  Corrections to the masses of baryons from baryon-meson loops can induce
splittings between baryons which are comparable to those arising from the
residual interactions between the quarks. These corrections are calculated
using a pair-creation model to give the momentum-dependent vertices, and a
model which includes configuration mixing to describe the wave functions of the
baryons. A large set of baryon-meson intermediate states are employed, with all
allowed SU(3)_f combinations, and excitations of the intermediate baryon states
up to and including the second band of negative-parity excited states. Roughly
half of the splitting between the nucleon and Delta ground states arises from
loop effects. The effects of such loops on the spectrum of negative-parity
excited states are examined, and the resulting splittings are sensitive to
configuration mixing caused by the residual interactions between the quarks.
With reduced-strength one-gluon-exchange interactions between the quarks fit to
the Delta-nucleon splitting, a comparison is made between model masses and the
bare masses required to fit the masses of the states extracted from data
analyses. This shows that it is necessary to also adjust the string tension or
the quark mass to fit the splitting between the average bare masses of the
ground states and negative-parity excited states, and that spin-orbit effects
are likely to be important.
