ON COLOR REARRANGEMENT IN HADRONIC W- EVENTS(W)

We discuss the possibility of colour rearrangement in e+e- --> W+W- -- > q1q2q3q4BAR events, i.e that the original colour singlets q1q2BAR an d q3q4BAR may be transmuted, for instance, into new singlets q1q4BAR a nd q3q2BAR. The effects on event properties could be quite large if su ch a rearrangement would occur instantaneously, so that gluon emission would be restricted to each of the new singlets separately. We argue that such a scenario is unlikely for two reasons. Firstly, the W+ and W- usually decay at separate times after the W+ W- production, which l eads to large relative phases for energetic radiation off the two cons tituents of a rearranged system, and a corresponding dampening of the QCD cascades. Secondly, within the perturbative scenario the colour tr ansmutation appears only in order alpha(s)2 and is colour-suppressed. Colour reconnection at longer time scales is quite feasible, however, and may affect the fragmentation phase. If so, the nature of non-pertu rbative QCD can be probed in a new way. We formulate several alternati ve toy models and use these to estimate the colour reconnection probab ility as a function of the event kinematics. Possible consequences for LEP 2 events are illustrated, with special attention to systematic er rors in W mass determinations.