Narrow Results

Observables in proton-deuteron scattering are sensitive probes of the nucleon-nucleon interaction and three-nucleon force effects. Several facilities, including the KVI, allow a detailed study of few-nucleon interactions below the pion-production threshold exploiting polarized proton and deuteron beams. In this contribution, some recent results are discussed and interpreted exploiting rigorous Faddeev calculations. Furthermore, experimental inconsistencies between two measurements of the cross section in elastic proton-deuteron scattering at 135 MeV/nucleon are reviewed.

Using chiral effective field theory (EFT) with explicit Δ degrees of freedom we calculated nuclear forces up to next-to-next-to-leading order (N²LO). We find a much improved convergence of the chiral expansion in all peripheral partial waves. We also present a novel lattice EFT method developed for systems with larger number of nucleons. Combining Monte Carlo lattice simulations with EFT allows one to calculate the properties of light nuclei, neutron and nuclear matter. Accurate description of two-nucleon phase-shifts and ground state energy ratio of dilute neutron matter up to corrections of higher orders show that lattice EFT is a promising tool for quantitative studies of low-energy few- and many-body systems.

In this paper, the ground state properties of neutron rich even–even Cd, Te and Xe isotopes are investigated using the Skyrme–Hartree–Fock–Bogoliubov (SHFB) methods with SKM* and SLy4 force parameters. These isotopes are vital to the structural studies of unstable nuclei taking place at near Z = 50 closed shell. The main subject of this paper is to calculate the binding energies per particle, the rms nuclear charge radii, the rms nuclear proton density radii, and the rms nuclear neutron density radii with SHFB methods. The results are compared with experimental data and with the results of relativistic meanfield theory (RMFT). In addition to these calculations the initial neutron and proton exciton numbers for ¹¹²Cd, ¹²⁴Te and ¹²⁶Xe isotopes, which have high cross sections for proton induced nuclear reactions (p, 2n) and used for radioisotopes production, will also be calculated. These exciton numbers can be used for pre-equilibrium proton induced (p, 2n) reactions on ¹¹²Cd, ¹²⁴Te and ¹²⁶Xe isotopes.

Binding energies and their differences are investigated to evaluate the two-neutron separation energies (S_2n), the two-proton separation energies (S_2p) and the average proton–neutron interaction strengths (δV_pn) of neutron-rich Sr, Zr and Mo isotopes in the mass region A = 86–110, including even–even nuclei. Calculations were performed using the Hartree–Fock–Bogoliubov (HFB) method with different Skyrme force parametrizations. The obtained results are discussed and compared with the results of experimental and relativistic mean-field theory (RMFT).

Using chiral effective field theory (EFT) with explicit Δ degrees of freedom we calculated nuclear forces up to next-to-next-to-leading order (NNLO). We found much better convergence of the chiral expansion in all peripheral partial waves. We also observe strong cancellations between charge-symmetry-breaking (CSB) contributions due to nucleon- and Δ-mass splittings in the two-pion-exchange potentials. The CSB potentials appear to be weaker in the Δ-full theory.

The validity of CPT invariance in the field of “nuclear binding masses” has been studied for nuclei (antinuclei) with two and three nucleons (antinucleons): $(\mathrm{\text{d}}∕\overline{\mathrm{\text{d}}})$ and ${(}^3\mathrm{\text{He}}∕{}^3\overline{\mathrm{\text{He}}})$. It is discussed the importance of investigating the transition from the world where gluons and quarks carry their QCD colors (QGCW) to the world where gluons and quarks exist only with zero-QCD-color (QGZCW).

The bases of the translation invariant shell model are used to construct the ground-state wave functions of ³T, ⁵He and ⁶Li. For ³T the bases used correspond to the number of quanta of excitation N up to ten. For ⁵He and ⁶Li the bases used correspond to the number of quanta of excitation N up to six. The model is applied to calculate the binding energy and the root mean square radius for ³T, ⁵He and ⁶Li nuclei. The residual interactions used consist of central, tensor, spin-orbit and quadratic spin-orbit terms with Gaussian radial dependence. The parameters of these interactions are chosen in such away that they represent the long range attraction and the short range repulsion of nucleon interactions. It was found that this potential is more suitable for calculating the characteristics of these nuclei, and better than other potentials, such as our previous potentials which were represented by the parameters of long range attraction forces only. For ³T we obtained good agreement between calculated and experimental values of both the ground state binding energy and the root mean square radius. For ⁵He and ⁶Li nuclei we obtained an acceptable improvement with these calculations over other potentials.

The unusual structure of ¹¹Li, the first halo nucleus found, is analyzed by the Preparata model of nuclear structure. By applying coherent nucleus theory, we derive a new interaction potential for the halo-neutrons that correctly reproduces the fundamental state of the system.

In this paper, the role of three-nucleon forces in ab initio calculations of nuclear systems is investigated. The difference between genuine and induced many-nucleon forces is emphasized. Induced forces arise in the process of solving the nuclear many-body problem as technical intermediaries toward calculationally converged results. Genuine forces make up the Hamiltonian. They represent the chosen underlying dynamics. The hierarchy of contributions arising from genuine two-, three- and many-nucleon forces is discussed. Signals for the need of the inclusion of genuine three-nucleon forces are studied in nuclear systems, technically best under control, especially in three-nucleon and four-nucleon systems. Genuine three-nucleon forces are important for details in the description of some observables. Their contributions to observables are small on the scale set by two-nucleon forces.

We review the recent progress made in studies of deuteron structure at small internucleon distances. This progress is largely facilitated by the new generation of experiments in deuteron electrodisintegration carried out at unprecedentedly high momentum transfer. The theoretical analysis of these data confirms the onset of the high energy eikonal regime in the scattering process which allows one to separate long-range nuclear effects from the effects genuinely related to the short distance structure of the deuteron. Our conclusion is that for the first time the deuteron is probed at relative momenta beyond 300 MeV/c without dominating long-range effects. As a result, at these large nucleon momenta the cross-section is sensitive to the nuclear dynamics at subfermi distances. Due to large internal momenta involved we are dealing with the relativistic bound state that is best described by the light-cone momentum distribution of nucleons in the deuteron. We present the first attempt of extracting the deuteron light-cone momentum distribution function from data and discuss the importance of this quantity for studies of quantum chromodynamics (QCD) structure of the bound nucleon in deep inelastic scattering (DIS) off the deuteron. We conclude the review giving an outlook of the next generation of high energy experiments which will extend our reach to much smaller distances in the deuteron.

The present note summarizes the discourse on power counting issues of chiral nuclear forces, with an emphasis on renormalization-group invariance. Given its introductory nature, I will lean toward narrating a coherent point of view on the concepts, rather than covering comprehensively the development of chiral nuclear forces in different approaches.

The nuclear force is the heart of nuclear physics and, thus, the significance of this force for all of nuclear physics can hardly be overstated. Research on this crucial force has by now spanned eight decades and we are still not done. I will first review the rich history of hope and desperation, which had spin-off far beyond just nuclear physics. Next, I will present the current status in the field which is characterized by the application of an effective field theory (EFT) that is believed to represent QCD in the low energy regime typical for nuclear physics. During the past two decades, this EFT has become the favorite vehicle to derive nuclear two- and many-body forces. Finally, I will take a look into the future: What developments can we expect from the next decades? Will the 30-year cycles of new and “better” ideas for efficiently describing nuclear forces go on for ever, or is there hope for closure?

Gerry Brown has played a major role in initiating and stimulating systematic work on the theories of nuclear forces. It is the purpose of this paper to review those theories — in his memory.

The scale-dependence of the nucleon–nucleon (NN) potential, which in recent years has been extensively analyzed within the context of chiral effective field theory, is, in fact, inherent in any models constrained by a fit to scattering data. A comparison between a purely phenomenological potential and a set of local interactions derived from chiral effective field theory suggests that — owing to the ability to describe NN scattering at higher energies, as well as the deuteron momentum distribution obtained from the $y$-scaling analysis of electro-disintegration data — purely phenomenological potentials are best suited to describe nuclear dynamics at the scale relevant to neutron star matter and correlation effects in nuclei. The breakdown of the paradigm based on the description of nuclear systems in terms of point-like protons and neutrons is briefly discussed.

The isospin splitting of the in-medium $NN\to N\mathrm{\Delta }$ cross-sections in asymmetric nuclear medium is investigated in the framework of the one-boson exchange model by including $\delta$ and $\rho$ mesons. Our results show that the medium correction factors $R={\sigma }_{NN\to N\mathrm{\Delta }}^{\ast }/{\sigma }_{NN\to N\mathrm{\Delta }}^{\text{free}}$ have $R_{pp\to n{\mathrm{\Delta }}^{++}}<R_{nn\to p{\mathrm{\Delta }}^{-}}$ and $R_{NN\to N{\mathrm{\Delta }}^{+}}<R_{NN\to N{\mathrm{\Delta }}^0}$ by using the without-$\delta$ sets. By including the $\delta$ meson, there appear the totally opposite results in the $R$ for different channels, i.e., $R_{pp\to n{\mathrm{\Delta }}^{++}}>R_{nn\to p{\mathrm{\Delta }}^{-}}$ and $R_{NN\to N{\mathrm{\Delta }}^{+}}>R_{NN\to N{\mathrm{\Delta }}^0}$.

I review the arguments in favor of Weinberg's power counting for chiral effective nuclear field theory.

I review recent progress in understanding the structure of the nuclear forces based on chiral effective field theory.

The theory of nuclear forces has made great progress since the turn of the millenium using the framework of chiral effective field theory (ChEFT). The advantage of this approach, which was originally proposed by Weinberg, is that it has a firm basis in quantum-chromodynamics and allows for quantitative calculations. Moreover, this theory generates two-nucleon forces (2NF) and many-body forces on an equal footing and provides an explanation for the empirically known fact that 2NF ≫ 3NF ≫ 4NF. I will present the recent advances in more detail and put them into historical context. In addition, I will also provide a critical evaluation of the progress made including a discussion of the limitations of the ChEFT approach.

Gerry Brown has played a major role in initiating and stimulating systematic work on the theories of nuclear forces. It is the purpose of this paper to review those theories — in his memory.