  A good fit to the CDF underlying event is obtained in the multiple parton
scattering picture using HERWIG, after modifying the cluster hadronization
algorithm as suggested by our previous study and adopting a larger maximum
cluster size. The number of scatters per event is generated simply as a Poisson
distribution. If our picture is correct, the baryon yield should be enhanced in
the underlying event. This effect may be studied by measuring the
proton-to-pion ratio.
