The Feynman-Wilson gas and the Lund model

We derive a partition function for the Lund fragmentation model and compare it with that of a classical gas. For a fixed rapidity "volume" this partit ion function corresponds to a multiplicity distribution which is very close to a binomial distribution. We compare our results with the multiplicity d istributions obtained from the JETSET Monte Carlo for several scenarios. Fi rstly, for the fragmentation vertices of the Lund string. Secondly, for the final state particles both with and a without decays.