Interactions between fermions and gauge bosons

Since our main focus is on interactions between the fermions and the vector gauge bosons W , W, Z° and 7, the corresponding interaction 

The various bilinear fermionic terms in the interaction Lagrangian are four-currents that interact with the gauge bosons. The Lagrange density 

Here j is the electromagnetic four-current, and j are weak charged currents and finally j° is the weak neutral current that couples to the Z° boson. This neutral current deserves our particular attention when we are interested in molecular parity violating effects. 

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