A recent proposed method for $\alpha$-decay energies ($Q_{\alpha }$) [J. M. Dong, W. Zuo, and W. Scheid, Phys. Rev. Lett. 107, 012501 (2011)] can reproduce experimental data of superheavy nuclei (SHN) with an rms value of less than 100 keV. However, a sinusoid-like periodic deviation from experiments, which limits the accuracy in predictions, is observed when using different reference nuclei. In this paper, we have further extended this hybrid method, i.e., to predict $Q_{\alpha }$ of the as-yet-unobserved SHN with the help of known nuclei. It is found that the systematic deviation seen in the previous study is rooted in the nuclear mass model employed. By further analyzing the source of errors, different nuclear mass models are evaluated based on the same procedure.

Motivated by the recent developments in the determination of the experimental values of the nucleon axial-vector coupling constant $g_A$ and the pion-nucleon coupling constant $g_{\pi NN}$, we carry out a heavy-baryon chiral perturbation calculation of the hyperfine-singlet $\mu p$ capture rate ${\Gamma }_0$ to next-to-next-to-leading order (N${}^2$LO), with the use of the latest values of $g_A$ and $g_{\pi NN}$. The calculated N${}^2$LO value is ${\Gamma }_0^{\mathrm{theor}}({\mu }^{-}p\to {\nu }_{\mu }n)=718\pm 7{\text{sec}}^{-1}$, where the estimated next-to-next-to-next-to-leading order contribution dominates the error. This value is in excellent agreement with the experimental value reported by the MuCap Collaboration.

The $g$ factor and $B\left(E2\right)$ of the first excited $2^{+}$ state have been measured following Coulomb excitation of the neutron-rich semimagic nuclide ${}^{134}$Te (two protons outside ${}^{132}$Sn) produced as a radioactive beam. The precision achieved matches related $g$-factor measurements on stable beams and distinguishes between alternative models. The $B\left(E2\right)$ measurement exposes quadrupole strength in the $2_1^{+}$ state beyond that predicted by current large-basis shell-model calculations. This additional quadrupole strength can be attributed to coupling between the two valence protons and excitations of the ${}^{132}$Sn core. However, the wave functions of the low-excitation positive-parity states in ${}^{134}$Te up to $6_1^{+}$ remain dominated by the $\pi {\left(g_{7/2}\right)}^2$ configuration.

Correlations between low-lying electric dipole ($E1$) strength and neutron-skin thickness are systematically investigated with a fully self-consistent random-phase approximation by using the Skyrme energy functionals. The presence of a strong correlation among these quantities is currently under dispute. We find that a strong correlation is present in properly selected nuclei, namely, in spherical neutron-rich nuclei in the region where the neutron Fermi levels are located at orbits with low orbital angular momenta. A significant correlation between the fraction of the energy-weighted sum value and the slope of the symmetry energy is also observed. A deformation in the ground state seems to weaken the correlation.

Recently, within the space of generalized Skyrme models, a submodel with a Bogomol'nyi-Prasad-Sommerfield (BPS) bound was identified that reproduces some bulk properties of nuclear matter already on a classical level and, as such, constitutes a promising field theory candidate for the detailed and reliable description of nuclei and hadrons. Here we extend and further develop these investigations by applying the model to the calculation of nuclear binding energies. Concretely, we calculate these binding energies by including the classical soliton energies, the excitation energies from the collective coordinate quantization of spin and isospin, the electrostatic Coulomb energies, and a small explicit isospin symmetry breaking, which accounts for the mass difference between proton and neutron. The integrability properties of the BPS Skyrme model allow, in fact, for an analytical calculation of all contributions, which may then be compared with the semi-empirical mass formula. We find that for heavier nuclei, where the model is expected to be more accurate on theoretical grounds, the resulting binding energies are already in excellent agreement with their physical values. This result provides further strong evidence for the viability of the BPS Skyrme model as a distinguished starting point and lowest-order approximation for the detailed quantitative investigation of nuclear and hadron physics.

Background: Coupled-cluster (CC) theory is a widely used many-body method for studying strongly correlated many-fermion systems. It allows for systematic inclusions of complicated many-body correlations beyond a mean field. Recent applications to finite nuclei have shown that first-principles approaches like CC theory can be extended to studies of medium-heavy nuclei, with excellent agreement with experiment. However, CC calculations of properties of infinite nuclear matter are rather few and date back more than 30 yr.

Purpose: The aim of this work is thus to develop the relevant formalism for performing CC calculations in nuclear matter and neutron-star matter, including thereby important correlations to infinite order in the interaction and testing modern nuclear forces based on chiral effective field theory. Our formalism includes also the exact treatment of the so-called Pauli operator in a partial-wave expansion of the equation of state.

Methods: Nuclear- and neutron-matter calculations are done using a coupled particle-particle and hole-hole ladder approximation. The coupled ladder equations are derived as an approximation of CC theory, leaving out particle-hole and nonlinear diagrams from the CC doubles amplitude equation. This study is a first step toward CC calculations for nuclear and neutron matter.

Results: We present results for both symmetric nuclear matter and pure neutron matter employing state-of-the-art nucleon-nucleon interactions based on chiral effective field theory. We employ also the newly optimized chiral interaction [Ekström et al., Phys. Rev. Lett. 110, 192502 (2013)] to study infinite nuclear matter. The ladder approximation method and corresponding results are compared with conventional Brueckner-Hartree-Fock theory. The ladder approximation is derived and studied using both exact and angular-averaged Pauli exclusion operators, with angular-averaged input momenta for the single-particle potentials in all calculations. The inclusion of an exact treatment of the Pauli operators in a partial-wave expansion yields corrections of the order of $1.7\%–2\%$ of the total energy in symmetric nuclear matter. Similarly, the inclusion of both hole-hole and particle-particle ladders result in corrections of the order $0.7\%–2\%$ compared to the approximation with only particle-particle ladders. Including these effects, we get at most almost a $6\%$ difference between our CC calculation and the standard Brueckner-Hartree-Fock approach.

Conclusions: We have performed CC calculations of symmetric nuclear matter and pure neutron matter including particle-particle and hole-hole diagrams to infinite order using an exact Pauli operator and angular-averaged single-particle energies. The contributions from hole-hole diagrams and exact Pauli operators add important changes to the final energies per particle.

The isotopic dependence of the complete fusion (capture) cross section is analyzed in the reactions ${}^{130,132,134,136,138,140,142,144,146,148,150}$Xe+${}^{48}$Ca with stable and radioactive beams. It is shown for the first time that the very neutron-rich nuclei ${}^{186-191}$W can be reached with relatively large cross sections by complete fusion reactions with radioactive ion beams at incident energies near the Coulomb barrier. A comparison between the complete fusion and fragmentation reactions for the production of neutron-rich W and neutron-deficient Rn isotopes is performed.

High-spin states of ${}^{126}$La have been populated using the ${}^{116}$Sn(${}^{14}$N, 4$n$)${}^{126}$La reaction at a beam energy of 77 MeV. A side band linking to the known yrast $\pi h_{11/2}\otimes \nu h_{11/2}$ band is observed. $B\left(M1\right)/B\left(E2\right)$ ratios and alignments of the side band and DCO ratios of linking transitions between the side band and the yrast band suggest that the side band has the same $\pi h_{11/2}\otimes \nu h_{11/2}$ configuration as that of the yrast band, and thus the side band is a second $\pi h_{11/2}\otimes \nu h_{11/2}$ band in ${}^{126}$La. The separation energy, $\Delta E\left(I\right)=E{\left(I\right)}_{\mathrm{side}}-E{\left(I\right)}_{\mathrm{yrast}}$, between the side band and the yrast band at the same spin, and the energy staggering parameter $S\left(I\right)$ of the second $\pi h_{11/2}\otimes \nu h_{11/2}$ band in ${}^{126}$La are compared to those of other odd-odd La isotopes. The variation trends of $\Delta E\left(I\right)$ and $S\left(I\right)$ both suggest that it is reasonable to interpret the second $\pi h_{11/2}\otimes \nu h_{11/2}$ band in ${}^{126}$La as an excited $\pi h_{11/2}\otimes \nu h_{11/2}$ band as proposed for ${}^{124}$La rather than to interpret it as a partner band of a near degenerate chiral doublet band as done for ${}^{128-134}$La.

It is pointed out that the triaxial bands in ${}^{138-140}$Nd and in the Lu/Er nuclei can be understood from the same shell structure effects. Two of the bands in ${}^{138}$Nd, interpreted as signature partners, exhibit a crossing at high spins with a signature splitting which is strongly reduced above the crossing. This behavior is unique among the yrast and close-to-yrast configurations, revealing the mechanism which induces a change of the rotation axis from short to intermediate in the triaxially deformed nucleus.

We study the nonperturbative renormalization of the nucleon-nucleon ($NN$) interaction at next-to-leading order (NLO) and next-to-next-to-leading order (NNLO) of chiral effective field theory. A systematic variation of the cutoff parameter is performed for values below the chiral symmetry breaking scale of about 1 GeV. The accuracy of the predictions is determined by calculating the ${\chi }^2$ for the reproduction of the $NN$ data for energy intervals below pion-production threshold. At NLO, $NN$ data are described well up to about 100 MeV laboratory energy and, at NNLO, up to about 200 MeV—with, essentially, cutoff independence for cutoffs between about 450 and 850 MeV.

Enhanced proton-neutron interactions occur in heavy nuclei along a trajectory of approximately equal numbers of valence protons and neutrons. This is also closely aligned with the trajectory of the saturation of quadrupole deformation. The origin of these enhanced $p$-$n$ interactions is discussed in terms of spatial overlaps of proton and neutron wave functions that are orbit-dependent. It is suggested for the first time that nuclear collectivity is driven by synchronized filling of protons and neutrons with orbitals having parallel spins, identical orbital and total angular momenta projections, belonging to adjacent major shells and differing by one quantum of excitation along the $z$ axis. These results may lead to a new approach to symmetry-based theoretical calculations for heavy nuclei.

The structure of neutron-rich nuclei with a few holes in respect of the doubly magic nucleus ${}^{132}$Sn is investigated by means of large-scale shell-model calculations. For a considerably large model space, including orbitals allowing both neutron and proton core excitations, an effective interaction for the extended pairing-plus-quadrupole model with monopole corrections is tested through detailed comparison between the calculation and experimental data. By using the experimental energy of the core-excited $21/2^{+}$ level in ${}^{131}$In as a benchmark, monopole corrections are determined that describe the size of the neutron $N=82$ shell gap. The level spectra, up to 5 MeV of excitation in ${}^{131}$In, ${}^{131}$Sn, ${}^{130}$In, ${}^{130}$Cd, and ${}^{130}$Sn, are well described and clearly explained by couplings of single-hole orbitals and by core excitations.

Background: The odd-$Z$ ${}^{105}$Nb nucleus is located in the $A=100$ neutron-rich region. The study of multi-phonon vibrational band structures is important for understanding nuclear structure in this region.

Purpose: To search for multi-phonon $\gamma$-vibrational bands in ${}^{105}$Nb.

Methods: The high spin states of ${}^{105}$Nb have been studied by measuring the prompt $\gamma$ rays emitted in the spontaneous fission of ${}^{252}$Cf. The data analysis is carried out using triple- and four-fold $\gamma$ coincidence methods.

Results: A new level scheme of ${}^{105}$Nb is established. The yrast band has been confirmed, and three new collective bands have been identified. Compared with previous results, a total of 14 new levels and 36 new $\gamma$ transitions are observed. Two bands built on 625.9 keV and 1231.9 keV levels are proposed as one-phonon- and two-phonon $\gamma$-vibrational bands, respectively. The evidences for supporting assignments of the multi-phonon $\gamma$-vibrational bands have been discussed. Triaxial projected shell model calculations for the $\gamma$-vibrational band structures are found in good agreement with the experimental data, thus further supporting the $\gamma$-vibrational interpretations for the experimental results in ${}^{105}$Nb.

Conclusions: The one-phonon- and two-phonon $\gamma$-vibrational bands have been identified in ${}^{105}$Nb. Our results provide new data to systematically understand the characteristics of the multi-phonon $\gamma$-vibrational bands in the $A=100$ neutron-rich region.

A coupled-channel effective Lagrangian model respecting unitary and gauge invariance is applied to the combined analysis of $(\pi ,\gamma )N\to K\Sigma$ reactions for center-of-mass energies up to 2 GeV. The recent photoproduction data obtained by the CLAS, CBELSA, LEPS, and GRAAL groups are included into our calculations with the aim to extract the resonance couplings to the $K\Sigma$ state. Both resonances and background contributions are found to be important to reproduce correct shapes of the angular distributions and polarization observables. Our description of the data is of good quality. The extracted properties of isospin $I=3/2$ resonances are discussed in detail while the $I=1/2$ resonances are largely determined by the nonstrangeness channels.

We analyze a change in a deficit of reactor antineutrinos at distances smaller than $100\mathrm{m}$ by changing the lifetime of the neutron from ${\tau }_n=885.7\mathrm{s}$ to ${\tau }_n=879.6\mathrm{s}$, calculated for the axial coupling constants $\lambda =-1.2694$ and $\lambda =-1.2750$, respectively, to get a result corresponding the new world average value ${\tau }_n=880.1\left(1.1\right)\mathrm{s}$. We calculate the angular distribution and cross section for the inverse $\beta$ decay, taking into account the contributions of the “weak magnetism” and the neutron recoil to next-to-leading order in the large baryon mass expansion and the radiative corrections of order $\alpha /\pi \sim {10}^{-3}$, calculated to leading order in the large baryon mass expansion. We obtain an increase of a deficit of reactor antineutrinos of about $0.734\%$. We discuss a universality of radiative corrections to order $\alpha$ to the neutrino (antineutrino) reactions induced by weak charged currents, pointed out by Kurylov, Ramsey-Musolf, and Vogel [Phys. Rev. C 67, 035502 (2003)], and calculate the antineutrino-energy spectrum of the neutron ${\beta }^{-}$ decay to order $\alpha /\pi$ and taking into account the contributions of the weak magnetism and the proton recoil.

We study microscopic structures of monopole pair vibrational modes and associated two-neutron transfer amplitudes in neutron-rich Sn isotopes by means of the linear response formalism of the quasiparticle random phase approximation (QRPA). For this purpose we introduce a method to decompose the transfer amplitudes with respect to two-quasiparticle components of the QRPA eigenmode. It is found that pair-addition vibrational modes in neutron-rich ${}^{132–140}$Sn and the pair rotational modes in ${}^{142–150}$Sn are commonly characterized by coherent contribution of quasaiparticle states having high orbital angular momenta $l\gtrsim 5$, which suggests transfer of a spatially correlated neutron pair. The calculation also predicts a high-lying pair vibration, the giant pair vibration, emerging near the one-neutron separation energy in ${}^{110–130}$Sn, and we find that they have the same di-neutron characters as that of the low-lying pair vibration in ${}^{132–140}$Sn.

Low-lying nuclear states of Sm isotopes are studied in the framework of a collective Hamiltonian based on covariant energy density functional theory. Pairing correlations are treated by both BCS and Bogoliubov methods. It is found that the pairing correlations deduced from relativistic Hartree-Bogoliubov (RHB) calculations are generally stronger than those deduced by relativistic mean field plus BCS ($\mathrm{RMF}+\mathrm{BCS}$) with the same pairing force. By simply renormalizing the pairing strength, the diagonal part of the pairing field is changed in such a way that the essential effects of the off-diagonal parts of the pairing field neglected in the $\mathrm{RMF}+\mathrm{BCS}$ calculations can be recovered, and consequently the low-energy structure is in a good agreement with the predictions of the RHB model.

We study the role of nuclear structure effects through radius in reaction dynamics via transverse flow and multifragmentation of isobaric colliding pairs. Our study reveals that isospin-dependent radius [proposed by Royer and Rousseau [Eur. Phys. J. A 42, 541 (2009)] has significant effect towards isospin effects. The collective flow behavior and fragmentation pattern of neutron-rich system with respect to neutron-deficient system is found to get reversed with isospin-dependent radius compared to that with liquid drop radius.

The relevance of coupling of quadrupole and octupole collective degrees of freedom in physical observables is explored in calculations with the Gogny force for the light radon, radium, and thorium isotopes. The results of the generator coordinate method calculations for the properties of negative parity states show an improvement over the traditional ones that consider just the octupole moment.