Interconnection Effects and W+W- Decays (a critical (p)(re)view)

Color reconnection and Bose-Einstein correlations not only can have an influence on the measurement of the W-mass in the fully hadronic W+W- decay channel at LEP2, but also can give essential information on the structure of the QCD vacuum and the space-time development of a q_1\bar q_2 system. Recent developments are critically analyzed, with particular emphasis on the models used in this field. More sensitive variables are needed to distinguish between color reconnection models, while more experimental knowledge has to be built into the Bose-Einstein models and, above all, these two closely related phenomena have to be treated in common. Both effects are determined by the space-time overlap of the W+ and W- decay products. Vital experimental information on the space-time development of the decay of the q_1\bar q_2 system is becoming available from the high-statistics data on hadronic Z decay and models will have to be able to explain this evidence before being used to predict interference effects in hadronic W+W- decay.