For a boson like the W , the scheme consider that such loops are produced by fermions, while for vector mesons, like the ρ , bosons are the natural particles in the loop. In general, the CP conserving electromagnetic vertex can be decomposed into the follow- ing Lorentz structure where the electromagnetic form factors can be identified as: |Q| ≡ α ( k $^{2}$) is the electric charge form factor ( in e units), | ⃗ µ | = β ( k $^{2}$) ≡ 1 + κ + λ is the magnetic dipole moment form factor (in e/ 2 M$_{V}$ units) and the electric quadrupole form factor is | X$_{E}$ | = κ − γ ( k $^{2}$) M 2 V ≡ κ − λ (in e/M 2 V units). The parameters κ and λ are of common use in the literature to refer to the electromagnetic multipoles [12, 13]. The static electromagnetic properties of a particle are defined for the case when the particle is on-shell and in the limit of ⃗ k → 0. At tree level, for example, the standard model predicts for the W to have α (0) = 1, β (0) = 2 and γ (0) = 0 ( κ = 1 and λ = 0), corresponding to |Q| = 1, | ⃗ µ | = 2 and | X$_{E}$ | = 1. Deviations from these values are generically called anomalous and are produced by the inclusion of higher order contributions [14]. In the present case such contributions are exclusively those required to maintain the electromagnetic gauge invariance, upon the introduction of the finite decay width. Let us identify the modification to the W boson form factors introduced by the correction to the electromagnetic vertex. For that purpouse we consider the explicit expression of the vertex obtained in ref. [10], where the mass of the emitting particles in the loop ( m ) and its weak partner ( m $^{′}$) have been considered. The Lorentz structure, transversality and on- shell condition of the boson along with the proper limit for k → 0 leads to the following expressions for the form factors, defined in equation (8): where Σ 2 ≡ m $^{2}$+ m $^{$^{′}$2}$, Δ 2 ≡ m $^{2}$− m $^{′}$2 and Q$_{i}$ is the electric charge of the radiating particle in the loop, Γ$_{i}$ /M$_{W}$ ≡ g 2 $_{i}$λ 3 / $^{2}$/ 48 π is the partial decay width for the modes corresponding A. W boson form factors • Electric charge Γ µνλ = α ( k $^{2}$) g $^{νλ}$( q 1 + q 2 ) µ + β ( k $^{2}$)( g $^{µν}$kλ − g $^{µλ}$k$^{ν}$) − γ ( k $^{2}$)( q 1 + q 2 ) $^{µ}$k$^{ν}$k$^{λ}$, (8) α (0) = 1 + ı ∑ i Q$_{i}$ Γ$_{i}$ M$_{W}$ ( 1 − 3 M 2 $_{W}$Σ $^{2}$(3Σ2 − 2 M 2 $_{W}$) + Δ $^{4}$( M 2 W − 2Σ $^{2}$) 2 M 6 $_{W}$λ 2 ) (9) 4