The contrast between the as-yet unmeasurable energy-loss effects in proton-nucleus collisions and the striking magnitude of the so-called high-momentum flow coefficients challenges our understanding of jet quenching mechanisms in large nucleus-nucleus collisions when applied to smaller systems. Intermediate-sized, light ion collisions will offer key insight into the system-size dependence of the interplay between jet energy loss and jet flow effects. To make quantitative predictions, we extend a semianalytic jet quenching framework by coupling it to state-of-the-art event-by-event hydrodynamics and, for the first time, incorporate pre-equilibrium energy loss via the hydrodynamic attractor. A Bayesian analysis shows that an early-time onset of energy loss is compatible with BNL Relativistic Heavy Ion Collider and CERN Large Hadron Collider measurements of jet suppression and jet elliptic flow in large systems, as well as hadron suppression, with the exception of hadron elliptic flow. Using these constraints, we predict both hadron and jet quenching observables in oxygen-oxygen collisions, finding sizable energy loss that exceeds the no-quenching baseline.

The chiral magnetic effect (CME) in relativistic heavy-ion collisions originates from a chirality imbalance among quarks within metastable QCD vacuum domains and may be linked to charge-parity violation, which is believed to play a crucial role in the matter-antimatter asymmetry of the universe. Over the past two decades, extensive experimental efforts at the BNL Relativistic Heavy Ion Collider (RHIC) and the CERN Large Hadron Collider have been devoted to the search for evidence of the CME. Recent advances have greatly improved our understanding of background contributions that can mimic CME-like signals. In particular, analyses utilizing techniques designed to suppress flow-related backgrounds indicate that the CME signal at the RHIC, if present, is small. To further investigate potential background sources, particularly those associated with strong electromagnetic fields, we estimate the contribution from coherent photon-nuclear interactions. These interactions are driven by intense electromagnetic fields produced in ultrarelativistic heavy-ion collisions, with cross sections that scale with the field strength. Notably, the polarization of the incident photons is aligned with the electric field, which is oriented along the impact parameter direction and perpendicular to the magnetic field. Consequently, such processes can generate charge-dependent correlations that mimic key features of the CME signal, yet originate from different physics mechanisms and are distinct from flow-induced backgrounds. In this study, we quantitatively assess the influence of these coherent photon-nuclear interactions on the precision measurement of the CME, aiming to improve the separation of the genuine CME signal from these background contributions.

We investigate the inclusive $J/\psi$ production in proton-proton $\left(pp\right)$ collisions at center-of-mass energies $\sqrt{s}=5.02$, 7, and 13 TeV using the parton and hadron cascade model PACIAE 4.0. This model extends PYTHIA 8.3 by incorporating partonic and hadronic rescatterings before and after hadronization, respectively. Compared to our earlier study [K.-F. Ye et al., Phys. Rev. C 109, 035201 (2024)], which considered only the color-singlet processes, the present work includes both the color-singlet and color-octet contributions within the nonrelativistic QCD (NRQCD) framework. In addition to the NRQCD, we also consider the contributions from the cluster collapse and weak decays of $b$ hadrons. We find that the simulated inclusive $J/\psi$ transverse momentum differential cross sections agree well with the experimental data at both the middle and forward rapidities. We provide a quantitative analysis of the relative contributions for different production mechanisms and their energy and rapidity dependence in the inclusive $J/\psi$ production. Furthermore, we offer a quantification of the relative contributions of the various components and their energy and rapidity dependence in the NRQCD channels, including the direct production via the hard scattering and the feed-down from the decays of heavier charmonium states such as $\psi \left(2S\right)$, ${\chi }_{c0}$, ${\chi }_{c1}$, and ${\chi }_{c2}$. Finally, we examine the effects of partonic and hadronic rescatterings and offer the quantitative estimate of their impact on the $J/\psi$ production. These results are entirely new and represent a significant step forward in understanding the mechanisms of the inclusive $J/\psi$ production in high-energy $pp$ collisions.

We present a theoretical description of proton radioactivity in ${}^{149}\mathrm{Lu}$, the most oblate deformed proton emitter known, by combining a deformed microscopic optical potential derived from ab initio nuclear matter calculations with the Wentzel-Kramers-Brillouin penetration probabilities and the assault frequency of the emitted proton estimated through a new harmonic-oscillator-inspired scheme. We predict a novel angular-dependent phenomenon unprecedented in spherical proton emitters: the disappearance of classically allowed regions at small polar angles $(\theta \le {21}^{\circ })$. Our framework yields a half-life $T_{1/2}={467}_{-108}^{+143}\mathrm{ns}$ for ${}^{149}\mathrm{Lu}$, in excellent agreement within uncertainties with the experimental value ${450}_{-100}^{+170}\mathrm{ns}$. Deformation analysis rigorously excludes configurations with $|{\beta }_2|\ge 0.32$. Extensions to ${}^{150,151}\mathrm{Lu}$ and their isomers also achieve excellent agreement with experimental half-life data. We further predict ${}^{148}\mathrm{Lu}$ as another highly oblate $({\beta }_2=-0.166)$ proton emitter with a half-life $T_{1/2}=4.42\mathrm{ns}$. This work validates deformed microscopic optical potentials as a robust predictive tool for drip-line proton emitters and provides quantitative evidence for deformation effects in exotic decays.

Solid ortho-deuterium is a widely used converter material in ultracold-neutron (UCN) sources. Although it has been studied with neutrons for more than two decades, some of its scattering properties remain poorly understood until this day. We remeasured the total scattering cross section of solid deuterium for ultracold neutrons and—as an improvement over previous experiments—eliminated side effects by employing low-roughness, transparent sample container windows. In this paper, we show the decomposition of the total scattering cross section into its constituents: incoherent elastic scattering, one-phonon up-scattering (using the corrected incoherent approximation), and coherent scattering from crystal defects. Applying both the Guinier approximation and a model using a spherical form factor to describe the defects, we were able to quantify the size and concentration of defects in the deuterium crystal at two different temperatures. Surprisingly, they account for about half of the total scattering cross section. Our work challenges the current picture of ultracold-neutron scattering in solid ortho-deuterium and explains the inability of state-of-the-art simulations to reproduce earlier experimental results. It represents a crucial step toward reliable scattering kernels for the planning of new UCN sources. Ultimately, our measurements allow to deduce the mean free path of UCNs in solid ortho-deuterium, which is 2.5 to 3.5 cm in the relevant temperature range and for a neutron velocity of 10 m/s. The optimal operating temperature for UCN converters is deduced to be between 10 and 12 K, contrary to the 5 K accepted hitherto.

We show that the maximum likelihood estimator (MLE) is an effective tool for mitigating nonflow effects in flow analysis. To this end, one constructs two toy models that simulate nonflow contributions corresponding to particle decay and momentum conservation, respectively. The performance of MLE is analyzed by comparing it against standard approaches such as particle correlation and event plane methods. For both cases, MLE is observed to provide a reasonable estimate of the underlying flow harmonics, and, in particular, its performance can be further improved when the specific form of the likelihood in the presence of nonflow can be assessed. The dependencies of extracted flow harmonics on the multiplicity of individual events and the total number of events are analyzed. Additionally, it is shown that the proposed approach performs efficiently in addressing deficiencies in detector acceptance. These findings suggest that MLE is a compelling alternative to standard methods for flow analysis.

The BUQEYE model for correlated effective-field theory (EFT) truncation errors assumes a regular pattern of dimensionless coefficients extracted from order-by-order observable calculations. This enables results from lower orders to inform statistical predictions for error estimates of omitted higher orders. We test the model for multiple chiral EFT $\left(\chi \mathrm{EFT}\right)$ nucleon-nucleon (NN) potentials using a suite of six common NN scattering observables represented as functions of relative momentum and scattering angle. First, we flag irregularity in the convergence patterns of potentials with so-called “soft” regulator scales, namely, that the sizes of the coefficients in the observables' expansions are mismatched between the even and odd orders. Second, we test the BUQEYE model's assumption of Gaussian process (GP) stationarity against the data and find that the GP's correlation structure, as encoded in its length scale, is nonstationary: The GP length scale in the angular dimension ${\ell }_{\theta }$ is approximately inversely proportional to the relative momentum of the scattering process. After we remediate this issue by allowing ${\ell }_{\theta }$ to vary with momentum, diagnostics show significant improvement, validating the application of the BUQEYE model after this modification. Third, we find that the good performance of the BUQEYE model relies on properly choosing the $\chi \mathrm{EFT}$ breakdown scale ${\mathrm{\Lambda }}_b$. With $m_{\mathrm{eff}}$ held fixed at the physical pion mass, we find ${\mathrm{\Lambda }}_b=600–750$ MeV for various $\mathrm{N}{}^3\mathrm{LO}$ interactions. Statistically consistent distributions for ${\mathrm{\Lambda }}_b$ across orders are only found for the semi-local momentum-space potential at a regulator scale of 450 or 500 MeV. All our results can be reproduced using a publicly available Jupyter notebook, which can be straightforwardly modified to analyze other $\chi \mathrm{EFT}$ NN potentials.

The rotational spectroscopic properties and the evolution of the octupole deformation with spin in ${}^{224}\mathrm{Ra}$ are investigated by using the cranking relativistic density functional theory on a three-dimensional lattice space together with the shell-model-like approach to introduce the pairing correlations. The available experimental data, including the $I\text{−}\omega$ relation and the electric transition probabilities $B\left(E2\right)$ and $B\left(E3\right)$, are well reproduced after introducing the pairing correlations. The average value of the calculated octupole deformation with (without) pairing correlations for the observed spin region ($I\le 28\hslash$) is approximately 0.124 (0.129), indicating the robustness of the octupole collectivity with the nuclear rotation in ${}^{224}\mathrm{Ra}$. It is found that the pairing correlations effect induces a more rigid octupole shape for ${}^{224}\mathrm{Ra}$ at the ground state $(\hslash \omega =0.00 \mathrm{MeV})$, while it becomes less pronounced with the increase of the rotational frequency.

Short-range correlation (SRC) in nuclei refers to nucleons forming temporally correlated pairs in close proximity, giving rise to the high momentum of the nucleons beyond the Fermi surface. It has been reported that bremsstrahlung $\gamma$ production from the neutron-proton process in heavy-ion reactions provides a potential probe to the SRC abundance in nuclei. In this paper, we present in detail the precision measurement of bremsstrahlung $\gamma$ rays in ${}^{124}\mathrm{Sn}+{}^{124}\mathrm{Sn}$ reactions at 25 MeV/nucleon using the Compact Spectrometer for Heavy IoN Experiment (CSHINE). A comprehensive experimental and analysis framework is established to ensure the reliability and robustness of the extracted results. Background contributions are evaluated and subtracted using independent methods, and the consistency of the analysis is systematically validated. By comparing the experimental $\gamma$ spectrum with isospin-dependent Boltzmann-Uehling-Uhlenbeck simulations, the high momentum tail (HMT) fraction of $R_{\mathrm{HMT}}=(20\pm 3)\%$ is derived in ${}^{124}\mathrm{Sn}$ nuclei. This work provides a detailed and validated experimental framework for extracting SRC information from bremsstrahlung $\gamma$-ray emission and demonstrates the feasibility of studying nucleon SRCs with high precision in low-energy heavy-ion collisions.

Recent experiments have shown that the mean transverse momentum $\langle p_T\rangle$ of outgoing particles increases as a function of the particle multiplicity in ultracentral nucleus-nucleus collisions at collider energies. This increase was originally predicted on the basis of simulations where the multiplicity increase occurred at constant volume, so that it implied a larger density and temperature. However, recent state-of-the-art simulations have shown that, for some models of initial condition, the volume may vary with the multiplicity in ultracentral collisions. We elucidate this effect by analytically relating the variation of the volume to the radial distribution of the one- and two-point functions of the fluctuating density field. We show that the volume variation is small if the total entropy of the ultracentral collisions scales with the mass number of the colliding isotopes. We argue that probing detailed transverse distributions of initial-state fluctuations through the ultracentral $\langle p_T\rangle$ has nontrivial implications for models of nuclear structure and of the pre-equilibrium stages.

The STAR Collaboration has reported a significant $\varphi$-meson global spin alignment $\left({\rho }_{00}\right)$ signal in $\mathrm{Au}+\mathrm{Au}$ collisions at $\sqrt{s_{NN}}\le 62$ GeV by measuring the polar angle distribution of $\varphi$-meson daughters with respect to the orbital angular momentum direction of the collision system. In this paper, a new method is explored for studying vector-meson global spin alignment in heavy-ion collisions by examining the two-dimensional (2D) polar and azimuthal angle distribution. This method allows simultaneous extraction of ${\rho }_{00}$ and off-diagonal spin density matrix elements (SDMEs), providing unique access to local quark-antiquark spin correlations and spin hydrodynamics in quark-gluon plasma. The new 2D method also removes potential biases from nonzero off-diagonal SDMEs on ${\rho }_{00}$ with the 1D method. A detailed procedure to correct for detector acceptance and resolution effects is also presented and validated by simulation studies.

Based on the eigenvector continuation, which is mathematically an instance of the reduced basis method (RBM), we construct an emulator for coupled-channels calculations for heavy-ion fusion reactions at energies around the Coulomb barrier. We apply this to the ${}^{16}\mathrm{O}+{}^{144,154}\mathrm{Sm},{}^{186}\mathrm{W}$ reactions and examine whether the emulator can be used to extract the deformation parameters of the target nuclei. We show that the emulator not only accelerates the calculations but also has an ability to accurately extract the nuclear shapes. This indicates that the emulator provides a powerful tool to systematically explore intrinsic shapes of atomic nuclei, enhancing our understanding of the fundamental properties of nuclear systems.

The quasielastic cross sections of charged-current neutrino and antineutrino scattering on ${}^{12}\mathrm{C}$ are calculated using the coherent density fluctuation model with a relativistic effective mass $m_N^{*}=0.8m_N$ $\left({\mathrm{CDFM}}_{M^{*}}\right)$. The model explicitly considers the modification of the relativistic effective mass of the nucleon within the relativistic mean-field (RMF) model of nuclear matter. In addition, our calculations include neutrino-induced two-particle emission processes, which are evaluated within the RMF model of nuclear matter. Utilizing the ${\mathrm{CDFM}}_{M^{*}}$, we provide predictions for the neutrino and antineutrino cross sections of ${}^{12}\mathrm{C}$, which have been observed in accelerator experiments, such as MiniBooNE, T2K, and MINERvA. Also, we analyze the axial form-factor value for the excitation of the $\mathrm{\Delta }$ at zero momentum transfer [commonly denoted as $C_5^A\left(0\right)$] which is important for the treatment of the $\mathrm{\Delta }$ current in the meson-exchange currents (MEC) calculation. In addition, the quasielastic results obtained within ${\mathrm{CDFM}}_{M^{*}}$ model are thoroughly evaluated for different regions of the momentum transfer.

The nuclear level density and the $\gamma$-ray strength function of the neutron-deficient ${}^{109}\mathrm{In}$ isotope were extracted for the first time with data from the ${}^{106}\mathrm{Cd}(\alpha ,p\gamma ){}^{109}\mathrm{In}$ reaction using a combination of the Oslo and the shape methods. Both quantities are consistent with those of neighboring Cd and Sn nuclei but show substantial discrepancies with currently available model predictions. In contrast to earlier observations in the neighboring isotopic chains, ${}^{109}\mathrm{In}$ does not exhibit any significant enhancement of the dipole strength near the neutron separation energy. To interpret this feature, random-phase time-blocking approximation calculations have been performed for ${}^{109}\mathrm{In}$ and the neighboring ${}^{110,112}\mathrm{Sn}$ nuclei. The experimental data were also employed to estimate cross sections and rates of the radiative neutron- and proton-capture reactions, ${}^{108}\mathrm{In}(n,\gamma ){}^{109}\mathrm{In}$ and ${}^{108}\mathrm{Cd}(p,\gamma ){}^{109}\mathrm{In}$, respectively, with the reaction code talys. Our ($p,\gamma )$ cross section is in excellent agreement with direct measurements over a wide range of proton energies, while the ($n,\gamma )$ cross section demonstrates notable deviations from predictions in the jina reaclib library. The new results on the statistical properties of ${}^{109}\mathrm{In}$ provide valuable constraints that may help address the problem of large model uncertainties compromising the accuracy of astrophysical $p$-process simulations.

States in the neutron-rich isotope ${}^{51}\mathrm{Ca}$ were populated via the ${}^{50}\mathrm{Ca}(d,p)$ transfer reaction in inverse kinematics at a beam energy of about $14A\mathrm{MeV}$. The experiment was performed using a decelerated radioactive ${}^{50}\mathrm{Ca}$ beam from the OEDO facility and the TiNA2 silicon array in combination with the SHARAQ magnetic spectrometer at RIBF/RIKEN. The energies of excited states in ${}^{51}\mathrm{Ca}$ were reconstructed via missing mass spectroscopy, and angular distributions of protons were measured to extract differential cross sections. From a comparison with adiabatic distorted wave approximation calculations, spectroscopic factors were deduced for several states, including the ground state and excited states up to 4.2 MeV. These results are compared with shell-model calculations, as well as ab initio valence-space in-medium similarity renormalization group predictions. The data support the assignment of the $1/2^{-}$ and $5/2^{-}$ single-particle states and provide evidence for a candidate $9/2^{+}$ state with a structure consistent with neutron excitation into the $0g_{9/2}$ orbital. These findings contribute new constraints on the single-particle structure and shell evolution in neutron-rich calcium isotopes.

This is an addendum to the article “Electromagnetic moments of ground and excited states calculated in heavy odd-$N$ open-shell nuclei” published in Phys. Rev. C 113, 024306 (2026). We update Table I by adding the column reporting the works by E. F. Zhou et al.

We present a systematic investigation of particle-number fluctuations in the crossover region near the critical end point of a first-order phase transition using molecular dynamics simulations of the classical Lennard-Jones fluid. We extend our prior studies to third- and fourth-order cumulants in both coordinate- and momentum-space acceptances and integrated correlation functions (factorial cumulants). We find that, even near the critical point, non-Gaussian cumulants equilibrate on timescales comparable to those of the second-order cumulants, but show stronger finite-size effects. The presence of interactions and of the critical point leads to strong deviations of the cumulants from the ideal-gas baseline in coordinate space; these deviations are expected to persist in momentum space in the presence of collective expansion. In particular, the kurtosis becomes strongly negative, $\kappa {\sigma }^2\ll -1$, on the crossover side of the critical point. However, this signal is significantly diluted once an efficiency cut used to distinguish protons from baryons is applied, leading to $|\kappa {\sigma }^2|\lesssim 1$ even in the presence of the critical point. We discuss our results in the context of ongoing measurements of proton-number cumulants in heavy-ion collisions in RHIC-BES-II.

This article presents the formulation and numerical implementation of a time-independent wave-packet (TIWP) asymptotic projection scheme for extracting sharp-energy rearrangement and breakup $S$ matrices from wave-packet solutions of the time-dependent Faddeev equations. The TIWP scheme is based on time-to-energy transforms of the numerically propagated interacting and free wave packets and allows the extraction of scattering observables in energy space. The time-dependent Faddeev equations are solved in momentum space for a given initial wave packet using finite-element-type discretizations of the Jacobi momenta in terms of local basis functions and a central-difference scheme for time propagation. Concurrently with the step-by-step numerical time evolution of the wave packet, its time-to-energy-transform is accumulated by trapezoidal rule to be obtained at selected values of the energy. Projection of the time-to-energy transform of the post-collision wave packet on the two-particle bound and continuum states yield sharp-energy rearrangement and breakup $S$ matrices, respectively. Rearrangement and breakup amplitudes over a wide range of collision energies are obtained from a single wave-packet propagation. For benchmark three-body models, rearrangement $S$ matrices are found to be in very good quantitative agreement with reference time-independent calculations. For breakup, the TIWP scheme reproduces the main qualitative features of the breakup amplitudes, although the numerical accuracy is presently limited by discretization and asymptotic-time constraints.

Excited states of ${}^{209}\mathrm{Ac}$ and ${}^{207}\mathrm{Ac}$ were observed, for the first time, by employing a highly selective recoil-decay tagging method and the recoil ion transport unit (RITU) gas-filled recoil separator. The nuclei were produced in the ${}^{180}\mathrm{Hf}({}^{35}\mathrm{Cl}, 6n){}^{209}\mathrm{Ac}$ and ${}^{175}\mathrm{Lu}({}^{36}\mathrm{Ar},4n){}^{207}\mathrm{Ac}$ fusion-evaporation reactions. The ${}^{209}\mathrm{Ac}$ isotope was studied using in-beam spectroscopy. Prompt $\gamma$ rays were observed by the JUROGAM3 Ge-detector array and a level scheme was deduced. The ${}^{207}\mathrm{Ac}$ isotope was probed at the focal plane spectrometer of the separator and a $13/2^{+}$ ($\pi i_{13/2}$) isomeric state was observed for the first time in any $N\le 126$ actinium isotope.

Within the framework of the two-center shell model, the influence of excitation energy and spin-orbit interaction on the potential energy surface and, accordingly, on the axially symmetric and mass-symmetric static fission paths selected on the basis of potential energy surfaces is considered. The relationship between the decay of shell corrections in the ground state and at the saddle point and the conservation of the fission barrier at moderate excitation energies of superheavy nuclei with atomic numbers $Z=108$, 114, 116, and 120 formed in a hot complete fusion reaction is discussed.