Tasks

List of tasks as indicated in the approved proposal:

Task 1: Description of the structure of stable and exotic nuclei with beyond-mean-field (BMF) approaches (INFN)

Subtask 1.1: Development of suitable effective interactions in mean-field and BMF theories (CNRS).

We plan to develop new effective interactions specifically tailored for BMF approaches using most recent advances in EFT. The power-counting analysis and the proper treatment of ultraviolet divergence will allow us to better control and possibly introduce in the interactions new terms that may have different relevance at the mean-field and the BMF levels. We also aim at a better understanding of specific interaction channels, like the neutron-proton asymmetry terms. Deliverables of this subtask (new less-empirical effective interaction) will be obtained as a priority since they are crucial for Subtasks 1.2 and 1.3.

Subtask 1.2: Fingerprint of correlations in BMF approaches (UMIL)

Using Subtask 1.1, we aim at describing effects beyond the independent-particle picture, including nuclei with odd particle number, and exploring different ways to deal with correlations such as particle-vibration coupling, many particle-many hole couplings or configuration-mixing. Outcome of this Subtask will serve as structure inputs for Subtasks 1.3 and 2.2.

Subtask 1.3: Improvement of BMF theory for small- and large-amplitude collective motion and dissipative aspects of nuclear dynamics (INFN)

BMF will be improved to include effects of Subtasks 1.1 and 1.2. Collective motion, either at low or medium energy, will be used to benchmark different approaches, to understand the appearance of new modes in exotic nuclei and provide new constraints on the nuclear effective interaction away from the beta stability line. This analysis, in parallel with the development of new, less empirical interactions based on EFT (Subtask 1.1), will also provide stringent constraints on the nuclear equation of state (EOS), that are crucial for the understanding of some important features of compact stellar objects. Outcome of this subtask will serve as structure inputs for Subtask 2.2.

Task 2: Calculate reaction observables to compare state-of-the-art structure models with novel experimental data in exotic nuclei (USE)

Subtask 2.1: Development of new reaction formalisms (ULB)

To develop models suited to the needs and particularities of reactions involving exotic nuclei we will proceed in three steps: (i) validate approximations made in state-of-the-art reaction models; (ii) when necessary, suggest corrections and improvements, such as the development of suitable polarisation potentials for elastic and transfer processes, or the inclusion of cluster collective degrees of freedom in few-body reaction models (CDCC, Eikonal, Faddeev, etc.); and (iii) develop new reliable reaction models, such as formalisms for quasi-free scattering processes or reactions involving three-body projectiles. Emphasis will be made on the interplay between the various reaction channels (elastic scattering, breakup, knock-out and transfer). Applications of these developments to reactions of astrophysical interest will also be studied, such as the calculation of production rates in two- and three-body capture reactions. Deliverables of this subtask will be used in Subtask 2.2.

Subtask 2.2: Improvement of the interface between nuclear structure and nuclear reactions (USE)

This subtask is a crucial step to properly analyse experiments made in new and future RIB facilities. Its goal is to develop proper interfaces between structure models, such as those mentioned in Task 1, and reaction models, like those developed in Subtask 2.1. This will provide clear signatures within reaction observables of the structure properties of exotic nuclei. In particular, the effect of correlation in nuclei will be studied through this Subtask. This includes inferring information on the structure of three-body nuclei from the analysis of breakup observables, such as fragment distributions. In connection with Subtask 2.1, we will study the influence of the collective degrees of freedom of the projectile clusters on reaction observables. The accurate analysis of the data collected in future RIB facilities will also benefit from the development of new reaction observables that are less sensitive to the reaction process, such as the ratio method developed in Brussels, Surrey and MSU. We plan to explore this method in more detail and to extend it to other reactions like three-body breakup and transfer reactions.