Within the relativistic Hartree-Fock-Bogoliubov (RHFB) theory, the structure properties of carbon isotopes are systematically studied. To provide better overall description, the finite-range Gogny force D1S with an adjusted strength factor is adopted as the effective paring interaction in the particle-particle channel. The self-consistent RHFB calculations with density-dependent meson-nucleon couplings indicate the single-neutron halo structures in both ${}^{17}$C and ${}^{19}$C, whereas the two-neutron halo in ${}^{22}$C is not well supported. It is also found that close to the neutron drip line there exists distinct odd-even staggering on neutron radii, which is tightly related with the blocking effects, and correspondingly the blocking effect plays a significant role in the single-neutron halo formation.

Three- and four-cluster breakup reactions in the ${}^{16}$C-proton scattering are studied using a three-body core-neutron-neutron model for ${}^{16}$C. Single-scattering approximation (SSA) of four-particle equations for transition operators is used to calculate three- and four-cluster breakup amplitudes at 200 and 300 MeV/nucleon energy near proton-neutron ($pn$) quasifree scattering (QFS) conditions. The differential cross section is sharply peaked at the $pn$ QFS point and decreases rapidly whenever kinematical conditions deviate from $pn$ QFS. The accuracy of the SSA for the three-cluster breakup is estimated from a three-body model and is found to be as good as 6$\%$ at higher reaction energies in suitable angular regimes. Furthermore, under an additional approximation the three-cluster breakup amplitude factorizes into the $pn$ transition operator and the overlap integral of two- and three-particle bound states. That approximation usually reduces the cross section, in some cases even up to 10$\%$.

Pre-saddle neutron multiplicity has been calculated for several fission reactions induced by heavy ions and light particles. Experimentally, it is impossible to determine the contribution of neutrons being emitted before the saddle point and those emitted between the saddle and the scission points. Determination of the pre-saddle neutron multiplicity in our research is based on the comparison between the experimental anisotropies and those predicted by the standard saddle-point statistical model. Analysis of the results shows that the pre-saddle neutron multiplicity depends on the fission barrier height and stability of the compound nucleus. In heavy-ion-induced fission, the number of pre-saddle neutrons decreases with increasing excitation energy of the compound nucleus. A main cause of this behavior is due to a reduction in the ground-state–to–saddle-point transition time with increasing excitation energy of the compound nucleus. However, in induced fission by light particles, the number of pre-saddle neutrons increases with increasing excitation energy of the compound nucleus.

We provide a theoretical analysis of recently measured fusion cross sections which show surprising enhancement at low $E_{\mathrm{c}}.\mathrm{m}.$ energies for the system ${}^{132}$Sn $+$ ${}^{40}$Ca as compared to the more neutron-rich system ${}^{132}\mathrm{Sn}+{}^{48}$Ca. Dynamic microscopic calculations are carried out on a three-dimensional lattice with a time-dependent density-constrained density functional theory. There are no adjustable parameters; the only input is the Skyrme effective NN interaction. Heavy-ion potentials $V\left(R\right)$, coordinate-dependent mass parameters $M\left(R\right)$, and total fusion cross sections $\sigma (E_{\mathrm{c}}.\mathrm{m}.)$ are calculated for both systems. We are able to explain the measured fusion enhancement in terms of the narrower width of the ion-ion potential for ${}^{132}$Sn $+$ ${}^{40}$Ca, while the barrier heights and positions are approximately the same in both systems.

The breakup of a one-neutron halo ${}^{15}$C on a proton target at 54 MeV/u incident energy is calculated using the the few-body Faddeev/Alt-Grassberger-Sandhas reaction framework. A two-body model is used for ${}^{15}$C, which involves an inert ${}^{14}$C(0${}^{+}$) core and a valence neutron with unity spectroscopic factor. The sensitivity of the calculated observables on the core-valence neutron interaction and in particular the introduction of an imaginary component in some partial waves is analyzed.

We construct interactions of nucleons $N$ with higher-spin resonances $R$ invariant under point and gauge transformations of the Rarita-Schwinger field. It is found for arbitrarily high spin of a resonance that the requirement of point and gauge invariance uniquely determines a Lagrangian of $NR$ interactions with pions, photons, and vector mesons, which might reduce model ambiguity in effective-field calculations involving such vertices. Considering the $NR$ interactions with photons and vector mesons, the symmetry provides a classification of three $NR$ vertices in terms of their differential order. The $Q^2$ dependencies of the point- and gauge-invariant form factors are considered in a vector-meson–dominance model. The model is in good agreement with experimental data. In addition, we point out some empirical patterns in the $Q^2$ dependencies of the form factors: low-$Q^2$ scaling of the $N\Delta \left(1232\right)$ form factor ratios and relations between form factors for $NN\left(1520\right)$ and $NN\left(1680\right)$ transitions.

Lifetimes of the excited states of a pair of positive-parity $\Delta I=2$ bands of ${}^{107}$Cd have been measured by using the Doppler-shift attenuation method. The obtained $B\left(E2\right)$ transition rates significantly decrease with increasing spin, a behavior typical of antimagnetic rotation (AMR). The observed results, interpreted by the semiclassical model (SCM) calculations, confirm these bands to be AMR bands resulting from the coupling of a pair of high-$\Omega$ $g_{9/2}$ proton holes to aligned $g_{7/2}{\left(h_{11/2}\right)}^2$ neutron particles. This is the first evidence for two AMR bands in a single nucleus.

The pygmy dipole resonance (PDR) is studied in various medium-heavy nuclei by using a Gogny interaction in a self-consistent Hartree-Fock plus random phase approximation method. We compare the details of the PDR structure with those of the giant dipole resonance (GDR). In the PDR protons and neutrons vibrate in phase, and the main contributions are given by particle-hole excitations involving the neutrons in excess. On the contrary, in the GDR protons and neutrons vibrate out of phase, and all the nucleons are involved in the excitation. The values of the parameters we used to define the collectivity of an excitation indicate that the PDR is less collective than the GDR. We also investigate the role of the residual interaction in the appearance of the PDR and we find a subtle interplay with the shell structure of the nucleus.

Measurements of neutron-adding, neutron-removing, and proton-adding reactions were carried out for the four stable even Ni isotopes. Particular attention was paid to obtaining precise values of the cross sections at the peaks of the angular distributions. Tests with sum rules for the neutron data indicate that the results are self-consistent at the level of a few tenths of a nucleon. Data on proton-adding reactions were also obtained and analyzed with a slightly different method—while these data are also consistent, the ambiguities are larger. The occupancies of the neutron orbits derived from the data, the proton vacancies, and the energy centroids of the neutron, neutron-hole, and proton single-particle excitations are obtained. The data also provide some estimate about the closure of the 0$f_{7/2}$ shell. The results are compared to shell-model calculations and may serve as a reference point for future exploration.

We use the recently proposed in-medium similarity renormalization group (IM-SRG) to carry out a systematic study of closed-shell nuclei up to ${}^{56}\mathrm{Ni}$, based on chiral two- plus three-nucleon interactions. We analyze the capabilities of the IM-SRG by comparing our results for the ground-state energy to coupled cluster calculations, as well as to quasiexact results from the importance-truncated no-core shell model. Using chiral two- plus three-nucleon Hamiltonians whose resolution scales are lowered by free-space SRG evolution, we obtain good agreement with experimental binding energies in ${}^4\mathrm{He}$ and the closed-shell oxygen isotopes, while the calcium and nickel isotopes are somewhat overbound.

Neutron-rich silver isotopes were populated in the fragmentation of a ${}^{136}$Xe beam and the relativistic fission of ${}^{238}$U. The fragments were mass analyzed with the GSI Fragment Separator and subsequently implanted into a passive stopper. Isomeric transitions were detected by 105 high-purity germanium detectors. Eight isomeric states were observed in ${}^{122-126}$Ag nuclei. The level schemes of ${}^{122,123,125}$Ag were revised and extended with isomeric transitions being observed for the first time. The excited states in the odd-mass silver isotopes are interpreted as core-coupled states. The isomeric states in the even-mass silver isotopes are discussed in the framework of the proton-neutron split multiplets. The results of shell-model calculations, performed for the most neutron-rich silver nuclei are compared to the experimental data.

An experiment to search for double-$\beta$ decay processes in ${}^{96}$Ru and ${}^{104}$Ru, which are accompanied by $\gamma$ rays, has been realized in the underground Gran Sasso National Laboratories of the I.N.F.N. (Italy). Ruthenium samples with masses of $\approx$0.5–0.7 kg were measured with the help of ultralow-background high-purity Ge $\gamma$-ray spectrometry. After 2162 h of data taking the samples were deeply purified to reduce the internal contamination of ${}^{40}$K. The last part of the data has been accumulated over 5479 h. New improved half-life limits on $2{\beta }^{+}/\varepsilon {\beta }^{+}/2\varepsilon$ processes in ${}^{96}$Ru have been established on the level of ${10}^{20}$ yr, in particular for decays to the ground state of ${}^{96}$Mo: $T_{1/2}^{2\nu 2{\beta }^{+}}\ge 1.4\times {10}^{20}$ yr, $T_{1/2}^{2\nu \varepsilon {\beta }^{+}}\ge 8.0\times {10}^{19}$ yr, and $T_{1/2}^{0\nu 2K}\ge 1.0\times {10}^{21}$ yr (all limits are at 90$\%$ C.L.). The resonant neutrinoless double-electron captures to the 2700.2 and 2712.7 keV excited states of ${}^{96}$Mo are restricted as $T_{1/2}^{0\nu KL}\ge 2.0\times {10}^{20}$ yr and $T_{1/2}^{0\nu 2L}\ge 3.6\times {10}^{20}$ yr, respectively. Various two-neutrino and neutrinoless $2\beta$ half-lives of ${}^{96}$Ru have been estimated in the framework of the quasiparticle random-phase approximation approach. In addition, the $T_{1/2}$ limit for $0\nu 2{\beta }^{-}$ transitions of ${}^{104}$Ru to the first excited state of ${}^{104}$Pd has been set as $\ge 6.5\times {10}^{20}$ yr.

Problems of production and study of new neutron-enriched heavy nuclei are discussed. Low-energy multinucleon transfer reactions are shown to be quite appropriate for this purpose. Reactions with actinide beams and targets are of special interest for synthesis of new neutron-enriched transfermium nuclei and not-yet-known nuclei with closed neutron shell $N=126$ having the largest impact on the astrophysical r-process. The estimated cross sections for the production of these nuclei look very promising for planning such experiments at currently available accelerators. These experiments, however, are rather expensive and difficult to perform because of low intensities of the massive projectile beams and problems of separating and detecting the heavy reaction products. Thus, realistic predictions of the corresponding cross sections for different projectile-target combinations are definitely required. Some uncertainty still remains in the values of several parameters used for describing the low-energy nuclear dynamics. This uncertainty does not allow one to perform very accurate predictions for the productions of new heavier-than-target (trans-target) nuclei in multinucleon transfer reactions. Most of these parameters (nucleon transfer rate, nuclear viscosity, and fission barriers) are fundamental characteristics of low-energy nuclear dynamics. Determination of the values of these parameters (as well as their temperature dependence) is of significance in its own right. The available experimental data on the production of heavy nuclei in low-energy multinucleon transfer reactions are still insufficient and fragmentary. Several new experiments are proposed, these include those in which the role of shell effects in reaction dynamics can be better clarified.

We study meson-baryon scattering with strangeness –1 in unitary chiral perturbation theory. Ten coupled channels are considered in our work, namely, ${\pi }^0\Lambda$, ${\pi }^0{\Sigma }^0$, ${\pi }^{-}{\Sigma }^{+}$, ${\pi }^{+}{\Sigma }^{-}$, $K^{-}p$, ${\overline{K}}^{0}n$, $\eta \Lambda$, $\eta {\Sigma }^0$, $K^0{\Xi }^0$, and $K^{+}{\Xi }^{-}$. A large amount of experimental data are analyzed, including the recent precise measurement by the SIDDHARTA Collaboration of the energy shift and width of the $1s$ state of kaonic hydrogen. This leads to a strong constraint on the free parameters in our theory and of the resulting meson-baryon scattering amplitudes. We also analyze the uncertainty that stems by using several different strategies to perform the fits to data. It is found that large uncertainties in the subthreshold extrapolation of the $K^{-}p$ scattering amplitude arise by either employing only one common weak pseudoscalar decay constant or distinguishing between $f_{\pi }$, $f_K$, and $f_{\eta }$. However, in both cases a good reproduction of experimental data is obtained. We also discuss the pole content of the resulting $S$-wave amplitudes, particularly in connection with the two-pole structure of the $\Lambda \left(1405\right)$ resonance.

Higashiyama and Yoshinaga [Phys. Rev. C 83, 034321 (2011)] neglected all previous studies of nuclei in the same region using the same approach (nucleon-pair-approximation calculations), the same Hamiltonian, and similar parameters. Their claim of the pair-truncated shell model as a “new approach” and their neglect of all previous formulations of the nucleon-pair approximation are misleading.

The nucleon momentum distribution $n_A\left(k\right)$ for $A=2$, 3, 4, 16, and 40 nuclei is systematically analyzed in terms of wave functions resulting from advanced solutions of the nonrelativistic Schrödinger equation, obtained within different many-body approaches based upon different realistic bare nucleon-nucleon ($NN$) interactions featuring similar short-range repulsion and tensor interactions. Particular attention is paid to the separation of the momentum distributions into the mean-field and short-range correlation (SRC) contributions. It is shown that although at high values of the momentum $k$ different approaches lead to some quantitative differences, these do not hinder the general conclusion that the high-momentum behavior ($k\gtrsim 1.5–2$ fm${}^{-1}$) of all nuclei considered are very similar, exhibiting the well-known scaling behavior with the mass number $A$, independently of the used many-body approach and the details of the bare $NN$ interaction. To analyze and understand the frequently addressed question concerning the relationships between the nucleus, $n_A\left(k\right)$, and the deuteron, $n_D\left(k\right)$, momentum distributions, the spin ($S$)-isospin ($T$) structure of few-nucleon systems and complex nuclei is analyzed in terms of realistic $NN$ interactions and many-body approaches. To this end, the number of $NN$ pairs in a given ($ST$) state, viz., $\left(ST\right)=\left(10\right)$, (00), (01), and (11), and the contribution of these states to the nucleon momentum distributions are calculated. It is shown that, apart from the (00) state, which has very small effects, all other spin-isospin states contribute to the momentum distribution in a wide range of momenta. It is shown that for all nuclei considered the momentum distributions in the states $T=0$ and $T=1$ exhibit at $k\gtrsim 1.5–2$ fm${}^{-1}$ very similar behaviors, which represents strong evidence of the $A$-independent character of SRCs. The ratio $n_A\left(k\right)/n_D\left(k\right)$ is analyzed in detail, stressing that in the SRC region it always increases with the momentum and the origin of such an increase is discussed and elucidated. The relationships between the one- and two-body momentum distributions, considered in a previous paper, are discussed and clarified, pointing out the relevant role played by the center-of-mass motion of a correlated pair in the (10) state. Eventually, the values of the the probability of high-momentum components in nuclei and the per nucleon probability $a_2$ of deuteronlike configurations in nuclei are calculated, and the relationship of the present approach with the many-body methods based upon low-momentum effective interactions is briefly discussed.

The ${}^{241}$Pu(n,f) cross sections have been determined by the surrogate ratio method in the equivalent neutron energy range 11.0–16.0 MeV by using ${}^{238}$U(${}^6$Li,$d$)${}^{242}$Pu and ${}^{232}$Th(${}^6$Li,$d$)${}^{236}$U transfer reactions at E${}_{\text{lab}}=39.6$ and 39.0 MeV, respectively. Results have been compared with direct measurement of ${}^{241}$Pu(n,f) cross-section data and predictions of statistical model code empire 3.1 for different sets of values of fission barrier heights from evaluated data libraries. The present ${}^{241}$Pu(n, f) cross-section data are observed to be consistent with the direct measurements, suggesting the applicability of surrogate methods. However, the empire 3.1 predictions are not in complete agreement with the experimental data in the neutron energy range 2.0–20.0 MeV for any set of the fission barrier data libraries. The consistency of experimental results on ${}^{241}$Pu(n,f) cross section data from direct and surrogate measurements suggests the need for fission barrier heights for Pu isotopes that are different from those used in standard libraries. The fission barrier heights for various Pu isotopes have been obtained for best fit to the experimental data in the neutron energy range 2.0–20.0 MeV.

Production and decay of the isotopes of Hs were studied in the ${}^{226}$Ra+${}^{48}$Ca reaction at beam energies $E_{\mathrm{lab}}=229$, 234, and 241 MeV. At the $E_{\mathrm{lab}}=234$ MeV energy, the maximum of the 4$n$-evaporation channel of the reaction, six identical $\alpha$-SF decay chains of the nucleus ${}^{270}$Hs were detected corresponding to a cross section of ${\sigma }_{4n}={16}_{-7}^{+13}$ pb. At the other ${}^{48}$Ca energies, no Hs isotopes were observed. Nuclei of ${}^{270}$Hs undergo $\alpha$ decay with a $Q_{\alpha }=9.15\pm 0.08$ MeV and the half-life of the daughter spontaneous fission (SF) isotope ${}^{266}$Sg is 0.28${}_{-0.08}^{+0.19}$ s, in good agreement with the data previously observed in the ${}^{248}$Cm(${}^{26}$Mg,4$n$)${}^{270}$Hs reaction. The partial $\alpha$-decay half-life of ${}^{270}$Hs was measured for the first time: $T_{\alpha }=7.6_{-2.2}^{+4.9}$ s. For the spontaneous fission, we determined a lower limit $T_{\mathrm{SF}}⩾10$ s. Decay properties of ${}^{270}$Hs corroborate theoretical predictions of its relatively high stability caused by the effect of the deformed shells at $Z=108$ and $N=162$.

We investigate the three-body Coulomb breakup of a two-neutron halo nucleus ${}^{11}$Li. We use the coupled-channel ${}^9$Li+$n$+$n$ three-body model, which includes the coupling between last neutron states and the various two-particle–two-hole ($2\text{p}$-$2\text{h}$) configurations in ${}^9$Li due to the tensor and pairing correlations. The three-body scattering states of ${}^{11}$Li are described by using the combined methods of complex scaling and the Lippmann-Schwinger equation. The calculated breakup cross section successfully reproduces the experiments. The large mixing of the $s$ state in the halo ground state of ${}^{11}$Li is shown to play an important role in the explanation of shape and strength of the breakup cross section. In addition, we predict the invariant mass spectra for binary subsystems of ${}^{11}$Li. It is found that the two kinds of virtual $s$ states of ${}^9$Li-$n$ and $n$-$n$ systems in the final three-body states of ${}^{11}$Li largely contribute to make low-lying peaks in the invariant mass spectra. On the other hand, in the present analysis, it is suggested that the contributions of the $p$-wave resonances of ${}^{10}$Li are hardly confirmed in the spectra.

The Monte Carlo hydjet$++$ model, that combines parametrized hydrodynamics with jets, is employed to study formation of second $v_2$ and fourth $v_4$ components of the anisotropic flow in ultrarelativistic heavy-ion collisions at energies of the Relativistic Heavy Ion Collider (RHIC) and the Large Hadron Collider (LHC), $\sqrt{s}=200$ $A$ GeV and $\sqrt{s}=2.76$ $A$ TeV, respectively. It is shown that the quenched jets contribute to the soft part of the $v_2\left(p_T\right)$ and $v_4\left(p_T\right)$ spectra. The jets increase the ratio $v_4/v_2^2$, thus leading to deviations of the ratio from the value of 0.5 predicted by the ideal hydrodynamics. Together with the event-by-event fluctuations, the influence of jets can explain quantitatively the ratio $v_4/v_2^2$ at $p_T\le 2$ GeV$/c$ for both energies and qualitatively the rise of its high-$p_T$ tail at LHC. Jets are also responsible for violation of the number-of-constituent-quark (NCQ) scaling at LHC despite the fact that the scaling is fulfilled for the hydro- part of particle spectra.