Isovector Monopole Resonance
Abstract
We present a theoretical study of the three isospin channels of the isovector giant monopole resonance (IVGMR) within self-consistent Skyrme Hartree-Fock plus Random-Phase Approximation. A modified charge-exchange monopole operator is introduced to remove the dominant isobaric-analog-state contribution, thereby isolating the genuine radial isovector response. We derive the associated non-energy- and energy-weighted sum rules and establish approximate relations between the charge-exchange and non-charge-exchange strengths. The relative locations of the three IVGMR centroids are interpreted in terms of Coulomb displacement energies, the neutron-proton mass difference, and the finite-nucleus symmetry potential. Calculations for 48Ca, 90Zr, and 208Pb show that the non-charge-exchange centroid is accurately approximated by the average of the two charge-exchange centroids in medium-heavy and heavy nuclei. Using a broad set of Skyrme energy-density functionals, we find that the centroid energies of the three channels display a weak model dependence for a fixed nucleus, whereas the non-charge-exchange monopole polarizability exhibits a clear sensitivity to the density dependence of the symmetry energy. These results clarify the isospin structure of the IVGMR and support its use as a complementary probe of isovector nuclear properties.
Related
BibTeX
@misc{maza2026isovector,
title = {{Isovector Monopole Resonance}},
author = {Xavier Roca Maza and Gianluca Colò},
howpublished = {arXiv},
year = {2026},
month = oct,
doi = {10.48550/arxiv.2610.23211},
eprint = {2610.23211},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2610.23211},
}
RIS
TY - UNPB
TI - Isovector Monopole Resonance
AU - Xavier Roca Maza
AU - Gianluca Colò
PY - 2026
DA - 2026/10/16
PB - arXiv
DO - 10.48550/arxiv.2610.23211
UR - https://arxiv.org/abs/2610.23211
AB - We present a theoretical study of the three isospin channels of the isovector giant monopole resonance (IVGMR) within self-consistent Skyrme Hartree-Fock plus Random-Phase Approximation. A modified charge-exchange monopole operator is introduced to remove the dominant isobaric-analog-state contribution, thereby isolating the genuine radial isovector response. We derive the associated non-energy- and energy-weighted sum rules and establish approximate relations between the charge-exchange and non-charge-exchange strengths. The relative locations of the three IVGMR centroids are interpreted in terms of Coulomb displacement energies, the neutron-proton mass difference, and the finite-nucleus symmetry potential. Calculations for ^48Ca, ^90Zr, and ^208Pb show that the non-charge-exchange centroid is accurately approximated by the average of the two charge-exchange centroids in medium-heavy and heavy nuclei. Using a broad set of Skyrme energy-density functionals, we find that the centroid energies of the three channels display a weak model dependence for a fixed nucleus, whereas the non-charge-exchange monopole polarizability exhibits a clear sensitivity to the density dependence of the symmetry energy. These results clarify the isospin structure of the IVGMR and support its use as a complementary probe of isovector nuclear properties.
ER -