We compute the $\beta$-decay $ft$ values within the frameworks of the energy density functional (EDF) and the interacting boson model (IBM). Based on the constrained mean-field calculation with the Gogny-D1M EDF, the IBM Hamiltonian for an even-even nucleus and essential ingredients of the interacting boson-fermion-fermion model (IBFFM) for describing the neighboring odd-odd nucleus are determined in a microscopic way. Only the boson-fermion and residual neutron-proton interaction strengths are determined empirically. The Gamow-Teller (GT) and Fermi (F) transition rates needed to compute the $\beta$-decay $ft$ values are obtained without any additional parameter or quenching of the $g_A$ factor. The observed $logft$ values for the ${\beta }^{+}$ decays of the even-even Ba into odd-odd Cs nuclei, and of the odd-odd Cs to the even-even Xe nuclei, with mass $A\approx 130$ are reasonably well described. The predicted GT and F transition rates represent a sensitive test of the quality of the IBM and IBFFM wave functions.

Spectroscopic strengths for the ${}^{18}{\mathrm{F}}^{g,m}(d,p){}^{19}\mathrm{F}$ reactions to members of the ground-state band in ${}^{19}\mathrm{F}$ are interpreted in the rotational model. The analysis considers two different coupling schemes, namely, the strong and decoupled limits of the particle rotor model to describe the ground and isomeric states of ${}^{18}\mathrm{F}$, as well as the transitions to the ground-state band in ${}^{19}\mathrm{F}$. Our results, obtained using Nilsson amplitudes for the neutron levels $\frac{1}{2}\left[220\right], \frac{3}{2}\left[211\right]$, and $\frac{5}{2}\left[202\right]$ calculated at a deformation ${\epsilon }_2=0.32$ are in agreement with the measurements and USDB shell-model calculations.

Proton-induced nonelastic cross sections for ${}^{12}\mathrm{C}, {}^{27}\mathrm{Al}, {}^{56}\mathrm{Fe}$, and ${}^{208}\mathrm{Pb}$ are investigated in a low-energy region below 100 MeV down to nearly 0 MeV based on a framework of an intranuclear cascade (INC) model. We point out that there is a scaling among the calculations including the Coulomb repulsion; two cases are shown: One is the scaling of the trajectories with different impact parameters, and the other is the incident-energy dependence of the cross sections. We point out for the first time that the calculated cross sections by the usual INC model follow a scaling and the discrepancy between the calculated cross sections and the experimental data indicates the scale breaking and that, for the explanation of the scale breaking, it is essential to include the discrete level constraints in addition to the Coulomb repulsion in the INC model.

The transverse momentum ($p_{\mathrm{T}}$) differential yields of (anti-)${}^3\mathrm{He}$ and (anti-)${}^3\mathrm{H}$ measured in $p$-Pb collisions at $\sqrt{s_{NN}}$ = 5.02 TeV with ALICE at the Large Hadron Collider (LHC) are presented. The ratios of the $p_{\mathrm{T}}$-integrated yields of (anti-)${}^3\mathrm{He}$ and (anti-)${}^3\mathrm{H}$ to the proton yields are reported, as well as the $p_{\mathrm{T}}$ dependence of the coalescence parameters $B_3$ for (anti-)${}^3\mathrm{He}$ and (anti-)${}^3\mathrm{H}$. For (anti-)${}^3\mathrm{He}$, the results obtained in four classes of the mean charged-particle multiplicity density are also discussed. These results are compared to predictions from a canonical statistical hadronization model and coalescence approaches. An upper limit on the total yield of ${}^4\overline{\mathrm{He}}$ is determined.

An absolute cross section for the radiative capture reaction ${}^2\mathrm{H}(p,\gamma ){}^3\mathrm{He}$ has been measured at the OMEGA laser facility using inertially confined plasmas. These high-temperature plasmas are created by imploding a fuel-containing capsule using laser ablation, and are advantageous in that they better mimic astrophysical systems. We measure an $S$ factor for this reaction of $0.429\pm 0.{026}_{\mathrm{stat}}\pm 0.{072}_{\mathrm{sys}}$ eV b at $E_{c.m.}=16.35\pm 0.40$ keV, which is higher than the adopted evaluations. This reaction is important as a source of nuclear energy in protostars and brown dwarfs. It is also a critical reaction during big-bang nucleosynthesis, and an accurate cross section can be used as a constraint on cosmology.

A self-consistent particle-vibration coupling (PVC) model without diagonal approximation is presented. The diagonal approximation, that neglects completely the interaction between the doorway states, has been removed by taking into account the interaction between the two particle-holes inside the doorway states. As applications, isoscalar giant monopole, dipole, and quadrupole resonances in ${}^{16}\mathrm{O}$ are investigated based on the use of Skyrme functionals. The diagonal approximation is found to clearly impact the strength distribution of the giant quadrupole resonance, and the description of the experimental data is improved without this approximation. The impact of the diagonal approximation is analyzed in detail, especially its effect on the eigenenergies and the induced coupling between neutron and proton particle-hole configurations. The latter is a direct and physically sound effect of the improvement on our formalism. The importance of using self-consistently the full effective interaction in the PVC vertex, and the effect of its renormalization via the subtraction method, are also discussed. For completeness, we also analyze the dependence of our results on the Skyrme parametrization.

The invariant-mass distribution of ${}^{11}\mathrm{O}$ fragments formed in two-neutron-knockout reactions with a ${}^{13}\mathrm{O}$ projectile and ${}^9\mathrm{Be}$ target has been further examined. Gating on events where the ${}^9\mathrm{C}$ decay fragments produced following $2p$ emission are recoiled transversely in the projectile's frame improves the overall invariant-mass resolution. The observed peak is now shown to have contributions from at least two ${}^{11}\mathrm{O}$ levels, in contradiction with the suggestion of Fortune [Phys. Rev. C 99, 051302(R) (2019)]. The data, however, do not differentiate between the ground-state properties obtained by the Gamow coupled-channels calculation and the prompt $2p$-decay model of Fortune. The ground-state $2p$-decay energy is 4.25(6) MeV in a two-level fit to the data, but lower values are possible if more states contribute to the observed spectrum, as suggested in the previous analysis.

Prompt-fission-neutron spectra from ${}^{239}\mathrm{Pu}$ ($\mathit{n},\mathit{f}$) were measured with respect to ${}^{252}\mathrm{Cf}$ spontaneous fission for incident neutron energies from 0.7 to $700\mathrm{MeV}$ at the Weapons Neutron Research facility (WNR) of the Los Alamos Neutron Science Center. A newly designed high-efficiency fission chamber was coupled to the highly segmented Chi-Nu neutron liquid scintillator array to detect neutrons emitted in fission events. The double time-of-flight technique was used to deduce the incident neutron energies from the spallation target and the outgoing-neutron energies from the fission chamber. Prompt-fission-neutron spectra (PFNS) were measured with respect to ${}^{252}\mathrm{Cf}$ spontaneous fission down to $200\mathrm{keV}$ and up to about $12\mathrm{MeV}$ for all the incident neutron energies with typical total uncertainties well below $2\%$ up to about 7-MeV outgoing-neutron energy. The general trend of PFNS is well reproduced by JEFF3.3 and ENDF evaluations, although a better agreement is found with JEFF3.3. Discrepancies were observed for the low-energy part of the spectra, especially around the opening of the second-, third- and fourth-chance fission. Neutron average kinetic energies as a function of incident neutron energy are obtained experimentally with reported total uncertainties below $0.5\%$. The measured values agree with the most recent data. The trend is fairly well reproduced by the JEFF3.3 evaluation, although it fails to reproduce the experimental values within their uncertainties.

In the present study, we have investigated the impact of the tensor force on fission paths, in particular the symmetric and asymmetric barriers in ${}^{230}\mathrm{Th}, {}^{226}\mathrm{Th}, {}^{222}\mathrm{Th}$, and ${}^{216}\mathrm{Th}$ isotopes which display an asymmetric to symmetric fission transition. This analysis has been performed within the HFB approach with (${\mathrm{Q}}_{20}, {\mathrm{Q}}_{30}, {\mathrm{Q}}_{40}$) as collective variable constraints, using the D1ST2a $\mathrm{Gogny}+\mathrm{tensor}$ term interaction and comparing to the standard D1S Gogny interaction results. The effects from the tensor term on the potential energy surface landscape, and especially on barrier heights and its topology by opening a new valley in agreement with experimental data, are found to be crucial in the description of exotic actinide fission. We conclude that a tensor term should be integrated to the long range part of the effective interaction for a better description of the fission.

Background: Reaction rates of radiative capture reactions can play a crucial role in the nucleosynthesis of heavy nuclei in explosive stellar environments. These reaction rates depend strongly on $\gamma$-ray decay widths in the reaction products, which are, for nonresonant capture reactions at high excitation energies, derived from the $\gamma$-ray strength function and the nuclear level density. Recently, the ratio method was applied to primary $\gamma$ rays observed from ($d,p$) reactions and nuclear resonance fluorescence measurements to extract the dipole strength in atomic nuclei and to test the generalized Brink-Axel hypothesis.

Purpose: The purpose of this work is to apply the ratio method to primary $\gamma$-ray intensities of the ${}^{63,65}\mathrm{Cu}(p,\gamma )$ reactions to extract $\gamma$-ray strength information on the nuclei ${}^{64,66}\mathrm{Zn}$. The impact of spin distribution, total $\gamma$-ray decay widths, level densities, and width fluctuations on the application of the ratio method will be discussed. Additionally, by comparing the relative $\gamma$-ray strength at different excitation energies, conclusions on the validity of the generalized Brink-Axel hypothesis can be made.

Method: The radiative proton capture reaction measurements have been performed at the HORUS $\gamma$-ray spectrometer of the University of Cologne at one excitation energy for each reaction. Primary $\gamma$-ray intensities have been determined by normalizing secondary $\gamma$-ray transitions in two-step cascades using their absolute branching ratio. The ratio method was applied to the measured primary $\gamma$-ray intensities as well as to previous measurements by Erlandsson $et$ $al.$ at different excitation energies.

Results: The relative strength function curve for ${}^{64}\mathrm{Zn}$ from our measurement shows no significant deviation from the previous measurement at a different excitation energy. The same is true for ${}^{66}\mathrm{Zn}$ where both measurements were at almost the same excitation energy. Absolute $\gamma$-strength function values have been obtained by normalizing the relative curves to quasiparticle random phase approximation calculations because of the absence of experimental data in the respective energy region.

Conclusion: The generalized Brink-Axel hypothesis, i.e., the independence of the strength function on the excitation energy, seems to hold in the studied energy region and nuclei. The method to obtain primary $\gamma$-ray intensities from two-step cascade spectra was shown to be a valuable and sensitive tool although its uncertainties are connected to the knowledge of the low-energy level scheme of the investigated nucleus. The scaling in the ratio method should be taken with care, because the relative strength is not a simple sum of $f_{E1}$ and $f_{M1}$ but a somewhat complex linear combination dependent on the excitation energy of the nucleus.

The observation of the gravitational wave signal GW170817, consistent with emission from the inspiral of a binary neutron-star system, provided information on the tidal deformation of the participating stars. The available data may be exploited to constrain the equation of state of dense nuclear matter as well as to shed light on the underlying models describing nuclear dynamics at the microscopic level. In this paper, we compare the experimental results to the predictions of different theoretical models, based on nonrelativistic nuclear many-body theory, the relativistic field-theoretical formalism, and a more phenomenological approach constrained by observed nuclear properties. Although the precision of the available data does not allow to resolve the degeneracy of the models, our analysis shows a distinct sensitivity to the star compactness predicted by the different equations of state, which turns out to be significantly affected by relativistic boost corrections to the nucleon-nucleon potential.

We approach the calculation of the nuclear matrix element of the neutrinoless double-$\beta$ decay process, considering the light-neutrino-exchange channel, by way of the realistic shell model. To this end, we start from a realistic nucleon-nucleon potential and then derive the effective shell-model Hamiltonian and $0\nu \beta \beta$ decay operator within the many-body perturbation theory. We focus on investigating the perturbative properties of the effective shell-model operator of such a decay process, aiming to establish the degree of reliability of our predictions. The contributions of the so-called short-range correlations and of the correction of Pauli-principle violations to the effective shell-model operator, the latter introduced in many-valence nucleon systems, are also taken into account. The subjects of our study are a few candidates to the $0\nu \beta \beta$ decay detection, in a mass interval ranging from $A=48$ up to $A=136$, whose spin- and spin-isospin-dependent decay properties we have studied in previous works. Our results provide evidence that the effect of the renormalization of the $0\nu \beta \beta$-beta decay operator on the values of the nuclear matrix elements is less relevant than what we have obtained in previous studies of the effective single-body Gamow-Teller transitions operating also in the two-neutrino double-$\beta$ decay

Cluster and hypernuclei production in heavy-ion collisions is presently under active experimental and theoretical investigation. Since clusters are weekly bound objects, their production is very sensitive to the dynamical evolution of the system and its interactions. The theoretical description of cluster formation is related to the $n$-body problem. Here we present the novel $n$-body dynamical transport approach PHQMD (parton-hadron-quantum-molecular dynamics) which is designed to provide a microscopic description of nuclear cluster and hypernucleus formation as well as of general particle production in heavy-ion reactions at relativistic energies. In contrast to the coalescence or statistical models, often used for the cluster formation, in PHQMD clusters are formed dynamically due to the interactions between baryons described on a basis of quantum molecular dynamics (QMD), which allows one to propagate the $n$-body Wigner density and $n$-body correlations in phase space, essential for the cluster formation. The clusters are identified by the MST (minimum spanning tree) procedure or the SACA (simulated annealing cluster algorithm) which finds the most bound configuration of nucleons and clusters. Collisions among hadrons as well as quark-gluon-plasma formation and parton dynamics in PHQMD are treated in the same way as in the established PHSD (parton-hadron-string dynamics) transport approach. In order to verify our approach with respect to the general dynamics, we present here the first PHQMD results for general “bulk” observables such as rapidity distributions and transverse mass spectra for hadrons ($\pi ,K,\overline{K}$, $p$, $\overline{p}$, $\mathrm{\Lambda }$, $\overline{\mathrm{\Lambda }}$) from SIS (the GSI heavy ion synchrotron) to RHIC (BNL Relativisitic Heavy Ion Collider) energies. We find a good description of the “bulk” dynamics which allows us to proceed with the results on cluster production, including hypernuclei.

Background: In order to study structure of protoneutron stars and those in subsequent cooling stages, it is of great interest to calculate inhomogeneous hot and cold nuclear matter in a variety of phases. The finite-temperature Hartree-Fock-Bogoliubov (FT-HFB) theory is a primary choice for this purpose; however, its numerical calculation for superfluid (superconducting) many-fermion systems in three dimensions requires enormous computational costs.

Purpose: To study a variety of phases in the crust of hot and cold neutron stars, we propose an efficient method to perform the FT-HFB calculation with the three-dimensional (3D) coordinate-space representation.

Methods: Recently, an efficient method based on the contour integral of Green's function with the shifted conjugate-orthogonal conjugate-gradient method was proposed [Phys. Rev. C 95, 044302 (2017)]. We extend the method to finite temperature, using the shifted conjugate-orthogonal conjugate-residual method.

Results: We benchmark the 3D coordinate-space solver of the FT-HFB calculation for hot isolated nuclei and fcc phase in the inner crust of neutron stars at finite temperature. The computational performance of the present method is demonstrated. Different critical temperatures of the quadrupole and the octupole deformations are confirmed for ${}^{146}\mathrm{Ba}$. The robustness of the shape coexistence feature in ${}^{184}\mathrm{Hg}$ is examined. For the neutron-star crust, deformed neutron-rich Se nuclei embedded in the sea of superfluid low-density neutrons appear in the fcc phase at a nucleon density of 0.045 ${\mathrm{fm}}^{-3}$ and a temperature of $k_{B}T=200$ keV.

Conclusions: The efficiency of the developed solver is demonstrated for nuclei and inhomogeneous nuclear matter at finite temperature. It may provide a standard tool for nuclear physics, especially for the structure of hot and cold neutron-star matter.

We compute with lattice field theory the vector and axial static structure factors of the unitary gas for arbitrary temperature above the superfluid transition and for fugacities $0.1<z<1.0$. Using the lattice formulation, we calculate beyond the validity of the virial expansion, a commonly used technique in many-body physics. We find qualitative differences in the behavior of the structure factors at high fugacity compared to the predictions of the virial expansion. Due to the large scattering length of neutrons, we expect the unitary gas structure factors to approximate the structure factors of hot neutron gases, and we therefore expect our calculations to be useful in supernova simulations, where neutron gas structure factors are needed to compute in-medium neutrino-neutron scattering rates.

The $\beta$-decay half-lives of 55 neutron-rich nuclei ${}^{134-139}\mathrm{Sn}$, ${}^{134-142}\mathrm{Sb}$, ${}^{137-144}\mathrm{Te}$, ${}^{140-146}\mathrm{I}$, ${}^{142-148}\mathrm{Xe}$, ${}^{145-151}\mathrm{Cs}$, ${}^{148-153}\mathrm{Ba}$, and ${}^{151-155}\mathrm{La}$ were measured at the Radioactive Isotope Beam Factory employing the projectile fission fragments of ${}^{238}\mathrm{U}$. The nuclear level structure, which relates to deformation, has a large effect on the half-lives. The impact of newly measured half-lives on modeling the astrophysical origin of the heavy elements is studied in the context of $r$ process nucleosynthesis. For a wide variety of astrophysical conditions, including those in which fission recycling occurs, the half-lives have an important local impact on the second ($A$ $\approx$ 130) peak.

The collective behavior of hadrons and of electromagnetic radiation in heavy-ion collisions has been widely used to study the properties of the quark-gluon plasma (QGP). Indeed this collectivity, as measured by anisotropic flow coefficients, can be used to constrain the transport properties of QGP. The goal of this contribution is to investigate the influence of the specific bulk viscosity $\left(\zeta /s\right)$ on dilepton production, both at Relativistic Heavy-Ion Collider and Large Hadron Collider energies. We explore the sensitivity of dileptons to dynamical features that bulk viscosity induces on the evolution of a strongly interacting medium, and highlight what makes them a valuable probe in the pursuit to also constrain $\zeta /s$.

Relativistic heavy ion collisions generate nuclear-sized droplets of quark-gluon plasma (QGP) that exhibit nearly inviscid hydrodynamic expansion. Smaller collision systems such as $p+\mathrm{Au}, d+\mathrm{Au}$, and ${}^3\mathrm{He}+\mathrm{Au}$ at the BNL Relativistic Heavy Ion Collider, as well as $p+\mathrm{Pb}$ and high-multiplicity $p+p$ at the CERN Large Hadron Collider may create even smaller droplets of QGP. If so, the standard time evolution paradigm of heavy ion collisions may be extended to these smaller systems. These small systems present a unique opportunity to examine pre-hydrodynamic physics and extract properties of the QGP, such as the bulk viscosity, where the short lifetimes of the small droplets make them more sensitive to these contributions. Here, we focus on the influence of bulk viscosity, its temperature dependence, and the implications of negative pressure and potential cavitation effects on the dynamics in small and large systems using the publicly available hydrodynamic codes sonic and music. We also discuss pre-hydrodynamic physics in different frameworks including anti–de Sitter/conformal field theory strong coupling, ip-glasma weak coupling, and free streaming.

Heavy quarks produced in relativistic heavy-ion collisions are known to be sensitive probes of the hot and dense QCD matter they traverse. In this paper we study how their dynamics is affected by the nature of the bulk evolution of the QCD matter, the initial condition of the system, and the treatment of elementary interactions between heavy quarks and the surrounding medium. For the same initial condition and the same quark-gluon plasma (QGP) expansion scenario we discuss the consequences of the assumption of a local equilibrium by comparing the consequences for the nuclear modification factor $R_{\mathrm{AA}}$ and the elliptic flows of charm quarks, scrutinizing the different components of the final distribution of charm quarks. For this purpose we employ the parton-hadron-string dynamics (PHSD) model, which is an off-shell microscopic transport approach, as well as the linearized-Boltzmann (LB) scheme obtained by coarse graining the PHSD bulk and assuming local equilibrium for the interactions of the charm quarks with the bulk. The $R_{\mathrm{AA}}$ of charm quarks stemming from the later LB approach is also compared to a genuine fluid dynamics evolution initiated by the coarse grained PHSD, which allows us to further assess the consequences of reducing the full $n$-body dynamics. We then proceed to a systematic comparison of PHSD (in its LB approximation) with MC@HQ, another transport model for heavy flavors which also relies on the LB approach. In particular, we investigate the consequences for the nuclear modification factor of charm quarks if we vary separately the initial heavy quark distribution function in matter, the expansion dynamics of the QGP, and the elementary interactions of heavy quarks of these models. We find that the results for both models vary significantly depending on the details of the calculation. However, both models achieve very similar predictions for key heavy quark observables for certain combinations of initial condition, bulk evolution, and interactions. We conclude that this ambiguity limits our ability to determine the different properties of the system based on the current set of observables.