Coupling Constants Of Nuclei Research Articles

Spherical nuclei near the stability line and far from it

Results of microscopic and semiphenomenological calculations of features of spherical nuclei lying near the stability line and far from it are presented. The reason why the nuclei being considered are spherical is that they are magic at least in one nucleon sort. The present analysis is performed for Z = 50 and Z = 28 isotopes and for N = 50 isotones, the region extending from neutron-rich to neutron-deficient nuclei being covered. The isotopic dependence of the mean-field spin–orbit nuclear potential is revealed; systematics of energies of levels and probabilities for electromagnetic transitions is examined; and root-mean-square radii of nuclei are calculated, along with the proton- and neutron-density distributions in them. Nuclei in the vicinity of closed shells are considered in detail, and the axial-vector weak coupling constant in nuclei is evaluated. A systematic comparison of the results of calculations with experimental data is performed.

The effective induced pseudoscalar coupling constant

The different mechanisms that contribute to the renormalization of the effective induced pseudoscalar coupling constant in nuclei are described. For a nucleon in the nuclear medium one has to consider four different induced pseudoscalar couplings, which are associated with the space- and time-like parts of the current and the pseudovector source function, respectively. All of these are renormalized in different ways in the medium. The net effect for weak processes with large time-like momentum transfer is a substantial quenching of the transition rates that increases with mass number in agreement with recent data on radiative muon capture on heavy nuclei.

Pauli principle and renormalization of the pion nucleon interaction in nuclei

We show that the exclusion principle provides an alternative mechanism to the Lorentz-Lorenz effect for the renormalization of the pion-nucleon coupling constant in nuclei. This mechanism proves to be less sensitive to the range of the π - N forces. The implications for pion-nucleus scattering are discussed.

Pionic field and renormalization of the axial coupling constant in nuclei

The renormalization of the axial coupling constant in nuclei is related by PCAC to the exchange effects in the pionic vertex. Using an optical potential as a model for the pion source function, it is shown that in large nuclei the renormalization arises from the short range correlations. The analogy between this problem and that of an electric dipole inside a dielectric medium is pointed out.

Magnetic Resonance Studies of Biradicals. III. Verdazyl Mono- and Biradicals

We have taken the NMR and ESR spectra of a series of verdazyl mono and biradicals. The susceptibility of each of the compounds was also measured. Zero field splitting parameters were determined from the ESR spectra while electron–nuclei coupling constants were determined from the NMR spectra. The coupling constants of nuclei contained in rings connecting the two monoradical halves proved to be the average of couplings from protons in corresponding positions in the monoradical while the coupling constants for nuclei in other parts of the molecules were one-half of the monoradicals couplings. The relative magnitudes of the various coupling constants were predicted by a simple perturbation calculation and by semiempirical MO calculations.