We present a test with which to evaluate the calculated isospin-symmetry-breaking corrections to superallowed $0^{+}\to 0^{+}$ nuclear $\beta$ decay. The test is based on the corrected experimental $\mathcal{F}t$ values being required to satisfy conservation of the vector current (CVC). When applied to six sets of published calculations, the test demonstrates quantitatively that only one set, the one based on the shell model with Saxon-Woods radial wave functions, provides satisfactory agreement with CVC. This test can easily be applied to any sets of calculated correction terms that are produced in future.

We develop a phenomenological statistical model for dilute star matter at finite temperature, in which free nucleons are treated within a mean-field approximation and nuclei are considered to form a loosely interacting cluster gas. Its domain of applicability, that is, baryonic densities ranging from about $\rho >{10}^8$ g/cm${}^3$ to normal nuclear density, temperatures between 1 and $20$ MeV, and proton fractions between $0.5$ and $0$, makes it suitable for the description of baryonic matter produced in supernovae explosions and proto-neutron stars. The first finding is that, contrary to the common belief, the crust-core transition is not first order, and for all subsaturation densities matter can be viewed as a continuous fluid mixture between free nucleons and massive nuclei. As a consequence, the equations of state and the associated observables do not present any discontinuity over the whole thermodynamic range. We further investigate the nuclear matter composition over a wide range of densities and temperatures. At high density and temperature our model accounts for a much larger mass fraction bound in medium nuclei with respect to traditional approaches as Lattimer-Swesty, with sizable consequences on the thermodynamic quantities. The equations of state agree well with the presently used EOS only at low temperatures and in the homogeneous matter phase, while important differences are present in the crust-core transition region. The correlation among the composition of baryonic matter and neutrino opacity is finally discussed, and we show that the two problems can be effectively decoupled.

Direct photon spectra from central Au $+$ Au and Cu $+$ Cu collisions at $\sqrt{s_{\mathrm{NN}}}=62.4,130,$ and $200A$ GeV are calculated within the ultrarelativistic quantum molecular-dynamics microscopic transport model and a $\text{micro}+\text{macro}$ hybrid model. In the latter approach, the high-density part of the transport evolution is replaced by an ideal $(3+1)$-dimensional hydrodynamic calculation. We study the impact of viscosity and full local thermalization and compare the calculations to measurements obtained by the PHENIX Collaboration. We find a reasonable agreement with the experimental data for calculations involving a quark-gluon-plasma phase.

Recent experimental data have revealed large mirror energy differences (MED) between high-spin states in the mirror nuclei ${}^{67}\mathrm{Se}$ and ${}^{67}\mathrm{As}$, the heaviest pair where MED have been determined so far. The MED are generally attributed to the isospin symmetry breaking caused by the Coulomb force and by the isospin-nonconserving part of the nucleon-nucleon residual interaction. The different contributions of the various terms have been extensively studied in the $\mathit{fp}$ shell. By employing large-scale shell-model calculations, we show that the inclusion of the $g_{9/2}$ orbit causes interference between the electromagnetic spin-orbit and the Coulomb monopole radial terms at high spin. The large MED are attributed to the aligned proton pair excitations from the $p_{3/2}$ and $f_{5/2}$ orbits to the $g_{9/2}$ orbit. The relation of the MED to deformation is discussed.

The high-spin level structure of ${}^{188}\mathrm{Au}$ has been investigated via the ${}^{173}\mathrm{Yb}$(${}^{19}\mathrm{F}$,$4n$$\gamma$) reaction at beam energies of 86 and 90 MeV. The previously reported level scheme has been modified and extended significantly. A new $I^{\pi }={20}^{+}$ state associated with $\pi h_{11/2}^{-1}\otimes \nu i_{13/2}^{-2}{h}_{9/2}^{-1}$ configuration and two new rotational bands, one of which is built on the $\pi h_{9/2}\otimes \nu i_{13/2}$ configuration, have been identified. The prolate-to-oblate shape transition through triaxial shape has been proposed to occur around ${}^{188}\mathrm{Au}$ for the $\pi h_{9/2}\otimes \nu i_{13/2}$ bands in odd-odd Au isotopes. Evidence for $\pi h_{11/2}^{-1}\otimes \nu i_{13/2}^{-1}$ structure of nonaxial shape with $\gamma <-{70}^{°}$ has been obtained by comparison with total Routhian surface and cranked-shell-model calculations.

The transient field (TF) technique in inverse kinematics was used to measure the $g$ factors of the low lying $2_1^{+}$, $4_1^{+}$, and $2_2^{+}$ states in ${}^{106}\mathrm{Pd}$. The $g$ factor of the $4_1^{+}$ state was determined and the $g(2_1^{+})$ and $g(2_2^{+})$ factors were remeasured. The values of $g(2_1^{+})$ and $g(2_2^{+})$ had been determined earlier in integral perturbed angular correlation (IPAC) experiments and the value of the former served to calibrate the TF. The three $g$ factors, $g(2_1^{+})$, $g(2_2^{+})$, and $g(4_1^{+})$, agree with each other and with the collective $Z/A$ value. The uncertainties in the $g(2_2^{+})$ and $g(4_1^{+})$ factors remain fairly large in spite of long measuring times because of the weak excitation of the two-phonon states. The lifetimes of the $2_2^{+}$ and $4_1^{+}$ states were newly determined from line-shape fits.

We suggest that an appreciable portion of the $1/2^{-}$ peak in a recent ${}^{13}{\mathrm{Be}}^{*}\to {}^{12}$Be $+$ $n$ experiment is actually due to $5/2^{+}$ decays to the excited 0${}^{+}$ state.

The transverse flow of intermediate mass fragments (IMFs) has been investigated for the 35 MeV/u ${}^{70}\mathrm{Zn}+{}^{70}\mathrm{Zn}$, ${}^{64}\mathrm{Zn}+{}^{64}\mathrm{Zn}$, and ${}^{64}\mathrm{Ni}+{}^{64}\mathrm{Ni}$ systems. A transition from the IMF transverse flow strongly depending on the mass of the system, in the most violent collisions, to a dependence on the charge of the system, for the peripheral reactions, is shown. This transition was shown to be sensitive to the density dependence of the symmetry energy using the antisymmetrized molecular-dynamics model. The results present an observable, the IMF transverse flow, that can be used to probe the nuclear equation of state. Comparison with the simulation demonstrated a preference for a stiff density dependence of the symmetry energy.

The $\mathit{pp}$ hard bremsstrahlung reaction, $p+p\to \mathit{pp}({}^1{S}_0)+\gamma$, in which the two protons in the final state are in the ${}^1{S}_0$ state, is investigated theoretically. Here, the most general spin structure of the $\mathit{NN}$ hard bremsstrahlung reaction, consistent with symmetry principles, is derived from a partial-wave expansion of this amplitude. Based on this spin structure, it is shown that there are only four independent spin matrix elements in this reaction, which is a direct consequence of reflection symmetry in the reaction plane. It is also shown that it requires at least eight independent observables to determine them uniquely. The present method provides the coefficients multiplying each spin operator in terms of the partial-wave or, equivalently, multipole amplitudes. Some observables are expressed explicitly in terms of these multipoles and a partial-wave analysis is performed. The results should be useful in the analyses of the experimental data on the $p+p\to \mathit{pp}({}^1{S}_0)+\gamma$ reaction being taken, in particular, at the COSY accelerator facility, as well as in providing some theoretical guidance to the future experiments in this area.

A calculation of the ${}^3\mathrm{He}$ transverse $(e,e^{\prime })$ inclusive response function, $R_T$, which includes $\Delta$ degrees of freedom, is performed using the Lorentz integral transform method. The resulting coupled equations are treated in impulse approximation, where the $\mathit{NNN}$ and $\mathit{NN}$$\Delta$ channels are solved separately. As $\mathit{NN}$ and $\mathit{NNN}$ potentials, we use the Argonne V18 and Urbana IX models, respectively. Electromagnetic currents include the $\Delta$-isobar currents, one-body $N$ currents with relativistic corrections, and two-body currents consistent with the Argonne V18 potential. $R_T$ is calculated for the breakup threshold region at momentum transfers near 900 MeV/$c$. Our results are similar to those of Deltuva et al. in that large $\Delta$-isobar current contributions are found. However, we find that these are largely canceled by the relativistic contribution from the one-body $N$ currents. Finally, a comparison is made between theoretical results and experimental data.

A new parametrization PC-PK1 for the nuclear covariant energy density functional with nonlinear point-coupling interaction is proposed by fitting to observables of 60 selected spherical nuclei, including the binding energies, charge radii, and empirical pairing gaps. The success of PC-PK1 is illustrated in the description of infinite nuclear matter and finite nuclei including the ground-state and low-lying excited states. In particular, PC-PK1 provides a good description for the isospin dependence of binding energy along either the isotopic or the isotonic chain, which makes it reliable for application in exotic nuclei. The predictive power of PC-PK1 is also illustrated for the nuclear low-lying excitation states in a five-dimensional collective Hamiltonian in which the parameters are determined by constrained calculations for triaxial shapes.

Evidence of the $3\alpha$-particle condensate character of the Hoyle state (the $0_2^{+}$ state at $7.65$ MeV in ${}^{12}\mathrm{C}$) implies not only an enhanced radius of ${}^{12}\mathrm{C}$ in this state, which was established by many theoretical calculations and confirmed by the recent diffraction model analysis, but also zero relative angular momenta between clusters. We performed coupled-channels model calculations of the angular distributions of $\alpha +{}^{12}$C elastic and inelastic (to the $4.44$-MeV $2$${}^{+}$, $7.65$-MeV $0$${}_2^{+}$, and $9.65$-MeV $3_1^{-}$ states) scattering at $110$ MeV and found the ratio of the empirical spectroscopic factors $S(L)$. As the differential cross sections of these reactions are characterized by pronounced enhancement and strong oscillations at large angles, we assumed a potential scattering in the forward hemisphere and the direct transfer of a ${}^8\mathrm{Be}$ cluster at ${\theta }_{\mathrm{c}.\mathrm{m}.}>{90}^{°}$ and took into account the direct transfer of ${}^8\mathrm{Be}$ in the ground state and in the first excited $2^{+}$ and $4^{+}$ states. We found that the cluster configuration with $L=0$ dominates in the $0_2^{+}$ state, being more than three times larger than that in the ground state. This result provides additional evidence of the condensed structure of the Hoyle state in ${}^{12}\mathrm{C}$ with a dominance of zero relative angular momentum. The negative-parity $3_1^{-}$ excited state in ${}^{12}\mathrm{C}$ observed above the $3\alpha$ threshold is also considered to have the $3\alpha$-cluster structure. The present calculations described well the structure of the large-angle cross section on this state. We found a positive interference for all allowed $\alpha +{}^8$Be configurations with a dominance of the $p$-orbital $(69\%)\alpha +{}^8$Be motion and confirmed the exotic, but hardly a condensed, structure of this state.

Experimental cross section data of the ${}^{67}\mathrm{Zn}$$(n,\alpha ){}^{64}$Ni reaction are very scanty because the residual nucleus ${}^{64}\mathrm{Ni}$ is stable and the commonly used activation method is not feasible. As a result, very large deviations (about 10 times) exist among different nuclear data libraries. In the present work, cross sections of the partial ${}^{67}\mathrm{Zn}$$(n,{\alpha }_0){}^{64}$Ni and total ${}^{67}\mathrm{Zn}$$(n,\alpha ){}^{64}$Ni reactions are measured at neutron energies of $4.0$ and $5.0$ MeV for the first time, and those of $6.0$ MeV are remeasured for consistency checking. A twin-gridded ionization chamber was used as the charged-particle detector and two enriched back-to-back-set ${}^{67}\mathrm{Zn}$ samples were adopted. Experiments were performed at the $4.5$ MV Van de Graaff Accelerator of Peking University. Neutrons were produced through the ${}^2\mathrm{H}$$(d,n){}^3$He reaction using a deuterium gas target. Absolute neutron flux was determined by counting the fission fragments from a ${}^{238}\mathrm{U}$ sample placed inside the gridded ionization chamber while a BF${}_3$ long counter was employed as neutron flux monitor. Present data are compared with results of previous measurements, evaluations, and talys code calculations.

The photodisintegration cross section of the radioactive nucleus ${}^{241}\mathrm{Am}$ has been obtained using activation techniques and monoenergetic $\gamma$-ray beams from the HI$\gamma$S facility. The induced activity of ${}^{240}\mathrm{Am}$ produced via the ${}^{241}\mathrm{Am}$$(\gamma ,n)$ reaction was measured in the energy interval from 9 to 16 MeV utilizing high-resolution $\gamma$-ray spectroscopy. The experimental data for the ${}^{241}\mathrm{Am}$$(\gamma ,n)$ reaction in the giant dipole resonance energy region are compared with statistical nuclear-model calculations.

The coupled-channels technique is applied to analyze recent fusion data for ${}^{48}\mathrm{Ca}$$+$${}^{48}\mathrm{Ca}$. The calculations include the excitations of the low-lying $2^{+}$, $3^{-}$, and $5^{-}$ states in projectile and target, and the influence of mutual excitations as well as the two-phonon quadrupole excitations is also investigated. The ion-ion potential is obtained by double-folding the nuclear densities of the reacting nuclei with the M3Y$+$repulsion effective interaction but a standard Woods-Saxon potential is also applied. The data exhibit a strong hindrance at low energy compared to calculations that are based on a standard Woods-Saxon potential but they can be reproduced quite well by applying the M3Y$+$repulsion potential with an adjusted radius of the nuclear density. The influence of the polarization of high-lying states on the extracted radius is discussed.

We study the possibility of testing experimentally signatures of $P$-odd effects related to the vorticity of the medium. The chiral vortaic effect is generalized to the case of conserved charges different from the electric one. In the case of baryonic charge and chemical potential, such an effect should manifest itself in neutron asymmetries measured by the Multipurpose Detector at the Nuclotron-Based Ion Collider Facility accelerator complex. The required accuracy may be achieved in a few months of accelerator running. We also discuss polarization of the hyperons and $P$-odd correlations of particle momenta (handedness) as probes of vorticity.

The production of $\eta$ mesons in proton-proton collisions has been studied using the WASA detector at the CELSIUS storage ring at excess energies of $Q=40$ MeV and $Q=72$ MeV. The $\eta$ was detected through its $2\gamma$ decay in a near-$4\pi$ electromagnetic calorimeter, whereas the protons were measured by a combination of straw chambers and plastic scintillator planes in the forward hemisphere. About $6.9\times {10}^4$ and $9.3\times {10}^4$ events were found at $Q=40$ MeV and $Q=72$ MeV, respectively, with background contributions of less than $5$$\%$. A simple parametrization of the production cross section in terms of low partial waves was used to evaluate the acceptance corrections. Strong evidence was found for the influence of higher partial waves. The Dalitz plots show the presence of $p$ waves in both the $\mathit{pp}$ and the $\eta \{\mathit{pp}\}$ systems and the angular distributions of the $\eta$ in the center-of-mass frame suggest the influence of $d$-wave $\eta$ mesons.

In the present article, the “pasta” phase is studied at finite temperatures within a Thomas-Fermi (TF) approach. Relativistic mean-field models, both with constant and density-dependent couplings, are used to describe this frustrated system. We compare the present results with previous ones obtained within a phase-coexistence description and conclude that the TF approximation gives rise to a richer inner “pasta” phase structure and the homogeneous matter appears at higher densities. Finally, the transition density calculated within TF is compared with the results for this quantity obtained with other methods.

The neutron removal cross section [${\sigma }_{-N}(Z)$] is defined for the projectile-like fragment isotopes and extended to the lower $Z$ isotopes in the projectile fragmentation reaction. The cross sections of fragments in 1 $A$ GeV even ${}^{42-52}\mathrm{Ca}$$+$${}^{12}\mathrm{C}$ projectile fragmentation reactions are calculated using the statistical abrasion-ablation model. The correlations between ${\sigma }_{-N}(Z)$ of different fragment isotopes and neutron skin thickness ($S$${}_n$) for finite neutron-rich nuclei are revisited. Good linear ${\sigma }_{-N}(Z)-S_n$ correlations are observed in fragment isotopes, and it is suggested that ${\sigma }_{-N}(Z)$ be used as an observable to determine $S$${}_n$ of neutron-rich nucleus in addition to ${\sigma }_{-N}$ for isotopes of the projectile nucleus.

Contrary to what is claimed in the article by R. J. Charity [Phys. Rev. C 82, 014610 (2010)], the papers by Gontchar and Aktaev [Phys. Rev. C 80, 044601 (2009)] and Lestone and McCalla [Phys. Rev. C 79, 044611 (2009)] do not contradict but rather complement each other with respect to the time delay of the fission process.