arXiv subjects

J. Z. Gu

Publications and source records attributed to J. Z. Gu.

9 recordsLinked to original sources

arXiv2021

Alpha-Cluster formation in heavy alpha-emitters within a multistep model

$α$-decay always has enormous impetuses to the development of physics and chemistry, in particular due to its indispensable role in the research of new elements. Although it has been observed in laboratories for more than a century, it remains a difficult problem to calculate accurately the formation probability $S_α$ microscopically. To this end, we establish a new model, i.e., multistep model, and the corresponding formation probability $S_α$ values of some typical $α$-emitters are calculated without adjustable parameters. The experimental half-lives, in particular their irregular behavior around a shell closure, are remarkably well reproduced by half-life laws combined with these $S_α$. In our strategy, the cluster formation is a gradual process in heavy nuclei, different from the situation that cluster pre-exists in light nuclei. The present study may pave the way to a fully understanding of $α$-decay from the perspective of nuclear structure.

nucl-th↗

arXiv2020

Two-proton radioactivity within a generalized liquid drop model

The generalized liquid drop model (GLDM) is firstly extended to study the two-proton ($2p$) radioactivity half-lives of the ground-state of nuclei. According to the comparison between the calculated half-lives and the experimental data, it is shown that the GLDM describes the $2p$ radioactivity half-lives well. In addition, by comparing its accuracy with other models, it is found that the GLDM has a comparable accuracy with them. Finally, the $2p$ radioactivity half-lives of some most probable candidates are predicted with the GLDM by inputting the \textit{Q}$_{2p}$ values (the released energy of the $2p$ radioactivity) from the updated AME 2016 Mass Table, which may be useful for future experiments.

nucl-th↗

arXiv2019

Beyond Wigner's isobaric multiplet mass equation: Effect of charge-symmetry-breaking interaction and Coulomb polarization

The quadratic form of the isobaric multiplet mass equation (IMME), which was originally suggested by Wigner and has been generally regarded as valid, is seriously questioned by recent high-precision nuclear mass measurements. The usual resolution to this problem is to add empirically the cubic and quartic $T_z$-terms to characterize the deviations from the IMME, but finding the origin of these terms remains an unsolved difficulty. Based on a strategy beyond the Wigner's first-order perturbation, we derive explicitly the cubic and quartic $T_z$-terms. These terms are shown to be generated by the effective charge-symmetry breaking and charge-independent breaking interactions in nuclear medium combined with the Coulomb polarization effect. Calculations for the $sd$- and lower $fp$-shells explore a systematical emergence of the cubic $T_z$-term, suggesting a general deviation from the original IMME. Intriguingly, the magnitude of the deviation exhibits an oscillation-like behavior with mass number, modulated by the shell effect.

nucl-th↗

arXiv2018

Generalized isobaric multiplet mass equation and its application to the Nolen-Schiffer anomaly

The Wigner Isobaric Multiplet Mass Equation (IMME) is the most fundamental prediction in nuclear physics with the concept of isospin. However, it was deduced based on the Wigner-Eckart theorem with the assumption that all charge-violating interactions can be written as tensors of rank two. In the present work, the charge-symmetry breaking (CSB) and charge-independent breaking (CIB) components of the nucleon-nucleon force, which contribute to the effective interaction in nuclear medium, are established in the framework of Brueckner theory with AV18 and AV14 bare interactions. Because such charge-violating components can no longer be expressed as an irreducible tensor due to density dependence, its matrix element cannot be analytically reduced by the Wigner-Eckart theorem. With an alternative approach, we derive a generalized IMME (GIMME) that modifies the coefficients of the original IMME. As the first application of GIMME, we study the long-standing question for the origin of the Nolen-Schiffer anomaly found in the Coulomb displacement energy of mirror nuclei. We find that the naturally-emerged CSB term in GIMME is largely responsible for explaining the Nolen-Schiffer anomaly.

nucl-th↗

arXiv2011

Correlation between muonic levels and nuclear structure in muonic atoms

A method that deals with the nucleons and the muon unitedly is employed to investigate the muonic lead, with which the correlation between the muon and nucleus can be studied distinctly. A "kink" appears in the muonic isotope shift at a neutron magic number where the nuclear shell structure plays a key role. This behavior may have very important implications for the experimentally probing the shell structure of the nuclei far away from the $β$-stable line. We investigate the variations of the nuclear structure due to the interaction with the muon in the muonic atom and find that the nuclear structure remains basically unaltered. Therefore, the muon is a clean and reliable probe for studying the nuclear structure. In addition, a correction that the muon-induced slight change in the proton density distribution in turn shifts the muonic levels is investigated. This correction to muonic level is as important as the Lamb shift and high order vacuum polarization correction, but is larger than anomalous magnetic moment and electron shielding correction.

nucl-th↗

arXiv2011

Effects of tensor interaction on pseudospin energy splitting and shell correction

In the framework of a Skyrme-Hartree-Fock approach combined with BCS method, the role of the tensor force on the pseudospin energy splitting for tin isotope chain is investigated. The tensor force turns out to obviously affect the pseudospin energy splitting of the spin-unsaturated nuclei. Since the tensor force shifts the single-particle levels, it modifies the single-particle level density and the shell correction energy thereof. The influence of the tensor interaction on shell correction energy is considerable according to our analysis taking a magic nucleus $^{132}$Sn as well as a superheavy nucleus $^{298}114$ as examples. This modification of the shell correction energy due to the tensor component affects the stability of the superheavy nuclei.

nucl-th↗

arXiv1999

Vacuum Condensates in the Global Color Symmetry Model

Based on the quark propagator in the instanton dilute liquid approximation, we calculate analytically the quark condensate $<\bar{q}q>$, the mixed quark gluon condensate $g_{s}<\bar{q}G_{μν}σ^{μν}q>$ and the four quark condensate $<\bar{q} Γq\bar{q} Γq>$ at the mean field level in the framework of global color symmetry model. The numerical calculation shows that the values of these condensates are compatible with the ranges determined by other nonperturbative approaches. Moreover, we find that for nonlocal four quark condensate the previous vacuum saturation assumption is not a good approximation even at the mean field level.

nucl-th↗

arXiv1999

Decay out of a Superdeformed Band

Using a statistical model for the normally deformed states and for their coupling to a member of the superdeformed band, we calculate the ensemble average and the fluctuations of the intensity for decay out of the superdeformed band and of the intraband decay intensity. We show that both intensities depend on two dimensionless variables: The ratio $Γ^{\downarrow}/Γ_S$ and the ratio $Γ_N/d$. Here, $Γ^{\downarrow}$ is the spreading width for the mixing of the superdeformed and the normally deformed states, $d$ is the mean level spacing of the latter, and $Γ_S$ ($Γ_N$) is the width for gamma decay of the superdeformed state (of the normally deformed states, respectively). This parametric dependence differs from the one predicted by the approach of Vigezzi et al. where the relevant dimensionless variables are $Γ_N/Γ_S$ and $Γ^{\downarrow}/d$. We give analytical and numerical results for the decay intensities as functions of the dimensionless variables, including an estimate of the error incurred by performing the ensemble average, and we present fit formulas useful for the analysis of experimental data. We compare our results with the approach of Vigezzi et al. and establish the conditions under which this approach constitutes a valid approximation.

nucl-th↗

arXiv1999

Relativistic description of J/ψdissociation in hot matter

The mass spectra and binding radii of heavy quark bound states are studied on the basis of the reduced Bethe-Salpeter equation. The critical values of screening masses for $c\bar{c}$ and $b\bar{b}$ bound states at a finite temperature are obtained and compared with the previous results given by non-relativistic models.

nucl-th↗