  Accurate numerical results are derived for transport properties of Kondo
impurity systems with potential scattering and orbital degeneracy. Using the
continuous-time quantum Monte Carlo (CT-QMC) method, static and dynamic
physical quantities are derived in a wide temperature range across the Kondo
temperature T_K. With strong potential scattering, the resistivity tends to
decrease with decreasing temperature, in contrast to the ordinary Kondo effect.
Correspondingly, the quasi-particle density of states obtains the antiresonance
around the Fermi level. Thermopower also shows characteristic deviation from
the standard Kondo behavior, while magnetic susceptibility follows the
universal temperature dependence even with strong potential scattering. It is
found that the t-matrix in the presence of potential scattering is not a
relevant quantity for the Friedel sum rule, for which a proper limit of the
f-electron Green's function is introduced. The optical theorem is also
discussed in the context of Kondo impurity models with potential scattering. It
is shown that optical theorem holds not only in the Fermi-liquid range but also
for large energies, and therefore is less restrictive than the Friedel sum
rule.
