International Journal of Modern Physics E

We review the elastic and diffractive scatterings of protons (called also the “forward physics”) with emphasis on the LHC data, especially those deviating from the expectations based on extrapolations from earlier measurements at the ISR and Fermilab and thus triggering searches for new ideas, models and theories. We list these new data and provide a brief introduction of available theoretical approaches, mainly those based on analyticity, crossing symmetry and unitarity, particularly the Regge pole model realizing these concepts. Fits to the data are presented and tensions between theoretical predictions and the data that may indicate the way to further progress are in the focus of our paper.

In this work, we use matrix models to study the problem of strength distributions. This is motivated by noticing near exponential falloffs of strengths in calculated magnetic dipole excitations. We emphasize that the quality of the exponential falloffs depends on the parameters in our matrices, especially the relative size of the couplings to the unperturbed level separations. We also find a dark matrix for which all transitions vanish.

Mixed-symmetry and isospin excited states are typical of the interacting boson model with isospin (IBM-3). With a view to look for such states, levels scheme of the IBM-3 dynamical symmetry is discussed. A systematic investigation in the proton and neutron degrees of freedom of the energy levels has been carried out. A sequence of isospin excitation bands has been identified. We have analyzed the wave functions and given the symmetrical labeling of the states. The transition probabilities between the isospin excitation states of model limits are analyzed in terms of isoscalar and isovector decompositions. The present calculations suggest that a combination of isospin excitation and mixed-symmetry states can provide substantial information on the structure of nuclear states. Calculations for ${}_{44}^{88}\mathrm{\text{Ru}}$ and ${}_{46}^{92}\mathrm{\text{Pd}}$ nuclei are presented and compared with the results of the shell model and available experimental data.

We present a strong absorption model with an $S$-matrix in a new form of an antisymmetrized Fermi distribution for describing diffraction patterns of neutron–nucleus scattering at intermediate energies. The proposed antisymmetric $S$-matrix has a form close to the conventional one and allows to obtain exact analytical expressions for the damping factor that determines the elastic scattering amplitude and the total cross-sections for interaction, reactions and elastic scattering. The use of an antisymmetrized Fermi function instead of the usual Fermi function in successful strong absorption models basically does not notably affect the calculated nucleon–nucleus elastic scattering differential cross-sections in the intermediate energy region.

We construct the quiescent neutron star models in the evolutionary calculations. The X-ray luminosities have been derived in terms of the time-averaged mass accretion rate for various neutron star masses and surface compositions. We compare the quiescent luminosities observed from X-ray transients in low mass X-ray binaries, where the stellar evolutionary calculations of accreting neutron stars include neutrino cooling due to strong pion condensations. Our results based on the evolutionary calculations suggest that stronger cooling process would be necessary to be consistent with observations.

A set of empirical formulae have been proposed to calculate the $\alpha$-decay half-lives from ground state to ground state transitions of 356 nuclei classified to different set of e–e, e–o, o–e and o–o isotopes. Within these formulae, modification of the previous set of Royer expressions were done by introducing three different physical terms, including the orbital angular momentum and isobaric asymmetry factors. The predicted $\alpha$-decay half-lives compared with those adopted by former proposed models for the depended experimental data, and significant improvements were noticed for all the studied sets of isotopes.

B(E1) and B(E2) reduced probabilities for intra- and inter-band transitions between the collective states of the yrast, first nonyrast and second nonyrast alternating-parity bands in the lanthanide nuclei ${}^{150}$Nd, ${}^{152,154}$Sm, ${}^{154}$Gd, ${}^{156}$Dy, ${}^{162,164}$Er and the actinides ${}^{232,234,236,238}$U are studied within a model with collective quadrupole–octupole degrees of freedom. The calculated B(E1)- and B(E2)-values and some ratios between probabilities for transitions with the same multipolarity are compared with available experimental data. In addition, the B(E2)-transition ratios are compared with the Alaga rules providing estimations for the sensitivity of the E2-transitions to the quadrupole deformation mode in the considered nuclei.

We investigated ground-state nuclear structure properties of even and odd ${}^{103–140}\mathrm{\text{Sb}}$, ${}^{105–143}\mathrm{\text{Te}}$, ${}^{107–145}\mathrm{\text{I}}$, ${}^{109–148}\mathrm{\text{Xe}}$ and ${}^{112–151}\mathrm{\text{Cs}}$ nuclei via the axially deformed solution of Skyrme Hartree–Fock Bogoliubov (HFB) based on the transformed harmonic oscillator (THO) and the harmonic oscillator. In the calculations, different Skyrme force parameters were used to obtain wide nuclear data of the nuclei. The calculated results were compared with the results of the experimental data and theoretical models, i.e., the finite-range liquid-drop model (FRDM) and relativistic mean-field theory (RMFT). Additionally, the deformation regions of neutron rich Sb, Te, I, Xe and Cs nuclei have also been discussed. Moreover, in addition to the binding energy per particle, charge, proton and neutron density radii, one-neutron $(S_N)$, and two-neutron separation energies $(S_{2N})$, the quadropule deformation parameter $({\beta }_2)$, the neutron skin thicknesses (NST), the quadrupole moments $(Q)$ and the pairing gap energies of the nuclei were determined by HFBTHO 2.00 code.

In this paper, the polarized neutron structure function $g_1^n$ in the ${}^3\mathrm{\text{He}}$ nucleus is investigated and an analytical solution based on the Laplace transform method for $g_1^n$ is presented. It is shown that the neutron spin structure function can be extracted directly from the polarized nuclear structure function of ${}^3\mathrm{\text{He}}$. The nuclear corrections due to the Fermi motion of the nucleons as well as the binding energy considerations are taken into account within the framework of the convolution approach and the polarized structure function of ${}^3\mathrm{\text{He}}$ nucleus is expressed in terms of the spin structure functions of nucleons and the light-cone momentum distribution of the constituent nucleons. Then, the numerical results for $g_1^n$ are compared with experimental data of the SMC and HERMES collaborations. We found that there is an overall good agreement between the theory and experiments.