In heavy-ion collision experiments, the global collectivity of final-state particles can be quantified by anisotropic flow coefficients $\left(v_n\right)$. The first-order flow coefficient, also referred to as the directed flow $\left(v_1\right)$, describes the collective sideward motion of produced particles and nuclear fragments in heavy-ion collisions. It carries information on the very early stage of the collision, especially at large pseudorapidity $\left(\eta \right)$, where it is believed to be generated during the nuclear passage time. Directed flow therefore probes the onset of bulk collective dynamics during thermalization, providing valuable experimental guidance to models of the pre-equilibrium stage. In 2018, the Event Plane Detector (EPD) was installed in STAR and used for the Beam Energy Scan phase-II (BES-II) data taking. The combination of EPD $(2.1<|\eta |<5.1)$ and high-statistics BES-II data enables us to extend the $v_1$ measurement to the forward and backward $\eta$ regions. In this paper, we present the measurement of $v_1$ over a wide $\eta$ range in $\mathrm{Au}+\mathrm{Au}$ collisions at $\sqrt{s_{NN}}=$ 19.6 and 27 GeV using the STAR EPD. The results of the analysis at $\sqrt{s_{NN}}=$ 19.6 GeV exhibit excellent consistency with the previous PHOBOS measurement, while elevating the precision of the overall measurement. The increased precision of the measurement also revealed finer structures in heavy-ion collisions, including a potential observation of the first-order event-plane decorrelation. Multiple physics models were compared to the experimental results. Only a transport model and a three-fluid hybrid model can reproduce a sizable $v_1$ at large $\eta$ as was observed experimentally. The model comparison also indicates $v_1$ at large $\eta$ might be sensitive to the QGP phase transition.

The incompressibility of infinite nuclear matter $\left(K_{\infty }\right)$ is a parameter in the description of the nuclear equation of state that governs the energy cost associated with density oscillations near the saturation density. The most direct experimental method for studying this property of infinite nuclear matter is to probe the isoscalar giant monopole resonance (ISGMR) in finite nuclei. This paper explores the use of ${}^6\mathrm{Li}$ as a probe to study the ISGMR in several stable nuclei: ${}^{58}\mathrm{Ni}$, ${}^{90}\mathrm{Zr}$, ${}^{116}\mathrm{Sn}$, and ${}^{208}\mathrm{Pb}$, as complementary to using inelastic scattering of $\alpha$ particles, which has been used to great effect over the last several decades. Elastic and inelastic scattering data for these targets were collected with 343-MeV ${}^6\mathrm{Li}$ beams. In all nuclei studied in this paper, the ISGMR strength distributions extracted from multipole decomposition analyses of the inelastic scattering spectra agree very well with the previously measured ISGMR responses from $\alpha$-particle scattering, establishing the feasibility of employing ${}^6\mathrm{Li}$ inelastic scattering in investigations of the ISGMR.

The isoscalar and isovector monopole ($L=0$), dipole ($L=1$), quadrupole ($L=2$), and octupole ($L=3$) strength functions and the associated giant resonances have been calculated in the recently measured ${}^{90,92,94}\mathrm{Zr}$ and ${}^{92,94,96,98,100}\mathrm{Mo}$ nuclei by using the spherical quasiparticle random-phase approximation (QRPA). In these calculations, Bonn-$A G$-matrix-based effective interactions and large no-core Woods-Saxon-based single-particle valence spaces have been used. We compare the obtained results with those of Bonasera et al. [G. Bonasera, S. Shlomo, D. Youngblood, Y.-W. Lui, Krishichayan, and J. Button, Nucl. Phys. A 992, 121612 (2019)] obtained by employing a spherical Hartree-Fock-based random-phase approximation (RPA) with Skyrme-type effective nucleon-nucleon interactions (Skyrme-RPA). Such comparison is of great interest since the QRPA is closely related to its proton-neutron counterpart, used to compute double-beta-decay rates of nuclei relevant to present and future double-beta-decay experiments. The comparison shows that the QRPA and Skyrme-RPA results for the locations of the isovector giant resonances are completely consistent with each other. For the isoscalar resonances, the QRPA results are fairly consistent with both the Skyrme-RPA and available data, except for the locations of the isoscalar giant dipole resonance, which for the QRPA are clearly lower than those for the Skyrme-RPA, and some 4–7 MeV lower than the experimental locations.

The fusion cross sections $\sigma \left(E\right)$ and the corresponding modified $S^{*}$ factors of the seven light nuclear reaction systems, $\alpha +\alpha$, $\alpha +{}^8\mathrm{Be}$, ${}^8\mathrm{Be}+{}^8\mathrm{Be}$, ${}^6\mathrm{Li}+{}^6\mathrm{Li}$, ${}^{12}\mathrm{C}+{}^{12}\mathrm{C}$, ${}^{12}\mathrm{C}+{}^{16}\mathrm{O}$, and ${}^{16}\mathrm{O}+{}^{16}\mathrm{O}$, at sub-barrier energies are evaluated using the neck model. The effects of excited states of the compound nucleus in the reaction energy range on the cross section are considered. The results show that the excited states of the compound nucleus can significantly enhance the fusion cross section in the resonant energy region, which, in turn, impacts stellar processes. A notable increase in the reaction rate has also been observed after incorporating the contributions from the excited states at a given temperature. We conclude that the contributions of different excited states on the reaction rate are closely associated to their energies and angular momenta.

The quasifission rate is improved by the harmonic oscillator approximation for the interaction potential at the barrier and pocket. Within the framework of the DNS model, the calculated production cross sections are in good agreement with the experimental data in ${}^{64}\mathrm{Ni}+{}^{208}\mathrm{Pb}$ reaction. The dependence of the cross sections on the isospin of the reaction partner is studied. The cross sections of neutron-rich isotopes in the reaction with the reaction partner having the highest $N/Z$ ratio are the largest, because of the lowest difference of potential energy surface and driving potential. As the scattering angle is smaller than the smaller rainbow angle, the differential cross section of the fragment decreases sharply, because of the much smaller partial cross section at a lower angular momentum. The angular distribution shifts to a larger angle at a higher incident energy. The angular distribution of the unknown isotopes near $N=126$ in ${}^{70}\mathrm{Ni}+{}^{202}\mathrm{Pt}$ reaction is located at ${75}^{\circ }–{150}^{\circ }$ and peaks at about ${80}^{\circ }$.

This study investigates the multiplicity information entropy of hadrons, antihadrons, baryons, and net-protons in central ${}^{197}\mathrm{Au}+{}^{197}\mathrm{Au}$ collisions with impact parameters of $0–3\mathrm{fm}$, using the ultrarelativistic quantum molecular dynamics model across various center-of-mass energies $\left(\sqrt{s_{NN}}\right)$ from 5.0 to 54.4 GeV. Our simulations employ hydrodynamic modes with different equations of state (EoS) and a default mode without hydrodynamics. The results reveal that the information entropies of baryons and net-protons are sensitive to the selected EoS. In particular, enhancements of the information entropies around $\sqrt{s_{NN}}\sim 30\mathrm{GeV}$, especially with chiral hadron gas and Bag model EoS, indicate a phase transition or critical endpoint behavior. These findings highlight the importance of the EoS in understanding the thermodynamic properties of matter produced in high-energy collisions.

The estimation of the antibaryon to baryon ratio is considered to be a useful tool for studying baryon number transport in $pp, pA$, and $AA$ collisions. For this paper, the Pythia event generator with various tunes is used to measure the $\overline{\mathrm{\Lambda }}/\mathrm{\Lambda }$ ratio as a function of rapidity ($y$), transverse momentum ($p_{\mathrm{T}}$ ), and multiplicity within both ALICE and LHCb acceptances. The results obtained using various Monte Carlo data for $pp$ collisions at $\sqrt{s}=0.9$ and 7 TeV are compared with the experimentally measured values of $\overline{\mathrm{\Lambda }}/\mathrm{\Lambda }$ ratio of ALICE and LHCb experiments. Out of the various studied tunes of Pythia 8.3, the string junction model is found to be the most successful to describe the experimentally observed results. Evidence of a considerable amount of baryon number transportation from the beam fragmentation to the ALICE and LHCb acceptances could be recognized.

The low-spin structure of the ${}^{206}\mathrm{Tl}$ nucleus was studied in the thermal neutron capture reaction ${}^{205}\mathrm{Tl}(n,\gamma ){}^{206}\mathrm{Tl}$ at the Institut Laue-Langevin in Grenoble making use of the multidetector HPGe array Fission Product Prompt $\gamma$-ray Spectrometer and $\gamma \gamma$-coincidence techniques. The information on discrete structures located below the neutron binding energy in ${}^{206}\mathrm{Tl}$ was extended: a total number of 99 $\gamma$ rays (75 new) were observed and 21 excited states (8 new) were located. The analysis of the angular correlations of $\gamma$ rays was used to extract information on transitions multipolarities, which helped with spin-parity assignments for the located levels. The obtained experimental results were compared to shell-model calculations involving one-proton-hole, one-neutron-hole excitations below the ${}^{208}\mathrm{Pb}$ core. The two-body nucleon-nucleon realistic interactions derived from CD-Bonn free nucleon-nucleon potential were used. Reasonable agreement is obtained for the excitation energies of the states which, according to calculations, have highly fragmented wave functions, particularly in the high-energy region where the density of levels increases. The observed discrepancies are interpreted as a consequence of the large uncertainties in the determination of the off-diagonal matrix elements of the realistic shell-model interaction, which are mainly responsible for the fragmentation of the wave functions.

The multifaceted impact of shape coexistence on the first-forbidden ${\beta }^{-}$ decay of the $0^{-}$ ground state of ${}^{98}\mathrm{Y}$ and the structure and dynamics of the populated low-spin states in ${}^{98}\mathrm{Zr}$ have been investigated within the complex excited Vampir variational model using an effective interaction derived from a $G$ matrix based on the charge-dependent Bonn CD potential and a large model space. The effects of shape coexistence and mixing revealed by the properties of the investigated $\beta$ decay of ${}^{98}\mathrm{Y}$ and the coexistence phenomena at low angular momentum in ${}^{98}\mathrm{Zr}$ are discussed and comparison to the available data is presented.

Stable xenon isotopes are widely used in experiments trying to detect neutrinoless double-$\beta$ decay ($0\nu \beta \beta$) and weakly interacting massive particles (WIMPs) in direct dark-matter search experiments. Both solar and supernova (anti)neutrinos impinge on the detector material causing potential background, but this also opens new possibilities for detection of important new physics. In this context calculated neutrino-nucleus scattering cross sections are of paramount importance since no measured cross sections exist. In the present work we perform computations of differential and total cross sections of charged-current supernova-(anti)neutrino and ${}^8\mathrm{B}$ solar neutrino scattering off the ${}^{128,130,132,134,136}\mathrm{Xe}$ isotopes, used in the large $0\nu \beta \beta$ and dark-matter experiments. We utilize a many-body framework rooted in the quasiparticle random-phase approximation, suitable for describing states in the final nuclei up to high excitation energies. Furthermore, we use G-matrix-based realistic effective two-nucleon interactions in large single-particle valence spaces. In the present work we go beyond earlier works on (anti)neutrino-nucleus scattering by adding the meson-exchange two-body currents (2BC) within an effective one-body approximation. The effect that two-body currents have on inelastic (anti)neutrino scattering from ${}^{128,130,132,134,136}\mathrm{Xe}$ is studied for the first time. Two-body currents naturally account for the quenching of the weak axial coupling $g_A$ and induced pseudoscalar coupling $g_P$ as functions of momentum exchange in the scattering process. A comparison with a phenomenological quenching model with $g_A$ determined from $\beta$ decays is provided. This model features a rather strong $g_A$ quenching. We find that the 2BC-computed scattering cross sections for both neutrinos and antineutrinos are of similar magnitude as in the phenomenological quenching model, affirming the importance of the 2BC contributions in (anti)neutrino-nucleus scattering calculations.

We present comparisons to experimental data along with predictions of observables for $\text{U}+\text{U}$ and $\text{Au}+\text{Au}$ collisions at 193 and 200 GeV respectively, using a multistage theoretical and computational framework consisting of boost-invariant IP-Glasma initial state, music hydrodynamics, and a hadronic transport cascade generated by is3d and smash. Two different Woods-Saxon parametrizations were used for both systems [W. Ryssens et al., Phys. Rev. Lett. 130, 212302 (2023); H. De Vries et al., At. Data Nucl. Data Tables 36, 495 (1987)], allowing for comparisons within our model. Our results show great agreement with existing anisotropic flow measurements from the BNL Relativistic Heavy Ion Collider [L. Adamczyk et al., Phys. Rev. Lett. 115, 222301 (2015); J. Adam et al., Phys. Rev. Lett. 122, 172301 (2019)]. We provide predictions for differential flow observables as well as multiparticle correlations and transverse-momentum-flow correlations. When possible, we compare our predictions to results from $\text{Au}+\text{Au}$ collisions at 200 GeV to properly outline the effects of deformation in the initial state on final-state observables.

The primary purpose of studying quarkonium production in relativistic heavy-ion collisions is to understand the properties of the quark-gluon plasma. At various collision systems, measurements of quarkonium states of different binding energies, such as $\mathrm{{\rm Y}}\left(nS\right)$, can provide comprehensive information. A model study has been performed to investigate the modification of $\mathrm{{\rm Y}}\left(nS\right)$ production in Pb-Pb collisions at $\sqrt{s_{NN}}=5.02\mathrm{TeV}$ and Au-Au collisions at $\sqrt{s_{NN}}=200\mathrm{GeV}$. A Monte Carlo simulation study is performed with a publicly available hydrodynamic simulation package for the quark-gluon plasma medium and a theoretical calculation of the temperature-dependent thermal width of $\mathrm{{\rm Y}}\left(nS\right)$ considering the gluodissociation and inelastic parton scattering for dissociation inside the medium. In addition, we perform a systematic study with different descriptions of initial collision geometry and formation time of $\mathrm{{\rm Y}}\left(nS\right)$ to investigate their impacts on yield modification. The model calculation with a varied parameter set can describe the experimental data of $\mathrm{{\rm Y}}\left(nS\right)$ in Pb-Pb collisions at 5.02 TeV and $\mathrm{{\rm Y}}\left(2S\right)$ in Au-Au collisions at 200 GeV but underestimates the modification of $\mathrm{{\rm Y}}\left(1S\right)$ at the lower collision energy. The nuclear absorption mechanism is explored to understand the discrepancy between the data and simulation.

The EPOS4 project is an attempt to construct a realistic model for describing relativistic collisions of different systems, from proton-proton ($pp$) to nucleus-nucleus ($AA$), at energies from several TeV per nucleon down to several GeV. We argue that a parallel scattering formalism (as in EPOS4) is relevant for primary scatterings in $AA$ collisions above 4 GeV, whereas sequential scattering (cascade) is appropriate below. We present briefly the basic elements of EPOS4, and then investigate heavy ion collisions from 62.4 GeV down to 7.7 GeV, to understand how physics changes with energy, studying in particular the disappearance of the fluid component at low energies.

Recent work [Fore and Reddy, Phys. Rev. C 101, 035809 (2020)] has shown that a population of thermal pions could modify the equation of state (EoS) and transport properties of hot and dense neutron-rich matter and introduce new reaction pathways to change the proton fraction. In this article we study their impact on the bulk viscosity of dense matter, focusing on the neutrino-trapped regime that would be realized in neutron star mergers and supernovae. We find that the presence of a thermal population of pions alters the bulk viscosity by modifying the EoS (via the susceptibilities) and by providing new reaction pathways to achieve beta equilibrium. In neutron star merger conditions, the bulk viscosity in neutrino-trapped $npe\mu$ matter (without pions) has its peak at temperatures of at most a couple MeV and is quite small at temperatures of tens of MeV. We find that thermal pions enhance the low-temperature peak of the bulk viscosity by a factor of a few and shift it to slightly lower temperatures. At higher temperatures, where the pion abundance is large but the bulk viscosity is traditionally small, pions can increase the bulk viscosity by an order of magnitude or more, although it is still orders of magnitude smaller than its peak value.

In this work, we perform a model-to-data comparison for $\text{U}+\text{U}$ and $\text{Au}+\text{Au}$ collisions performed at the BNL Relativistic Heavy Ion Collider at $\sqrt{s_{\mathrm{NN}}}=193\mathrm{GeV}$ and $200\mathrm{GeV}$ using a multistage framework. Model calculations for various configurations of ${}^{238}\mathrm{U}$ and ${}^{197}\mathrm{Au}$ are used to compare with measurements of $\rho (v_n{\left\{2\right\}}^2,\langle p_T\rangle )$, the elliptic-flow-momentum correlator. It is found that momentum-flow correlations measured in high-energy nuclear collisions, combined with the flow harmonics themselves, are excellent probes of nuclear deformation and of nuclear structure in general.

The complex low-spin structure of the proton-rich ${}_{53}{}^{114}\mathrm{I}_{61}$ nucleus has been investigated with the JUROGAM 3 germanium array coupled with the MARA mass separator using the ${}^{58}\mathrm{Ni}({}^{64}\mathrm{Zn},\alpha 3\mathrm{pn}$) fusion-evaporation reaction. The depopulation of the previously known high-spin bands to low-spin states is firmly established, fixing the excitation energies, spins and parities of the states. The present results combined with fragmentary communications and results published from the decay of separated mass-114 beams measured long time ago at ORNL and GSI, led to the conclusion that the previously known 6 s, 266 keV, $I=\left(7\right)$ isomer has to be repositioned at 134 keV and its spin-parity changed to $4^{+}$. Three new isomers are identified from intensity imbalance of the populating and depopulating transitions, one at 204 keV with $I=6^{+}$ and a half-life longer than several nanoseconds, and two at 635 and 966 keV with $I=5^{-}$ and $I=7^{-}$, respectively, with half-lives of a few nanoseconds. The spins of one high-spin band are changed from odd to even and a new interpretation of the two resulting bands with even spins is proposed based on cranked Nilsson-Strutinsky calculations. From the comparison of the observed low-spin states with shell-model calculations it is suggested that the states of the ground-state cascade are oblate, while the other positive-parity states and the high-spin negative-parity bands are prolate.

${}^{187}\mathrm{Ta}$ ($Z=73, N=114$) is located in the neutron-rich $A\approx 190$ region where a prolate-to-oblate shape transition via triaxial softness is predicted to take place. A preceding work on the $K^{\pi }=(25/2^{-})$ isomer and a rotational band to which the isomer decays carried out by the same collaboration revealed that axial symmetry is slightly violated in this nucleus. This paper focuses on a higher-lying isomer, which was previously identified at 2933(14) keV by mass measurements with the Experimental Storage Ring at GSI. The isomer of interest has been populated by a multinucleon transfer reaction with a ${}^{136}\mathrm{Xe}$ primary beam incident on a natural tungsten target, using the KEK Isotope Separation System at RIKEN. New experimental findings obtained in the present paper include the internal and external $\beta$-decay branches from the high-spin isomer and a revised half-life of 136(24) s. The evaluated hindrances for $K$-forbidden transitions put constraints on the spin-parity assignment, which can be interpreted as being ascribed to a prolate shape with a five-quasiparticle configuration by model calculations.

An earlier study revealed an unexpected enhancement in valence proton-neutron interaction strengths in certain heavy deformed even-even nuclei with equal numbers of valence protons and valence neutrons. The paper reports on an extension of those results to the entire span of deformed nuclei from Sm to W using mass data taken in the interim.

In hypernuclear systems, interactions involving nucleons and hyperons are intricately influenced by the surrounding particles, particularly by the density and isospin feature of the nuclear medium. By studying several observed quantities relevant to hypernuclear bulk and single-particle properties, nuclear in-medium effects and the nonperturbative nature of the strangeness-bearing nuclear force could be revealed. In this paper, the relativistic mean-field theory is adopted to describe the structure of several typical ${\mathrm{\Xi }}^{-}$ hypernuclei. Sets of $\mathrm{\Xi }N$ effective interactions, by taking a density-dependent meson-nucleon (-hyperon) coupling perspective, are developed by fitting experimental data on the ${\mathrm{\Xi }}^{-}$ hyperon $1s$ and $1p$ state separation energy of ${}_{{\mathrm{\Xi }}^{-}}{}^{15}\mathrm{C}$ as well as the $1p$ state separation energy of ${}_{{\mathrm{\Xi }}^{-}}{}^{13}\mathrm{B}$. It is found that the density-dependent behavior of meson-hyperon coupling strengths sensitively affects the description of hyperon single-particle levels, which play a crucial role in the consistent description of the theoretical separation energies with experimental data. In fact, the density-dependent meson-baryon coupling strengths introduce additional rearrangement contributions to the hyperon self-energy. Correspondingly, detailed forms of density dependence in these coupling strengths and different considerations of meson-baryon coupling channels will impact the hyperon single-particle properties within hypernuclei. Especially with the additional inclusion of the isovector scalar $\delta$ meson, the significant enhancement of rearrangement terms in the effective interaction $\mathrm{DD}\text{−}\mathrm{ME}\delta$ impacts the shape of the hyperon potential and alters the characteristics of the isovector channel dynamics balance in the effective nuclear force. As the difference in the ${\mathrm{\Xi }}^{-}1s$ separation energy of ${}_{{\mathrm{\Xi }}^{-}}{}^{15}\mathrm{C}$ remains large among three sets of $\mathrm{\Xi }N$ effective interactions, a possible explanation to understand the experimental results is taken further by considering the mixing between the ${\mathrm{\Xi }}^{-}$ state in ${}^{14}\mathrm{N}$ and the ${\mathrm{\Xi }}^0$ state in ${}^{14}\mathrm{C}$. Relevant research underscores the importance of precisely accounting for in-medium effects in hyperon-nucleon interactions and incorporating a more comprehensive set of meson-exchange degrees of freedom in effective nuclear forces, offering a potential solution for more self-consistently describing the featured hyperon single-particle behavior of various hypernuclei and for reducing uncertainties in theoretical descriptions.