BOSE-EINSTEIN EFFECTS AND W-MASS DETERMINATIONS

In e(+)e(-) --> W+W- --> q(1) (q) over bar(2)q(3) (q) over bar(4) even ts at LEP 2, the two W decay vertices are much closer to each other th an typical hadronization distances. Therefore the Bose-Einstein effect s, associated with the production of identical bosons (mainly pions), may provide a 'cross-talk' between the W+ and the W- decay products. I f so, the observable W masses are likely to be affected. We develop al gorithms for the inclusion of Bose-Einstein effects in multi-hadronic events. In this way we can study potential uncertainties in the W mass determination. In some scenarios the effects are significant, so that this source of uncertainty cannot be neglected.