Electromagnetic form factors of light vector mesons

Abstract

The electromagnetic form factors ${G}_{E}{(q}^{2}), {G}_{M}{(q}^{2}),$ and ${G}_{Q}{(q}^{2}),$ charge radii, magnetic and quadrupole moments, and decay widths of the light vector mesons ${\ensuremath{\rho}}^{+}{,K}^{*+},$ and ${K}^{*0}$ are calculated in a Lorentz-covariant, Dyson-Schwinger-equation-based model using algebraic quark propagators that incorporate confinement, asymptotic freedom, and dynamical chiral symmetry breaking, and vector-meson Bethe-Salpeter amplitudes closely related to the pseudoscalar amplitudes obtained from phenomenological studies of $\ensuremath{\pi}$ and K mesons. Calculated static properties of vector mesons include the charge radii and magnetic moments $〈{r}_{\ensuremath{\rho}+}^{2}{〉}^{1/2}=0.61 \mathrm{fm}, 〈{r}_{{K}^{*+}}^{2}{〉}^{1/2}=0.54 \mathrm{fm},$ and $〈{r}_{{K}^{*0}}^{2}〉=\ensuremath{-}0.048 {\mathrm{fm}}^{2}$ and ${\ensuremath{\mu}}_{\ensuremath{\rho}+}=2.69, {\ensuremath{\mu}}_{{K}^{*+}}=2.37,$ and ${\ensuremath{\mu}}_{{K}^{*0}}=\ensuremath{-}0.40.$ The calculated static limits of the $\ensuremath{\rho}$-meson form factors are similar to those obtained from light-front quantum mechanical calculations, but begin to differ above ${q}^{2}=1 {\mathrm{GeV}}^{2}$ due to the dynamical evolution of the quark propagators in our approach.