Gregory Potel

We present a review of theoretical studies of the structure and reactions of N = 7 and N = 8 nuclei in the vicinity of ¹¹Li, carried out within a framework based on Nuclear Field Theory. The coupling of valence nucleons to low-lying surface vibrations of the spherical core plays a central role, giving rise to self-energy processes that renormalize single-particle states and transfer form factors, as well as to an induced pairing interaction arising from the exchange of collective vibrations, which renormalizes the bare pairing force. Excitation spectra and cross sections for one- and two-nucleon transfer reactions populating states in the quasi-continuum are calculated and compared with available experimental data. Collective excitations in the particle-particle channel are investigated, with particular emphasis on Giant Pairing Vibrations and on their damping mechanisms arising from coupling to more complex configurations and continuum states. Comparisons with other theoretical schemes are also presented. We conclude that a coherent understanding of experimental data requires the detailed consideration of particle-vibration coupling effects.

This document summarizes the discussions and outcomes of the Facility for Rare Isotope Beams (FRIB) Theory Alliance topical program ‘The path to Superheavy Isotopes’ held in June 2024 at FRIB. Its content is non-exhaustive, reflecting topics chosen and discussed by the participants. The program aimed to assess the current status of theory in superheavy nuclei (SHN) research and identify necessary theoretical developments to guide experimental programs and determine fruitful production mechanisms. This report details the intersection of SHN research with other fields, provides an overview of production mechanisms and theoretical models, discusses future needs in theory and experiment, explores other potential avenues for SHN synthesis, and highlights the importance of building a strong theory community in this area.

The concepts of globule and random coil were developed to describe the phases of homopolymers and then used to characterize the denatured state of structured cytosolic proteins and intrinsically disordered proteins. Using multi-scale molecular dynamics simulations, we were able to explore the conformational space of the disordered conformations of both types of protein under biological conditions in an affordable amount of computational time. By studying the size of the protein and the density correlations in space, we conclude that the standard phases of homopolymers and the tools to detect them cannot be applied straightforwardly to proteins.

We present a theoretical framework for treating the full excitation spectrum of J^{π}=0^{+} pair addition modes, including the well-known low-lying and bound pairing vibrations on par with the predicted high-lying pairing vibrations, often called giant pairing vibrations. Our formalism includes the coupling to low-energy collective quadrupolar modes of the core, in such a way that both single-particle self-energy effects and the pairing interaction induced by phonon exchange are accounted for. The coupling with the continuum plays an important role and is also taken into account. The theory is applied to the case of the excitation spectrum of ^{14}C, recently populated by two-neutron transfer reactions.

It is a fascinating phenomenon in nuclear physics that states with a pronounced few-body structure can emerge from the complex dynamics of many nucleons. Such halo or cluster states often appear near the boundaries of nuclear stability. As such, they are an important part of the experimental program beginning at the Facility for Rare Isotope Beams (FRIB). A concerted effort of theory and experiment is necessary both to analyze experiments involving effective few-body states, as well as to constrain and refine theories of the nuclear force in light of new data from these experiments. As a contribution to exactly this effort, this paper compiles a collection of ``perspectives'' that emerged out of the Topical Program ``Few-body cluster structures in exotic nuclei and their role in FRIB experiments'' that was held at FRIB in August 2022 and brought together theorists and experimentalists working on this topic.