  We have studied the hadronization of jet parton showers based on the quark
recombination model. This is achieved by letting gluons at the end of the
perturbative shower evolution undergo a non-perturbative splitting into quark
and antiquark pairs, then applying a Monte-Carlo version of instantaneous quark
recombination, and finally subjecting remnant quarks (those which have not
found a recombination partner) to Lund string fragmentation. When applied to
parton showers from the PYTHIA Monte Carlo generator, the final hadron spectra
from our calculation compare quite well to PYTHIA jets that have been
hadronized with the default Lund string fragmentation. Modeling the quark gluon
plasma produced in heavy ion collisions by a blast wave model, we have further
studied medium effects on the hadronization of jet shower partons by also
including their recombination with the thermal partons from the quark gluon
plasma. We find that the latter leads to a significant enhancement of
intermediate transverse momentum pions and protons at both RHIC and LHC. Our
results thus suggest that medium modification of jet fragmentation provides a
plausible explanation for the enhanced production of intermediate transverse
momentum hadrons observed in experiments.
