1207.4392 (G. Ramalho et al.)

The shape of the $Δ$ baryon in a covariant spectator quark model    [PDF]

G. Ramalho, M. T. Pena, A. Stadler

Using a covariant spectator quark model that describes the recent lattice QCD data for the $\Delta$ electromagnetic form factors and all available experimental data on $\gamma N \to \Delta$ transitions, we analyze the charge and magnetic dipole distributions of the $\Delta$ baryon and discuss its shape. We conclude that the quadrupole moment of the $\Delta$ is a good indicator of the deformation and that the $\Delta^+$ 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.

View original: http://arxiv.org/abs/1207.4392