International Journal of Modern Physics E

The drag and diffusion coefficients of heavy quarks propagating through quark–gluon plasma (QGP) have been estimated by shielding the infra-red divergences using electric and magnetic screening masses. The electric-type screening in perturbative quantum chromodynamics (pQCD) has been widely studied and used in evaluating the diffusion coefficient of heavy quarks (HQs). The impact of magnetic screening on diffusion coefficients of HQs is not studied before to the best of our knowledge. We explore the effect of magnetic screening mass on the drag and diffusion coefficients of HQs and found it to be non-negligible. Therefore, the effect of magnetic screening should be taken into consideration to characterize hot and dense matter formed in the collisions of nuclei at ultra-relativistic energies. We estimate the suppression of heavy flavored mesons in heavy ion collisions compared to proton+proton collisions at high transverse momenta and found that the suppression is less with the inclusion of magnetic screening. The value of the magnetic screening mass is not known exactly because of its nonperturbative nature. Moreover, it may not be possible to single out the effect of magnetic mass because of the uncertainties in other parameters involved in the diffusion process of HQs. Still it is important to include the effects of magnetic screening because of its physical origin in QCD.

In this paper, we have made an attempt to analyze the alpha-decay half-lives of in the atomic number range $62\le Z\le 118$ by considering an effective liquid drop model. The role of pre-formation probability by including iso-spin effect is included during an evaluation of half-lives. We have also compared the studied alpha-decay half-lives with that of semi-empirical formulae such as Viola Seaborg semi-empirical formulae (VSS) [J. Inorg. Nucl. Chem. 28 (1966) 741; Nucl. Phys. A 848 (2010) 279], Royer formulae [J. Phys. G: Nucl. Part. Phys. 26 (2000) 1149; Phys. Rev. C 101 (2020) 034307] and also with that of the available experiments. From this comparison, it can be concluded that the effective liquid drop model produces an alpha-decay half-lives close to the experiments.

The low-lying collective spectra for axially symmetric nuclei are described within the Bohr–Hamiltonian by considering deformation-dependent mass coefficients and Kratzer potential in $\beta$ part. The energy eigenvalues and the total wave function of the problem are obtained in compact forms by means of the asymptotic iteration method. The numerical calculations are carried out for energy spectra as well as electromagnetic transition probabilities, and compared with experimental data in both cases: within and without the deformation-dependent mass (DDM) formalism. We investigate the nuclear observables of four even-A nuclei ${}^{154}$Sm, ${}^{156}$Gd, ${}^{172}$Yb, ${}^{182}$W and two odd-A nuclei ${}^{173}$Yb, ${}^{163}$Dy. Moreover, we will show that the choice of the Kratzer potential minimizes the level spacings within the $\beta$ band, which are usually overestimated by Bohr–Hamiltonian with Davidson potential.

The problem of mismatching of the level energies, in the ground band and the $K^{\pi }=2^{+}\gamma$-band of triaxially deformed atomic nuclei, as predicted in the rigid triaxial rotor (RTR) approximation of Davydov and Filippov (DF) model, with experiment, is well known. Here, we illustrate the solutions suggested in the literature, and the deviations observed in the converted energy values, from the experiment. We analyze the source of problem of this mismatch with experiment. This enables a physical picture of the DF (or RTR) model spectra. Our analysis will help in understanding the merits and the limitation of the RTR model in this respect.

The effective nucleon mass splits into two components, one for the proton and another for the neutron, in the case of adding the isovector coupling channel of the nuclear interaction, while being the same in the case of considering only the isoscalar coupling. A quantitative measure of the splitting is defined by the root mean square (RMS) value of the effective nucleon mass splitting and applied to the effective nucleon mass splitting in lead and tin isotopes. The isospin splitting of the effective nucleon mass is found to increase almost linearly with the asymmetry parameter.

In this study, we have performed a detailed analysis of genuine pion correlations and fluctuations in terms of the normalized factorial comulant moments of second and third orders, $K_2$ and $K_3$, in case of ${}^{16}$O–AgBr interactions at $60$A and $200$A GeV/c. The experimental results are compared with the predictions of AMPT and UrQMD model simulated events. The UrQMD model reproduces the trends in experimental results but the strength of correlation is much smaller. However, the AMPT model does not also replicate all features of the experimental data. The genuine two-particle and three-particle correlations are found to become weaker with the increase in momentum of the projectile nucleus.

We have performed a systematic study for the nuclear structure of superheavy nuclei with a special emphasis on the nuclei with possible central depletion of proton and neutron density in the mass region $\mathrm{\text{A}}\sim 300$ using the Relativistic Hartree–Bogoliubov (RHB) framework. It has been observed that in the case of neutron density distribution, the occurrence of central depletion is related to the occupancy of 4s orbital and it is found to decrease with increasing occupancy of the 4s orbital. On the other hand, in the case of proton density distribution, the central density depletion is mainly due to the lowering of weakly bound p-orbital states close to the continuum as it is energetically favored to lower the Coulomb repulsion in the case of superheavy nuclei. Also, occupation probability of the lower angular momentum states (p-orbitals) lying near the Fermi level is strongly suppressed due to the weak centrifugal barrier and strong Coulomb repulsion in comparison to large angular momentum states (contributing to surface region mainly), resulting in central density depletion. Among the considered cases in the present work, the maximum depletion is observed for ${}^{292}120$ and for ${}^{294}$Og under spherically symmetric and axially deformed cases, respectively.

The main aim of this paper is to present some interesting results on event-by-event maximum 2-particle gap ($\mathrm{\Delta }{\eta }_{\mathrm{\text{max}}}$) in the pseudorapidity space of the relativistic charged particles $n_s$ produced in the ${}^{16}$O-AgBr interactions at 3.7, 60 and 200A GeV/c. The distribution of $\mathrm{\Delta }{\eta }_{\mathrm{\text{max}}}$ has been obtained for the experimental and AMPT simulated data. Distinct peaks are obtained in the $\mathrm{\Delta }{\eta }_{\mathrm{\text{max}}}$-distributions of the relativistic charged particles in low $\mathrm{\Delta }{\eta }_{\mathrm{\text{max}}}$-region. Further, the position of the peak is found to depend on the incident energy. The experimental results are not well supported by the results obtained for the AMPT simulated data. The findings presented here may be found useful in understanding the mechanism of the multiparticle production in relativistic nuclear interactions.

In this work, we study the differential scattering cross-section (DSCS) in the first-order Born approximation. It is not difficult to show that the DSCS can be simplified in terms of the system response function. Also, the system response function has this property to be written in terms of the spectral function and the momentum distribution function in the impulse approximation (IA) scheme. Therefore, the DSCS in the IA scheme can be formulated in terms of the spectral function and the momentum distribution function. On the other hand, the DSCS for an electron off the ${}^4\mathrm{\text{He}}$ and ${}^{16}\mathrm{\text{O}}$ nuclei is calculated in the harmonic oscillator shell model. The obtained results are compared with the experimental data, too. The most important result derived from this study is that the calculated DSCS in terms of the spectral function has a high agreement with the experimental data at the low-energy transfer, while the obtained DSCS in terms of the momentum distribution function does not. Therefore, we conclude that the response of a many-fermion system to a probe particle in IA must be written in terms of the spectral function for getting accurate theoretical results in the field of collision. This is another important result of our study.

The direct reaction component of the ${}^{19}$F($p,{\alpha }_0$) reaction at $E_{\mathrm{\text{cm}}}=180-600$keV is studied for the data that became very recently available. This component is significant in this work using the direct pickup model in the framework of the DWBA formalism and indicate the strong cluster structure of ${}^{19}$F. The direct component of astrophysical S-factor is calculated for ${}^{19}$F($p,{\alpha }_0$).

This paper presents a study of bin–bin correlation of the produced shower particles in the pseudo-rapidity space by the method of factorial correlator in ${}^{16}$O-AgBr and ${}^{32}$S-AgBr interactions at 4.5$A$GeV/$c$. The correlated moments are found to increase with decreasing bin–bin separation D, following a power law. Strong bin–bin correlation is exhibited by the experimental data. Experimental data also supports the validity of log normal approximation. Experimental analysis has been compared with the results obtained from the analysis of events simulated by UrQMD model.

The high-intensity heavy ion accelerator facility is a next-generation advanced heavy-ion accelerator facility built by the Institute of Modern Physics, Chinese Academy of Sciences. The RFQ is designed to provide a continuous wave beam and 2mA pulse beam with high-quality longitudinal beam distribution for the injection linear accelerator. Two different designs of aiming to suppress the longitudinal emittance were studied, and the optimized scheme which composed of a three-harmonic pre-buncher and an RFQ accelerator with small longitudinal acceptance was chosen. More emphasis is put on the section between pre-buncher and RFQ, where the space charge effect becomes severe with bunched beam. The optimal design and the analysis are presented in this paper.

In this work, Bohr Hamiltonian is used to explain the behavior of triaxial nuclei. A new potential, called Morse plus screened Kratzer potential, has been developed for the $\beta$-part with $\gamma$ fixed at $\frac{\pi }{6}$. The Extended Nikiforov–Uvarov method involving Confluent Heun functions is used to derive the wave function and energy expression. The electric quadrupole transition rates and energy spectrum of platinum ${}^{192,194,196}\mathrm{\text{Pt}}$ are determined and compared with the experimental data and some theoretical results.

In this paper, an empirical formula to describe the heavy cluster decay with $Z_c>20$ ($Z_c$ is the charge number of the emitted cluster) from superheavy elements is proposed. The predictions of our formula are compared with the predictions of Coulomb and Proximity Potential Model (CPPM), the predictions of Analytical Super Asymmetric Fission (ASAF) model and the predictions by UDL formula of Qi et al. Excellent agreement is found between the predictions of CPPM and ASAF models and those of the present formula. Using our formula, we have calculated the decay half-lives of various heavy cluster emission from superheavy elements leading to doubly magic ${}^{208}$Pb and compared with the predictions of CPPM. The predictions of UDL formula deviate considerably from the predictions of this formula, CPPM and ASAF model, giving much lower decay half-lives, as the order of decay half-life increases. Possible heavy cluster emissions from $Z=120,121$ and 122 nuclei leading to ${}^{208}$Pb and ${}^{209}$Bi are also predicted.

Dark Matter particles can be detected directly via their elastic scattering with nuclei. Next generation experiments can eventually find physical evidences about dark matter candidates. With this motivation in mind, we have calculated the expected signals of dark matter particles in xenon detectors. The calculations were performed by considering different masses and parameters within the minimal supersymmetric standard model. Since the detectors can also detect neutrinos, we have analyzed the supernova neutrino signal including a sterile neutrino in the formalism. Using this $3+1$ scheme, we make predictions for both the normal and inverse mass hierarchy. In order to perform a study of the response of planned direct-detection experiments, to be located in ANDES (Agua Negra Deep Experimental Site), we have calculated the neutrino contributions to the background by taken into account reactor’s neutrinos and geoneutrinos at the site of the lab. As a test detector, we take a Xenon1T-like array.