Machine learning is employed to build an energy density functional for self-bound nuclear systems for the first time. By learning the kinetic energy as a functional of the nucleon density alone, a robust and accurate orbital-free density functional for nuclei is established. Self-consistent calculations that bypass the Kohn-Sham equations provide the ground-state densities, total energies, and root-mean-square radii with a high accuracy in comparison with the Kohn-Sham solutions. No existing orbital-free density functional theory comes close to this performance for nuclei. Therefore, it provides a new promising way for future developments of nuclear energy density functionals for the whole nuclear chart.

Background: The nucleus ${}^{32}\mathrm{Mg}$ ($N=20$ and $Z=12$) plays a central role in the so-called “island of inversion,” where in the ground states $sd$-shell neutrons are promoted to the $fp$-shell orbitals across the shell gap, resulting in the disappearance of the canonical neutron magic number $N=20$.

Purpose: The primary goals of this work are to extend the level scheme of ${}^{32}\mathrm{Mg}$, provide spin-parity assignments to excited states, and discuss the microscopic structure of each state through comparisons with theoretical calculations.

Method: In-beam $\gamma$-ray spectroscopy of ${}^{32}\mathrm{Mg}$ was performed using two direct-reaction probes: one-neutron (two-proton) knockout reactions on ${}^{33}\mathrm{Mg}$ (${}^{34}\mathrm{Si}$). Final-state exclusive cross sections and parallel momentum distributions were extracted from the experimental data and compared with eikonal-based reaction model calculations combined with shell-model overlap functions.

Results: Owing to the remarkable selectivity of the one-neutron and two-proton knockout reactions, a significantly updated level scheme for ${}^{32}\mathrm{Mg}$, which exhibits negative-parity intruder and positive-parity normal states, was constructed. The experimental results were confronted with four different nuclear structure models.

Conclusions: In some of these models, different aspects of ${}^{32}\mathrm{Mg}$ and the transition into the island of inversion are well described. However, unexplained discrepancies remain, and, even with the help of these state-of-the-art theoretical approaches, the structure of this key nucleus is not yet fully captured.

An energetic parton traveling through a quark-gluon plasma loses energy via occasional hard scatterings and frequent softer interactions. Whether or not these interactions admit a perturbative description, the effect of the soft interactions can be factorized and encoded in a small number of transport coefficients. In this work, we present the numerical implementation of a hard-soft factorized parton energy loss model which combines a stochastic description of soft interactions and rate-based modeling of hard scatterings. We introduce a scale to estimate the regime of validity of the stochastic description, allowing for a better understanding of the model's applicability at small and large coupling. We study the energy and fermion-number cascade of energetic partons as an application of the model.

We study correlations between harmonic flow vectors squared measured at different transverse momenta. One of the flow harmonics squared is taken at a fixed transverse momentum and correlated to the momentum-averaged harmonic flow squared of the same order. Such four-particle correlators, dependent on transverse momentum, have been recently measured experimentally. Factorization coefficients based on the ratio of such four-particle correlators allow the independent measurement of the flow vector and the flow magnitude factorization-breaking coefficient. Moreover, the correlation of the angles of flow harmonics as a function of transverse momentum can be extracted. Results are compared to preliminary data of the ALICE Collaboration. We also present predictions for the momentum-dependent factorization-breaking coefficient between mixed flow harmonics. The correlators with squares of mixed harmonics can serve as a way to independently measure the flow vector, the flow magnitude, and the flow angle correlations and could be used to gain additional information on the fluctuating initial state and the dynamics in heavy-ion collisions.

Neutron-rich ${}^{119}\mathrm{Pd}$ nuclei were produced in fission of natural uranium, induced by 25-MeV protons. Fission fragments swiftly extracted with the Ion Guide Isotope Separation On-Line method were mass separated using a dipole magnet and a Penning trap, providing mono-isotopic samples of ${}^{119}\mathrm{Pd}$. Their ${\beta }^{-}$ decay was measured with $\gamma \gamma$- and $\beta \gamma$-spectroscopy methods using low-energy germanium detectors and a thin plastic scintillator. Two distinct nuclear-level structures were observed in ${}^{119}\mathrm{Ag}$, based on the $1/2^{-}$ and $7/2^{+}$ isomers reported previously. The ${\beta }^{-}$-decay work was complemented by a prompt-$\gamma$ study of levels in ${}^{119}\mathrm{Ag}$ populated in spontaneous fission of ${}^{252}\mathrm{Cf}$, performed using the Gammasphere array of germanium detectors. Contrary to previous suggestions, our data show that the $1/2^{-}$ isomer is located below the $7/2^{+}$ isomer and is proposed as a new ground state of ${}^{119}\mathrm{Ag}$ with the $7/2^{+}$ isomer excitation energy determined to be 33.4 keV. Our data indicate that there are two $\beta$ unstable isomers in ${}^{119}\mathrm{Pd}$, a proposed ground state of ${}^{119}\mathrm{Pd}$ with tentative spin $1/2^{+}$ or $3/2^{+}$ and a half-life of 0.88 s and the other one about 350 keV above, having spin ($11/2^{-}$) and a half-life of 0.85 s. The higher-energy isomer probably decays to the $1/2^{+}$ or $3/2^{+}$ ground state via a $\gamma$ cascade comprising 18.7-219.8-$\mathrm{X}$-keV transitions. The unobserved isomeric transition with energy $X\approx 100$ keV probably has an $E3$ multipolarity. Its hindrance factor is significantly lower than for analogous $E3$ isomeric transitions in lighter Pd isotopes, suggesting an oblate deformation of levels in ${}^{119}\mathrm{Pd}$. Oblate configurations in ${}^{119}\mathrm{Ag}$ are discussed also.

Based on a holographic far-from-equilibrium calculation of the chiral magnetic effect (CME) in an expanding quark gluon plasma, we study collisions at various energies. We compute the time evolution of the CME current in the presence of a time-dependent axial charge density and subject to a time-dependent magnetic field. The plasma expansion leads to a dilution of the CME current. We study distinct combinations of how the initial magnetic field and initial axial charge behave with changing initial energy as proposed in previous literature. Most scenarios we consider lead to an increasing time-integrated CME current upon increasing the initial energy. This would make it more likely to observe the CME at higher collision energies.

We add an ensemble of nuclei to the equation of state for homogeneous nucleonic matter to generate a new set of models suitable for astrophysical simulations of core-collapse supernovae and neutron star mergers. We implement empirical constraints from (i) nuclear mass measurements, (ii) proton-proton scattering phase shifts, and (iii) neutron star observations. Our model is also guided by microscopic many-body theory calculations based on realistic nuclear forces, including the zero-temperature neutron matter equation of state from quantum Monte Carlo simulations and thermal contributions to the free energy from finite-temperature many-body perturbation theory. We ensure that the parameters of our model can be varied while preserving thermodynamic consistency and the connection to experimental or observational data, thus providing a probability distribution of the astrophysical hot and dense matter equation of state. We compare our results with those obtained from other available equations of state. While our probability distributions indeed represent a large number of possible equations of state, we cannot yet claim to have fully explored all of the uncertainties, especially with regard to the structure of nuclei in the hot and dense medium.

Nucleon removal reactions have been shown to be an effective tool for studying the single particle structure of nuclei. This work continues efforts to experimentally probe and benchmark the reaction and structure models used to calculate the removal reaction cross sections when using microscopic nuclear structure inputs. Three different single nucleon removal reactions were performed, from $p$-shell nuclei with masses $A=7$, 9, and 10. The residual nuclei from the reactions were detected in coincidence with $\gamma$ rays to determine partial cross sections to individual final states. The eikonal direct-reaction model is combined with overlap functions and residual nucleus densities from microscopic, variational Monte Carlo calculations to provide consistent nuclear structure input to the partial cross section calculations. Comparisons of measured and calculated cross sections, including for mirror reactions, are presented. The analysis of the partial cross sections leading to the ground states shows a similar behavior to the one observed from analyses of inclusive cross sections using shell model nuclear structure input: the theoretical description of the removal process is in better agreement with the data when removing weakly bound nucleons, than when removing well-bound ones. The two mirror reaction pairs presented here show consistent results between the respective members of the pairs. The results obtained for the population of the excited states, however, show a systematically different trend that appears connected to the structure part of the calculation. Additional cases are needed to better understand the respective roles of structure and dynamical effects in the deviations.

Motivated by the newly observed ${}^{39}\mathrm{Na}$ in experiments, systematic calculations of global nuclear binding energies with seven Skyrme forces are performed. We demonstrate the strong correlation between the two-neutron separation energies of ${}^{39}\mathrm{Na}$ and the total number of bound nuclei of the whole nuclear landscape. Furthermore, with calculated nuclear masses, we perform astrophysical rapid neutron capture process ($r$-process) simulations by using the nuclear reaction code talys and the nuclear reaction network code skynet. $r$-process abundances from ejecta of neutron star mergers (NSM) and core-collapse supernova are compared. Prominent covariance correlations between nuclear landscape boundaries and $r$-process abundances in the NSM scenario before the third peak are shown. We also see that statistical correlations disappear where shell effects dominated. This study highlights the need for further experimental studies of drip-line nuclei around ${}^{39}\mathrm{Na}$ for better constraints on nuclear landscape boundaries and the $r$-process in extremely neutron-rich environments.

Within the framework of the dinuclear system model, the reaction mechanisms for synthesizing target-like isotopes from Bk to compound nuclei Lv are thoroughly investigated in complete and incomplete fusion reactions of ${}^{48}\mathrm{Ca}$ $+{}^{248}\mathrm{Cm}$ near Coulomb barrier energies. The production cross section of ${}^{292,293}\mathrm{Lv}$ as a function of excitation energy in fusion-evaporation reactions and target-like isotopic yields in multinucleon transfer reactions are evaluated, and a statistical approach is used to describe the decay process of excited nuclei. The available experimental data can be reproduced reasonably well with the model. The products of all possible formed isotopes in the dynamical preequilibrium process for collision partners at incident energy $E_{\mathrm{lab}}=5.5$ MeV/nucleon are exported, systematically. It was found that the quasifission fragments are dominant in the yields. The optimal pathway from the target to compound nuclei shows up along the valley of potential surface energy. The effective impact parameter of two colliding partners leading to compound nuclei is selected from head-on collision to semicentral collision with $L=52\hslash$. The timescale boundary between complete fusion and multinucleon transfer reactions is about $5.7\times {10}^{-21}\mathrm{s}$ with effective impact parameters. The synthesis cross sections of unknown neutron-rich actinides from Bk to Rf have been predicted to be around several nanobarns.

The possible presence of deconfined matter in the cores of massive neutron stars is the subject of a large debate. In this context, it is important to set limits on the size and characteristics of a hypothetical quark core compatible with the present astrophysical constraints. To this aim, we present a Bayesian analysis of the properties of nonrotating hybrid stars at equilibrium with quark matter cores, as described by the SU(3) Nambu–Jona-Lasinio (NJL) model. The hadronic phase is described by a unified metamodeling approach, with a prior parameter space covering the present uncertainties on nuclear matter properties with nucleonic degrees of freedom. The parameter space of the NJL model includes vector-isoscalar and vector-isovector couplings and, additionally, an effective bag constant for the quark pressure is introduced as a free parameter. The phase transition is assumed to be first order with charge neutral phases, following the Maxwell construction. Our Bayesian framework includes filters on the experimental and theoretical low-density nuclear physics knowledge (atomic masses, ab initio calculations of the EoS) and high density constraints from astrophysical observations (maximum mass of J0348 $+$ 0432, binary tidal deformability of the GW170817 event). We find that microscopic vector interactions play an important role in quark matter in order to stiffen the equation of state sufficiently to reach high star masses, in agreement with previous studies. Even within a very large prior for both the hadronic phase and the quark phase and the important freedom brought by the effective bag constant, our posterior quark cores tend to be relatively small and only appear in very heavy stars ($M\gtrsim 2M_{\odot }$). Coincidentally, the inclusion of the nucleon-quark transition (deconfinement transition) only weakly affects the radii of compact stars, foreshadowing a very low observability of a possible phase transition using x-ray radii measurements.

It is common to study the strong decay of a heavy nucleus as a tunneling phenomenon where the $\alpha$ $\left({}^4\mathrm{He}\right)$ or a light nuclear cluster tunnels through the Coulomb barrier formed by its interaction with the heavier daughter nucleus. The position and width of the Coulomb barrier is determined by the total interaction potential between the two daughter nuclei. We examine the effects of including nonlocality and deformation in the interaction potential by calculating the half-lives, $t_{1/2}$, and thereby phenomenological preformation factors of several nuclei, which have the possibility of decaying by emitting either an $\alpha$ or a light nuclear cluster. The effect of deformation manifests itself by a decrease in $t_{1/2}$ for all the decays studied. The effect of nonlocality is studied within two different models of the nuclear potential: the energy independent but angular momentum $\left(l\right)$ dependent Mumbai (M) potential and the energy dependent Perey-Buck (PB) potential. The nonlocal nuclear interaction leads to a decrease in all half-lives studied. Though the decrease is larger due to the Perey-Buck potential, half-lives evaluated using the Mumbai potential show a strong sensitivity to the $l$ value in the decay. This feature of the $\alpha$ and cluster decay half-lives can provide a complementary tool in addition to scattering data which are more commonly used to fix the parameters of a nonlocal potential in literature.

For the first time, the calculation of the nuclear matrix element of the double-$\beta$ decay of ${}^{100}\mathrm{Mo}$, with and without the emission of two neutrinos, is performed in the framework of the nuclear shell model. This task is accomplished starting from a realistic nucleon-nucleon potential, then the effective shell-model Hamiltonian and decay operators are derived within the many-body perturbation theory. The exotic features which characterize the structure of Mo isotopes—such as shape coexistence and triaxiality softness—push the shell-model computational problem beyond its present limits, making it necessary to truncate the model space. This has been done with the goal to preserve as much as possible the role of the rejected degrees of freedom in an effective approach that has been introduced and tested in previous studies. This procedure is grounded on the analysis of the effective single-particle energies of a large-scale shell-model Hamiltonian, that leads to a truncation of the number of the orbitals belonging to the model space. Then, the original Hamiltonian generates a new one by way of a unitary transformation onto the reduced model space, to retain effectively the role of the excluded single-particle orbitals. The predictivity of our calculation of the nuclear matrix element for the neutrinoless double-$\beta$ decay of ${}^{100}\mathrm{Mo}$ is supported by comparison with experiments of the calculated spectra, electromagnetic transition strengths, Gamow-Teller transition strengths, and the two-neutrino double-$\beta$ nuclear matrix elements.

We perform coupled-cluster calculations of ground- and dipole excited-state properties of the ${}^8\mathrm{He}$ halo nucleus with nucleon-nucleon and three-nucleon interactions from chiral effective field theory, both with and without explicit delta degrees of freedom. By increasing the precision in our coupled-cluster calculations via the inclusion of leading-order three-particle three-hole excitations in the cluster operator, we obtain a ground-state energy and a charge radius that are consistent with experiment, albeit with a slight underbinding. We also investigate the excited states induced by the electric dipole operator and present a discussion on the Thomas-Reiche-Kuhn and cluster sum rules. Finally, we compute the electric dipole polarizability, providing a theoretical benchmark for future experimental determinations that will study this exotic nucleus.

We report measured cross-section data of the residues produced in the ${}^{13}\mathrm{C}$-induced reaction on ${}^{93}\mathrm{Nb}$ within the 63.7–87.1-MeV energy range. The off-line $\gamma$-ray spectroscopy method has been used to measure the cross sections of the radionuclides produced in this system. The analysis of present measured cross-section data has been carried out within the light of well-established statistical model code pace4. The excitation function of residues populated via $xn$ and/or $pxn$ channels are found to be in fair agreement with those estimated by the theoretical model code, which confirms the assembly of these residues via complete fusion process. A considerable enhancement in the measured cross-section data has been observed for the residues involving $\alpha$-emitting channels as compared to the theoretical predictions. The observed enhancement in the cross sections has been assigned to the incomplete fusion processes. Furthermore, in order to have a better insight into the onset and strength of incomplete fusion, termed as the incomplete fusion fraction has been deduced for the present paper and is compared with ${}^{16}\mathrm{O}$ and ${}^{18}\mathrm{O}$ beams on the same target ${}^{93}\mathrm{Nb}$. This suggests that the incomplete fusion fraction is strongly influenced by the entrance channel, which may be understood in terms of the projectile $Q_{\alpha }$ value. The comparison of this paper with literature data also shows that the incomplete fusion probability increases with various entrance channel parameters, such as projectile structure, projectile energy, and mass asymmetry of interacting partners.

The hyperfine coupling constants of the proton dripline odd-odd ${}^{40}\mathrm{Sc}$ nucleus were deduced from the hyperfine spectrum of the $3d4s{}^3{\text{D}}_2\leftrightarrow 3d4p{}^3{\text{F}}_3^{\circ }$ transition in Sc II, measured by the bunched beam collinear laser spectroscopy technique. The ground-state magnetic-dipole and electric-quadrupole moments were determined as $\mu =+5.57\left(4\right)\left(2\right){\mu }_N$ and $Q=+42\left(38\right)\left(28\right)e^2{\mathrm{fm}}^2$, respectively. The magnetic moment is well reproduced by the additivity rule with magnetic moments of neighboring odd-even nuclei in the vicinity of the doubly magic ${}^{40}\mathrm{Ca}$ nucleus. An ab initio multishell valence-space Hamiltonian was also employed to calculate the magnetic moment of ${}^{40}\mathrm{Sc}$, which spans across the $sd$ and $fp$ nuclear shells, where we obtained good agreements.

The synthesis of superheavy elements based on fusion reactions and multinucleon transfer reactions is sensitive to the reaction energies, where the Coulomb barrier plays a crucial role as it must be overcome for the projectile and target to contact each other. The Coulomb barrier cannot be measured directly, and the synthesis of superheavy elements is sensitive to it. In this study, we systematically extract the barrier information from the experimental fusion excitation functions by the empirical cross section formula, which is based on a single-Gaussian distribution of fusion barrier heights. A total of 403 sets of experimental data are fitted, among which 243 sets have good results with ${\chi }^2/pt$ less than one. The extracted fusion barrier is a dynamical barrier, which includes the overall effect of coupled channels. Different from the prediction of the WKJ formula, the new scaling law proposed in this work is almost identical to the CW76 Coulomb barrier at the $z=170–300$ region and reproduces well the centroid barrier extracted from quasielastic scattering. The comparison to the other 14 bare potential models and exploration of the very large $z$ region is also discussed. It is also remarkable to find that the predictions of the DP2015 potential, including of the contributions of the macroscopic and shell correction terms, are highly consistent with the extracted results in this work and the CW76 potential. The numerical results demonstrated that the dynamical fusion barrier and the centroid barrier extracted from the quasielastic reaction (the reaction threshold) could be the same physical quantity for superheavy reactions. This study could provide important references for the synthesis of superheavy nuclei based on fusion reactions and very heavy multinucleon transfer reactions.

Collective enhancement in nuclear level density (CELD) and its fadeout has been studied experimentally using neutron and high energy $\gamma$-ray spectra earlier. Attempts to probe CELD with $\alpha$-particle spectra were made for compound nucleus (CN) ${}^{178}\mathrm{Hf}$ in the excitation energy $54–124$ MeV, but no signature of CELD was found. The possible reason behind this nonobservance has been discussed in a few subsequent reports. In our previous study, evidence of CELD was found using neutron spectra and enhancement faded away near 25 MeV of excitation energy. This implies that the effect of CELD on $\alpha$ particles, if any, would be found at excitation lower than 25 MeV. With the aim to observe CELD and its fadeout with $\alpha$-particle spectra, two reactions ${}^{12}\mathrm{C}+{}^{116}\mathrm{Sn},{}^{159}\mathrm{Tb}$, forming CN in different mass region ($A\approx 128$ and $A\approx 171$) were studied. Evaporation $\alpha$-particle spectra were measured for these reactions in singles as well as in coincidence with neutrons. Experimental data were compared with statistical model calculations and inverse level density parameter ($k$) were obtained from $\alpha$-particle spectra. As a function of CN excitation energy, the $k$ value showed peak like structure for the reaction ${}^{12}\mathrm{C}+{}^{159}\mathrm{Tb}$ which indicates fadeout of CELD. No such evidence was found for the reaction ${}^{12}\mathrm{C}+{}^{116}\mathrm{Sn}$. Collective enhancement factor for daughter nuclei populated in ${}^{12}\mathrm{C}+{}^{159}\mathrm{Tb}$ reaction was extracted. Critical energy of the fadeout was found to be similar to that of mass $A\approx 188$ region.

The stable gallium isotopes, ${}^{69,71}\mathrm{Ga}$, are mostly produced by the weak slow ($s$) process in massive stars. We report here on measurements of astrophysically relevant neutron capture cross sections of the ${}^{69,71}\mathrm{Ga}(n,\gamma )$ reactions. The experiments were performed by the activation technique using a high-intensity ($3–5\times {10}^{10}$ n/s), quasi-Maxwellian neutron beam that closely mimics conditions of stellar $s$-process nucleosynthesis at $kT\approx$ 40 keV. The neutron field was produced by a mA proton beam at $E_p=1925$ keV (beam power of 2–3 kW) from the Soreq Applied Research Accelerator Facility (SARAF), bombarding the liquid-lithium target (LiLiT). A 473-mg sample of ${\mathrm{Ga}}_2{\mathrm{O}}_3$ of natural isotopic composition was activated in the LiLiT neutron field and the activities of ${}^{70,72}\mathrm{Ga}$ were measured by decay counting via $\gamma$ spectrometry with a high-purity germanium detector. The Maxwellian-averaged cross sections at $kT=30\mathrm{keV}$ of ${}^{69}\mathrm{Ga}$ and ${}^{71}\mathrm{Ga}$ determined in this work are 136(8) and 105(7) mb, respectively, in good agreement with previous experimental values. Astrophysical implications of the measurements are discussed.