International Journal of Modern Physics E

The internal structure of neutron stars and the physical properties of nuclei depend on the equation of state (EOS) of neutron matter. Dilute neutron matter is a quantum system of spin-1/2 Fermi particles interacting via s-wave scattering. Although a nuclear system and an ultracold atomic system have length scales and energy scales that differ by several orders of magnitude, both systems follow a common universal EOS considering their nondimensional universal interaction parameters. In this study, we determine the EOS of neutron matter in the dilute region, where the influence of the s-wave scattering length is dominant but that of the effective range is small, by utilizing a quantum simulator of ultracold ⁶Li atoms with Feshbach resonance.

The 2018 update of the discovery of nuclide project is presented. Fifty new nuclides were observed for the first time in 2018. A large number of isotopes are still only published in conference proceedings or internal reports.

Employing the projected-Hartree-Fock-Bogoliubov (PHFB) model in conjunction with four different parametrizations of pairing plus multipolar effective two-body interaction and three different parametrizations of Jastrow short-range correlations, nuclear transition matrix elements for the neutrinoless double-$\beta$ decay of ${}^{94,96}\mathrm{\text{Zr}}$, ${}^{100}\mathrm{\text{Mo}}$, ${}^{110}\mathrm{\text{Pd}}$, ${}^{128,130}\mathrm{\text{Te}}$ and ${}^{150}\mathrm{\text{Nd}}$ isotopes are calculated within mechanisms involving light Majorana neutrino mass and right-handed current. Statistically, model specific uncertainties in sets of twelve nuclear transition matrix elements are estimated by calculating the averages along with the standard deviations. For the considered nuclei, the most stringent extracted on-axis limits on the effective light Majorana neutrino mass $〈m_{\nu }〉$, the effective weak coupling of right-handed leptonic current with right-handed hadronic current $〈\lambda 〉$, and the effective weak coupling of right-handed leptonic current with left-handed hadronic current $〈\eta 〉$ from the observed limit on half-life $T_{1/2}^{0\nu }$ of ${}^{130}\mathrm{\text{Te}}$ isotope are $0.33$eV, $4.57\times 10^{-7}$ and $4.72\times 10^{-9}$, respectively.

Lawson has shown that one can obtain sensible wave functions even in the weak deformation limit of the Nilsson model as long as one projects out states of good total angular momentum. We apply this method to obtain wave functions and magnetic $g$ factors of excited states of select even–even Ar isotopes with emphasis on the comparison of ${}^{40}$Ar and ${}^{44}$Ar. These $g$ factors are compared with the values that are obtained by matrix diagonalization in the same space using the WBT residual interaction.

We investigate whether the mass and momentum spectra of emitted particles in $K^{-}+{}^6\mathrm{\text{Li}}$ reaction can be used for disentangling the nature of $\mathrm{\Lambda }$(1405) and how the signature of the $\mathrm{\Lambda }$(1405) resonance appears in the cross-sections of the kaon-lithium reaction on the physical real energy. We used different types of $\bar{K}N-\pi \mathrm{\Sigma }$ potentials to study the dependence of the results to the fundamental kaon-nucleon interaction. The momentum spectra are calculated for final pions and neutrons. The possibility of the observation of the $\mathrm{\Lambda }$(1405) resonance in the mass spectra is studied. It was demonstrated that the $\pi \mathrm{\Sigma }$ mass and neutron momentum spectra are more suitable than the pion momentum spectra to see the trace of the $\mathrm{\Lambda }$(1405) resonance and it is a useful tool for investigating the subthreshold behavior of the $\bar{K}N$ interaction.

We investigate the dense-plasma screening effects on the thermonuclear ${}^3\mathrm{\text{H}}{{(}^2\mathrm{\text{H}},n)}^4\mathrm{\text{He}}$ fusion reaction. In this study, we focus on the strong screening with the weak quantum effect in the thermonuclear region. At the first step, we calculate the cross-section and $S$-factor of the bare $d\mathrm{\text{–}}t$ fusion using a model inspired by halo/cluster effective field theory approach. The evaluations of the plasma screening corrections in the $S$-factor and the reaction rate would be studied in the next step. Concentrating on the thermonuclear region, we use the Salpeter’s potential justifying the electron cloud around reactant as an incompressible and uniformly charged liquid drop. Finally, we show the changes in the $S$-factor and production rate due to the screening electrons.

Based on a simple site-independent approach, we attempt to reproduce the solar $r$-process abundance with four nuclear mass models, and investigate the impact of the nuclear mass uncertainties on the $r$ process. In this paper, we first analyze the reliability of an adopted empirical formula for $\beta$-decay half-lives which is a key ingredient for the $r$ process. Then we apply four different mass tables to study the $r$-process nucleosynthesis together with the calculated $\beta$-decay half-lives, and the existing $\beta$-decay data from FRDM+QRPA is also considered for comparison. The numerical results show that the main features of the solar $r$-process pattern and the locations of the abundance peaks can be reproduced well via the $r$-process simulations. Moreover, we also find that the mass uncertainties can significantly affect the derived astrophysical conditions for the $r$-process site, and resulting in a remarkable impact on the $r$ process.

This work examined the fusion dynamics of ${}^{16}\mathrm{\text{O}}+{}^{76}\mathrm{\text{Ge}}$ and ${}^{18}\mathrm{\text{O}}+{}^{74}\mathrm{\text{Ge}}$ reactions within the framework of the static Woods–Saxon potential model, the energy dependent Woods–Saxon potential (EDWSP) model and coupled channel formulation. The effects of inelastic surface excitations, static deformation of colliding pairs and /or neutron transfer channels on fusion process are investigated through the coupled channel method. The calculations based upon static Woods–Saxon potential in conjunction with one-dimensional Wong formula strongly under predict the fusion data of ${}^{16}\mathrm{\text{O}}+{}^{76}\mathrm{\text{Ge}}$ and ${}^{18}\mathrm{\text{O}}+{}^{74}\mathrm{\text{Ge}}$ reactions at sub-barrier energies. However, such discrepancies are removed if one uses couplings to nuclear structure degrees of freedom of reacting nuclei. The coupled channel calculations obtained by considering the vibrational nature of the colliding nuclei fairly reproduce the fusion data of ${}^{18}\mathrm{\text{O}}+{}^{74}\mathrm{\text{Ge}}$ reactions. For this reaction, the neutron transfer channels, which are expected to influence strongly the fusion yields at below barrier energies, in reality contribute very weakly to fusion process. While in case of ${}^{16}\mathrm{\text{O}}+{}^{76}\mathrm{\text{Ge}}$ reaction, the consideration of vibrational couplings as well as the rotational couplings for target provides a reasonable explanation to the fusion cross-section data at near and above barrier energies. In distinction, the energy dependence in the nucleus–nucleus potential causes barrier modulation effects and subsequently modifies the barrier profile of the interaction barrier in such a way that the effective fusion barrier between the colliding pair reduces. This ultimately brings larger fusion cross-sections over the outcomes of one-dimensional barrier penetration model and the EDWSP model based calculations appreciably explained the fusion dynamics of chosen reaction at energy spanning around the Coulomb barrier. Both models (EDWSP and coupled channel model) lead to barrier lowering effects and modeled quantum tunneling in different way, henceforth, adequately explore the fusion dynamics of the studied reactions in near and above barrier energy regions.

The generic form of space-time dynamics as a classical gauge field theory has recently been derived, based on only the action principle and on the principle of general relativity. It was thus shown that Einstein’s general relativity is the special case where (i) the Hilbert Lagrangian (essentially the Ricci scalar) is supposed to describe the dynamics of the “free” (uncoupled) gravitational field, and (ii) the energy–momentum tensor is that of scalar fields representing real or complex structureless (spin-$0$) particles. It followed that all other source fields — such as vector fields representing massive and nonmassive spin-$1$ particles — need careful scrutiny of the appropriate source tensor. This is the subject of our actual paper: we discuss in detail the coupling of the gravitational field with (i) a massive complex scalar field, (ii) a massive real vector field, and (iii) a massless vector field. We show that different couplings emerge for massive and nonmassive vector fields. The massive vector field has the canonical energy–momentum tensor as the appropriate source term — which embraces also the energy density furnished by the internal spin. In this case, the vector fields are shown to generate a torsion of space-time. In contrast, the system of a massless and charged vector field is associated with the metric (Hilbert) energy–momentum tensor due to its additional $\mathrm{\text{U}}(1)$ symmetry. Moreover, such vector fields do not generate a torsion of space-time. The respective sources of gravitation apply for all models of the dynamics of the “free” (uncoupled) gravitational field — which do not follow from the gauge formalism but must be specified based on separate physical reasoning.

Structural properties and the decay modes of the superheavy elements $Z=122,120$ and 118 are studied in a microscopic framework. We evaluate the binding energy, one- and two- proton and neutron separation energy, shell correction and density profile of even and odd isotopes of $Z=122,120,118$ $(284\le A\le 352)$ which show a reasonable match with FRDM results and the available experimental data. Equilibrium shape and deformation of the superheavy region are predicted. We investigate the possible decay modes of this region specifically $\alpha$-decay, spontaneous fission (SF) and the $\beta$-decay and evaluate the probable $\alpha$-decay chains. The phenomena of bubble like structure in the charge density is predicted in ${}^{330}122$, ${}^{292,328}120$ and ${}^{326}118$ with significant depletion fraction around 20–24% which increases with increasing Coulomb energy and diminishes with increasing isospin ($N-Z$) values exhibiting the fact that the coulomb forces are the main driving force in the central depletion in superheavy systems.

We investigated the orientation behavior of the interaction potential between highly-deformed oblate ${}^{28}$Si nuclei and its influences on the fusion process. The deformed–deformed potential is calculated using the double-folding model based on the realistic M3Y-Reid nucleon–nucleon interaction. We found that the Coulomb barrier parameters and the sub-barrier fusion data strongly depend on the polar orientation angles of the involved deformed nuclei, with a rather less dependence on the azimuthal angles. For interacting oblate nuclei, the elongated configuration corresponding to the lowest Coulomb barrier is obtained at orthogonal polar orientations, while the hexadecapole deformation determines the compact configuration obtained at nonzero polar orientations. The orientation behavior of the Coulomb barrier radius (height and curvature) consistently follow (inversely reflex) the orientation variation of the sum of the half-density radii of the two deformed nuclei, along their centers-of-mass separation vector. The deformations of the colliding nuclei increase their fusion cross-section at sub- and around-barrier energies. The calculations based on the parabolic barrier approximation overestimate the sub-barrier cross-section. The coupled channels calculations with couplings up to the 2${}^{+}$ and 4${}^{+}$ excitation states of ${}^{28}$Si nuclei are needed to reproduce the ${}^{28}\mathrm{\text{Si}}+{}^{28}\mathrm{\text{Si}}$ fusion cross-section, and the corresponding logarithmic slope and barrier distribution, over the full energy region.

The paper discusses the results of measurement for three components of tensor analyzing power for the reaction of incoherent ${\pi }^0$-meson photoproduction on a deuteron within the proton energy range of 15–200MeV and the neutron energy range of 15–150MeV. The experiment was performed on the deuterium internal gas target of VEPP-3 electron accelerator using the protons and neutrons coincidence counting technique. The results of measurements of the tensor analyzing power’s components are compared with the results of statistical modeling performed within the frameworks of a theoretical model.

In recent years, the physics of hypernuclei has been in progress dramatically both in experiments and theories. In this regard, there have been considerable interests in the study of $\mathrm{\Lambda }$-particle 1s state in hypernuclei using relativistic quantum mechanics. Many theoretical results have been obtained numerically in the relativistic frameworks. In this work, using the relativistic Dirac equation, we study the properties of $\mathrm{\Lambda }$-particle in the hypernuclei analytically and, specifically, we determine its binding energies of ground state in a single $\mathrm{\Lambda }$-hypernuclei. The $\mathrm{\Lambda }$-N potential is considered as a spin-dependent term and the radial dependence of potential is approximated by a Gaussian function. For a more complete analysis, we will also compute the hypernuclei mass, its wave function and the root mean square (RMS) radii of $\mathrm{\Lambda }$ orbits in $\mathrm{\Lambda }$-hypernuclear system.

On January 26, 2019, we lost one of the eminent nuclear theorist Prof. Raj Kumar Gupta, Emeritus Professor of Panjab University, Chandigarh, India. He breathed his last at 2 am in the early morning of 26th, due to sudden health ailments. He was a great and renowned scholar, fatherly figure to many of his students, kind-hearted person to his colleagues and friends.