This table gives the values of the electric charge (the coupling to the photon, referred to in this article as Q ϵ ϵ ). Also listed are the approximate weak charge Q w (the vector part of the Z boson coupling to fermions), weak isospin T 3 (the coupling to the W bosons), weak hypercharge Y w (the coupling to the B boson) and the approximate Z boson coupling factors ( Q L and Q R in the "Theoretical" section, below).