International Journal of Modern Physics E

Quantum hadrodynamics (QHD) is a framework for describing the nuclear many-body problem as a relativistic system of baryons and mesons. Motivation is given for the utility of such an approach and for the importance of basing it on a local, Lorentz-invariant lagrangian density. Calculations of nuclear matter and finite nuclei in both renormalizable and nonrenormalizable, effective QHD models are discussed. Connections are made between the effective and renormalizable models, as well as between relativistic mean-field theory and more sophisticated treatments. Recent work in QHD involving nuclear structure, electroweak interactions in nuclei, relativistic transport theory, nuclear matter under extreme conditions, and the evaluation of loop diagrams is reviewed.

It is shown that a heavy gluon giant resonance state which is highly collective exists in a gluon plasma. This arises when the finite size effects are taken properly into account.

We have investigated the gross structural properties of Ne, Mg, Si, S, Ar and Ca nuclei, starting from the proton-drip line till the neutron drip-line. An axially deformed self-consistent relativistic mean-field approach is used. All possible shapes (prolate, oblate or spherical) are searched, using three sets of force parameter, the NL2, NL-SH and TM2. Agreement between the calculation and experiment is found to be good, particularly for the TM2 force parameters. We find a sizeable deformation of the neutron/proton-rich Ne and Mg isotopes near the drip lines. Also, deformations of nuclei at and near the spherical magic shell N=28 are found to be large, in agreement with experiments. The breaking/non-breaking of the spherical shell gap at N=28 is also observed, dependent on the choice of force parameters and pairing strength. A large number of cases of shape coexistence are identified. The effects of pairing strength on the calculated properties are also discussed.

The modern nucleon-nucleon interaction of Myers and Swiatecki, adjusted to the properties of finite nuclei, the parameters of the mass formula, and the behavior of the optical potential is used to calculate the properties of β-equilibrated neutron star matter, and to study the impact of this equation of state on the properties of (rapidly rotating) neutron stars and their cooling behavior. The results are in excellent agreement with the outcome of calculations performed for a broad collection of sophisticated nonrelativistic as well as relativistic models for the equation of state.

The spin and flavor fractions of constituent quarks in the baryon octet are obtained from their lowest order chiral fluctuations involving Goldstone bosons. SU(3) breaking suggested by the mass difference between the strange and up, down quarks is included, as are relativistic effects by means of a light-cone quark model for the proton, and the gluon contribution from the axial anomaly in the singlet channel. Magnetic moments from the Karl-Sehgal formulas are analyzed in this framework as well.