Subscribe to the gold package and get unlimited access to Shamra Academy
Register a new userQuark structure and nuclear effective forces
99
0
0.0
(
0
)
Ask ChatGPT about the research
No Arabic abstract
We formulate the quark meson coupling model as a many-body effective Hamiltonian. This leads naturally to the appearance of many-body forces. We investigate the zero range limit of the model and compare its Hartree-Fock Hamiltonian to that corresponding to the Skyrme effective force. By fixing the three parameters of the model to reproduce the binding and symmetry energy of nuclear matter, we find that it allows a very satisfactory interpretation of the Skyrme force.
rate research
Read More
We review the main achievements of the research programme for the study of nuclear forces in the framework of chiral symmetry and discuss some problems which are still open.
We give a short review of the quark-meson coupling (QMC) model, the quark-based model of finite nuclei and hadron interactions in a nuclear medium, highlighting on the relationship with the Skyrme effective nuclear forces. The model is based on a mean field description of nonoverlapping nucleon MIT bags bound by the self-consistent exchange of Lorentz-scalar-isoscalar, Lorentz-vector-isoscalar, and Lorentz-vector-isovector meson fields directly coupled to the light quarks up and down. In conventional nuclear physics the Skyrme effective forces are very popular, but, there is no satisfactory interpretation of the parameters appearing in the Skyrme forces. Comparing a many-body Hamiltonian generated by the QMC model in the zero-range limit with that of the Skyrme force, it is possible to obtain a remarkable agreement between the Skyrme force and the QMC effective interaction. Furthermore, it is shown that 3-body and higher order N-body forces are naturally included in the QMC-generated effective interaction.
Charge independence and symmetry are approximate symmetries of nature. The observations of the small symmetry breaking effects and the consequences of those effects are reviewed. The effects of the mass difference between up and down quarks and the off shell dependence $q^2$ of $rho^0$-$omega$ mixing are stressed. In particular, I argue that models which predict a strong $q^2$ dependence of $rho^0$-$omega$ mixing seem also to predict a strong $q^2$ variation for the $rho^0$-$gamma^*$ matrix element, in contradiction with experiment.
Recent ab initio lattice studies have found that the interactions between alpha particles (4He nuclei) are sensitive to seemingly minor details of the nucleon-nucleon force such as interaction locality. In order to uncover the essential physics of this puzzling phenomenon without unnecessary complications, we study a simple model involving two-component fermions in one spatial dimension. We probe the interaction between two bound dimers for several different particle-particle interactions and measure an effective potential between the dimers using external point potentials which act as numerical tweezers. We find that the strength and range of the local part of the particle-particle interactions play a dominant role in shaping the interactions between the dimers and can even determine the overall sign of the effective potential.
The connection from the structure and dynamics of atomic nuclei (finite nuclear system) to the nuclear equation of state (thermodynamic limit) is primarily made through nuclear energy-density functional (EDF) theory. Failure to describe both entities simultaneously within existing EDF frameworks means that we have either seriously misjudged the scope of EDF or not fully taken advantage of it. Enter the versatile KIDS Ansatz, which is based on controlled, order-by-order extensions of the nuclear EDF with respect to the Fermi momentum and allows a direct mapping from a given, immutable equation of state to a convenient Skyrme pseudopotential for applications in finite nuclei. A recent proof-of-principle study of nuclear ground-states revealed the subversive role of the effective mass. Here we summarize the formalism and previous results and present further explorations related to giant resonances. As examples we consider the electric dipole polarizability of 68Ni and the giant monopole resonance (GMR) of heavy nuclei, particularly the fluffiness of 120Sn. We find that the choice of the effective mass parameters and that of the compression modulus affect the centroid energy of the GMR to comparable degrees.
Log in to be able to interact and post comments
comments
Fetching comments
Sign in to be able to follow your search criteria
