 Electroweak gauge boson

An electroweak gauge boson is a field quantum associated with the $SU(2{)}_L\times U(1{)}_Y$ electroweak interaction. Before electroweak symmetry breaking, the gauge fields are the three weak-isospin fields $W^1,W^2,W^3$ and the hypercharge field $B$.

After electroweak symmetry breaking, charged combinations form the W bosons, while neutral combinations give the massive Z boson and massless photon. The W bosons mediate weak charged currents, changing the electric charge of the participating matter fields. The Z boson mediates a weak neutral current, and the photon couples to electric charge. The mixing explains why the neutral electromagnetic and weak interactions share an underlying gauge description despite having different low-energy ranges.