Hypercharge ($Y$)

Hypercharge is the generator of the electroweak $U(1{)}_Y$ factor. With the convention $D_{\mu }={\partial }_{\mu }-ig{W}_{\mu }^a{T}^a-i{g}^{\prime }Y{B}_{\mu }$, electric charge is $Q=T^3+Y$.

Charge quantization is the restriction of electric charges to discrete multiples of a basic unit. In the Standard Model, Yukawa gauge invariance and gauge-anomaly cancellation relate the quark and lepton hypercharges and imply that the proton and electron have opposite charges.