  Recent neutron star observations suggest that the masses and radii of neutron
stars may be smaller than previously considered, which would disfavor a purely
nucleonic equation of state. In our model, we use a the flavor SU(3) sigma
model that includes delta resonances and hyperons in the equation of state. We
find that if the coupling of the delta resonances to the vector mesons is
slightly smaller than that of the nucleons, we can reproduce both the measured
mass-radius relationship and the extrapolated equation of state.
