The YGLO (Yang-Grasso-Lacroix-Orsay) functional is applied for the first time to investigate ground-state properties of different isotopic chains, from oxygen to lead. Mean-field Hartree-Fock calculations are carried out to analyze global trends for separation energies, binding energies, radii, neutron skins, and density profiles. We have three objectives: (i) we study whether this functional leads to a reasonable description of ground-state properties (despite the fact that it was not adjusted on nuclei) and we discuss the associated limitations; (ii) we investigate whether the correct description of the low-density nuclear gas, which is the peculiarity of this functional, has any relevant impact on predictions for nuclei; (iii) we connect nuclear energies, radii, and density profiles with properties of the corresponding equations of state of infinite matter. In particular, we identify a link existing between the isoscalar effective mass and spatial properties in neutron-deficient nuclei, namely proton radii and tails of proton densities. On the other side, we show that the slope of the symmetry energy is connected with spatial properties in neutron-rich nuclei: the slope computed at saturation density is related to neutron skin thicknesses, as is already well known, whereas the slope calculated at lower densities is linked to the tails of neutron densities. The YGLO effective mass turns out to be quite low. Directions to improve this aspect are explored and suggested at the end of the paper.

The structure of ${}^{33}\mathrm{Mg}$ was investigated by means of two knockout reactions, one-neutron removal from ${}^{34}\mathrm{Mg}$ and one-proton removal from ${}^{34}\mathrm{Al}$. Using comparative analysis of the population of observed excited states in the residual ${}^{33}\mathrm{Mg}$, the nature of these states can be deciphered. In addition, the long-standing controversy about the parity of the ${}^{33}\mathrm{Mg}$ ground state is resolved using momentum distribution analysis, showing a clear signature for negative parity. Partial cross section measurements are compared with the results of eikonal reaction theory combined with large-scale shell model calculations of this complex nucleus located in the island of inversion, where configuration mixing plays a major role.

We report the first direct determination of the ground-state to ground-state electron-capture $Q$ value for the ${}^{72}\mathrm{As}$ to ${}^{72}\mathrm{Ge}$ decay by measuring their atomic mass difference utilizing the double Penning trap mass spectrometer, JYFLTRAP. The $Q$ value was measured to be 4343.596(75) keV, which is more than a fiftyfold improvement in precision compared to the value in the most recent Atomic Mass Evaluation 2020. Furthermore, the new $Q$ value was found to be 12.4(40) keV (3.1 $\sigma$) lower. With the significant reduction of the uncertainty of the ground-state to ground-state $Q$ value combined with the level scheme of ${}^{72}\mathrm{Ge}$ from $\gamma$-ray spectroscopy, we confirm that the five potential ultralow $Q$-value ${\beta }^{+}$ decay or electron capture transitions are energetically forbidden, thus precluding all the transitions as possible candidates for the electron neutrino mass determination. However, the discovery of small negative $Q$ values opens up the possibility to use ${}^{72}\mathrm{As}$ for the study of virtual $\beta \text{−}\gamma$ transitions.

The $\beta$-delayed two-proton ($\beta 2p$) decay of ${}^{27}\mathrm{S}$ was studied using a state-of-the-art silicon array and Clover-type HPGe detectors. An energy peak at 6372(15) keV with a branching ratio of 2.4(5)% in the decay-energy spectrum was identified as a two-proton transition via the isobaric-analog state in ${}^{27}\mathrm{P}$ to the ground state of ${}^{25}\mathrm{Al}$ in the $\beta$ decay of ${}^{27}\mathrm{S}$. Two-proton angular correlations were measured by the silicon array to study the mechanism of two-proton emission. Based on experimental results and Monte Carlo simulations, it was found that the main mechanism for the emission of $\beta 2p$ by ${}^{27}\mathrm{S}$ is of sequential nature.

The potential-energy surfaces (PESs) for ground states of even-even ${}^{102–112}\mathrm{Cd}$ isotopes are obtained by using the three-dimensional relativistic Hartree-Bogoliubov model with the density-dependent meson exchange interaction. The quadrupole deformation parameters are extracted from the PES calculations and employed in the beyond mean-field projected shell model to study the yrast and excited states of these isotopes. Besides, the $E2$ transition probabilities and $g$ factors are obtained and compared with the experimental data. The present calculations support the experimental finding that yrast $8^{+}$ states of light Cd isotopes are of ${\left(\pi g_{9/2}\right)}^2$ character whereas the yrast ${10}^{+}$ states of medium-mass Cd isotopes are found to possess ${\left(\nu h_{11/2}\right)}^2$ character.

A low-energy magnetic dipole $\left(M1\right)$ spin-scissors resonance (SSR) located just below the ordinary orbital scissors resonance (OSR) was recently predicted in deformed nuclei within the Wigner function moments (WFM) approach. We analyze this prediction using fully self-consistent Skyrme quasiparticle random phase approximation (QRPA) method. Skyrme forces SkM*, SVbas, and SG2 are implemented to explore SSR and OSR in ${}^{160,162,164}\mathrm{Dy}$ and ${}^{232}\mathrm{Th}$. Accuracy of the method is justified by a good description of $M1$ spin-flip giant resonance. The calculations show that isotopes ${}^{160,162,164}\mathrm{Dy}$ indeed have at 1.5–2.4 MeV (below OSR) $I^{\pi }K=1^{+}1$ states with a large $M1$ spin strength ($K$ is the projection of the total nuclear moment to the symmetry $z$ axis). These states are almost fully exhausted by $pp[411\uparrow ,411\downarrow ]$ and $nn[521\uparrow ,521\downarrow ]$ spin-flip configurations corresponding to $pp[2d_{3/2},2d_{5/2}]$ and $nn[2f_{5/2},2f_{7/2}]$ structures in the spherical limit. So the predicted SSR is actually reduced to low-orbital ($l=2,3$) spin-flip states. Following our analysis and in contradiction with WFM spin-scissors picture, deformation is not the principle origin of the low-energy spin $M1$ states but only a factor affecting their features. The spin and orbital strengths are generally mixed and exhibit interference: weakly destructive in SSR range and strongly constructive in OSR range. In ${}^{232}\mathrm{Th}$, the $M1$ spin strength is very small. Two groups of $I^{\pi }=1^{+}$ states observed experimentally at 2.4–4 MeV in ${}^{160,162,164}\mathrm{Dy}$ and at 2–4 MeV in ${}^{232}\mathrm{Th}$ are mainly explained by fragmentation of the orbital strength. Distributions of nuclear currents in QRPA states partly correspond to the isovector orbital-scissors flow but not to the spin-scissors one.

It has been recently shown that some Gogny finite-range interactions suffer from finite-size instabilities in coordinate-space calculations [Eur. Phys. J. A 55, 150 (2019)]. We confirm this finding by using the Hartree-Fock (HF) method in the quasilocal approximation to finite-range forces. The use of the quasilocal approximation substantially simplifies the calculations as compared with those including the exact exchange contribution to the energy and HF fields. The quantity most affected by the finite-size instabilities in the coordinate-space calculations is the spatial density at the origin that wildly oscillates as the HF iterative process proceeds. In addition to the recent ${\mathrm{D1M}}^{*}$ parametrization of the Gogny force, we find that the D1M parametrization also shows this deficiency in several nuclei. We find that the harmonic-oscillator basis with its ultraviolet cutoff provides converged results in a wide and realistic range of basis sizes. This result serves as a justification of the numerous calculations with D1M and ${\mathrm{D1M}}^{*}$ in finite nuclei that show no trace of instability.

The role of the tensor part of the nuclear interaction is actively investigated in recent years due to experimental advancement yielding new data in nuclei far from the $\beta$-stability line. In this article we study the effect of this part of the nuclear interaction on deformed neutron magic numbers in the rare-earth region within the Skyrme energy-density functional for various TIJ [T. Lesinski, M. Bender, K. Bennaceur, T. Duguet, and J. Meyer, Phys. Rev. C 76, 014312 (2007)] parametrizations. Two quantities signaling magic numbers are considered: two-neutron separation energies and single-particle energies. They are calculated in isotopic series involving well-deformed rare-earth nuclei ranging from $Z=64$ to $Z=72$ in the $N=100$ region. Obtained results show that, whereas the neutron-proton tensor contribution to binding energies is important to reproduce neutron subshell closure at $N=104$ in heavier rare earths $\mathrm{Yb}(Z=70)$ and $\mathrm{Hf}(Z=72)$ isotopes, like-particle tensor also plays a role in the single-particle spectrum around Fermi level and is even favored in lighter $\mathrm{Gd}(Z=64)$ and $\mathrm{Dy}(Z=66)$ rare-earth isotopes.

$\gamma$-ray emission from ${}^{12}\mathrm{C}$ and ${}^{13}\mathrm{C}$ samples irradiated with deuterium-tritium fusion neutrons was experimentally measured at the Omega Laser Facility and at the Ohio University Edwards Accelerator Laboratory. The intent of these measurements was to determine the feasibility of using ${}^{13}\mathrm{C}$-based plastic ablators with embedded ${}^{12}\mathrm{C}$ layers for “dark mix” diagnosis of inertial confinement fusion implosions. Spectrally resolved measurements at Ohio University identified significant 4.44-MeV $\gamma$-ray emission from the ${}^{13}\mathrm{C}(n,2n\gamma ){}^{12}\mathrm{C}$-L1 reaction channel. The recorded 4.44-MeV ${}^{13}\mathrm{C}$ signal was compared against emission from an identically irradiated ${}^{12}\mathrm{C}$ target with known ${}^{12}\mathrm{C}$($n,n^{\prime }\gamma ){}^{12}\mathrm{C}$-L1 cross section, which resulted in an average ${}^{13}\mathrm{C}(n,2n\gamma ){}^{12}\mathrm{C}$-L1 cross section of 117 $\pm$ 17 mb over the incident neutron energy distribution range from 14.4 to 15.8 MeV. Integrated ${}^{13}\mathrm{C}$ $\gamma$-ray signals above 2.9 MeV recorded with the Gas Cherenkov Detector at Omega exceeded MCNP6.1 predictions by a factor of 3. The additional signal was attributed to 4.44-MeV $\gamma \mathrm{s}$ resulting in an inferred ${}^{13}\mathrm{C}(n,2n\gamma ){}^{12}\mathrm{C}$-L1 cross section of $95\pm 11$ mb at 14.1-MeV average incident neutron energy. As a result, the ${}^{13}\mathrm{C}$-based “dark mix” diagnostic concept was deemed infeasible.

In this followup article to Ducru et al. [Phys. Rev. C 103, 064608 (2021)], we establish new results on scattering matrix pole expansions for complex wave numbers in $R$-matrix theory. In the past, two branches of theoretical formalisms emerged to describe the scattering matrix in nuclear physics: $R$-matrix theory and pole expansions. The two have been quite isolated from one another. Recently, our study of Brune's alternative parametrization of $R$-matrix theory has shown the need to extend the scattering matrix (and the underlying $R$-matrix operators) to complex wave numbers. Two competing ways of doing so have emerged from a historical ambiguity in the definitions of the shift $\mathit{S}$ and penetration $\mathit{P}$ functions: the legacy Lane and Thomas's “force closure” approach versus analytic continuation (which is the standard in mathematical physics). The $R$-matrix community has not yet come to a consensus as to which to adopt for evaluations in standard nuclear data libraries, such as ENDF. In this article, we argue in favor of analytic continuation of $R$-matrix operators. We bridge $R$-matrix theory with the Humblet-Rosenfeld pole expansions, and discover new properties of the Siegert-Humblet radioactive poles and widths, including their invariance properties to changes in channel radii $a_c$. We then show that analytic continuation of $R$-matrix operators preserves important physical and mathematical properties of the scattering matrix—canceling spurious poles and guaranteeing generalized unitarity—while still being able to close channels below thresholds.

Nuclear cross sections are basic inputs to any nuclear computation. Campaigns of experiments are fitted with the parametric $R$-matrix model of quantum nuclear interactions, and the resulting cross sections are documented—both pointwise and as resonance parameters (with uncertainties)—in standard evaluated nuclear data libraries (ENDF, JEFF, BROND, JENDL, CENDL, TENDL): these constitute our common knowledge of fundamental low-energy nuclear cross sections. In the past decade, a collaborative effort has been deployed to establish a new nuclear cross-section library format—the Windowed Multipole Library—with the goal of considerably reducing the computational cost of cross-section calculations in nuclear transport simulations. This paper lays the theoretical foundations underpinning these efforts. From general $R$-matrix scattering theory, we derive the windowed multipole representation of nuclear cross sections. Though physically and mathematically equivalent to $R$-matrix cross sections, the windowed multipole representation is particularly well suited for subsequent temperature treatment of angle-integrated cross sections, in particular Doppler broadening, which is the averaging of cross sections over the thermal motion of the target atoms. Doppler broadening is of critical importance in neutron transport applications, as it ensures the stability of many nuclear reactors (negative thermal reactivity). Yet, Doppler broadening of nuclear cross sections has been a considerable bottleneck for nuclear transport computations, often requiring memory-costly pretabulations. We show that the windowed multipole representation can perform accurate Doppler broadening analytically (up to the first reaction threshold), from which we derive cross-section temperature derivatives to any order—all computable on the fly (without precalculations stored in memory). Furthermore, we here establish a way of converting the $R$-matrix resonance parameters uncertainty (covariance matrices) into windowed multipole parameters uncertainty. We show that generating stochastic nuclear cross sections by sampling from the resulting windowed multipole covariance matrix can reproduce the cross-section uncertainty in the original nuclear data file. The windowed multipole representation is therefore a novel nuclear physics formalism able to generate Doppler broadened stochastic nuclear cross sections on the fly, unlocking breakthrough computational gains for nuclear computations. Through this foundational paper, we hope to make the windowed multipole representation accessible, reproducible, and usable for the nuclear physics community, as well as provide the theoretical basis for future research on expanding its capabilities.

High statistics data sets from experiments at the Relativistic Heavy Ion Collider (RHIC) and the Large Hadron Collider (LHC) with small and large collision species have enabled a wealth of new flow measurements, including the event-by-event correlation between observables. One exciting such observable $\rho (v_n^2,\left[p_T\right])$ gauges the correlation between the mean transverse momentum of particles in an event and the various flow coefficients ($v_n$) in the same event [P. Bożek, Phys. Rev. C 93, 044908 (2016)]. Recently it has been proposed that very low multiplicity events may be sensitive to initial-state glasma correlations [G. Giacalone, B. Schenke, and C. Shen, Phys. Rev. Lett. 125, 192301 (2020)] rather than flow-related dynamics. We find utilizing the ip-jazma framework that the color domain explanation for the glasma results are incomplete. We then explore predictions from pythia8, and the version for including nuclear collisions called pythia-angantyr, which have only nonflow correlations, and from the ampt model which has both nonflow and flow-type correlations. We find that pythia-angantyr has nonflow contributions to $\rho (v_n^2,\left[p_T\right])$ in $p+\mathrm{O}$, $p+\mathrm{Pb}$, and $\mathrm{O}+\mathrm{O}$ collisions that are positive at low multiplicity and comparable to the glasma correlations. It is striking that in pythia8 in $p+p$ collisions there is actually a sign change from positive to negative $\rho (v_n^2,\left[p_T\right])$ as a function of multiplicity. The ampt results match the experimental data general trends in Pb+Pb collisions at the LHC, except at low multiplicity where ampt has the opposite sign. In $p+\mathrm{Pb}$ collisions, ampt has the opposite sign from experimental data and we explore this within the context of parton geometry. Predictions for $p+\mathrm{O}$, $\mathrm{O}+\mathrm{O}$, and $\mathrm{Xe}+\mathrm{Xe}$ are also presented.

The observation of secondary $\gamma$-rays provides an alternative method of measuring cross sections that populate excited final states in nuclear reactions. The angular distributions of these $\gamma$-rays also provide information on the underlying reaction mechanism. Despite the large number of data of this type in the literature, publicly available $R$-matrix codes do not have the ability to calculate these types of angular distributions. In this paper, the mathematical formalism derived by C. R. Brune and R. J. deBoer [Phys. Rev. C 102, 024628 (2020)] is implemented in the $R$-matrix code azure2 and calculations are compared with previous data from the literature for the ${}^{15}\mathrm{N}(p,{\alpha }_1\gamma ){}^{12}\mathrm{C}^{*}$ reaction. In addition, new measurements, made at the University of Notre Dame Nuclear Science Laboratory using the Hybrid Array of Gamma Ray Detectors (HAGRiD), are reported that span the energy range from $E_p=0.88$ MeV to $E_p=4.0\mathrm{MeV}$. Excellent agreement between the data and the phenomenological fit is obtained up to the limit of the previous fit at $E_p=2.0\mathrm{MeV}$ and the $R$-matrix fit is extended from $E_x\approx 13.5$ MeV up to $E_x\approx 15.3$ MeV, where ${}^{15}\mathrm{N}+p$ and ${}^{12}\mathrm{C}+\alpha$ reactions are fit simultaneously for the first time. An excellent reproduction of the ${}^{15}\mathrm{N}(p,{\alpha }_1\gamma ){}^{12}\mathrm{C}^{*}$ and ${}^{12}\mathrm{C}(\alpha ,\alpha ){}^{12}\mathrm{C}$ data is achieved, but inconsistencies and difficulty in fitting other data are encountered and discussed.

We study the superfluid dynamics of the outer core of neutron stars by means of a generalized hydrodynamic model made of a neutronic superfluid and a protonic superconductor, coupled by both the dynamic entrainment and the Skyrme SLy4 nucleon-nucleon interactions. The resulting nonlinear equations of motion are probed in the search for dynamical instabilities triggered by the relative motion of the superfluids that could be of potential relevance to observational features of neutron stars. Through linear analysis, the origin and expected growth of the instabilities is explored for varying nuclear-matter density. Differently from previous findings, the dispersion of linear excitations in our model shows rotonic structures below the pair-breaking energy threshold, which lies at the origin of the dynamical instabilities and could eventually lead to emergent vorticity along with modulations of the superfluid density.

Four-boson Efimov physics is well known in the negative energy regime but far less above the four-body breakup threshold. The part of this region with negative two-boson scattering length is studied solving rigorous four-particle scattering equations for transition operators in the momentum space. Moving away from the unitary limit, the Efimov tetramers evolve from unstable bound states into resonances. Their energies and widths are studied as functions of the two-boson scattering length; a universal behavior is established and given in a dimensionless representation. The Efimov tetramers have finite width in the whole regime; they broaden rapidly in the resonance regime but remain narrower than the associated trimer. The resonant behavior is most clearly seen in the four-particle recombination rate.

Background: Low-energy dipole states have been popular topics in studies of stable and unstable nuclei. In ${}^{24}\mathrm{Mg}$, two low-energy dipole modes, the toroidal and compressional states have been theoretically proposed recently. The former state has been associated with cluster structure, but there is no explicit analysis of the cluster structure.

Purpose: Our purpose is to investigate low-lying $1^{-}$ states in ${}^{24}\mathrm{Mg}$ and clarify their properties such as the dipole transition strengths, nuclear vorticity, and cluster features.

Method: Wave functions of $1^{-}$ states of ${}^{24}\mathrm{Mg}$ are described within the antisymmetrized molecular dynamics framework combined with the generator coordinate method. Excitation energies and dipole transition strengths are calculated. Cluster wave functions are explicitly taken into account to reveal the role of cluster correlations in $1^{-}$ states. Intrinsic matter density and transition current density are analyzed.

Results: Two low-lying dipole states, the $1_{K=1}^{-}$ and $1_{K=0}^{-}$, are obtained. The $1_{K=1}^{-}$ state has the strongest isoscalar toroidal dipole strength and shows two-vortex structure in the intrinsic transition current density. The $1_{K=0}^{-}$ state features the isoscalar compressional dipole strength and exhibits the ${}^{16}\mathrm{O}+{}^8\mathrm{Be}$ cluster correlation.

Conclusions: The toroidal and compressional dipole modes separately appear as $K=1$ and $K=0$ states in the deformed ${}^{24}\mathrm{Mg}$ system. The $1_{K=1}^{-}$ state is the toroidal dipole state with the strong nuclear vorticity but no prominent cluster structure, and the $1_{K=0}^{-}$ state is the compressional dipole state having enhanced cluster structure but weaker vorticity.

Equation of state and electric (isospin) charge fluctuations are studied for matter composed of interacting pions. The pion matter is described by self interacting scalar fields via a ${\varphi }^4\text{−}{\varphi }^6$-type Lagrangian. The mean-field approximation is used, and interaction parameters are fixed by fitting lattice QCD results on the isospin density as a function of the isospin chemical potential at zero temperature. Two scenarios for fixing the model parameters—with and without the first-order phase transition—are considered, both yielding a satisfactory description of the lattice data. Thermodynamic functions and isospin charge fluctuations are studied and systematically compared for these two scenarios, yielding qualitative differences in the behavior of isospin charge susceptibilities. These differences can be probed by lattice simulations at temperatures $T\lesssim 100$ MeV.

Nuclear state densities are important inputs to statistical models of compound-nucleus reactions. State densities are often calculated with self-consistent mean-field approximations that do not include important correlations and must be augmented with empirical collective enhancement factors. Here, we benchmark the static-path plus random-phase approximation (SPA + RPA) to the state density in a chain of samarium isotopes ${}^{148\text{–}155}\mathrm{Sm}$ against exact results (up to statistical errors) obtained with the shell-model Monte Carlo (SMMC) method. The SPA + RPA method incorporates all static fluctuations beyond the mean field together with small-amplitude quantal fluctuations around each static fluctuation. Using a pairing plus quadrupole interaction, we show that the SPA + RPA state densities agree well with the exact SMMC densities for both the even- and odd-mass isotopes. For the even-mass isotopes, we also compare our results with mean-field state densities calculated with the finite-temperature Hartree-Fock-Bogoliubov (HFB) approximation. We find that the SPA + RPA repairs the deficiencies of the mean-field approximation associated with broken rotational symmetry in deformed nuclei and with the violation of particle-number conservation in the pairing condensate. In particular, in deformed nuclei the SPA + RPA reproduces the rotational enhancement of the state density relative to the mean-field state density.

Experimental near-barrier fusion cross sections for ${}^{17}\mathrm{F}+{}^{12}\mathrm{C}$ are compared to the fusion excitation functions for ${}^{16,17,18}\mathrm{O}, {}^{19}\mathrm{F}$, and ${}^{20}\mathrm{Ne}$ ions on a carbon target. Normalized or reduced fusion cross sections are utilized in order to compare the different systems and account for the differing static size of the incident ions as well as changes in fusion barrier. Fusion excitation functions for the case of the mirror nuclei ${}^{17}\mathrm{F}$ and ${}^{17}\mathrm{O}$ with a single $\mathit{sd}$ nucleon are compared. The ${}^{17}\mathrm{F}$ data are also juxtaposed with nuclei involving multiple $\mathit{sd}$ nucleons. Trends of the fusion cross section above the barrier beyond the expected systematic behavior are observed. These trends are interpreted as the interplay of the $\mathit{sd}$ protons and neutrons. The experimental data are also compared to a widely used analytic model of near-barrier fusion, a time-dependent Hartree-Fock model, and coupled channels calculations.