I would like to ask you 2 completely separate questions... Since both concern the W,Zs I don't want to create more than one post (that could be spamming)... 1. what are the consequences (theoretically and experimentally) ,if there are, of the fact that the masses of W and Z bosons don't match? For example experimentally the only thing I can think about, is that the Z and Ws couple differently because of the propagator's dependence on mass (~/M) Theoretically there is the Weinberg's angle θW that is given by the ratio of that mass... Where does that angle appear in the theoretical scheme? 2. When we create the SU(2)LxU(1)Y theory we have 4 massless boson fields (W+, W-,W0 and B0) which after the higgs mechanism mass-giving we end up with the massive W,Z and the photon. My question is about Z, why do we write it as a combination of W0 and B0 alone? Couldn't it be a combination of W- and W+ as well ? (since the total charge will remain 0). Except for that it'd give an instinct polarization to the Z0 boson, is there any more serious problem (that I'm missing) in that approach? by the way, hello PF!