Either of two charged intermediate vector bosons that have a positive or a negative charge and a mass about 157,350 times that of the electron and that mediate weak interactions in which the charges of participating particles change.
A subatomic particle with positive electric charge that mediates the weak nuclear force. The W boson has a mass 160,000 times that of the electron. Unlike the other weak force mediator (the Z boson), the W boson changes particles it interacts with into other kinds of particles; for example, in beta-plus decay (a kind of beta decay ), an up quark in a proton decays into a down quark by emitting a W boson, changing the proton into a neutron. The W boson itself decays into a positron and an electron neutrino.