Regular Article - Theoretical Physics
Pygmy resonances and symmetry energy
Department of Physics and Astronomy, Texas A&M University-Commerce, 75429, Commerce, TX, USA
* e-mail: Carlos.Bertulani@tamuc.edu
Accepted: 31 May 2019
Published online: 3 December 2019
I present a brief summary of the first three decades of studies of pygmy resonances in nuclei and their relation to the symmetry energy of nuclear matter. I discuss the first experiments and theories dedicated to study the electromagnetic response in halo nuclei and how a low energy peak was initially identified as a candidate for the pygmy resonance. This is followed by the description of a collective state in medium heavy and heavy nuclei which was identified as a pygmy resonance. The role of the slope parameter of the symmetry energy in determining the properties of neutron stars is stressed. The theoretical and experimental information collected on pygmy resonances, neutron skins, and the numerous correlations found with the slope parameter is briefly reviewed.
© Società Italiana di Fisica and Springer-Verlag GmbH Germany, part of Springer Nature, 2019