International Journal of Modern Physics E

The 2015 update of the discovery of nuclide project is presented. Twenty new nuclides were observed for the first time in 2015. An overall review of all previous assignments was made in order to apply the discovery criteria consistently to all elements. In addition, a list of isotopes published so far only in conference proceedings or internal reports is included.

An expression of the particle-number projected nuclear moment of inertia (MOI) has been established in the neutron–proton (np) isovector pairing case within the cranking model. It generalizes the one obtained in the like-particles pairing case. The formalism has been, as a first step, applied to the picket-fence model. As a second step, it has been applied to deformed even–even nuclei such as $(N-Z)=0,2,4,$ and of which the experimentally deduced values of the pairing gap parameters ${\mathrm{\Delta }}_{t{t}^{\prime }}$, $t,t^{\prime }=n,p$, are known. The single-particle energies and eigenstates used are those of a deformed Woods–Saxon mean-field. It was shown, in both models, that the np pairing effect and the projection one are non-negligible. In realistic cases, it also appears that the np pairing effect strongly depends on $(N-Z)$, whereas the projection effect is practically independent from the same quantity.

A set of global ${}^6$He phenomenological optical model potential (OMP) parameters with incident energies up to 250MeV is obtained. They are based on a smooth, unique functional form for the energy dependence of the potential depths, and on physically constrained geometry parameters. The available experimental data including the reaction cross-sections and elastic scattering angular distributions from target ${}^6$Li to ${}^{209}$Bi are used. The global OMP parameters obtained for ${}^6$He are analyzed and used to calculate the reaction for ${}^8$He projectile. It is found that the present form of the global OMP can reproduce the experimental data for ${}^6$He and ${}^8$He projectiles.

The grey particle production following 60 A and 200A GeV ${}^{16}$O interactions with emulsion nuclei is investigated at different centralities. The evaporated target fragment multiplicity is voted as a centrality parameter. The target size effect is examined over a wide range, where the C, N and O nuclei present the light target group while the Br and Ag nuclei are the heavy group. In the framework of the nuclear limiting fragmentation hypothesis, the grey particle multiplicity characteristics depend only on the target size and centrality while the projectile size and energy are not effective. The grey particle is suggested to be a multisource production system. The emission direction in the 4$\pi$ space depends upon the production source. Either the exponential decay or the Poisson’s peaking curves are the usual characteristic shapes of the grey particle multiplicity distributions. The decay shape is suggested to be a characteristic feature of the source singularity while the peaking shape is a multisource super-position. The sensibility to the centrality varies from a source to other. The distribution shape is identified at each centrality region according to the associated source contribution. In general, the multiplicity characteristics seem to be limited w.r.t. the collision system centrality using light target nuclei. The selection of the black particle multiplicity as a centrality parameter is successful through the collision with the heavy target nuclei. In the collision with the light target nuclei it may be qualitatively better to vote another centrality parameter.

A method for the determination of the pairing-strength constants, in the neutron–proton (n–p) isovector plus isoscalar pairing case, is proposed in the framework of the BCS theory. It is based on the fitting of these constants to reproduce the experimentally known pairing gap parameters as well as the root-mean-squared (r.m.s) charge radii values. The method is applied to some proton-rich even–even nuclei. The single-particle energies used are those of a deformed Woods–Saxon mean field. It is shown that the obtained value of the ratio $G_{np}^{T=0}/G_{np}^{T=1}$ is of the same order as the ones, arbitrary chosen, of some previous works. The effect of the inclusion of the isoscalar n–p pairing in the r.m.s matter radii is then numerically studied for the same nuclei.

The rapidity distributions of $J/\psi$ mesons produced in proton-lead ($p$-Pb) collisions at center-of-mass energy per nucleon pair $\sqrt{s_{NN}}=5$TeV are studied by using a multisource thermal model and compared with the experimental data of the LHCb and ALICE Collaborations. Correspondingly, the pseudorapidity distributions are accurately obtained from the parameters extracted from the rapidity distributions. At the same time, the transverse momentum distributions in the same experiments are described by the simplest Erlang distribution which is the folding result of two exponential distributions which are contributed by the target and projectile partons, respectively.

Compact stars are classified into three categories: neutron stars (NSs), quark stars (QSs) and hybrid stars (HSs). Stars having only hadronic matter are NSs, QSs having only quark matter up to u, d and s quarks and stars having quark core surrounded by a mixed matter (hadronic matter and quark matter) followed by hadronic matter are HSs. The mixed matter is well distributed to both hadron and quark matters. A huge magnetic field is predicted in the core of the neutron star and is observed in the surface of the neutron star. We study the effect of such huge magnetic field in the matter inside the compact objects basically the equation of state (EOS) of the matters. Since matter inside the star are very dense both hadronic and quark matter, we consider relativistic mean field theory in the hadronic matter and simple MIT bag model in the quark matter in the presence of strong magnetic field. We calculate the phase transition between hadronic and quark phases, maximum mass and eigenfrequencies of radial pulsation of NS, HS and QS in the presence of such a huge magnetic field. The mixed phase is constructed by using Glendenning conjecture in between hadron and quark phases. We find in the presence of magnetic field, the EOS in both matter becomes soft. As a result, the maximum mass is reduced and the period of oscillation is changed significantly and there is a sudden dip in the period of oscillations in the HS, which signifies the transition from one to another matter.

The models variable moment of inertia (VMI), two-parameter $(ab)$ formula and Harris ${\omega }^2$ expansion have been applied to 16 rotational superdeformed bands in the $A\sim 80$ mass region to obtain band head spin $(I_0)$. The band head spins of these 16 bands in the $A\sim 80$ mass region are predicted by least-squares fitting method. Intraband $\gamma$-rays energies are fitted in these models to extract model parameters so as to obtain a minimum root mean square (RMS) deviation between calculated and the observed transition energies. The calculated transition energies depend upon the prescribed spins. When a legitimate band head spin is assigned, the calculated transition energies are in good agreement with the observed transition energies.

We establish sharp (or ’refined’) comparison theorems for the Klein–Gordon equation. We show that the condition $V_a\le V_b$, which leads to $E_a\le E_b$, can be replaced by the weaker assumption $U_a\le U_b$ which still implies the spectral ordering $E_a\le E_b$. In the simplest case, for $d=1$, $U_i(x)={\int }_0^x{V}_i(t)dt$, $i=a$ or $b$ and for $d>1$, $U_i(r)={\int }_0^r{V}_i(t)t^{d-1}dt$, $i=a$ or $b$. We also consider sharp comparison theorems in the presence of a scalar potential $S$ (a ‘variable mass’) in addition to the vector term $V$ (the time component of a four-vector). The theorems are illustrated by a variety of explicit detailed examples.

In this work, we report on our computation results for the best value of the shear viscosity to entropy ratio of quark–gluon plasma produced in the relativistic Au–Au collisions at $\sqrt{s_{\mathrm{\text{NN}}}}=200$GeV. Time evolution of heavy quarks distribution functions is calculated by solving the Fokker–Planck evolution equation using the new technique: Iterative Laplace transform method. We compute the drag and diffusion coefficients by considering the hard thermal loop corrections and also temperature dependence running strong coupling, up to complete interactions of leading order.

The nonextensive behavior of entropy is exploited to explain the regularity in multiplicity distributions in $e^{+}{e}^{-}$ collisions at high energies. The experimental data are analyzed by using Tsallis $q$-statistics. We propose a new approach of applying Tsallis $q$-statistics, wherein the multiplicity distribution is divided into two components; two-jet and multijet components. A convoluted Tsallis distribution is fitted to the data. It is shown that this method gives the best fits which are several orders better than the conventional fit of Tsallis distribution.

Three-nucleon systems are considered assuming the neutrons and protons to be distinguishable particles. The configuration space Faddeev equations are exploited to calculate ground state energies of ³H and ³He nuclei within an $s$-wave approach applying the Malfliet–Tjon, Tamagaki G3RS and Afnan–Tang ATS3 NN potentials. We modify the potentials by scaling strength parameters to define $nn$, $pp$ and $np$ singlet components. The scaling parameters are fixed to reproduce experimental scattering lengths. The charge symmetry breaking energy is numerically evaluated. The relation between $nn$, $pp$ and $np$ singlet potentials is discussed.

The reactions including the stable weakly bound nucleus ⁹Be have been studied using the classical trajectory model accompanied with the experimental breakup function and the Aage-Winther interaction potential (AW95). In these calculations, the no-capture breakup and the incomplete fusion cross-sections as well as their competition at around the Coulomb barrier have been investigated. Our calculations showed that at a given far-Coulomb-barrier energy the incomplete fusion reaction in different distributions of angular momentum and energies can dominate the no-capture breakup reaction. This dominating process is reversed at the near-barrier energies.

The nuclear potential energies of Lu isotopes with neutron number $N=90-98$ up to high spins are computed within the framework of the unpaired cranked Nilsson–Strutinsky method. The potential and the macroscopic Lublin–Strasbourg drop (LSD) energy-surface diagrams are analyzed in terms of quadrupole deformation and triaxiality parameter. The shape evolution of these isotopes with respect to angular momentum, as well as the neutron number is studied.