We have shown that some negatively charged particles may produce a positive charge density. Our everyday experience tells us that it is impossible. Indeed, ordinary particles like negatively charged electrons produce negative charge density everywhere, any time. However, the situation is different for W-bosons. These are fundamental particles, which mediate the weak interaction that is responsible for beta-decay of unstable nuclear isotopes.

The reason why W-bosons demonstrate this mysterious behaviour stems from the fact that they are described by the relativistic quantum mechanics. The spin S of W-bosons is large, S=1 (in comparison, electrons have spin=1/2). In simple terms, the W-boson rotates vigorously around its axes. It is precisely this strong rotation, combined with the effects of special relativity, that leads to the puzzling phenomenon of the ‘wrong sign’ of the charge distribution. This effect does not contradict the charge conservation, i.e. no charge disappeared or was created. For example, W-bosons at rest have a given negative charge. For fast, relativistic W-bosons there are some areas of space with positive charge and some areas with negative charge, but the total overall charge does not change.