Nuclear Theory·nucl-th
9 papers—3 primary·6 cross-listed
Avraham Gal🇮🇱 · Daniel Gazda🇸🇪
Charge symmetry breaking (CSB) is particularly strong in the A=4 mirror hypernuclei H--He. Recent four-body no-core shell model calculations that confront this CSB by introducing - mixing to leading-order chiral effective field theory hyperon-nucleon potentials are reviewed, and a shell-model approach to CSB in p-shell hypernuclei is outlined.
S. Sudár (1) · S. M. Qaim (2) ((1) Institute of Experimental Physics, University of Debrecen, Hungary, (2) Institut für Neurowissenschaften und Medizin, INM-5: Nuklearchemie, Forschungszentrum Jülich GmbH, Germany)
The parameter of the spin distribution of the level density was determined for 61 nuclei covering the mass range of 44 to 200. The experimental isomeric cross-section ratios for 25 isomeric pairs were compared with the model calculation to find the best fit to the experimental data. The model calculations were carried out with the TALYS code using the BSFG model for the level density. The reduced values were calculated to describe the deviation of the experimental data from the model calculation. An was introduced calculating the value from the low energy discrete levels of the nucleus. The values seem to be independent of the mass number, their average value near to one. The values also seem to be independent of the average excitation energy in the continuum, indicating that is independent of the excitation energy. The mass number and (N-Z) dependence of the values were studied. The values for the nuclei with odd mass number show an exponential decrease as a function of A or (N-Z). The values for the odd-odd type of nuclei appear to be constant, near one, up to the mass number 110 or (N-Z) of 13. Above these values, the values show exponential decrease. The values for even-even type nuclei decrease exponentially up to A equal to 142 or (N-Z) equal to 20. The values are lower than those for the nearby odd-odd type nuclei. The values increase for nuclei with A between 142 and 156 and (N-Z) between 20 and 28, and they finally reach the value of odd-odd type systematics.
Tochtli Yépez-Martínez🇦🇷 · Osvaldo Civitarese🇦🇷 · Peter O. Hess🇲🇽
The low-energy sector of the mesonic spectrum exhibits some features which may be understood in terms of the SO(4) symmetry contained in the QCD-Hamiltonian written in the Coulomb Gauge. In our previous work we have shown that this is indeed the case when the Instantaneous Color-Charge Interaction (ICCI) is treated by means of non-perturbative many-body linearization techniques. Continuing along this line of description in this work we calculate the width of meson states belonging to the low portion of the spectrum (E <1 GeV ). In spite of the rather simple structure of the Hamiltonian used to calculate the spectra of pseudoscalar and vector mesons, the results for the width of these states follow the pattern of the data.
first authorsco-authorsvia INSPIRE