Shape of theΔbaryon in a covariant spectator quark model

Abstract

Using a covariant spectator quark model that describes the recent lattice QCD data for the $\ensuremath{\Delta}$ electromagnetic form factors and all available experimental data on $\ensuremath{\gamma}N\ensuremath{\rightarrow}\ensuremath{\Delta}$ transitions, we analyze the charge and magnetic dipole distributions of the $\ensuremath{\Delta}$ baryon and discuss its shape. We conclude that the quadrupole moment of the $\ensuremath{\Delta}$ is a good indicator of the deformation and that the ${\ensuremath{\Delta}}^{+}$ charge distribution has an oblate shape. We also calculate transverse moments and find that they do not lead to unambiguous conclusions about the underlying shape.