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The CSR and a variety of
coincidence measurements suggest the limitations of the quasifree picture.
The dip region has long been recognized to have strength well in excess of
one-body expectations. One of the most direct pieces of evidence comes
from longitudinal-transverse separations in (e,e
p) at
MIT/Bates [Ul87] and NIKHEF [La90][St88] on carbon, lithium and
oxygen targets. The MIT/Bates 
C(e,ep) data are shown in
Figure 
where an excess of transverse strength at large
missing energies is apparent. The important role played by the continuum
is evidenced by the observation that the difference between the
longitudinal and transverse responses starts increasing above missing
energies of 28 MeV, the threshold for two-nucleon emission. This effect
has also been observed at NIKHEF via 
Li(e,ep) where the 2N threshold
is only 8 MeV compared to 28 MeV in carbon. In all cases, the increased
transversality is associated with the two-nucleon knockout threshold.
One concludes that the dominant part of the inclusive differences resides
in the additional two- (or many-) body strength. Recent progress in
large-scale numerical calculation for the lithium isotopes [Pa95]
should allow rigorous confrontation with the data.
The shortcomings of the quasifree picture discussed above were revealed in
response functions separations at modest momentum transfers. In contrast,
measurements of the unseparated (e,ep) cross section in the NE18
experiment at SLAC appear consistent with impulse approximation ideas over
a broad range of 
. [Ma94] Indeed, the nucleon momentum
distributions in carbon extracted for from 1.0 to 6.8 (GeV/c)
agree quite well in shape with those determined at Saclay at much lower
momentum transfers. However, further elucidation of possible multi-
nucleon phenomenology awaits response function separations under more
extreme kinematic situations as well as multi-particle coincidence
experiments.