A novel description of charge-exchange reactions at intermediate energies is developed, based on both phenomenological or microscopic eikonal phase-shift functions. The results obtained within this eikonal approach are in good agreement with the distorted-wave Born approximation calculations within the energy region where both approximations should be valid. They also compare well with the experimental data, even at relatively low energy domain. At higher energies, relativistic kinematics have also been added and shown to be relevant. Owing to the microscopic feature of the formulation, our theory also has the advantage that it can be applied to high energies where the phenomenological optical potentials are rarely available.

The heaviest observed antinucleus to date is $\overline{{}^4\mathrm{He}}$ which was detected at the STAR experiment at the Relativistic Heavy Ion Collider. From previous scattering experiments, we know that the ${}^4\mathrm{Li}$ has a very short lifetime, about $1.197\times {10}^{-22}\text{s}$, and can decay into proton and ${}^3\mathrm{H}\mathrm{e}$. In experiments, the correlation function of $\overline{\mathrm{p}}\text{−}\overline{{}^3\mathrm{He}}$ provides us a method to observe $\overline{{}^4\mathrm{Li}}$. In this paper we use the blast-wave model and the Lednický-Lyuboshitz analytical model to obtain a prediction of the correlation function of $\overline{\mathrm{p}}\text{−}\overline{{}^3\mathrm{He}}$ with and without $\overline{{}^4\mathrm{Li}}$ decay in Au $+$ Au collisions at $\sqrt{S_{NN}}$ = 200 GeV. The magnitude of event number needed to detect $\overline{{}^4\mathrm{Li}}$ experimentally is estimated from the error of the correlation function. The correlation function with $\overline{{}^4\mathrm{Li}}$ decay is found to exhibit a peak at $k^{*}\approx$ 0.073 GeV/c. The results offer a reference for the experimental search for $\overline{{}^4\mathrm{Li}}$ in relativistic heavy-ion collisions.

In this paper, we continue our phenomenological studies of heavy-ion collisions using $3+1\mathrm{D}$ anisotropic hydrodynamics (aHydro). In previous works, we compared quasiparticle aHydro (aHydroQP) with ALICE 2.76 TeV Pb-Pb and BNL Relativistic Heavy Ion Collider 200 GeV Au-Au collision results. At both energies, the agreement was quite good between aHydroQP and the experimental data for many observables. In this work, we present comparisons of the Hanbury Brown–Twiss (HBT) radii and their ratios determined using ${\pi }^{+}{\pi }^{+}$ pairs produced in 200 GeV Au-Au collisions. We first present comparisons with STAR results for the HBT radii and their ratios. We then present comparisons with PHENIX results for the HBT radii and their ratios. In both cases, we find reasonable agreement between aHydroQP predictions and available experimental results for the ratios of HBT radii. At the level of the radii themselves, in some cases quantitative differences on the order of 10–20% remain, which deserve further study.

We analyze the spinodal instabilities of spin-polarized asymmetric nuclear matter at zero temperature for several configurations of the neutron and proton spins. The calculations are performed with the Brueckner-Hartree-Fock (BHF) approach using the Argonne V18 nucleon-nucleon potential plus a three-nucleon force of Urbana type. An analytical parametrization of the energy density, which reproduces with good accuracy the BHF results, is employed to determine the spinodal instability region. We find that, independently of the of the orientation of the neutron and proton spins, the spinodal instability region shrinks when the system is polarized, its size being smaller when neutron and proton spins are antiparallel than when they are oriented in a parallel way. We find also that the spinodal instability is always dominated by total density fluctuation independently of the degree of polarization of the system, and that restoration of the isospin symmetry in the liquid phase, i.e., the so-called isospin distillation or fragmentation effect, becomes less efficient with the polarization of the system.

A systematic investigation of the ground-state and fission properties of even-even actinides and superheavy nuclei with $Z=90–120$ from the two-proton up to two-neutron drip lines with proper assessment of systematic theoretical uncertainties has been performed for the first time in the framework of covariant density functional theory (CDFT). These results provide a necessary theoretical input for the $r$-process modeling in heavy nuclei and, in particular, for the study of fission cycling. Four state-of-the-art globally tested covariant energy density functionals (CEDFs), namely, DD-PC1, DD-ME2, NL3*, and PC-PK1, representing the major classes of the CDFT models are employed in the present paper. Ground-state deformations, binding energies, two-neutron separation energies, $\alpha$-decay $Q_{\alpha }$ values and half-lives, and the heights of fission barriers have been calculated for all these nuclei. Theoretical uncertainties in these physical observables and their evolution as a function of proton and neutron numbers have been quantified and their major sources have been identified. Spherical shell closures at $Z=120, N=184$, and $N=258$ and the structure of the single-particle (especially, high-$j$) states in their vicinities as well as nuclear matter properties of employed CEDFs are two major factors contributing to theoretical uncertainties. However, different physical observables are affected in a different way by these two factors. For example, theoretical uncertainties in calculated ground-state deformations are affected mostly by the former factor, while theoretical uncertainties in fission barriers depend on both of these factors.

Collinear laser spectroscopy measurements were performed on ${}^{69,71,73}\mathrm{Ge}$ isotopes ($Z=32$) at ISOLDE-CERN. The hyperfine structure of the $4s^{2}4p^2{}^{3}P_1\to 4s^{2}4p5s{}^{3}P_1^o$ transition of the germanium atom was probed with laser light of 269 nm, produced by combining the frequency-mixing and frequency-doubling techniques. The hyperfine fields for both atomic levels were calculated by using state-of-the-art atomic relativistic Fock-space coupled-cluster method. A new ${}^{73}\mathrm{Ge}$ quadrupole moment was determined from these calculations and previously measured precision hyperfine parameters, yielding $Q_{\mathrm{s}}=-0.198\left(4\right)$ b, in excellent agreement with the literature value from molecular calculations. The moments of ${}^{69}\mathrm{Ge}$ have been revised: $\mu =+0.920\left(5\right){\mu }_N$ and $Q_{\mathrm{s}}=+0.114\left(8\right)\mathrm{b}$, and those of ${}^{71}\mathrm{Ge}$ have been confirmed. The experimental moments around $N=40$ are interpreted with large-scale shell-model calculations using the JUN45 interaction, revealing rather mixed wave-function configurations, although their $g$ factors are lying close to the effective single-particle values. Through a comparison with neighboring isotones, the structural change from the single-particle nature of nickel to deformation in germanium is further investigated around $N=40$.

We discuss major differences between electric and magnetic excitations in nuclei appearing in self-consistent calculations based on Skyrme energy-density functionals (EDFs). For this we calculate collective low- and high-lying electric and magnetic excitations in ${}^{208}\mathrm{Pb}$ within a self-consistent Skyrme EDF approach using the random-phase approximation (RPA) and a more sophisticated particle-hole plus phonon-coupling model, coined the time-blocking approximation (TBA). Tools of analysis are Landau-Migdal parameters for bulk properties and the RPA and TBA results for finite nuclei. We show that the interplay between the effective mass and the effective particle-hole interaction, well known in the Landau-Migdal theory, renders the final results rather independent of the effective mass by virtue of the “backflow effect.” It explains the success of self-consistent calculations of electric transitions in such approaches. This effect, however, is absent in the magnetic case and leads to higher fluctuations in the results. It calls for further developments of the Skyrme functional in the spin channel.

Background: Zr region is characterized by very rapid changes in the ground-state structure of the nuclei. In particular, the onset of deformation when passing from ${}^{98}\mathrm{Zr}$ to ${}^{100}\mathrm{Zr}$ is one of the fastest ever observed in the nuclear chart. It has been probed both experimentally and theoretically that certain low-lying excited states of Zr isotopes own different shapes than the ground state.

Purpose: We intend to disentangle the interplay between the sudden changes in the ground-state shape, i.e., the existence of a quantum phase transition, and the presence in the spectra of coexisting states with very different deformation, i.e., the presence of shape coexistence.

Method: We rely on a previous calculation using the interacting boson model with configuration mixing (IBM-CM), which reproduces in detail the spectroscopic properties of ${}^{96-110}\mathrm{Zr}$. This IBM-CM calculation allows to compute mean-field energy surfaces, wave functions, and any other observable related with the presence of shape coexistence or with a quantum phase transition.

Results: We obtain energy surfaces and the equilibrium value of the deformation parameter $\beta$, the U(5) decomposition of the wave functions, and the density of states.

Conclusions: We confirm that Zr is a clear example of quantum phase transition that originates from the crossing of two configurations with a very different degree of deformation. Moreover, we observe how the intruder configuration exhibits its own evolution, which resembles a quantum phase transition too.

Level lifetimes of the yrast $(5/2^{-})$ to $13/2^{-}$ states in the neutron-rich nucleus ${}^{53}\mathrm{Ti}$, produced in a multinucleon-transfer reaction, have been measured for the first time. The recoil distance Doppler-shift method was employed and lifetimes of the excited states were extracted by a lineshape analysis aided by Geant4-based Monte-Carlo simulations. The experiment was performed at the Grand Accélérateur National d'Ions Lourds facility in Caen, France, by using the Advanced Gamma Tracking Array for the $\gamma$-ray detection coupled to the large-acceptance variable mode spectrometer for an event-by-event particle identification and the Cologne plunger for deep-inelastic reactions. Reduced transition probabilities, deduced from the lifetimes, give new information on the nuclear structure of ${}^{53}\mathrm{Ti}$, and are used to benchmark different shell-model calculations using established interactions in the $fp$ shell.

Fine structure in the $\alpha$ decay of ${}_{90}{}^{221}\mathrm{Th}$, populating excited states in ${}_{88}{}^{217}\mathrm{Ra}$, was studied using $\alpha \gamma$-coincidence spectroscopy. Two $\alpha$-decay branches from ${}^{221}\mathrm{Th}$ have been newly observed, with $E_{\alpha }\left(\mathrm{keV}\right)\left[b_{\alpha }(\%)\right]=7951\left(8\right)\left[0.14\left(3\right)\right]$ and 8247(3)[1.51(12)], together with three previously known branches. Also, two new states in ${}^{217}\mathrm{Ra}$ were identified at $E$ = 177 and 227 keV. The ground-state configurations of the odd-$A$, $N$ = 131 transitional isotones above ${}^{208}\mathrm{Pb}$ are interpreted from their $\alpha$-decay fine structure systematics and considered in terms of predictions using spherical shell and reflection-asymmetric models.

Background: The electric giant-dipole resonance (GDR) is the most established collective vibrational mode of excitation. A charge-exchange analog, however, has been poorly studied in comparison with the spin (magnetic) dipole resonance (SDR).

Purpose: I investigate the role of deformation on the charge-exchange dipole excitations and explore the generic features as an isovector mode of excitation.

Methods: The nuclear energy-density functional method is employed for calculating the response functions based on the Skyrme-Kohn-Sham-Bogoliubov method and the proton-neutron quasiparticle-random-phase approximation.

Results: The deformation splitting into $K=0$ and $K=\pm 1$ components occurs in the charge-changing channels and is proportional to the magnitude of deformation as is well known for the GDR. For the SDR, however, a simple assertion based on geometry of a nucleus cannot be applied for explaining the vibrational frequencies of each $K$ component. A qualitative argument on the strength distributions for each component is given based on the non-energy-weighted sum rules taking nuclear deformation into account. The concentration of the electric dipole strengths in low energy and below the giant resonance is found in neutron-rich unstable nuclei.

Conclusions: The deformation splitting occurs generically for the charge-exchange dipole excitations as in the neutral channel. The analog pygmy dipole resonance can emerge in deformed neutron-rich nuclei as well as in spherical systems.

The differential cross sections of the ${}^{11}\mathrm{B}({}^3\mathrm{He},d){}^{12}\mathrm{C}$ reaction leading to formation of the $0^{+}$ ground state and the 15.11-MeV 1 ${}^{+}$, 16.57-MeV $2^{-}$, and 17.23-MeV $1^{-}$ excited states of ${}^{12}\mathrm{C}$ are measured at $E_{\text{lab}}=25$ MeV. The analysis of the data is carried out within the coupled-reaction-channels method for the direct proton transfer to the bound and unbound states. The rms radii of the last proton in all states studied are determined. A comparison of the rms radii of the ${}^{12}\mathrm{B}, {}^{12}\mathrm{C}$, and ${}^{12}\mathrm{N}$ nuclei in the isobaric analog states (IASs) with isospin $T=1$ determined by different methods allows us to arrive at a conclusion that these nuclei in the $1^{-}$ excited states at $E_x=2.62, 17.23,$ and $1.80$ MeV, respectively, possess one-nucleon (neutron or proton) halo structure. The enlarged radii and a large probability of the last neutron to be outside of the range of the interaction potential are also found for the $2^{-}$ states of ${}^{12}\mathrm{B}, {}^{12}\mathrm{C}$, and ${}^{12}\mathrm{N}$ at $E_x=1.67, 16.57,$ and $1.19$ MeV, respectively. These IASs also can be regarded as candidates for states with one-nucleon (neutron or proton) halo.

To shed light on the conditions for synthesizing some new heavy neutron-rich nuclei using multinucleon transfer reactions, the reaction systems ${}^{40}\mathrm{Ca}+{}^{208}\mathrm{Pb}$, ${}^{58}\mathrm{Ni}+{}^{208}\mathrm{Pb}$, ${}^{40}\mathrm{Ar}+{}^{208}\mathrm{Pb}$, ${}^{64}\mathrm{Ni}+{}^{208}\mathrm{Pb}$, and ${}^{136}\mathrm{Xe}+{}^{208}\mathrm{Pb}$ are investigated within improved dinuclear system (DNS) $\mathrm{model}+$gemini$++$. The transfer cross sections are calculated and compared with existing experimental data. The calculated results are in good agreement with available data. One found the projectiles are changed from the neutron-deficient ${}^{40}\mathrm{Ca}$ and ${}^{58}\mathrm{Ni}$ to moderately neutron-rich ${}^{40}\mathrm{Ar}$, and neutron-rich ${}^{64}\mathrm{Ni}$ and ${}^{136}\mathrm{Xe}$ projectiles on ${}^{208}\mathrm{Pb}$ target, the transfer flux its trend gradually evolves from proton stripping and neutron pickup to the proton pickup and neutron stripping and pickup (pickup and stripping are referring to the projectilelike fragment).

The STAR Collaboration at the Relativistic Heavy Ion Collider reports the first measurement of inclusive jet production in peripheral and central Au+Au collisions at $\sqrt{s_{NN}}=200$ GeV. Jets are reconstructed with the anti-$k_T$ algorithm using charged tracks with pseudorapidity $\left|\eta \right|<1.0$ and transverse momentum $0.2<p_{T,\mathrm{jet}}^{\mathrm{ch}}<30$ $\mathrm{GeV}/c$, with jet resolution parameter $R=0.2$, 0.3, and 0.4. The large background yield uncorrelated with the jet signal is observed to be dominated by statistical phase space, consistent with a previous coincidence measurement. This background is suppressed by requiring a high-transverse-momentum (high-$p_T$) leading hadron in accepted jet candidates. The bias imposed by this requirement is assessed, and the $p_T$ region in which the bias is small is identified. Inclusive charged-particle jet distributions are reported in peripheral and central Au+Au collisions for $5<p_{T,\mathrm{jet}}^{\mathrm{ch}}<25 \mathrm{GeV}/c$ and $5<p_{T,\mathrm{jet}}^{\mathrm{ch}}<30 \mathrm{GeV}/c$, respectively. The charged-particle jet inclusive yield is suppressed for central Au+Au collisions, compared to both the peripheral Au+Au yield from this measurement and to the $pp$ yield calculated using the PYTHIA event generator. The magnitude of the suppression is consistent with that of inclusive hadron production at high $p_T$ and that of semi-inclusive recoil jet yield when expressed in terms of energy loss due to medium-induced energy transport. Comparison of inclusive charged-particle jet yields for different values of $R$ exhibits no significant evidence for medium-induced broadening of the transverse jet profile for $R <0.4$ in central Au+Au collisions. The measured distributions are consistent with theoretical model calculations that incorporate jet quenching.

Four models for the initial conditions of a fluid dynamic description of high-energy heavy-ion collisions are analyzed and compared. We study expectation values and event-by-event fluctuations in the initial transverse energy density profiles from Pb-Pb collisions. Specifically, introducing a Fourier-Bessel mode expansion for fluctuations, we determine expectation values and two-mode correlation functions of the expansion coefficients. The analytically solvable independent point-sources model is compared to an initial-state model based on Glauber theory and two models based on the color glass condensate framework. We find that the large-wavelength modes of all investigated models show universal properties for central collisions and also discuss to what extent general properties of initial conditions can be understood analytically.

We study the light-unflavored mesons as relativistic bound states in the nonperturbative Hamiltonian formalism of the basis light-front quantization approach. The dynamics for the valence quarks of these mesons is specified by an effective Hamiltonian containing the one-gluon exchange interaction and the confining potentials both introduced in our previous work on heavy quarkonia, supplemented additionally by a pseudoscalar contact interaction. We diagonalize this Hamiltonian in our basis function representation to obtain the mass spectrum and the light-front wave functions (LFWFs). Based on these LFWFs, we then study the structure of these mesons by computing the electromagnetic form factors, the decay constants, the parton distribution amplitudes, and the parton distribution functions. Our results are comparable to those from experiments and other theoretical models.

The structure and $B\left(E1\right)$ transition strength of ${}^{19}\mathrm{B}$ are investigated in a ${}^{17}\mathrm{B}+n+n$ model, triggered by a recent experiment showing that ${}^{19}\mathrm{B}$ exhibits a well-pronounced two-neutron halo structure. Preliminary analysis of the experimental data was performed by employing contact $n\text{−}n$ interactions, which are known to underestimate the $s$-wave content in other halo nuclei, such as ${}^{11}\mathrm{Li}$. In the present Rapid Communication, the three-body hyperspherical formalism with finite-range two-body interactions is used to describe ${}^{19}\mathrm{B}$. In particular, two different finite-range $n\text{−}n$ interactions will be used as well as a simple central Gaussian potential whose range is progressively reduced. The purpose is to determine the main properties of the nucleus and investigate how they change when using contactlike $n\text{−}n$ potentials. Special attention is also paid to the dependence on the prescription used to account for three-body effects, i.e., a three-body force or a density-dependent $n\text{−}n$ potential. We have found that the three-body model plus finite-range potentials provide a description of ${}^{19}\mathrm{B}$ consistent with the experimental data. The results are essentially independent of the short-distance details of the two-body potentials, giving rise to a ${\left(s_{1/2}\right)}^2$ content of about 55%, clearly larger than the initial estimates. Very little dependence has been found as well on the prescription used for the three-body effects. The total computed $B\left(E1\right)$ strength is compatible with the experimental result, although we slightly overestimate the data around the low-energy peak of the $dB\left(E1\right)/d\varepsilon$ distribution. Finally, we show that a reduction of the $n\text{−}n$ interaction range produces a significant reduction of the $s$-wave contribution, which then should be expected in calculations using contact interactions.

Structure of the neutron-rich nucleus ${}^{30}\mathrm{Mg}$, which is located close to the region of the $N=20$ “island of inversion,” has been investigated by $\beta \text{−}\gamma$ spectroscopy of spin-polarized ${}^{30}\mathrm{Na}$. From the detailed $\gamma \text{−}\gamma$ coincidence relations, nine new states have been established in ${}^{30}\mathrm{Mg}$. The spin-polarization of ${}^{30}\mathrm{Na}$ enabled firm spin-parity assignments for seven states in ${}^{30}\mathrm{Mg}$ by means of the spatial asymmetry of $\beta$-ray counts in coincidence with the ${}^{30}\mathrm{Mg}\gamma$ rays. Based on the experimental information, it is shown that various characteristic structures coexist in ${}^{30}\mathrm{Mg}$: (i) the ground-state vibrational-like band, (ii) the deformed band built on the $0_2^{+}$ state at 1.788 MeV, (iii) the $\gamma$-vibrational band built on the $2_3^{+}$ state at 3.543 MeV, and (iv) four states around 5 MeV associated with large $\beta$-transition probabilities: $1^{+}$ and $2^{+}$ states with spherical nature, $1^{+}$ and $2^{+}$ states with collective nature. The experimental results are compared with three theoretical calculations of the CHFB $+$ LQRPA, the AMD $+$ GCM, and the large-scale shell model with the EEdf1 interaction. All these theories reasonably reproduce the three bands.

The neutron-rich barium nuclei have been the subject of intense interest due to the enhanced octupole correlations they are predicted to exhibit. The observation of enhanced octupole collectivity in ${}^{144,146}\mathrm{Ba}$ as measured in sub-barrier Coulomb excitation, consistent with static octupole deformation, has further heightened this interest. In the present work, these studies are extended to the neighboring odd-mass ${}^{143}\mathrm{Ba}$ to investigate the interplay between single-particle and collective octupole degrees of freedom. A new measurement of the first ${\frac{9}{2}}^{-}$-state lifetime is also presented. Reflection-Asymmetric Triaxial Particle Rotor Model calculations indicate that the negative-parity bands in ${}^{143}\mathrm{Ba}$ can be understood as a decoupled structure of $\nu h_{9/2}$ parentage, while the positive-parity bands are built on a decoupled octupole phonon. No evidence for $E3$ excitation is observed in this work, but an upper limit is placed on the $E3$ matrix element to the lowest octupole band.

The structure of odd-$A {}^{115,117}\mathrm{Rh}$ and ${}^{115,117}\mathrm{Pd}$ isotopes is studied by means of the neutron-proton interacting boson-fermion model (IBFM-2). $J^P={\frac{1}{2}}^{+}$ quantum number assignment for the ${}^{115,117}\mathrm{Pd}$ ground states is critically discussed and the predicted energy levels are compared to the existing experimental data. The resulting nuclear wave functions are used to compute the $\beta$-decay $ft$ values of the transitions from ${}^{115,117}\mathrm{Rh}$ to ${}^{115,117}\mathrm{Pd}$ in the microscopic IBFM-2 and the results compared with the data.