  Continuing earlier work, we apply the mean field method to the world sheet
representation of a simple field theory. In particular, we study the higher
order terms in the mean field expansion, and show that their cutoff dependence
can be absorbed into a running coupling constant. The coupling constant runs
towards zero in the infrared, and the model tends towards a free string. One
cannot fully reach this limit because of infrared problems, however, one can
still apply the mean field method to the high energy limit (high mass states)
of the string.
