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

Abstract

Electromagnetic form factors and electromagnetic properties of $\Delta$ 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 $\Delta^{++}$, $\Delta^{+}$, and $\Delta^{-}$, observables are dominated by the three-quark core, with small meson-cloud corrections superimposed. For neutral $\Delta^{0}$, 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 $\Delta^{0}$. This work provides consistent, parameter-free predictions for $\Delta$ baryon structure and highlights the role of meson cloud fluctuations.