Speaker
Description
A. Porro1,T. Duguet1;2, V. Som?a1, M. Frosini3, J.-P. Ebran4;5
1 IRFU, CEA, Universit?e Paris-Saclay, 91191 Gif-sur-Yvette, France
2 Department of Physics and Astronomy, Instituut voor Kern- en Stralingsfysica, KU Leuven, 3001,
Leuven, Belgium
3 CEA, DEN, IRESNE, DER, SPRC, 13108 Saint-Paul-l?es-Durance, France
4 CEA, DAM, DIF, 91297, Arpajon, France
5 Universite Paris-Saclay, CEA, Laboratoire Mati?ere en Conditions Extr^emes, 91680 Bruyeres-le-Chatel,
France
Giant monopole resonances have a long-standing theoretical importance in nuclear structure. The interest resides notably in the so-called breathing mode that has been established as a standard observable to constrain the nuclear incompressibility [1]. The Random Phase Approximation (RPA) within the frame of phenomenological Energy Density Functionals (EDF) has become the standard tool to address (monopole) giant resonances and extensive studies, mostly in doubly-closed-shell systems, have been performed hroughout the years, including via the use of so-called sum rules [2]. A proper study of collective excitations in the ab-initio context is, however, missing.
In this perspective, the ?rst systematic ab-initio predictions of (giant) monopole resonances will be presented [3, 4, 5]. Ab-initio Quasiparticle-RPA (QRPA) [6] and Projected Generator Coordinate Method (PGCM) [7] calculations of monopole resonances are compared in light- and mid-mass closed- and open-shell nuclei, which allows in particular to investigate the role of super uidity from an ab-initio standpoint.
Sum rules are also employed within both many-body chemes to characterize the fragmentation of the monopole strength. The study further focuses on the dependence of the results on the starting nuclear Hamiltonian derived within the frame of chiral effective field theory.
Monopole resonance represents, thus, the first step towards the investigation of higher multipolarities.
Eventually, the mid-term goal to establish PGCM as a new method to study resonances in the light- and medium-mass region of the nuclide chart will be discussed: interpretation and analysis of resonance data in lighter nuclei is a very demanding task on which ab-initio PGCM could shed new promising light.
References
[1] J. P. Blaizot, D. Gogny, and B. Grammaticos, \Nuclear compressibility and monopole resonances,"
Nuclear Physics A, vol. 265, pp. 315{336, July 1976.
[2] O. Bohigas, A. Lane, and J. Martorell, \Sum rules for nuclear collective excitations," Physics Reports, vol. 51, pp. 267{316, Apr. 1979.
[3] Porro, A., Frosini, M., Duguet, T., Som?a, V., Ebran, J.-P. and Roth, R., \Ab initio description of
monopole resonances in light- and medium-mass nuclei: I. Theoretical frame and proof of principle calculations," In preparation, 2022.
[4] Porro, A., Duguet, T., Frosini, M., Som?a, V., Ebran, J.-P. and Roth, R., \Ab initio description of monopole resonances in light- and medium-mass nuclei: II. Moments evaluation and comparison to sum rules," In preparation, 2022.
A.P. is supported by the CEA NUMERICS program, which has received funding from the European Unions Horizon
2020 research and innovation program under the Marie Sk lodowska-Curie grant agreement No 800945.
[5] Porro, A., Frosini, M., Duguet, T., Som?a, V., Ebran, J.-P. and Roth, R., \Ab initio description of monopole resonances in light- and medium-mass nuclei: III. Application to systems of experimental interest," In preparation, 2022.
[6] Beaujeault-Taudi?ere, Y and Frosini, M and Ebran, J-P and Duguet, T and Roth, R and Som?a, V, \Ab initio description of multipolar responses in super uid and deformed nuclei at ?nite temperature: application to dipole modes in 56 Fe," arXiv preprint arXiv:2203.13513, 2022.
[7] Frosini, Mikael and Duguet, Thomas and Ebran, J-P and Som?a, V, \Multi-reference many-body perturbation theory for nuclei," The European Physical Journal A, vol. 58, no. 4, pp. 1{28, 2022.
