The photoabsorption cross section and ground-state branching ratio of ${}^{142}$Nd were measured using quasimonoenergetic $\gamma$-ray beams at several beam energies. Two peaks corresponding to the pygmy dipole resonance (PDR) were identified. The branching ratios were compared to statistical-model calculations. We found that the Brink hypothesis is violated, and that the branching ratios are only reproduced by introducing a possible new decay mode of the observed PDR.

We study recently proposed ultraviolet and infrared momentum regulators of the model spaces formed by construction of a variational trial wave function which uses a complete set of many-body basis states based upon three-dimensional harmonic oscillator (HO) functions. These model spaces are defined by a truncation of the expansion characterized by a counting number ($\mathcal{N}$) and by the intrinsic scale ($\hslash \omega$) of the HO basis—in short by the ordered pair ($\mathcal{N},\hslash \omega$). In this study we choose for $\mathcal{N}$ the truncation parameter $N_{\max }$ related to the maximum number of oscillator quanta, above the minimum configuration, kept in the model space. The uv momentum cutoff of the continuum is readily mapped onto a defined uv cutoff in this finite model space, but there are two proposed definitions of the ir momentum cutoff inherent in a finite-dimensional HO basis. One definition is based upon the lowest momentum difference given by $\hslash \omega$ itself and the other upon the infrared momentum which corresponds to the maximal radial extent used to encompass the many-body system in coordinate space. Extending both the uv cutoff to infinity and the ir cutoff to zero is prescribed for a converged calculation. We calculate the ground-state energy of light nuclei with “bare” and “soft” nucleon-nucleon ($NN$) interactions. By doing so, we investigate the behaviors of the uv and ir regulators of model spaces used to describe ${}^2$H, ${}^3$H, ${}^4$He, and ${}^6$He with $NN$ potentials Idaho N${}^3$LO and JISP16. We establish practical procedures which utilize these regulators to obtain the extrapolated result from sequences of calculations with model spaces characterized by ($\mathcal{N},\hslash \omega$).

We develop a complex scaling method for describing the resonances of deformed nuclei and present a theoretical formalism for the bound and resonant states on the same footing. With ${}^{31}$Ne as an illustrated example, we have demonstrated the utility and applicability of the extended method and have calculated the energies and widths of low-lying neutron resonances in ${}^{31}$Ne. The bound and resonant levels in the deformed potential are in full agreement with those from the multichannel scattering approach. The width of the two lowest-lying resonant states shows a novel evolution with deformation and supports an explanation of the deformed halo for ${}^{31}$Ne.

The isoscalar giant monopole resonance (ISGMR) in Cd, Sn, and Pb isotopes has been studied within the self-consistent Skyrme $\text{Hartree-Fock}+\text{BCS}$ and quasiparticle random phase approximation (QRPA). Three Skyrme parameter sets are used in the calculations (i.e., SLy5, SkM${}^{*}$, and SkP) since they are characterized by different values of the compression modulus in symmetric nuclear matter; namely, $K_{\infty }=230$, 217, and 202 MeV, respectively. We also investigate the effect of different types of pairing forces on the ISGMR in Cd, Sn, and Pb isotopes. The various calculated energies and the strength distributions of the ISGMR are compared with available experimental data. We find that SkP underestimates the various energies for all isotopes due to its low value of the nuclear matter incompressibility; namely, $K_{\infty }=202$ MeV. However, it can give a better description on the constrained energies for Cd isotopes and a reasonable peak energy for some nuclei. On the other hand, the SLy5 parameter set, supplemented by an appropriate pairing interaction, gives a reasonable description of the scaling energies in Cd and Sn isotopes and a good centroid energy in Pb isotopes. A better description of ISGMR in Cd and Sn isotopes is achieved by the SkM${}^{*}$ interaction, which has a somewhat softer value of the nuclear incompressibility.

High-spin states in the odd-proton thulium isotopes ${}^{173}$Tm and ${}^{175}$Tm have been studied using deep-inelastic reactions and $\gamma$-ray spectroscopy. In ${}^{173}$Tm, the low-lying structure has been confirmed and numerous new states have been identified, including a three-quasiparticle $K^{\pi }=$ $19/2^{-}$ isomer with a lifetime of $\tau =360\left(100\right)$ ns at 1906 keV and a five-quasiparticle $K^{\pi }=35/2^{-}$ isomer with a lifetime of $\tau =$ 175(40) ns at 4048 keV. The $K^{\pi }=35/2^{-}$ state is interpreted as a $t$-band configuration that shows anomalously fast decays. In ${}^{175}$Tm, the low-lying structure has been reevaluated, a candidate state for the $9/2^{-}$[514] orbital has been identified at 1175 keV, and the $7/2^{-}$[523] bandhead has been measured to have a lifetime of $\tau =$ 460(50) ns. Newly identified high-$K$ structures in ${}^{175}$Tm include a $K^{\pi }=15/2^{-}$ isomer with a lifetime of $\tau =$ 64(3) ns at 947 keV and a $K^{\pi }=$ $23/2^{+}$ isomer with a lifetime of $\tau =$ 30(20) $\mu$s at 1518 keV. The $K^{\pi }=15/2^{-}$ isomer shows relatively enhanced decays to the $7/2^{-}$[523] band that can be explained by chance mixing with the $15/2^{-}$ member of the $7/2^{-}$ band. Multiquasiparticle calculations have been performed for ${}^{173}$Tm and ${}^{175}$Tm, the results of which compare well with the experimentally observed high-spin states.

We apply degenerate many-body perturbation theory at high orders for the ab initio description of ground states and excitation spectra of open-shell nuclei using soft realistic nucleon-nucleon interactions. We derive a recursive formulation of standard degenerate many-body perturbation theory that enables us to evaluate order-by-order perturbative energy and state corrections up to the 30th order. We study ${}^{6,7}\mathrm{Li}$ as test cases using a similarity renormalization group (SRG) evolved nucleon-nucleon interaction from chiral effective field theory. The simple perturbation series exhibits a strong, often oscillatory divergence, as was observed previously for ground states of closed-shell nuclei. Even for very soft interactions resulting from SRG evolutions up to large flow parameter, i.e., low-momentum scales, the perturbation series still diverges. However, a resummation of the perturbation series via Padé approximants yields very stable and converged ground and excited-state energies in very good agreement with exact no-core shell-model calculations for the same model space.

Background: Superallowed $\beta$-decay rates provide stringent constraints on physics beyond the standard model of particle physics. To extract crucial information about the electroweak force, small isospin-breaking corrections to the Fermi matrix element of superallowed transitions must be applied.

Purpose: We perform systematic calculations of isospin-breaking corrections to superallowed $\beta$ decays and estimate theoretical uncertainties related to the basis truncation, to time-odd polarization effects related to the intrinsic symmetry of the underlying Slater determinants, and to the functional parametrization.

Methods: We use the self-consistent isospin- and angular-momentum-projected nuclear density functional theory employing two density functionals derived from the density-independent Skyrme interaction. Pairing correlations are ignored. Our framework can simultaneously describe various effects that impact matrix elements of the Fermi decay: symmetry breaking, configuration mixing, and long-range Coulomb polarization.

Results: Isospin-breaking corrections to the $I=0^{+}$, $T=1\to I=0^{+}$, $T=1$ pure Fermi transitions are computed for nuclei from $A=10$ to $A=98$ and, for the first time, to the Fermi branch of the $I,T=1/2\to I$, $T=1/2$ transitions in mirror nuclei from $A=11$ to $A=49$. We carefully analyze various model assumptions impacting theoretical uncertainties of our calculations and provide theoretical error bars on our predictions.

Conclusions: The overall agreement with empirical isospin-breaking corrections is very satisfactory. Using computed isospin-breaking corrections we show that the unitarity of the CKM matrix is satisfied with a precision of better than 0.1$\%$.

We compare nuclear and neutron matter predictions based on two different ab initio approaches to nuclear forces and the nuclear many-body problem. The first consists of a realistic meson-theoretic nucleon-nucleon potential together with the relativistic counterpart of the Brueckner-Hartree-Fock theory of nuclear matter. The second is based on chiral effective field theory, with density-dependent interactions derived from leading-order chiral three-nucleon forces. We find the results to be very close and conclude that both approaches contain important features governing the physics of nuclear and neutron matter.

Background: Neutrino oscillation probabilities, which are being measured in long-baseline experiments, depend on neutrino energy. The energy in a neutrino beam, however, is broadly smeared so that the neutrino energy in a particular event is not directly known, but must be reconstructed from final state properties.

Purpose: To investigate the effects of different reaction mechanisms on the energy-reconstruction method widely used in long-baseline neutrino experiments taking also pion production into account, and to clarify how the oscillation signal depends on the energy reconstruction.

Methods: The Giessen Boltzmann-Uehling-Uhlenbeck (GiBUU) transport model is used for a detailed study of neutrino-nucleus events.

Results: The difference between the true-QE and QE-like cross sections in the MiniBooNE experiment is investigated in detail. It is shown that fake QE-like events lead to significant distortions in neutrino energy reconstruction. Flux-folded and unfolded cross sections for QE-like scattering are calculated as functions of both true and reconstructed energies. Flux-folded momentum transfer distributions are calculated as functions of both true and reconstructed momentum transfer. Distributions versus reconstructed values are compared with the experimental data. Also presented are the conditional probability densities of finding a true energy for a given reconstructed energy. We show how the energy-reconstruction procedure influences the measurement of oscillation parameters in T2K experiments.

Conclusions: For the reconstruction procedure based on quasielastic (QE) kinematics all other reaction channels besides true-QE scattering show a shift of the reconstructed energy towards lower values as compared to the true energy. In the MiniBooNE and T2K experiments this shift is about 100–200 MeV and depends on energy. The oscillation signals are similarly affected. These uncertainties may limit the extraction of a $\mathrm{CP}$ violating phase from an oscillation result.

The mass-yield distributions of various fission products in the 45- and 80-MeV bremsstrahlung-induced fission of ${}^{232}$Th have been determined by using a recoil catcher and an offline γ-ray spectrometric technique in the electron linac at the Pohang Accelerator Laboratory, Korea. The mass-yield distributions were obtained from the fission-product yield data using charge-distribution corrections. The peak-to-valley (P/V) ratio, the average value of light mass ($\langle A_{\mathrm{L}}\rangle$) and heavy mass ($\langle A_{\mathrm{H}}\rangle$), and the average number of neutrons ($\langle \nu \rangle$) in the bremsstrahlung-induced fission of ${}^{232}$Th at different excitation energies were obtained from the mass-yield data. From the present measurements and the existing data from the ${}^{232}$Th(γ,$f$) reaction and those from the ${}^{232}$Th($n$,$f$) reaction at various energies, the following observations were obtained: (i) The mass-yield distributions in the ${}^{232}$Th(γ,$f$) reaction at various energies are triple humped, similar to those of the ${}^{232}$Th($n$,$f$) reaction. (ii) The yields of fission products for $A$ $=$ 133–134, $A$ $=$ 138–139, and $A$ $=$ 143–144 and their complementary products in the ${}^{232}$Th(γ,$f$) reaction are higher than those of other fission products due to the nuclear structure effect. (iii) The yields of symmetric fission products for $A$ $=$ 133–134 and their complementary products in the ${}^{232}$Th(γ,$f$) reaction are lower than those in the ${}^{232}$Th($n$,$f$) reaction, whereas those for $A$ $=$ 143–144 and their complementary products are reversed. (iv) The result of increasing of the symmetric product yield causes the decreasing of the peak-to-valley ratio with increasing the excitation energy. However, it is surprising to see that the increasing trends for the symmetric products yields and the decreasing trends for the P/V ratio in the ${}^{232}$Th(γ,$f$) and ${}^{232}$Th($n$,$f$) reactions are not similar but those in the ${}^{238}$U(γ,$f$) and ${}^{238}$U($n$,$f$) reactions are similar to each other. (v) The average values of $\langle A_{\mathrm{L}}\rangle$, $\langle A_{\mathrm{H}}\rangle$, and $\langle \nu \rangle$ at different excitation energies in the ${}^{232}$Th(γ,$f$) and ${}^{232}$Th($n$,$f$) reactions are similar but those in the ${}^{238}$U(γ,$f$) and ${}^{238}$U($n$,$f$) reactions are different.

The High Acceptance Di-Electron Spectrometer (HADES) data on strangeness production in Ar + KCl collisions at 1.76$A$ GeV are analyzed within a minimal statistical model. In the model the total negative strangeness content is fixed by the observed $K^{+}$ multiplicities. Particles with negative strangeness are assumed to remain in chemical equilibrium with themselves and in thermal equilibrium with the environment until a common freeze-out. Exact strangeness conservation in each collision event is explicitly preserved. This implies that $\Xi$ baryons can be released only in events where two or more kaons are produced. An increase of the fireball volume due to application of a centrality trigger in HADES experiments is taken into account. We find that experimental ratios of $K^{-}/K^{+}$, $\Lambda /K^{+}$, and $\Sigma /K^{+}$ can be satisfactorily described provided in-medium potentials are taken into account. However, the calculated ${\Xi }^{-}/\Lambda /K^{+}$ ratio proves to be significantly smaller compared to the measured value (eight times less than the experimental median value and three times less than the lower error bar). Various scenarios to explain observed $\Xi$ enhancement are discussed. Arguments are given in favor of the $\Xi$ production in direct reactions. The rates of the possible production processes are estimated and compared.

We have used the dynamically constrained phase space coalescence model to investigate the production of light nuclei (antinuclei) based on the $1.134\times {10}^7$ hadronic final states generated by the parton and hadron cascade (PACIAE) model for the 0–5$\%$ most central Au+Au collisions at $\sqrt{s_{NN}}=200$ GeV with $\left|y\right|<1$ and $p_T<5$ acceptances. The STAR data of $\overline{{}_{\overline{\Lambda }}^3\mathrm{H}}$, ${}_{\Lambda }^3\mathrm{H}$, ${}^3\overline{\mathrm{He}}$, and ${}^3\mathrm{He}$ yields and ratios are well reproduced by the corresponding PACIAE results. The transverse momentum distribution of $\overline{{}^3\mathrm{He}}$ (${}^3\mathrm{He}$) and $\overline{{}_{\overline{\Lambda }}^3\mathrm{H}}$ (${}_{\Lambda }^3\mathrm{H}$) is also given. It turned out that the transverse momentum distribution of light nuclei is close to that of the corresponding antinuclei.

High spin states of ${}^{112}$In were investigated using the reaction ${}^{110}$Pd(${}^7$Li,5$n$)${}^{112}$In at a beam energy of 50 MeV. A new level sequence has been found in this nucleus and the configuration $\pi g_{9/2}^{-2}{g}_{7/2}\otimes \nu h_{11/2}$ before the alignment and the configuation $\pi g_{9/2}^{-2}{g}_{7/2}\otimes \nu h_{11/2}^3$ after the alignment are assigned. The self-consistent titled axis cranking relativistic mean-field model calculations are performed to interpret the rotational structure and the characteristic features of antimagnetic rotation have been presented for the band after backbend.

The present study deals with the extraction of the symmetry energy from heavy-ion collisions at intermediate energies. Using the isospin quantum molecular dynamical (IQMD) model, the dependence of the sum of the charge number for fragments with $Z\ge 2$($Z_{\mathrm{bound}}$) on the multiplicity of neutrons ($M_n$) from the projectile spectator fragmentation of ${}^{124}$Sn and ${}^{124}$La at 600 MeV/nucleon is compared with the experimental results of the ALADIN-2000 Collaboration. The comparison suggests a soft symmetry energy. In addition, the sensitivities of the symmetry energy toward the $Z_{\mathrm{bound}}$ dependence on proton multiplicity ($M_p$), neutron-to-proton single [$R(n/p)$] and double ratio [$R_D(n/p)$], are also examined. The $Z_{\mathrm{bound}}$ dependence of $R(n/p)$ is found to be the most sensitive observable toward the symmetry energy. The ALADIN Collaboration should extend the results for $R(n/p)$ in the near future.

The equilibrium properties of the outer crust of cold nonaccreting magnetars (i.e., neutron stars endowed with very strong magnetic fields) are studied using the latest experimental atomic mass data complemented with a microscopic atomic mass model based on the Hartree-Fock-Bogoliubov method. The Landau quantization of electron motion caused by the strong magnetic field is found to have a significant impact on the composition and the equation of state of crustal matter. It is also shown that the outer crust of magnetars could be much more massive than that of ordinary neutron stars.

The nonaxial reflection-asymmetric ${\beta }_{32}$ shape in some transfermium nuclei with $N=150$, namely, ${}^{246}$Cm, ${}^{248}$Cf, ${}^{250}$Fm, and ${}^{252}$No, are investigated with multidimensional constrained covariant density functional theories. By using the density-dependent point-coupling covariant density functional theory with the parameter set DD-PC1 in the particle-hole channel, it is found that, for the ground states of ${}^{248}$Cf and ${}^{250}$Fm, the nonaxial octupole deformation parameter ${\beta }_{32}>0.03$ and the energy gain due to the ${\beta }_{32}$ distortion is larger than 300 keV. In ${}^{246}$Cm and ${}^{252}$No, shallow ${\beta }_{32}$ minima are found. The occurrence of the nonaxial octupole ${\beta }_{32}$ correlations is mainly from a pair of neutron orbitals, $\left[734\right]9/2$ ($\nu j_{15/2}$) and $\left[622\right]5/2$ ($\nu g_{9/2}$), which are close to the neutron Fermi surface, and a pair of proton orbitals, $\left[521\right]3/2$ ($\pi f_{7/2}$) and $\left[633\right]7/2$ ($\pi i_{13/2}$), which are close to the proton Fermi surface. The dependence of the nonaxial octupole effects on the form of the energy density functional and on the parameter set is also studied.

We propose a method of obtaining of polarized nuclei in a crystal of ionic insulator, which is placed in a magnetic field and cooled to cryogenic temperatures. Polarization is a result of inelastic scattering of the conduction electrons of the metallic covering of a sample from the nuclei. This method (in a simplified form without the magnetic field) is suitable for obtaining aligned nuclei. We have derived the formulas (a) for the cross section of the process of electron-nucleus inelastic scattering, and (b) for the longitudinal relaxation time $T_1$. As an example, we consider the spin relaxation process for the ${}^{93}$Nb nucleus inside the Nb${}_2$O${}_5$ dielectric sample with a gold covering.

The lifetime of the 2${}_1^{+}$ state in ${}^{174}$Os was measured in a fast timing experiment using LaBr${}_3$(Ce) crystals for $\gamma$-ray detection. The excellent energy resolution in conjunction with the superb time properties of the new material allows for the reliable handling of the background, thus providing very precise lifetime values. The resulting $B(E2,2_1^{+}\to 0_1^{+})$ transition strength is discussed in relation to the systematics of the previously reported $B(E2,2_1^{+}\to 0_1^{+})$ values in the Os isotopes and compared to predictions of several models. The maximum of the transition probabilities of the 2${}_1^{+}$ states at $N=98$ for W and Os nuclei may be interpreted as resulting from the effects of the deformed subshell at $N=98$ as well as the “intruder” proton $h_{9/2}$ orbital.