Appearance of an artificial length scale in JETSET Bose-Einstein simulation

Abstract.

This work studies the algorithm which implements the Bose-Einstein correlation effect in the JETSET 7.4 event generator. This algorithm attempts to reproduce an expected correlation function with a given correlation radius and amplitude. The two-particle correlation function is studied in the generated $Z^0$ hadronic decays for different values of the built-in radius parameter. Samples consisting of only charged particles are used, as well as subsamples of pions, pions coming from the string decay and pions from the resonance decays. The Bose-Einstein correlation function, extracted from the generated events, is parameterized analogously to the built-in JETSET correlation function and its parameters are compared with the input ones. We found that the measured correlation function reproduces the built-in one, if the input radius parameter is larger than 1 fm. For lower input radii an artificial new length scale appears due to the way the Bose-Einstein correlation is implemented.