Weak Interaction Carrier Particles
W Bosons
The mass of the W boson is about 80 GeV/c2, that is about eighty times the mass of the proton or neutron, or roughly the mass of a Bromine atom.
There are two types of W boson with electric charges +1 and -1. Each is the antiparticle of the other, but neither of them are matter particles, instead they are carrier particles for weak interactions.
Processes where a W boson is emitted or absorbed are the only way that quark flavor can be changed.
W-bosons decay to produce either a quark and a differently charged antiquark or a charged lepton and a neutrino (or antineutrino).
Z Bosons
The mass of a Z-boson is about 91 GeV/c2 or roughly the same as an Zirconium atom.
The Z boson has no electric charge and no other distinguishable quantum number so the antiparticle of a Z boson is a Z boson.
Z bosons mediate weak interactions that do not involve charge and flavor changes. Because the mass of the Z is large compared to the mass of the photon in most low energy situations the effects of Z-exchanges are tiny compared to photon exchanges.
Z bosons produced by colliding electron and positron beams with just the right energy to make a single Z are the main object of study for the linear collider at SLAC.
Z bosons decay to produce either quark and its matching flavor antiquark or a lepton and its matching anti-lepton.
The decays of these particles produce several quite distinct event types.
