  The soliton formation is considered in the Nambu-Jona-Lasinio model with
local four quark interaction and various schemes to regularize the energy
contribution of the polarized vacuum. No additional constraints are admitted in
order to stabilize the soliton. While solitons are unstable in the proper-time
regularized version the three momentum cut-off regularization apparently is
more appropriate. Using a semi-classical approach multi-quark solitons obtained
from that scheme are discussed. However, no self-consistent non-trivial unit
baryon number configuration has been found. We also study a renormalizable
extension of the model. In this case no stable multi-quark solitons are
obtained within the semi-classical approach.

Nuclear Theory