A PHYSICIST DOODLES A W BOSON TAKING A WALK

The simplest way this can happen is for the W boson to move from here to there, which we conventionally draw with a wiggly line (1.) following rules proposed by Richard Feynman. Quantum funkiness, however, means that the W boson could just as easily split into a pair of quarks (2.) which then recombine to form a W boson. Or it could split into other particles, or randomly launch other particles in the strange variety of combinations in the remaining diagrams. These effects are known as “loop effects” because the doodles that describe them contain loops of particles.