An enhanced $\overline{\Lambda }/\overline{p}$ ratio in heavy-ion relative to $p+p$ collisions has been proposed as one of the signatures for the quark-gluon plasma (QGP) formation. A significantly large $(\overline{\Lambda }+{\overline{\Sigma }}^0+1.1{\overline{\Sigma }}^{-})/\overline{p}$ ratio of 3.5 has been observed in the midrapidity and low transverse momentum region in central Au+Au collisions at the nucleon-nucleon center-of-mass energy of $\sqrt{s_{{}_{NN}}}=4.9$ GeV at the Alternating Gradient Synchrotron (AGS). This is an order of magnitude larger than the values in peripheral Au+Au collisions and $p+p$ collisions at the corresponding energy. By using the ultrarelativistic quantum molecular dynamics (UrQMD) transport model, we demonstrate that the observed large ratio can be explained by strong absorption of $\overline{p}$'s ($\sim$99.9$\%$) and $\overline{\Lambda }$'s ($\sim$99$\%$) in dense nuclear matter created in central collisions. We find within the model that the initial $\overline{\Lambda }/\overline{p}$ ratio, mainly from string fragmentation, does not depend on the collision centrality, and is consistent with that observed in $p+p$ collisions. This suggests that the observed large $(\overline{\Lambda }+{\overline{\Sigma }}^0+1.1{\overline{\Sigma }}^{-})/\overline{p}$ ratio at the AGS does not necessarily imply the formation of the QGP. We further study the excitation function of the ratio in UrQMD, which may help in the search and study of the QGP.

We discuss the subleading contact interactions, or counterterms, of the triplet channels of nucleon-nucleon scattering in the framework of chiral effective field theory, with $S$ and $P$ waves as the examples. The triplet channels are special in that they allow the singular attraction of one-pion exchange to modify Weinberg's original power-counting (WPC) scheme. With renormalization group invariance as the constraint, our power counting for the triplet channels can be summarized as a modified version of naive dimensional analysis in which, when compared with WPC, all of the counterterms in a given partial wave (leading or subleading) are enhanced by the same amount. More specifically, this means that WPC needs no modification in ${}^3{S}_1-{}^3{D}_1$ and ${}^3{P}_1$, whereas a two-order enhancement is necessary in both ${}^3{P}_0$ and ${}^3{P}_2-{}^3{F}_2$.

As the first step of systematic studies on neutron-rich Mg isotopes, the structure of ${}^{28}$Mg has been investigated by $\beta$-decay spectroscopy of spin-polarized ${}^{28}$Na at TRIUMF. Spin-parity assignments have been successfully performed for levels in ${}^{28}$Mg by taking advantage of the anisotropic $\beta$ decay. Previous assignments for three levels were reconfirmed. New assignments were performed for four levels including a newly found 2${}^{+}$ level at 7.461 MeV. The experimental results were compared, on a level-by-level basis, with the shell-model calculation in the model space restricted to the $sd$ shell. Overall good agreement between the experimental and theoretical results indicates dominance of the normal configurations in most of the ${}^{28}$Mg levels. High performance of the present method promises successful application to heavier Mg isotopes to elucidate the shell evolution in the region of the $N=20$ island of inversion.

Theoretical studies of isomers through nuclear reaction model calculations significantly assist the estimation of the different experimental data reported from different databases. In this paper, the production methods and the applications of mercury radionuclides are reviewed with special attention to the feasibility of the cyclotron production of mercury radionuclides, including ${}^{195}$Hg${}^{m,g}$ and ${}^{197}$Hg${}^{m,g}$. First, talys and empire codes were employed to illustrate the formation of both the isomeric and the ground states of the mercury radionuclides. Then the excitation function was calculated via a variety of nuclear processes using the codes and the data taken from the TENDL database. Then we compared the data with the reported experimental measurement. The mercury radionuclide production yield was evaluated with concentration on the excitation function calculations and the stopping powers of the projectiles in the targets. Last, the ${}^{197}$Au($d$,2n) and ${}^{197}$Au($p$,3$n$) reactions were selected as the best reactions to produce ${}^{197}$Hg${}^{m,g}$ and ${}^{195}$Hg${}^{m,g}$, respectively.

The autocorrelation function, and the correlation time are calculated for a series of the first 2${}^{+}$ states of 466 even-even nuclei classified by different parameters related to nuclear structure. The results indicate enhanced values for the $P$ factor compared with other classifying parameters to cumulate nuclei having similar properties nearby each other.

The role of prolate and oblate deformations of colliding nuclei in the sub-barrier capture process is studied within the quantum diffusion approach. The calculated and existing experimental capture cross sections are compared in the reactions ${}^{28}$Si + ${}^{198}$Pt and ${}^{40}$Ca + ${}^{194}$Pt with the heavy oblate nuclei. The possibility of the transition of heavy nucleus from the potential minimum with an oblate deformation of the ground state to the minimum with a prolate deformation during the capture process is discussed. The capture cross sections and mean angular momenta of the captured systems are predicted for the reactions ${}^{48}$Ca,${}^{36}$S + ${}^{194}$Pt, where the detection of this transition is possible.

Fragmentation of the dipole strength in the $N=82$ isotones ${}^{140}$Ce, ${}^{142}$Nd, and ${}^{144}$Sm is calculated using the second random-phase approximation (SRPA). In comparison with the result of the random-phase approximation (RPA), the SRPA provides additional damping of the giant dipole resonance and the redistribution of the low-energy dipole strength. Properties of the low-energy dipole states are significantly changed by the coupling to two-particle–two-hole (2p-2h) states, which are also sensitive to the correlation among the 2p-2h states. Comparison with available experimental data shows a reasonable agreement for the low-energy $E1$ strength distribution.

The dominance of the deuteron breakup mechanism around the Coulomb barrier is shown by an analysis of the ${}^{231}$Pa$(d,3n)$${}^{230}$U reaction excitation function, while the same attribute was found within a former assessment for the deuteron-induced fission. The present alternative result is obtained by taking into account, in addition to pre-equilibrium and compound-nucleus processes, the opposite effects of deuteron breakup, namely the decrease of the deuteron total reaction cross section, and the inelastic-breakup enhancement of various deuteron-induced reaction channels.

The phenomenon of $\alpha$ decay for ${}^{293,294}$117 superheavy nuclei is investigated within the Coulomb and proximity potential model for deformed nuclei (CPPMDN), in order to emphasize the recent experimental works on the element. The computed $\alpha$-decay half-lives are in good agreement with the experimental results. It is clear that the values calculated using our formalisms match well with the values computed using the Viola-Seborg systematic, and with the values reported by the generalized density dependent cluster model. The $\alpha$-decay calculations have also been performed for the decay chains of ${}^{293,294}$117 nuclei keeping the parents and daughter in spherical nuclear shape. These comparative studies ensure the validity of the CPPMDN.

Jet suppression is considered to be a powerful tool to study the properties of a QCD medium created in ultrarelativistic heavy ion collisions. However, theoretical predictions obtained by using jet energy loss in a static QCD medium show disagreement with experimental data, which is known as the heavy flavor puzzle at Relativistic Heavy Ion Collisider (RHIC). We calculate the suppression patterns of pions and single electrons for $\text{Au}+\text{Au}$ collisions at RHIC by including the energy loss in a finite size dynamical QCD medium, with finite magnetic mass effects taken into account. We here report a notably improved agreement with the experimental results compared to the static case; this agreement is robust with respect to a realistic range of magnetic mass values. Therefore, the inclusion of dynamical QCD medium effects provides an important step toward understanding the heavy flavor puzzle at RHIC.

The half-life of ${}^{46}$V has been measured to be 422.66(6) ms, which is a factor of two more precise than the best previous measurement. Our result is also consistent with the previous measurements, with no repeat of the disagreement recently encountered with $Q_{\mathrm{EC}}$ values measured for the same transition. The $\mathcal{F}t$ value for the ${}^{46}$V superallowed transition, incorporating all world data, is determined to be 3074.1(26) s, a result consistent with the average $\overline{\mathcal{F}t}$ value of 3072.08(79) s established from the 13 best-known superallowed transitions.

Even though the “free” neutrons in the inner crust of a neutron star are superfluid, they are still strongly coupled to nuclei due to nondissipative entrainment effects. These effects have been systematically studied in all regions of the inner crust in the framework of the band theory of solids. Using concepts from solid-state physics, it is shown that the density of conduction neutrons, i.e., neutrons that are effectively free, can be much smaller than the density of unbound neutrons (by an order of magnitude in some layers) due to Bragg scattering. These results suggest that a revision of the interpretation of various observable neutron-star phenomena might be necessary.

The neutron-capture cross sections of ${}^{64}$Zn, ${}^{68}$Zn, and ${}^{70}$Zn have been measured with the activation technique in a quasistellar neutron spectrum corresponding to a thermal energy of $kT=25$ keV. By a series of repeated irradiations with different experimental conditions, an uncertainty of 3$\%$ could be achieved for the ${}^{64}$Zn($n,\gamma$)${}^{65}$Zn cross section and for the partial cross section ${}^{68}$Zn($n,\gamma$)${}^{69}$Zn${}^m$ feeding the isomeric state in ${}^{69}$Zn. For the partial cross sections ${}^{70}$Zn($n,\gamma$)${}^{71}$Zn${}^m$ and ${}^{70}$Zn($n,\gamma$)${}^{71}$Zn${}^g$, which had not been measured so far, uncertainties of only 16$\%$ and 6$\%$ could be reached because of limited counting statistics and decay intensities. Compared to previous measurements on ${}^{64,68}$Zn, the uncertainties could be significantly improved, while the ${}^{70}$Zn cross section was found to be two times smaller than existing model calculations. From these results Maxwellian average cross sections were determined between 5 and 100 keV. Additionally, the $\beta$-decay half-life of ${}^{71}$Zn${}^m$ could be determined with significantly improved accuracy. The consequences of these data have been studied by network calculations for convective core He burning and convective shell C burning in massive stars.

We calculate the equation of state of neutron matter with realistic two- and three-nucleon interactions using quantum Monte Carlo techniques and illustrate that the short-range three-neutron interaction determines the correlation between neutron matter energy at nuclear saturation density and higher densities relevant to neutron stars. Our model also makes an experimentally testable prediction for the correlation between the nuclear symmetry energy and its density dependence—determined solely by the strength of the short-range terms in the three-neutron force. The same force provides a significant constraint on the maximum mass and radius of neutron stars.

The radii of nucleon distribution, bulk density, and neutron skin in nuclei beyond the $\beta$-stability line are studied within the direct variational method. We evaluate the partial equation of state of finite nuclei and demonstrate that the bulk density decreases beyond the $\beta$-stability line. We show that the growth of the neutron skin in unstable nuclei does not obey the saturation condition because of the polarization effect. The value of the neutron-skin thickness $\Delta r_{np}=\sqrt{\langle r_n^2\rangle }-\sqrt{\langle r_P^2\rangle }$ is caused by the different radii (skin effect) and only slightly by the different shapes (halo effect) of neutron and proton distributions. The relative contribution of both effects depends on the competition between the symmetry energy and the spin-orbit and Coulomb interactions. The calculations of the isovector shift of the nuclear radius $\Delta r_{np}$ show its primarily linear dependence on the asymmetry parameter $X=(N-Z)/A$.

We describe the fusion-fission processes within a two-stage reaction model. In the first stage (the approach phase) we calculate the properties of the system at the touching point. In the second stage we describe the evolution of the compact system. It is assumed that in the approach process the colliding ions are oriented “nose to nose”; i.e., their symmetry axes coincide. The distributions at the touching point obtained at the first step are used as the initial conditions for the evolution of a compact system. Both the approach phase and the evolution of the compact system are described in terms of Langevin equations for the collective coordinates (deformation parameters). At both stages the shell structure of the colliding ions and that of the compound nucleus are taken into account. Within this model we obtain information on the touching probability and on the observables measured in the fusion-fission reactions (mass and energy distributions of the fission fragments, the touching and fusion cross sections, and the evaporation residue cross sections). Results obtained for the reactions ${}^{16,18}\mathrm{O}+{}^{208}\mathrm{Pb}\to {}^{224,226}\mathrm{Th}$ and ${}^{48}\mathrm{Ca}+{}^{208}\mathrm{Pb}\to {}^{256}\mathrm{No}$, involving nuclei that are spherical in their ground state, are compared with the available experimental data.

A good understanding of the level structure of ${}^{19}\mathrm{Ne}$ around the proton threshold is critical to estimating the destruction of long-lived ${}^{18}\mathrm{F}$ in novae. Here we report the properties of levels in ${}^{19}\mathrm{Ne}$ in the excitation energy range of 6.9 $⩽$ $E_x$ $⩽$ 8.4 MeV studied via the proton-transfer ${}^{18}\mathrm{F}(d,n){\mathrm{Ne}}^{*}$ reaction at the Holifield Radioactive Ion Beam Facility. The populated ${}^{19}\mathrm{Ne}$ levels decay by breakup into $p+{}^{18}\mathrm{F}$ and $\alpha +{}^{15}\mathrm{O}$ particles. The results presented in this manuscript are those of levels that are simultaneously observed from the breakup into both channels. An $s$-wave state is observed at 1468 keV above the proton threshold, which is a potential candidate for a predicted broad $J^{\pi }$ $=$ 1/2${}^{+}$ state. The proton and $\alpha$ partial widths are deduced to be ${\Gamma }_p$ $=$ 228 $\pm$ 50 keV and ${\Gamma }_{\alpha }$ $=$ 130 $\pm$ 30 keV for this state.

We establish a correlation for the symmetry energy at saturation density $S_0$, slope parameter $L$, and curvature parameter $K_{\text{sym}}$ based on widely different mean-field interactions. With the help of this correlation and available empirical and theoretical information, the density-dependent behavior around the saturation density is determined. We compare the results obtained with the present approach with those by other analyses. With this obtained density-dependent behavior of the symmetry energy, the neutron skin thickness of ${}^{208}$Pb and some properties of neutron stars are investigated. In addition, it is found that the expression $S\left(\rho \right)=S_0(\rho /{\rho }_0){}^{\gamma }$ or $S\left(\rho \right)=12.5\left(\rho /{\rho }_0\right){}^{2/3}+C_p\left(\rho /{\rho }_0\right){}^{\gamma }$ does not reproduce the density dependence of the symmetry energy as predicted by the mean-field approach around nuclear saturation density.

Jet momentum balance measurements, such as those recently performed by the CMS collaboration, provide an opportunity to quantify the energy transferred from a parton shower to the underlying medium in heavy-ion collisions. Specifically, I argue that the Cooper-Frye freeze-out distribution associated with the energy and momentum deposited by the parton shower is controlled to a significant extent by the distribution of the underlying bulk matter and independent of the details of how deposited energy is redistributed in the medium, which is largely determined by transport coefficients such as shear viscosity. Thus, by matching the distribution of momentum associated with the secondary jet in such measurements to the thermal distribution of the underlying medium, one can obtain a model-independent estimate on the amount of parton shower energy deposited.

We report on the observation of a new isomeric state in ${}^{68}$Ni. We suggest that the newly observed state at 168(1) keV above the first 2${}^{+}$ state is a $\pi (2\mathrm{p}-2\mathrm{h})$ 0${}^{+}$ state across the major $Z=28$ shell gap. Comparison with theoretical calculations indicates a pure proton intruder configuration and the deduced low-lying structure of this key nucleus suggests a possible shape coexistence scenario involving a highly deformed state.