We perform a comprehensive Bayesian analysis of Au $+$ Au collision data at 1.23 GeV/nucleon using an isospin-dependent Boltzmann-Uehling-Uhlenbeck transport model that incorporates a momentum-dependent mean field and medium-modified baryon-baryon cross sections. The model parameters are calibrated to empirical properties of nuclear matter at saturation density, with particular attention to variations in the incompressibility $K_0$. Within a Bayesian statistical framework and using a Gaussian Process emulator, we simultaneously extract constraints on the incompressibility $K_0$ and the in-medium baryon-baryon scattering modification factor $X$ by systematically comparing model predictions with HADES measurements of proton collective flow, including the slopes ($F_1$ and $F_3$) of directed and triangular flow, as well as elliptic ($v_2$) and quadrupole ($v_4$) flow observables. We find that the extracted incompressibility favors relatively small values, indicating a soft nuclear equation of state, while the inferred average $X$ values fall at $0.9–1.0$, suggesting mild suppression of baryon-baryon cross sections in the medium. Furthermore, we demonstrate that transport models employing momentum-independent mean fields require stiffer equations of state and stronger in-medium corrections to reproduce the same observables. These results highlight the critical role of momentum dependence in the mean field and its interplay with in-medium scattering in constraining the properties of dense nuclear matter from heavy ion collisions.

The method of $Q$ cumulants has been shown as a powerful tool to study the fine details of the azimuthal anisotropies in high-energy nucleus-nucleus collisions. A new method for the fast calculation of arbitrary order $Q$-cumulant $v_n\left\{2k\right\}$ values, based on the partition of a non-negative integer $l\le m$ for calculation of the $2m$-particle azimuthal correlations is presented in this paper. Unlike the standard $Q$-cumulants method in which the calculation of high-order multiparticle calculations is impractical, the newly proposed method enables easy calculation. The validity of the method is proven via a toy model that uses the elliptic power distribution to simulate anisotropic emission of particles. The method enables the study of fine details of the $v_2$ distribution, such as higher-order central moments of the $v_2$ distribution, as well as the hydrodynamic behavior of the quark-gluon plasma.

We employ the SMASH transport model to provide event-by-event initial conditions for the energy-momentum tensor and conserved charge currents in hydrodynamic simulations of relativistic heavy-ion collisions. We study the fluctuations and dynamical evolution of three conserved charge currents (net baryon, net electric charges, and net strangeness) with a four-dimensional lattice-QCD-based equation of state, NEOS-4D, in the hydrodynamic phase. Out-of-equilibrium corrections at the particlization are generalized to finite densities to ensure the conservation of energy, momentum, and the three types of charges. These theoretical developments are integrated within the X-SCAPE code as a unified framework for studying the nuclear matter properties in the Beam Energy Scan program.

A new measurement of the ${}^{75}\mathrm{As}$($n,2n$) measurement was performed using the 14.1 MeV neutron pulse produced by fusion experiments at the National Ignition Facility (NIF). The target material consisted of GaAs foils encapsulated in aluminum irradiation containers, along with Au monitor foils, and positioned in the NIF chamber during high neutron yield shots. After irradiation, the GaAs and Au foils were counted with high purity germanium detectors to assess the production of ($n,2n$) activation products to determine the flux and the cross section of interest. The measured cross section was $966\pm 71$ mb at $14.1\pm 0.37$ MeV. This work provides a proof of concept for a platform for performing “ride-along” cross section measurements at NIF to contribute to existing nuclear data as well as measure new cross sections in the future.

In this work, we present a systematic study of low-lying states and electromagnetic properties of the semimagic $N=82$ isotonic chain with proton number $Z$ = 51–77, using the full configuration interaction shell model with a newly developed high-quality effective interaction. The calculations are performed in a large model space that includes all proton orbitals between $Z=50$ and 82: $0g_{7/2}, 1d_{5/2}, 1d_{3/2}, 2s_{1/2}$, and $0h_{11/2}$. The effective interaction is derived through the principal component analysis approach, starting from 160 two-body matrix elements and five single-particle energies and considering up to 30 degrees of freedom. Those are optimized by fitting to 204 available experimental energy levels. The resulting root-mean-square deviation is as low as 102 keV. The new interaction successfully reproduces the binding energies, low-lying spectra, electric quadrupole transition probabilities $B\left(E2\right)$, and magnetic dipole moments across both even-even and odd-mass isotones. The nuclear structure of low-lying states is analyzed in detail. Additionally, predictions are made for several more proton-rich nuclei beyond current experimental reach, including ${}^{155}\mathrm{Ta}, {}^{156}\mathrm{W}, {}^{157}\mathrm{Re}, {}^{158}\mathrm{Os}$, and ${}^{159}\mathrm{Ir}$.

The excited nuclear states of ${}^{125}\mathrm{Te}$ were populated in a fusion-evaporation reaction using a target of ${}^{124}\mathrm{Sn}$ and $\alpha$ beam at 31 and 35 MeV energies. All the $\gamma \text{−}\gamma$ coincidences were recorded using the Indian National Gamma Array at VECC, India, and processed by a digital data acquisition system. A total of 92 new $\gamma$ rays were identified and placed within the level scheme. Six new structures, three of positive parity and three with negative parity, have been identified. Previously observed level scheme has been verified and extended up to $\approx 5.7$ MeV. The results were interpreted in the framework of the particle rotor model and possible configurations were assigned to the structures.

Emitters of two-proton (2p) radioactivity usually exist in the proton-rich region of the nuclide chart with relatively large proton number and isospin asymmetry. By using the density-dependent M3Y effective interactions (BDM3Y1, DDM3Y1, and CDM3Y6), the decay half-lives of 2p-radioactivity emitters are calculated within the density-dependent cluster model. Considering the isospin-asymmetric effect in the decay system, the proton skin thickness of the daughter nucleus is introduced into the calculation of the nuclear potential between the 2p cluster and the daughter nucleus, which includes both isoscalar and isovector parts. Hence the symmetry energy $E_{\mathrm{sym}}\left({\rho }_0\right)$ and its density slope $L\left({\rho }_0\right)$ at the normal density ${\rho }_0$ can be extracted from the properties of 2p radioactivity within the Hartree-Fock approach. Under the well-constrained range of the symmetry energy $E_{\mathrm{sym}}\left({\rho }_0\right)$, the corresponding extraction of its density slope $L\left({\rho }_0\right)$ is consistent with previous calculations. Meanwhile, the proton skin thickness of the daughter nucleus is also predicted and a good linear dependence of the proton skin thickness on the isospin asymmetry is obtained.

Background: Fusion hindrance refers to steeper descent of measured fusion excitation function compared with the predictions of standard coupled-channels models. Owing to experimental challenges, fusion measurements for asymmetric systems down to deep sub-barrier energies have been performed for only a handful of systems.

Purpose: We aim to investigate whether the entrance channel mass asymmetry affects the onset of fusion hindrance by measuring excitation functions for asymmetric systems and comparing the results with that of symmetric systems having similar values of the system parameter $\zeta$.

Method: Fusion cross sections were measured for the systems ${}^{16}\mathrm{O}+{}^{116}\mathrm{Cd}$ and ${}^{16}\mathrm{O}+{}^{142}\mathrm{Ce}$ down to energies $\simeq 13\%$ below the Bass barrier using a recoil mass spectrometer. Fusion barrier distributions were derived from the data employing the Gaussian analytic recipe, in addition to the usual double-derivative method. Experimental results were compared with predictions of coupled-channels calculations. Logarithmic slopes and astrophysical $S$-factors were extracted from the measured cross sections. Results of the present measurements were compared with the same from symmetric systems with nearly the same $\zeta$.

Results: Experimental excitation functions and barrier distributions were reproduced reasonably well by coupled-channels calculations in the range of energies considered in this study. Extrapolations of logarithmic slopes and $S$-factors to lower energies suggests onset of fusion hindrance for both systems. The energy, $4\sigma$ below the centroid of the lowest barrier, is found to be a good measure of the threshold for fusion hindrance.

Conclusions: Presence of fusion hindrance is inferred by extrapolation in both the systems. The Gaussian analytic recipe is found to be quite effective to obtain an unambiguous barrier distribution which, in turn, can be used for determining the threshold energy for fusion hindrance. Comparison of results between asymmetric and symmetric systems points to the fact that fusion hindrance is a generic feature of all the studied systems, independent of their entrance channel mass asymmetry.

In this study, fusion cross sections for the ${}^9\mathrm{Be}+{}^{116}\mathrm{Sn}$ reaction have been measured at near-barrier energies, within the range of 0.75 $V_b < E_{\mathrm{lab}}$(MeV) $<1.16 V_b$. This investigation aims to explore the influence of the intrinsic structure of the ${}^9\mathrm{Be}$ projectile on fusion dynamics. The experimentally measured fusion excitation functions have been analyzed and interpreted using the coupled-channel approach using the ccfull code, which includes couplings to the collective excitations of both the projectile and target nuclei. While these calculations adequately describe sub-barrier fusion, they indicate a significant suppression of fusion (approximately 35%) at above-barrier energies, suggesting the impact of noncollective effects, such as projectile breakup. The barrier height, determined from the analysis of the barrier distribution, is found to be $\approx 26.11\pm 0.30$ MeV. The reduced excitation functions of the ${}^9\mathrm{Be}+{}^{116}\mathrm{Sn}$ system have been contrasted with those involving more tightly bound projectiles, such as ${}^{16,18}\mathrm{O}$ and ${}^{32}\mathrm{S}$. It has been observed that ${}^9\mathrm{Be}$ exhibits the highest enhancement in sub-barrier fusion and a considerable suppression at above-barrier energies. This highlights the dependence on projectile structure, particularly given the low breakup threshold of ${}^9\mathrm{Be}$. Furthermore, the systematic behavior of fusion suppression involving the ${}^9\mathrm{Be}$ projectile with various targets, ${}^9\mathrm{Be}+x$, has also been investigated by applying the universal fusion function and the improved fusion function to the experimentally measured excitation functions. The results of this study indicate that the target nuclei have minimal to no influence on the observed fusion suppression.

New experimental data for the ${}^6\mathrm{He}{+}^{27}\mathrm{Al}$ collision at $E_{\mathrm{lab}}=17.9$ MeV bombarding energy is presented. An abundant production of $\alpha$ particles has been observed with energies close to those of the scattered ${}^6\mathrm{He}$ beam. The ${}^6\mathrm{He}{+}^{27}\mathrm{Al}$ elastic scattering and the $\alpha$-particle angular and energy distributions were obtained. Theoretical analyzes were performed using continuum-discretized coupled-channels calculations in both three- and four-body frameworks, nonelastic breakup calculations via the Ichimura-Austern-Vincent (IAV) model, and fusion-evaporation simulations. The results demonstrate that $\alpha$-particle production is predominantly driven by nonelastic breakup processes with negligible contributions from elastic breakup and $\alpha$- particle evaporation.

Heavy quarks are predominantly generated at the initial stage of relativistic heavy-ion collisions such that heavy flavor observables have the potential to provide information on the pre-equilibrium medium dynamics. In this study, we investigate the sensitivity of D-meson $R_{AA}$ and $v_2$ to early-time charm quark dynamics in $\mathrm{Pb}+\mathrm{Pb}$ collisions at $\sqrt{s_{NN}}=5.02$ TeV. We employ the $\text{IP-Glasma}+\mathrm{MUSIC}+\mathrm{UrQMD}$ framework to model the evolution of the bulk medium. Charm quarks are generated using PYTHIA with nuclear parton distribution functions and evolved using Langevin dynamics within MARTINI. We observe that even though there is significant momentum broadening in the earliest stage, D-meson $R_{AA}$ and $v_2$ are only weakly sensitive to pre-equilibrium interactions.

Centrality determination remains one of the major sources of systematic uncertainty in intermediate-energy heavy-ion collision analyses, especially for probing the nuclear equation of state (EOS) at suprasaturation densities, to quantitatively assess the uncertainties associated with different centrality determination methods, and to investigate their effects on final-state EOS-sensitive observables. Within the ultrarelativistic quantum molecular dynamics model, $\mathrm{Au}+\mathrm{Au}$ collisions at $\sqrt{s_{NN}}=2.4$ GeV are performed within a soft and a hard EOS. Event centrality is determined using the multiplicity of all charged particles ($M_{\mathrm{ch}}$) and two impact parameter-based centrality filters, one based on a geometrical interpretation and the other based on the Glauber Monte Carlo (MC) model, denoted as $b_f$ and $b_r$, respectively. It is shown that there exist significant differences between the real impact parameter distributions of event samples selected by $M_{\mathrm{ch}}, b_f$, and $b_r$, particularly between $M_{\mathrm{ch}}$ and $b_r$. When the $b_f$ is employed, uncertainties associated with centrality selection have a weaker influence on observables than the effects induced by the EOS. In contrast, when the $b_r$ is used, the influence of centrality-related uncertainties becomes more pronounced than that of the EOS. These results demonstrate that a rigorous and consistent mapping between $M_{\mathrm{ch}}$ and impact parameter is essential to impose quantitative constraints on the high-density nuclear EOS. Furthermore, our study indicates that the geometrical interpretation of centrality remains valid and consistent with dynamical multiplicity selection, whereas the Glauber MC-based centrality determination becomes unreliable at the investigated energy.

Within many-body systems governed by Skyrme density functional, we confirm that the correlations between neutron skin thickness $\mathrm{\Delta }{R}_{\mathrm{np}}$ (or charge radius difference of mirror nuclei,$\mathrm{\Delta }{R}_{\mathrm{mirr}}$) and the isospin asymmetry ($I=\frac{N-Z}{A}$) persistently emerge, demonstrating the parameter-independent nature of these correlations when using the Skyrme force. We further determine that the slopes of the linear $\mathrm{\Delta }{R}_{\mathrm{mirr}}\text{−}I$ or $\mathrm{\Delta }{R}_{\mathrm{np}}\text{−}I$ correlations (denoted as $C_{\mathrm{np}}$ and $C_{\mathrm{mirr}}$, respectively) are also correlated to the slope of the symmetry energy ($L$), which may offer a new approach to constrain $L$ while mitigating the influence of density irregularities in specific nuclei. The linear correlations of $C_{\mathrm{np}}\text{−}L$ and $C_{\mathrm{mirr}}\text{−}L$ are adopted to constrain $L$ to 12–44 MeV with $1\sigma$ confidence. Shape coexistence, or shape effect on charge radius, is considered to explain the experimental deviation of ${}^{18}\mathrm{O}/\mathrm{Ne}$ and some odd-$A\mathrm{\Delta }{R}_{\mathrm{mirr}}\text{'}\mathrm{s}$ from the $\mathrm{\Delta }{R}_{\mathrm{mirr}}\text{−}I$ linearity. Considering the deviation of ${}^{18}\mathrm{O}/\mathrm{Ne}\mathrm{\Delta }{R}_{\mathrm{mirr}}$ due to shape coexistence, the $1\sigma$ range for $L$ is further narrowed to 24–40 MeV, suggesting a soft equation of state for nuclear matter.

The excited states in ${}^{67}\mathrm{Ga}$ were investigated using the in-beam $\gamma$-ray spectroscopic technique. The investigation was conducted through the ${}^{52}\mathrm{Cr}({}^{18}\mathrm{O}, 1p2n$) fusion-evaporation reaction at a beam energy of 72.5 MeV. The deexciting $\gamma$ rays from the excited states of the residual nuclei were detected in coincidence mode with 14 Compton-suppressed HPGe clover detectors of the Indian National Gamma Array stationed at the Inter University Accelerator Centre, New Delhi. The spins and parities of the several states were determined using the coincidence angular anisotropy and polarization measurements of the $\gamma$ transitions depopulating the corresponding excited states. The crossing phenomenon observed in the rotational-like band structure is presented, and the necessary interpretation is made following the results obtained from the calculations carried out within the framework of the cranking model as well as the particle plus triaxial rotor model.

We investigate the clustering structure of ${}^{10}\mathrm{C}$ using a microscopic four-body $\alpha + \alpha + p + p$ cluster model. The calculated low-lying energy spectrum agrees well with the experimental data. Based on the analysis of reduced width amplitudes and spectroscopic factors for the two-body configurations (${}^9\mathrm{B} + p, {}^6\mathrm{Be} + \alpha$, and ${}^8\mathrm{Be} + {}^{2}p$), as well as the three-body configuration (${}^8\mathrm{Be} + p + p$), several cluster structures are suggested. The analysis reveals that the $0_1^{+}$ state corresponds to a compact structure, while the $0_2^{+}$ and $2_3^{+}$ states show nonnegligible diproton clustering components. In particular, the $0_2^{+}$ state is found to exhibit a mixed structure, involving both the ${}^6\mathrm{Be} + \alpha$ and ${}^8\mathrm{Be} + p + p$ configurations, consistent with previous theoretical predictions and experimental observations. It is also indicated that the $2_1^{+}$ and $2_2^{+}$ states are dominated by the ${}^9\mathrm{B}+p$ configuration, while the $0_3^{+}$ state features a more spatially extended configuration.

Data tables on the equation of state (EOS) and microscopic structures for cold dense stellar matter with proton fractions $Y_p=0.01$–0.65 and baryon number densities $n_{\text{b}}={10}^{-8}–2{\mathrm{fm}}^{-3}$ are obtained adopting 13 different relativistic density functionals, i.e., NL3, PK1, PK1r, GM1, MTVTC, DD-LZ1, PKDD, DD-ME2, TW99, DD-MEX, DD-MEX1, DD-MEX2, and DD-MEY. The EOSs of dense stellar matter inside neutron stars with baryon number densities $n_{\text{b}}=7.6\times {10}^{-11}–2{\mathrm{fm}}^{-3}$ are obtained as well fulfilling $\beta$-stability condition, where those with TW99, DD-MEY, DD-MEX1, DD-ME2, DD-MEX, and DD-LZ1 are generally consistent with the constraints obtained by Huth et al. [Nature (London) 606, 276 (2022)] at $n_{\text{b}}\lesssim 0.19{\mathrm{fm}}^{-3}$ and at larger densities only TW99 gives satisfactory predictions. In general, the dense stellar matter exhibits droplet phase at $n_{\mathrm{b}}\lesssim 0.015{\mathrm{fm}}^{-3}$, while more exotic structures such as rods, slabs, tubes, and bubbles appear sequentially as density increases. The critical proton fractions $Y_p^{\mathrm{drip}}$ ($\approx 0.26$–0.31) for neutron drip are obtained, where neutron gas emerges outside of nuclei at $Y_p<Y_p^{\mathrm{drip}}$. For dense stellar matter at small densities ($n_{\text{b}}\lesssim {10}^{-5}{\mathrm{fm}}^{-3}$) or large proton fractions ($n_{\text{b}}\lesssim 0.1{\mathrm{fm}}^{-3}$ and $Y_p\gtrsim Y_p^{\mathrm{drip}}$), the EOSs and microscopic structures are generally insensitive to the adopted density functionals. With the onset of neutron drip at $Y_p\lesssim Y_p^{\mathrm{drip}}$, the uncertainties emerge and peak at $n_{\text{b}}\approx 0.02{\mathrm{fm}}^{-3}$ within the range ${10}^{-5}\lesssim n_{\text{b}}\lesssim 0.1{\mathrm{fm}}^{-3}$. At $n_{\text{b}}\gtrsim 0.1{\mathrm{fm}}^{-3}$, the dense stellar matter becomes uniform and muons eventually appear, where the uncertainties in the EOSs grow significantly.

Spin polarization provides a novel probe of the rotational properties of the quark-gluon plasma formed in relativistic heavy-ion collisions. This work investigates the equation of state, particularly its transport and thermodynamic coefficients in noncentral $\mathrm{O}+\mathrm{O}$ collisions, employing a parton distribution function that incorporates spin polarization induced by thermal vorticity. Within a kinetic theory framework, one finds that the magnitude of the squared speed of sound ($c_s^2$) is only weakly modified by spin polarization, whereas the specific shear viscosity ($\eta /s$), specific bulk viscosity ($\zeta /s$), and mean free path ($\lambda$) show substantial changes. When spin polarization is included, both $c_s^2$ and $\zeta /s$ develop a nonmonotonic dependence on the collision energy, with an inflection point near $\sqrt{s_{NN}}=27$ GeV, corresponding to an average parton chemical potential of $\langle {\mu }_p\rangle =0.021$ GeV. These results suggest that spin polarization may serve as a useful probe for constraining the effective equation of state of QCD matter.

The energy-dependent hotspot model is used to predict cross sections for vector-meson diffractive photonuclear production off oxygen ($\gamma \mathrm{O}$) and neon ($\gamma \mathrm{Ne}$) that can be extracted from ultraperipheral O-O and Ne-Ne collisions, recently recorded at the CERN Large Hadron Collider. In both cases, two models are used to describe the nuclear shapes. Woods-Saxon prescriptions for O and Ne as well as an alpha-cluster description of O and a bowling-pin-like shape for Ne, according to the projected generator coordinate method (PGCM) formalism. Predictions are presented for the dependence on the center-of-mass energy of the photon-nucleus system, as well as on Mandelstam $t$, of the cross sections for the coherent and the incoherent photonuclear production of ${\rho }^0$ and $J/\psi$ vector mesons. Furthermore, the rapidity dependence of the ultraperipheral cross section is reported for all cases. It is found that the incoherent process provides a measurable signature for the approach to the gluon-saturation regime, and that the simultaneous determination of ${\rho }^0$ and $J/\psi$ coherent and incoherent production provides a strong constraint on nuclear models for both O and Ne.

Given the importance of nuclear mass predictions, numerous models have been developed to extrapolate the measured data into unknown regions. While neural networks—the core of modern artificial intelligence—have been recently suggested as powerful methods, showcasing high predictive power in the measured region, their ability to extrapolate remains questionable. This limitation stems from their ‘black box’ nature and large number of parameters entangled with nonlinear functions designed in the context of computer science. In this study, we demonstrate that replacing such nonlinear functions with domain-informed functions significantly improves extrapolation performance. Using only the information about neutron ($\mathit{\text{N}}$) and proton ($\mathit{\text{Z}}$) numbers without any existing global mass models or knowledge of magic numbers, we developed a highly accurate model that covers light nuclei ($\mathit{\text{N}}, \mathit{\text{Z}} >$ 0) up to the drip lines. The extrapolation performance was rigorously evaluated using the outermost nuclei in the measurement landscape, and only the data in the inner region was used for training. We present details of the method and model, along with opportunities for future improvements.

We investigate the effects of different basis model spaces on the calculation of reduced width amplitude (RWA) and asymptotic normalization coefficient (ANC) for the ${}^7\mathrm{Li}$ and ${}^7\mathrm{Be}$ nuclei. The two-cluster model ($\alpha +t/{}^3\mathrm{He}$) and the three-cluster model ($\alpha +np+n/p$) with the generator coordinates method are applied to calculate the wave functions of ${}^7\mathrm{Li}$ and ${}^7\mathrm{Be}$. Specifically, the model space for the three-cluster model is constructed upon a sufficiently broad space of two-cluster configuration bases by further including three-cluster configuration bases. We compare the impact on the results from two basis sets for these added three-cluster bases: one with a compact and one with a broad spatial distribution. The final results reveal that the two-cluster model cannot accurately reproduce the binding energies of ${}^7\mathrm{Li}$ and ${}^7\mathrm{Be}$, and tends to overestimate their ANCs. Regarding the calculations with the three-cluster model, while the two basis sets do not give significant differences in energy or energy spectrum, the basis set with a compact model space fails to describe the asymptotic behavior of the RWA adequately. This introduces excessive uncertainty into the ANC calculation. In the end, we conclude that when calculating ANC via a microscopic framework, particular attention must be paid to ensuring sufficient model space, especially for the components describing the breakup channels. This approach provides ANC values for ${}^7\mathrm{Li}$ and ${}^7\mathrm{Be}$ that agree well with experimental results.