Jet Fragmentation

The Monte Carlo generators produce the final four vectors of all the particles in the main process. However the quarks and $\tau$ leptons fragment into showers of particles. To model this process and also Final State Radiation (FSR), hadronisation programs are employed. There are two main fragmentation schemes used at OPAL; JETSET [84] which is the fragmentation scheme from PYTHIA, and the HERWIG fragmentation scheme. Both these hadronisation programs have been tuned using data measured at OPAL [88,89] to give the best representation of true fragmentation.