We present a theoretical calculation for the $A=2,3$, and 4 nuclear contact coefficients within the generalized contact formalism, using both local and nonlocal chiral potentials. The hyperspherical harmonics method is employed to calculate the nuclear wave functions, from which we derive two-body momentum distributions and density functions to extract the contact coefficients. We have extracted the contact coefficients from two-body momentum distributions or from density functions, for a given nucleus and potential, and we have found that the generalized contact formalism predictions are verified in the triplet spin channel for local and nonlocal potentials. On the other hand, some significant tensions exist for the singlet channels, especially when studied with nonlocal potentials. We have also analyzed the model-independence of the ratios between the contact coefficients, which we have found to be quite satisfied. This study extends previous works based on local interaction models only.

Stable and consistent experimental extraction of $\beta$-shape functions, $C\left(W\right)$, is challenging. Comparing different experimental $\beta$ shapes to each other and to those predicted by theory in a consistent manner is difficult. This difficulty is compounded when different parametrizations of the $\beta$-shape function are used. Usually some form of a power polynomial of the total electron energy is chosen for this parametrization, but choosing a power polynomial results in extracted coefficients that are highly correlated, with their physical meaning and numerical value dependent on the order of polynomial chosen. This is true for both theoretical and experimental coefficients, and leads to challenges when comparing coefficients between polynomials of different orders. Accurately representing the highly correlated uncertainties is both difficult and subtle and limits the underlying physical interpretation of shape-function parameters. In this manuscript an alternative approach based on orthogonal polynomials is offered. Orthogonal polynomials offer more stable coefficient extraction with less dependence on the order of the polynomial, allow for easier comparison between theory and experimental coefficients from different order polynomials, can offer reduced correlations between coefficients, while also offering simple physical meaning and clarifying statistical limits of the extracted coefficients.

Levels in ${}^8\mathrm{B}$ have been investigated experimentally using the invariant-mass technique and compared with ab initio calculations. Datasets obtained using $E/A$ = 69-MeV ${}^9\mathrm{C}$ and ${}^{13}\mathrm{O}$ beams on a Be target have been further analyzed to extend the level scheme of ${}^8\mathrm{B}$ for $E^{*}\lesssim 10$ MeV. New levels were observed in the $2p+{}^6\mathrm{Li}, p+{}^3\mathrm{He}+\alpha$, and the $p+{}^7\mathrm{Be}+\gamma$ exit channels. Momentum correlations between the decay fragments were also investigated in order to deduce the decay pathways and whether the decays are prompt or sequential. This nucleus and its mirror were also investigated in the ab initio symmetry-adapted no-core shell model. Correspondence between the newly observed and predicted levels was made based on the level energy and the decay modes. For positive-parity levels with $J\le 3$, all predicted levels can be connected to an experimental counterpart (at least tentatively) for $E^{*}\le 8.4$ MeV.

An investigation of the $N=20{}^{36}\mathrm{S}$ nucleus has been performed through a detailed study of the ${}^{36}\mathrm{S}(p,d){}^{35}\mathrm{S}$ neutron-removal reaction, employing a 66-MeV proton beam at iThemba Laboratory for Accelerator Based Sciences and an innovative target design. Using the high-resolution $K$ = 600 magnetic spectrometer, 98 states in ${}^{35}\mathrm{S}$ were identified up to 16-MeV excitation energy, including 47 previously unobserved states. Angular distributions and spectroscopic factors, including isobaric analog-state contributions, were extracted for 81 levels. A pronounced $j$ dependence in the angular distributions of $\ell =2$ states provides refined insights into the spin-orbit splitting. Finite-range adiabatic distorted-wave approximation calculations qualitatively reproduce the observed $j$ dependence. Comparisons of the measured $1d_{5/2}$ spectroscopic strength distribution with large-scale shell-model and ab initio calculations show good agreement overall, and the robustness of the $N=20$ shell closure in ${}^{36}\mathrm{S}$ is confirmed when comparing the relatively low $fp$ orbital occupancies in ${}^{40}\mathrm{Ca}$ and ${}^{36}\mathrm{S}$ across the Fermi surface. This study underscores the utility of neutron-removal reactions in probing nuclear structure and the Fermi surface of $sd$ nuclei and beyond. The findings advance our understanding of shell evolution and offer constraining data for theoretical models.

We apply the complex-scaling method (CSM) to the $\alpha +\alpha +N$ three-body model to study the nuclear structure of ${}^9\mathrm{Be}$ and ${}^9\mathrm{B}$ nuclei, focusing mainly on mirror symmetry in the resonant states. In our previous paper [Phys. Rev. C 110, 064316 (2024)], we reported the energy-level structure below about 15 MeV excitation energy in ${}^9\mathrm{Be}$ and ${}^9\mathrm{B}$ nuclei and discussed the significant effect of the Coulomb force. In this paper, we investigate the wave functions of these states, i.e., the matter- and charge-distribution radii, and the cluster-channel amplitudes. The results show a clear mirror-symmetry breaking between ${}^9\mathrm{Be}$ and ${}^9\mathrm{B}$ nuclei, which is mainly due to the Coulomb interaction.

A direct comparison and analysis of published spectra for the $7\alpha$ disassembly of ${}^{28}\mathrm{Si}$ projectiles excited in collisions with ${}^{12}\mathrm{C}$ at 35 MeV/nucleon reveals significant agreement in the derived excitation energies of high excitation energy resonances observed in two different experiments, in contrast to some earlier conclusions reported in the literature. Many of the observed resonances have excitation energies consistent with those arrived at in recent theoretical investigations explicitly predicting the excitation energies and spins of toroidal nuclei. An artificial intelligence (AI) assisted application of well-established statistical filtering techniques reveals identical structures in all spectra investigated. Some additional peaks are observed. The possibility that they correspond to other favored geometries is discussed.

Measurements of the variation of anisotropic flow-plane angles (${\mathrm{\Psi }}_n$) with rapidity, commonly known as the flow-plane decorrelation, provide important insights into the initial conditions of the matter produced in heavy-ion collisions. In this paper, using data collected by the STAR experiment, we report the first measurement of the four-plane correlator observable $T_n\{ba;dc\}=\langle \langle sin\left[n({\mathrm{\Psi }}_n^b-{\mathrm{\Psi }}_n^a)\right]sin\left[n({\mathrm{\Psi }}_n^d-{\mathrm{\Psi }}_n^c)\right]\rangle \rangle$, where superscripts $a, b, c$, and $d$ denote sequential pseudorapidity ($\eta$) regions with $a$ corresponding to the most backward region, $b$ and $c$ close to midrapidity with ${\eta }_b<0$ and ${\eta }_c>0$, and $d$ being the most forward. The measurement is performed for the elliptic and triangular flow (i.e., $n=2$ and 3) in Au + Au and isobar (Ru + Ru, Zr + Zr) collisions at $\sqrt{s_{{}_{\mathrm{NN}}}}=200$ GeV. The goal of calculating the correlation of the flow-plane angle variations from backward to midcentral, and from midcentral to forward regions, is to probe the systematic variation of flow angle over a wide $\eta$ range. In midcentral collisions ($10–30\%$ centrality), we find $T_2\{ba;dc\}=-0.004\pm 0.001\left(\mathrm{stat}\right)\pm 0.002\left(\mathrm{syst}\right)$ independent of the collision system. Such a small value of $T_2$ favors a “random-walk” variation of the flow-plane angles, where the rapidity correlation length is smaller than the entire region under study. These measurements provide new information on the decorrelation patterns in the system and offer a quantitative estimate of possible systematic variations in anisotropic flow angles such as “twist” between forward and backward regions. This opens new opportunities for understanding the three-dimensional structure and the time evolution of the quark-gluon plasma created in heavy-ion collisions.

Ultrarelativistic collisions of heavy ions provide a rich spectrum of possibilities to discuss the response of the nucleus to photons. Newly published neutron and proton multiplicities measured in the ALICE experiment in ultraperipheral collisions allow us to investigate the influence of the electromagnetic fields on colliding nuclei for the ${}^{208}\mathrm{Pb}+{}^{208}\mathrm{Pb}$ at $\sqrt{s_{NN}}=5.02$ TeV. The theoretical predictions are done within a hybrid model including equivalent photon approximations, GiBUU modeling of preequilibrium processes, and generation of the excited nuclear remnants, where decay is modeled by a statistical approach: GEM2 or $\text{GEMINI}++$. The cross sections of the mass-charge distributions of nuclear remnants as well as the neutron, proton, and other charged particle multiplicities are estimated. We concentrate on production of protons and isotopes coming from the electromagnetic dissociation. Special attention is devoted to emission of a single proton. It is explained in the paper that cross section for $1p$ emission is very close to maximal available one based on reactions of photon with individual nucleons (protons or neutrons) inside the nucleus.

Based on the ultrarelativistic quantum molecular dynamics transport model, combined with experimental data of directed flow, elliptic flow, and nuclear stopping power measured by FOPI in ${}^{197}\mathrm{Au}+{}^{197}\mathrm{Au}$ collisions at beam energies ($E_{\mathrm{lab}}$) of 0.25 and 0.4 GeV/nucleon, the incompressibility of the nuclear equation of state $K_0$, the nucleon effective mass $m^{*}$, and in-medium correction factor ($F$, with respect to free-space values) on the nucleon-nucleon elastic cross sections are studied by Bayesian analysis. It is found that both $m^{*}$ and $F$ can be tightly constrained with the uncertainties $\le 15\%$, however, $K_0$ cannot be constrained tightly. We deduce $m^{*}/m_0=0.{78}_{-0.10}^{+0.09}$ and $F=0.{75}_{-0.07}^{+0.08}$ with experimental data at $E_{\mathrm{lab}}=0.25$ GeV/nucleon, and these values increased to $m^{*}/m_0=0.{88}_{-0.03}^{+0.03}$ and $F=0.{88}_{-0.07}^{+0.06}$ at $E_{\mathrm{lab}}=0.4$ GeV/nucleon. The obtained results are further verified with rapidity-dependent flow data.

We study light-hadron production in $\mathrm{Au}+\mathrm{Au}$ collisions at $\sqrt{s_{\mathrm{NN}}}=7.7–39\mathrm{GeV}$ using an extended Integrated HydroKinetic Model (iHKMe). Focusing on transverse momentum spectra, we investigate the sensitivity to key model parameters, particularly the thermalization timescale. We consider two distinct equations of state: one featuring a crossover and the other a first-order phase transition. In both cases, thermalization begins shortly before full nuclear overlap and lasts approximately $1\mathrm{fm}/c$ across all energies. Both equations of state provide a similarly good description of the soft particle momentum spectra once the other parameters are slightly adjusted. The most pronounced differences arise at the lower RHIC BES energy of $\sqrt{s_{\mathrm{NN}}}=7.7\mathrm{GeV}$, particularly in proton and kaon yields, reflecting their sensitivity to the freezeout parameters.

Background: Abundance calculations of $p$ nuclei require knowledge of cross sections for numerous nuclear reactions. Since measuring all relevant cross sections is unfeasible, these calculations typically rely on predictions from Hauser-Feshbach theory. The accuracy of these predictions depends on the reliability of key nuclear models: the optical model potential (OMP), nuclear level density (NLD), and $\gamma$-ray strength function ($\gamma \mathrm{SF}$).

Purpose: This study presents cross-section measurements for the ${}^{63}\mathrm{Cu}(\alpha ,\gamma ){}^{67}\mathrm{Ga}$ reaction at center-of-mass energies between $\approx 4.9$ and 8 MeV, which fully cover the Gamow window relevant to $p$-process nucleosynthesis, for typical temperatures between $1.8\times {10}^9\text{and}3.3\times {10}^9\mathrm{K}$.

Method: Experiments were performed at the Dynamitron Tandem Laboratory of Ruhr-University Bochum, Germany, using a $12\times 12\text{-in.}$ NaI(Tl) scintillator detector and the $4\pi \gamma$-summing technique.

Results: The measured ${}^{63}\mathrm{Cu}(\alpha ,\gamma ){}^{67}\mathrm{Ga}$ cross sections show very good agreement with existing data. Results were compared with calculations performed with the talys (version 2.0) nuclear reaction code.

Conclusions: The cross sections measured for the ${}^{63}\mathrm{Cu}(\alpha ,\gamma ){}^{67}\mathrm{Ga}$ reaction are in overall good agreement with previously reported cross sections measured through the activation technique. Despite limited independent data on NLDs and $\gamma \mathrm{SF}$ and the inability to isolate the $\alpha$-particle nucleus OMP, the dispersion semimicroscopic model of Demetriou et al. [P. Demetriou, C. Grama, and S. Goriely, Nucl. Phys. A 718, 510 (2003)] satisfactorily reproduces the experimental cross sections and $S$ factors without further tuning.

We study the impact of crust-core connection procedures on various neutron-star properties, especially on the tidal deformability. We consider three types of connection procedures to treat the discontinuity in a nonunified equation of state around the crust-core transition: (1) the direct connection procedure, (2) the crossover connection procedure, and (3) the segmented method. Our results indicate that the mass-radius relations of neutron stars are almost unaffected by the details of the connection procedure. However, the tidal deformabilities of neutron stars are sensitive to the crust-core connection procedures. The tidal deformability is closely related to gravitational-wave measurements. For a canonical $1.4M_{\odot }$ neutron star, uncertainties in the tidal deformability ${\mathrm{\Lambda }}_{1.4}$ from different connection procedures can exceed 20%. We find that the direct connection procedure yields significantly larger uncertainties in the tidal deformability, while the segmented method and crossover connection procedure provide relatively stable results.

The favorable energy configurations of nuclei at magic numbers of $N$ neutrons and $Z$ protons are fundamental for understanding the evolution of nuclear structure. The $Z=50$ (tin) isotopic chain is a frontier for such studies, with particular interest at and around the doubly magic ${}^{100}\mathrm{Sn}$ isotope, for which the mass is a topic of debate. Precise mass values for neutron-deficient isotopes provide necessary anchor points for mass models to test extrapolations near the proton drip line, where experimental studies remain out of reach. In this work, we report a Penning trap mass measurement of ${}^{101}\mathrm{Sn}$. The determined mass excess of $-59889.89\left(96\right)$ keV for ${}^{101}\mathrm{Sn}$ represents a factor-of-300 improvement over the current precision and indicates that ${}^{101}\mathrm{Sn}$ is less bound than previously thought. Mass predictions from a recently developed Bayesian model combination framework employing statistical machine learning and nuclear masses computed within seven global models based on nuclear density functional theory agree within $1\sigma$ with experimental masses from the $48\le Z\le 52$ isotopic chains. The framework's resilience to new mass data gave confidence in the extrapolation of tin masses down to $N=46$. Our calculations suggest that ${}^{96}\mathrm{Sn}$ is a two-proton drip line nucleus and predict a mass excess of $-58090\left(800\right)$ keV for ${}^{100}\mathrm{Sn}$, showing a preference within $1\sigma$ for the mass of ${}^{100}\mathrm{Sn}$ derived from the $\beta$-delayed $Q$ value measured at GSI.

Fusion cross sections have been measured for the asymmetric system ${}^{11}\mathrm{B}+{}^{169}\mathrm{Tm}$ at near- and deep sub-barrier energies to investigate the occurrence of fusion hindrance. Cross sections down to $\approx 200$ nb have been measured. The fusion cross sections have been compared with coupled-channels calculations. The onset of fusion hindrance appears to occur at $E_{\mathrm{c}.\mathrm{m}.}=37.0\pm 1.5$ MeV, where a deviation in the slope of the experimental logarithmic derivative of $E\sigma$, compared to that of the coupled-channels calculations, has been observed. The adiabatic model with a Yukawa-plus-exponential potential and damping of coupling effects can reproduce the data at deep sub-barrier energies. The damping parameters for the present system are consistent with previous observations for far-asymmetric systems. Although the present system has a permanently deformed rotational rare-earth target nucleus, the extracted damping parameters are closer to those of stiff asymmetric systems such as ${}^{16}\mathrm{O}+{}^{208}\mathrm{Pb}$ and ${}^{48}\mathrm{Ca}+{}^{96}\mathrm{Zr}$, compared to the systems with vibrational target nuclei ${}^{11}\mathrm{B}+{}^{197}\mathrm{Au}$ and ${}^{12}\mathrm{C}+{}^{198}\mathrm{Pt}$. This may indicate a different trend of damping for rotational couplings, compared to the damping of vibrational couplings. More measurements of deep sub-barrier fusion with permanently deformed rare-earth target nuclei could help clarify the fundamental difference between the damping of rotational and vibrational couplings in the deep sub-barrier region.

The ${}^{244}\mathrm{Pu}({}^{48}\mathrm{Ca},xn){}^{292-x}\mathrm{Fl}$ reaction was investigated at Lawrence Berkeley National Laboratory’s 88 Inch Cyclotron using the Berkeley Gas-filled Separator (BGS), the newly installed Superheavy Recoil detector, along with an upgraded digital electronics and data acquisition system. Seven decay chains were observed starting with an evaporation residue, followed by a single $\alpha$ decay and a spontaneous fission. The decay characteristics of these seven decay chains led to an assignment to ${}^{288}\mathrm{Fl}$, the product of the $4n$ reaction channel. Two additional chains were (tentatively) assigned to the decay of the $3n$ exit channel, ${}^{289}\mathrm{Fl}$. Cross sections for the $4n$ and $3n$ exit channels were ${\sigma }_{\mathrm{prod}}=6.7{(}_{25}^{36})$ pb and ${\sigma }_{\mathrm{prod}}=1.6{(}_{11}^{22})$ pb, respectively. Another decay chain, tentatively assigned to the $5n$ exit channel through the ${}^{48}\mathrm{Ca}+{}^{244}\mathrm{Pu}$ reaction or the $3n$ exit channel of the ${}^{48}\mathrm{Ca}+{}^{242}\mathrm{Pu}$ reaction, was also detected. Detailed information regarding the observed decay chains and their nuclear structure aspects is discussed, along with the performance of the BGS and the new detection system.

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.