Narrow Results

Symmetry energy coefficients of explicitly isospin asymmetric nuclear matter at variable densities (from 0.5ρ₀ up to 2ρ₀) are studied as generalized screening functions. An extended stability condition for asymmetric nuclear matter is proposed. We find the possibility of obtaining stable asymmetric nuclear matter even in some cases for which the symmetric nuclear matter limit is unstable. Skyrme-type forces are extensively used in analytical expressions of the symmetry energy coefficients derived as generalized screening functions in the four channels of the particle hole interaction producing alternative behaviors at different ρ and b (respectively, the density and the asymmetry coefficient). The spin and spin-isospin coefficients, with corrections to the usual Landau Migdal parameters, indicate the possibility of occurring instabilities with common features depending on the nuclear density and n–p asymmetry. Possible relevance for high energy heavy ions collisions and astrophysical objects is discussed.

Nucleon structure study is one of the most important research areas in modern physics and has challenged us for decades. Spin has played an essential role and often brought surprises and puzzles to the investigation of the nucleon structure and the strong interaction. New experimental data on nucleon spin structure at low to intermediate momentum transfers combined with existing high momentum transfer data offer a comprehensive picture in the strong region of the interaction and of the transition region from the strong to the asymptotic-free region. Insight into some aspects of the theory for the strong interaction, Quantum Chromodynamics (QCD), is gained by exploring lower moments of spin structure functions and their corresponding sum rules (i.e., the Bjorken, Burkhardt–Cottingham, Gerasimov–Drell–Hearn (GDH), and the generalized GDH). These moments are expressed in terms of an operator-product expansion using quark and gluon degrees of freedom at moderately large momentum transfers. The higher-twist contributions have been examined through the evolution of these moments as the momentum transfer varies from higher to lower values. Furthermore, QCD-inspired low-energy effective theories, which explicitly include chiral symmetry breaking, are tested at low momentum transfers. The validity of these theories is further examined as the momentum transfer increases to moderate values. It is found that chiral perturbation theory calculations agree reasonably well with the first moment of the spin structure function g₁ at low momentum transfer of 0.05–0.1 GeV² but fail to reproduce some of the higher moments, noticeably, the neutron data in the case of the generalized polarizability δ_LT. The Burkhardt–Cottingham sum rule has been verified with good accuracy in a wide range of Q² assuming that no singular behavior of the structure functions is present at very high excitation energies.

The nuclear potential energies of neutron deficient even–even rare earth nuclei ¹⁵⁸Er and ¹⁶²Hf for the spin range 0–60 are computed within the framework of cranked Nilsson–Strutinsky shell correction method. The potential energy surface diagrams are analyzed in terms of quadrupole deformation and triaxiality parameter. The shape evolution of these isotopes with respect to spin is studied. The spin dependence of nuclear equilibrium potential energy is also verified.

The US Nuclear Science Advisory Committee (NSAC) recently recommended the construction of a high-luminosity, high-energy Electron Ion Collider (EIC), with polarized beams capable of colliding polarized electrons with polarized proton and light ion beams, and with any nucleus. The $\sqrt{s}$ range between 40GeV and 140GeV, and luminosity range from $10^{33-34}{\mathrm{\text{cm}}}^{-2}{\mathrm{\text{s}}}^{-1}$ were recommended. It is anticipated that under the current guidance from the DOE, the collider could become operational in the second half of the 2020’s. This paper summarizes its science and the scope of this over all project.

The antiferromagnetic properties of nuclei are studied within the Wigner function moments method. The solution of the time dependent Hartree–Fock–Bogoliubov equations predicts four low-lying $1^{+}$ states. Three of them are known as various scissors modes. Fourth state is disposed below all scissors modes and represents one of three branches of $2^{+}$ multiplet which can exist in spherical nuclei and which is split in deformed nuclei. It is discovered, that the antiferromagnetic properties of nuclei lead to the splitting of $2^{+}$ states already at the zero deformation. It is shown that the splitting caused by nuclear antiferromagnetism is comparable to the Zeeman splitting in an external uniform magnetic field.