  The recent announcement by the PREX collaboration of an unanticipated thick
neutron skin in 208Pb (Rskin208) has challenged our understanding of neutron
rich matter in the vicinity of nuclear saturation density. Whereas earlier
constraints indicate that the symmetry energy is relatively soft, the PREX-2
result seems to suggest the opposite. We confront constraints on the symmetry
energy obtained from measurements of the electric dipole polarizability against
those informed by the PREX-2 measurement of Rskin208 and by the correlations
that it entails. Covariant energy density functionals informed by the
properties of finite nuclei are used to compute the electric dipole response of
48Ca, 68Ni, 132Sn, and 208Pb. The set of functionals used in this work are
consistent with experimental data, yet are flexible enough in that they span a
wide range of values of Rskin208. It is found that theoretical predictions of
the electric dipole polarizability that are consistent with the PREX-2
measurement systematically overestimate the corresponding values extracted from
the direct measurements of the distribution of electric dipole strength. The
neutron skin thickness of 208Pb extracted from parity violating electron
scattering and the electric dipole polarizability measured in photoabsorption
experiments are two of the cleanest experimental tools used to constrain the
symmetry energy around nuclear saturation density. However, the recent value of
Rskin208 that suggests a fairly stiff symmetry energy stands in stark contrast
to the conclusions derived from the electric dipole polarizability. At present,
we offer no solution to this dilemma.
