
term proportional to df(k)/dk modifies the result for the one-loop quantum mass
M^(1) as obtained from naive momentum cut-off regularization, which now agrees
with previous results, both for the nonsusy and susy case. We also introduce a
new regularization scheme for the evaluation of the one-loop correction to the
central charge Z^(1), with a cut-off K for the Dirac delta function in the
canonical commutation relations and a cut-off \Lambda for the loop momentum.
The result for Z^(1) depends only on whether K>\Lambda or K<\Lambda or
K=\Lambda. The last case yields the correct result and saturates the BPS bound,
M^(1)=Z^(1),in agreement with the fact that multiplet shortening does occur in
this N=(1,1) system. We show how to apply mode number regularization by
considering first a kink-antikink system, and also obtain the correct result
with this method. Finally we discuss the relation of these new schemes to
previous approaches based on the Born expansion of phase shifts and
higher-derivative regularization.
