Valence-quark-core and meson-cloud effects on electromagnetic form factors of $Δ$ baryons

Electromagnetic form factors and electromagnetic properties of $Δ$ baryons are studied in the perturbative chiral quark model (PCQM) using quark wavefunctions predetermined from proton charge form factor data. Our predictions agree reasonably with lattice-QCD and other phenomenological results. For charged $Δ^{++}$, $Δ^{+}$, and $Δ^{-}$, observables are dominated by the three-quark core, with small meson-cloud corrections superimposed. For neutral $Δ^{0}$, the leading-order quark core contribution vanishes, so meson-cloud corrections fully determine its electromagnetic response. The PCQM gives a nonzero magnetic moment, a negative charge radius, and a sizable magnetic radius for $Δ^{0}$. This work provides consistent, parameter-free predictions for $Δ$ baryon structure and highlights the role of meson cloud fluctuations.