We study the Lagrangian density for freely propagating gauge fields on the basis of the Stan- dard Model (SM); namely its fractional counterpart. From this, we attain some free fractional Klein- Gordon equations, associated with the electromagnetic, weak, and strong forces. In addition to that, we verify that the Lagrange density is gauge invariant by virtue of the fractional Hessian condition. Also, using the fractional energy density we establish the fractional continuity equation for the freely propa- gating gauge bosons. And finally, a fractional analog of the Riemann-Silberstein vector and its equation is presented. Hence, we formulate fractional analogs of the Riemann-Silberstein and gravitoelectro- magnetic equations, which are compared to the fractional Maxwell’s equations.