During core helium and carbon burning in massive stars, neutrons are produced mainly by the ${}^{22}\mathrm{Ne}(\alpha ,n){}^{25}\mathrm{Mg}$ reaction. Some of these released neutrons are captured by heavy seed nuclei from previous nucleosynthesis events, resulting in the slow production of many of the elements between masses 60 $\le A\le$ 90 via the weak $s$ process. Determining the overall neutron flux available in this environment is one of the main challenges in modeling its contributions to heavy element production. Not only must the reaction rate be well defined for the primary neutron source, but the rates of neutron poison and recycling reactions must also be well determined. One critical reaction in the simulation network is ${}^{25}\mathrm{Mg}(\alpha ,n){}^{28}\mathrm{Si}$. This reaction, together with ${}^{25}\mathrm{Mg}(n,\gamma ){}^{26}\mathrm{Mg}$ and ${}^{25}\mathrm{Mg}(\alpha ,\gamma ){}^{29}\mathrm{Si}$, determine how ${}^{25}\mathrm{Mg}$ nuclei affect the available neutron flux. Past attempts to measure the ${}^{25}\mathrm{Mg}(\alpha ,n){}^{28}\mathrm{Si}$ cross section using neutron moderator counters have been greatly hindered by lower-$Z$ background reactions. In the present work, neutron spectroscopy with deuterated liquid scintillator detectors has been used. The experimental spectra have been analyzed by applying spectrum unfolding techniques to achieve improved background discrimination for the ${}^{25}\mathrm{Mg}(\alpha ,n){}^{28}\mathrm{Si}$ reaction at low energies, down to $E_{\alpha }=1.75$ MeV. The separation of the different background contributions gives further insight into the results of previous moderator counter measurements and the measurements lead to a revised and more reliable determination of the reaction rate.

Machine learning techniques have emerged as powerful tools for tackling nonperturbative challenges in quantum chromodynamics. In this study, we introduce a data-driven framework employing deep neural networks to systematically predict the temperature-dependent behavior of the screening mass $m_D\left(T\right)$ and the strong coupling constant ${\alpha }_s\left(T\right)$ within a quark-gluon plasma medium. These medium-sensitive quantities are subsequently employed to compute the thermal widths ${\mathrm{\Gamma }}_{\text{n}}\left(T\right)$ and binding energies $E_B\left(T\right)$ of heavy quarkonia states, specifically charmonia and bottomonia, by numerically solving the Schrödinger equation with medium-modified heavy quark potentials. To estimate the dissociation temperatures $T_d$ of various quarkonia states, we employ two complementary dissociation criteria: the conventional one, where $2E_B\left(T_d\right)={\mathrm{\Gamma }}_{\text{n}}\left(T_d\right)$, and an additional lower bound criterion defined by $E_B\left(T_d\right)=3T_d$. This dual-criterion approach provides a more constrained and physically motivated estimate of the temperature range over which quarkonia states dissolve in the quark-gluon plasma (QGP) environment. Our machine learning-enhanced predictions show excellent agreement with available lattice quantum chromodynamics results, especially for the ground states $\mathrm{{\rm Y}}\left(1S\right)$ and $J/\psi$, and offer new perspectives on the sequential suppression pattern detected in relativistic heavy-ion collision experiments. Overall, this work advances the quantitative description of quarkonium suppression and demonstrates the prospect of modern machine learning methods to bridge theoretical predictions and experimental observations, thereby contributing significantly to QGP tomography.

In this work, we present new phenomenological extractions of the nucleon charge and magnetic radii based on its Dirac and Pauli flavor-separated $F_{(1,2)}^{(u,d)}\left(Q^2\right)$ form factors, over the extended range 0.0155 $<Q^2<$ 1.00 ${\mathrm{GeV}}^2$. Building upon the framework introduced by M. A. Albloushi et al. [Phys. Rev. C 109, 065201 (2024)] for the charge sector, the present study extends the analysis to include the magnetic radii, expands the fit procedure to ten overlapping $Q^2$ ranges, and employs a correlation-aware Generalized Least Squares (GLS) framework to quantify inter-range correlations. Both two-photon-exchange (TPE) corrected and uncorrected datasets are analyzed, and the impact of including or neglecting TPE corrections on the extracted radii is systematically investigated. In the TPE-corrected GLS analysis we obtain ${\langle r_p\rangle }_E=0.8478\pm 0.{0015}_{\text{(stat.)}}\pm 0.{0034}_{\text{(sys.)}}$ fm, ${\langle r_n^2\rangle }_E=-0.0885\pm 0.{0018}_{\text{(stat.)}}\pm 0.{0019}_{\text{(sys.)}}$ ${\mathrm{fm}}^2$, ${\langle r_p\rangle }_M=0.8468\pm 0.{0008}_{\text{(stat.)}}\pm 0.{0139}_{\text{(sys.)}}$ fm, and ${\langle r_n\rangle }_M=0.8935\pm 0.{0011}_{\text{(stat.)}}\pm 0.{0300}_{\text{(sys.)}}$ fm. The proton charge radius agrees with the ultrahigh precise muonic hydrogen ($\mu \mathrm{H}$) Lamb shift and PRad-I results and is smaller than the Mainz A1 extraction, while the neutron charge radius is below in magnitude the value obtained by the recent precise measurements of the neutron $G_E^n\left(Q^2\right)$ form factor at low $Q^2$ utilizing the connection between the $N\to \mathrm{\Delta }$ quadrupole transitions and $G_E^n\left(Q^2\right)$. The magnetic radii are compatible with global dispersion, lattice-QCD constrained, and TPE-aware analyses, with ${\langle r_p\rangle }_M$ and ${\langle r_n\rangle }_M$ differing by $\approx$ 5%, in accord with SU(6) spin-flavor symmetry expectations. These findings demonstrate that implementing TPE corrections within a correlation-aware GLS framework yields a statistically robust, phenomenological description of the nucleon's electromagnetic structure.

We investigate the radiative decay of fragments populated in neutronless spontaneous fission of ${}^{252}\mathrm{Cf}$, accurately identified using the double-energy method. The present study focuses on the ${}^{118}\mathrm{Pd}/{}^{134}\mathrm{Te}$ channel for which we measure the total excitation-energy distribution. The properties of the gamma-ray spectrum associated with this channel, and its evolution with total excitation energy, allow us to extract the excitation-energy and spin distributions at scission for each fragment. We find that the heavy fragment remains weakly excited, most of the excitation energy being carried away by its light partner. A sizable width of about 1.3 MeV in the excitation-energy distribution is required to reproduce the data. The evolution with excitation energy of the spin-cutoff parameter of the fragments is well accounted for by a temperature law incompatible with large angular-momentum removal by neutrons. Comparison with calculations performed with the microscopic scission-point model spy shows that it underestimates the deformation of the light fragment and supports the orientation-pumping mechanism for angular-momentum generation in fission.

Experimental and theoretical studies of photonuclear reactions on a natural mixture of erbium isotopes were performed. The cross sections per equivalent photon and the yields of photonuclear reactions were measured using bremsstrahlung γ radiation with an end-point energy of 55 MeV. The cross sections for photoproton reactions on a natural mixture of erbium isotopes were obtained for the first time. The experimental results are compared with calculations based on the combined model of photonucleon reactions and simulations using the TALYS 2.0 code with different photon strength functions. Theoretical calculations within the combined model of photonucleon reactions included contributions from various mechanisms of $\gamma$-ray interaction with the nucleus: the giant dipole resonance accounting for its isospin splitting and overtone, the isovector quadrupole resonance, and the quasideuteron mechanism of photoabsorption. Additionally, the radiochemical yields of reactions on a natural mixture of erbium isotopes, leading to the formation of the target medical isotope ${}^{166}\mathrm{Ho}$ and by-product nuclides, were determined.

Anisotropic flows in heavy-ion collisions provide a basic experimental observable to understand nuclear collision dynamics and to constrain the dense nuclear matter equation of state (EOS). Within the framework of the lattice Boltzmann-Uehling-Uhlenbeck transport model, we present a systematic study of proton anisotropic flow observables measured by the HADES Collaboration, by utilizing the recently developed nuclear effective interaction based on the density-, momentum-, and isospin-dependent N5LO Skyrme pseudopotential. In particular, we investigate the impacts of the momentum dependence of nucleon mean-field potentials, the stiffness of the symmetric nuclear matter (SNM) EOS, the high-density behaviors of the symmetry energy, and the in-medium modification of nucleon-nucleon elastic cross sections on proton directed ($v_1$), elliptic ($v_2$), triangular ($v_3$), and quadrangular ($v_4$) flows in $\mathrm{Au}+\mathrm{Au}$ collisions at $\sqrt{s_{NN}}=2.4\text{GeV}$. Our results show that the proton anisotropic flows are strongly sensitive to the momentum dependence of the nucleon mean-field potential as well as the incompressibility coefficient $K_0$ of SNM. In addition, the transverse momentum dependence of the proton $v_2$ exhibits a modest sensitivity to the higher-order skewness coefficient $J_0$ and kurtosis coefficient $I_0$ of SNM as well as the momentum dependence of the symmetry potential, while the transverse momentum dependence of the proton $v_1$ is shown to modestly depend on the in-medium modification of nucleon-nucleon elastic cross sections. Moreover, the high-density symmetry energy seems to have limited effects on the proton anisotropic flows. These findings highlight the necessity of considering the momentum dependence of nucleon mean-field potentials including the symmetry potential, the higher-order characteristic parameters of the SNM EOS beyond $K_0$, and the in-medium modification of nucleon-nucleon elastic cross sections, in future Bayesian transport model analyses on proton anisotropic flows in heavy-ion collisions at HADES energies, for the purpose of extracting information on the nuclear matter EOS as well as the associated underlying nuclear effective interactions.

I present a fully microscopic description of the ${}^{12}\mathrm{C}+{}^{12}\mathrm{C}$ fusion reaction at stellar energies. Utilizing the multichannel resonating group method (RGM), my model explicitly includes ${}^{12}\mathrm{C}+{}^{12}\mathrm{C}$ and $\alpha {+}^{20}\mathrm{Ne}$ reaction channels (with excited states). This approach provides a consistent, simultaneous description of fusion, elastic scattering, and ${}^{24}\mathrm{Mg}$ spectroscopy. Results for ${}^{12}\mathrm{C}+{}^{12}\mathrm{C}$ elastic scattering show excellent agreement with experimental data, significantly improving the single-channel approximations. Spectroscopic analysis reveals that ${}^{24}\mathrm{Mg}$ states and resonances are highly mixed configurations, contradicting the concept of pure “molecular states.” The calculated fusion $S$ factor is consistent with available experimental data and predicts both narrow and broad resonances near the Coulomb barrier. Main resonance widths originate primarily from the $\alpha +{}^{20}\mathrm{Ne}$ exit channels. The $S$ factor exhibits a decrease at low energies, providing a microscopic support for the hypothesis of fusion hindrance. This work is a first step toward a reliable theoretical extrapolation of the ${}^{12}\mathrm{C}+{}^{12}\mathrm{C}$ reaction to deep stellar burning temperatures. Future works should include the neutron and proton channels to provide a complete description of the ${}^{12}\mathrm{C}+{}^{12}\mathrm{C}$ fusion.

The present work investigates the causal parameter space of the Mueller-Israel-Stewart second-order theory for heat-conducting fluids in the Eckart frame for one-dimensional fluid flow in systems with finite baryon density. It is shown that this parameter space is highly constrained and particularly sensitive to the equation of state and second-order transport coefficients. Through numerical analysis of the characteristic equations, the present analysis identifies regions of strong hyperbolicity, weak hyperbolicity, and nonhyperbolicity, mapping the boundaries of causality violation as functions of the heat flux to energy density ratio $q/\varepsilon$ and relaxation parameters. The present work also explores the causality conditions using a realistic lattice QCD based equation of state. Using the Navier-Stokes approximation, an estimate is made of the heat flow magnitude to assess causality criteria for one-dimensional heat conduction in heavy-ion collisions. The present calculations reveal unrealistically large heat flux values ($\left|\mathbf{q}\right|/\varepsilon \approx 330–811$) for typical conditions at the BNL Relativistic Heavy Ion Collider when using thermal conductivity estimates from kinetic theory models, suggesting either significant overestimation of transport coefficients or breakdown of the fluid approximation in these extreme conditions. The pressure gradient corrections reduce the heat flow by approximately 15% but do not resolve the causality concerns.

We study how the inclusion of energy dependence as dictated by quantum chromodynamic (QCD) small-$x$ evolution equations affects key observables in ultrarelativistic heavy-ion collisions. Specifically, we incorporate JIMWLK evolution into the IP-Glasma framework, which serves as the initial condition for a simulation pipeline that includes viscous relativistic hydrodynamics and a hadronic afterburner. This approach enables a consistent modeling of highly energetic nuclei across varying Bjorken-$x$ values, which are relevant for different collision energies and rapidity regions. In comparison to the standard IP-Glasma setup without small-$x$ evolution, we observe pronounced changes in particle multiplicities and spectral distributions, especially in smaller systems and at the highest available energies. We further explore effects on anisotropic flow observables and correlations between mean transverse momentum and elliptic flow. Our findings underscore the critical role of nonlinear QCD evolution in accurately modeling the early stages of heavy-ion collisions, as well as its implications for extracting transport properties of the quark-gluon plasma.

We introduce a dilated coordinate method to address computational challenges in nuclear lattice effective field theory for weakly bound few-body systems. The approach employs adaptive mesh refinement via analytic coordinate transformations, dynamically adjusting spatial resolution to resolve short-range nuclear interactions with fine grids while efficiently capturing long-range wave function tails with coarse grids. Numerical demonstrations for two- and three-body systems confirm accelerated convergence towards infinite-volume limit compared to uniform lattices, particularly beneficial for accessing highly excited states and shallow bound states near the continuum threshold. This method establishes a foundation for ab initio studies of exotic nuclear systems near the dripline and light hypernuclei, with direct extensions to scattering and reaction processes.

Discretizing the Dirac equation on a uniform grid with the central difference formula often generates spurious states. We propose a staggered-grid scheme in the framework of the finite-difference method that suppresses these spurious states without introducing Wilson terms or $\mathit{ad}$ hoc filtering. In this approach, the large and small components of the Dirac equation are placed on interlaced nodes, and the first-order derivatives are evaluated between staggered points, yielding a Hamiltonian that breaks the unitary transformation between $H_{\kappa }$ and $H_{-\kappa }$. Benchmarks with the nuclear Woods–Saxon potentials demonstrate one-to-one agreement with the eigenvalues obtained from the shooting method and the asymmetric finite-difference method, rapid convergence for weakly bound states, and reduced box-size sensitivity. The method retains the simplicity of central differences and standard matrix diagonalization, while naturally extending to higher-order and multidimension systems. It provides a compact and efficient tool for relativistic bound-state and scattering calculations.

In this work, the particle number projection at finite temperature is incorporated into self-consistent Skyrme density functional calculations. In particular, the energies of compound nuclei as a function of deformations are calculated rigorously based on projected densities. Results show that the even-odd staggering effect in the partition function gradually diminishes as the system approaches the critical temperature. The obtained fission barriers are similar to that without projection at finite temperature, although projected energies are different. The nuclear level density at the ground state and the barrier are also studied using the projection method and the discrete Gaussian method.

We analyze the elastic $\alpha -{}^{12}\mathrm{C}$ scattering including the contribution of resonance states below the $p-{}^{15}\mathrm{N}$ breakup threshold energy. We use the cluster effective field theory in which scattering amplitude is expanded in terms of the effective range expansion parameters for the angular momentum states from $l=0$ to $l=6$. The amplitude contains 37 parameters, which are determined by fitting to 11 392 differential cross section data points of the elastic $\alpha -{}^{12}\mathrm{C}$ scattering. To optimize the fitting process, we implement the differential evolution (DE) algorithm, which performs a global search over the high-dimensional parameter space and consistently converges to the same minimum ${\chi }^2$ value across independent runs, suggesting proximity to the global minimum within the explored domain. In parallel, the Markov chain Monte Carlo (MCMC) method is used to crosscheck the DE results and to estimate the parameter uncertainties. The best fit yields ${\chi }^2/N\simeq 6.2$ for the elastic scattering data. Using the determined 37 parameters, we calculate the differential cross sections and the phase shifts of the elastic $\alpha -{}^{12}\mathrm{C}$ scattering and compare the results with experimental data and those of an $R$-matrix analysis. Our result of the cross section agrees with the experimental data as accurately as an $R$-matrix analysis. The results demonstrate that the cluster effective field theory, combined with global optimization and uncertainty quantification based on DE-MCMC methods, provides a reliable and systematic framework for applications to low energy phenomena relevant to stellar evolution and nucleosynthesis.

In this work, I present a phenomenological search for light neutral spin-1 vector mediators in elastic electron-proton ($ep$) scattering using a two-photon-exchange (TPE)-consistent framework. A vector boson that couples to electrons and protons modifies the $\varepsilon$-independent part of the unpolarized reduced elastic cross section ${\sigma }_R(\varepsilon ,Q^2)$ through interference with the photon, producing a characteristic shift in the Rosenbluth intercept. Using the full set of available Rosenbluth separations and a TPE-corrected baseline constructed from the Borisyuk-Kobushkin parametrization, I extract the intercept deviation across all measured $Q^2$ values spanning $0.0155\le Q^2\le 5.5{\mathrm{GeV}}^2$ and perform a profile-likelihood analysis to determine mass-dependent limits on the effective vector coupling. The data show no evidence for a vector contribution over the vector mass $m_V$ range of 0.04–10 GeV, and the resulting one-sided 95% C.L. upper bounds reach the few $\times {10}^{-4}-{10}^{-3}$ level at low mediator masses, weakening to the ${10}^{-3}-{10}^{-2}$ level at larger $m_V$ as expected from propagator suppression. These results provide strict, model-independent constraints on light vector interactions in elastic $ep$ scattering once TPE effects are consistently included.

Rapidity asymmetry of jet-hadron correlation has been proposed as a robust signal of dijet‐induced diffusion wake in quark-gluon plasma in high‐energy heavy-ion collisions. We generalize this observable to other jet configurations such as $\gamma /Z^0$ jets and propose a new method to compute the rapidity asymmetry that is free of background. In this new method, the rapidity of the trigger is fixed or restricted to a symmetrical range while the rapidity of the associated jet is varied. The rapidity asymmetry is defined as the difference between the hadron rapidity distribution in the opposite azimuthal direction of the jet (or the same direction of the trigger) with different associated jet rapidities. Since the background in this hadron rapidity distribution with different associated jet rapidity is identical, it will be completely canceled in the rapidity asymmetry. Such background-free rapidity asymmetry caused by jet-induced diffusion wake is demonstrated in CoLBT-hydro simulations of dijets and $\gamma$-jets in $\mathrm{Pb}+\mathrm{Pb}$ collisions at the CERN Large Hadron Collider, which weakens as hadron $p_T$ increases, and subtraction of a $p+p$ baseline has a negligible effect.

We formulate a microscopic theory to calculate cross section of the radiative neutron capture on neutron-rich nuclei using the continuum quasiparticle random-phase approximation. This formulation is designed to be applied to neutron-rich nuclei around the $r$-process path, for which the compound nuclear model may not be appropriate. It takes into account effects of various excitation modes such as the soft dipole excitation, the giant resonances, and the quasiparticle resonance in addition to the surface vibrations such as quadrupole and octupole modes. We perform numerical calculations to demonstrate new features of the present theory, employing reactions ${}^{89}\mathrm{Ge}(n,\gamma ){}^{90}\mathrm{Ge}$ and ${}^{91}\mathrm{Zn}(n,\gamma ){}^{92}\mathrm{Zn}$ with $E1$ transitions populating the ground state, collective $2_1^{+}$ and $3_1^{-}$ states in ${}^{90}\mathrm{Ge}$ and ${}^{92}\mathrm{Zn}$. With these examples, we discuss enhanced resonance contributions in the $(n,\gamma )$ reaction at low energy, which originate from the quasiparticle resonance and the pygmy quadrupole resonance located just above the one neutron separation energy, and from combination with the low-lying octupole vibrational state.

Single-nucleon transfer reactions offer a valuable way to probe nuclear structure. We explore the effect of directly introducing overlap functions computed using the Gamow shell model (GSM) into reaction calculations, taking the ${\langle }^7\mathrm{Li}\mid {}^6\mathrm{He}+p\rangle$ single-proton overlap as a case study. By incorporating both internucleon correlations and continuum coupling, the GSM provides accurate overlap functions in both interior and asymptotic regions, together with the corresponding spectroscopic factors (SFs). These theoretical SFs and overlap functions were included in a coupled-channels Born-approximation analysis of the ${}^6\mathrm{He}{}^7\mathrm{Li}$ transfer reaction. Overlap functions derived from ab initio no-core shell-model (NCSM) calculations as well as standard single-particle (s.p.) wave functions were also considered for comparison. Our results reveal significant differences between the calculated angular distributions when employing theoretical SFs with standard s.p. wave functions compared to the full theoretical overlap functions. Discrepancies were also observed between angular distributions calculated with GSM and NCSM overlap functions, highlighting the importance of internal structure and correct asymptotic behavior in reliable reaction calculations. The GSM overlap functions also provided a good description of the ${}^{208}\mathrm{Pb}{(}^7\mathrm{Li}{,}^6\mathrm{He}$)${}^{209}\mathrm{Bi}$ reaction when included in a coupled reaction-channels calculation.

The production of light hypernuclei in relativistic heavy-ion collisions provides a unique opportunity to probe hyperon-nucleon interactions and possible three-body forces, which are central to the resolution of the hyperon puzzle in neutron star matter. In this work, we develop a data-guided coalescence framework in which the source size is extracted from proton and deuteron yields and used, together with measured proton and $\mathrm{\Lambda }$ spectra, to predict the production of $A=3$ nuclei $(t,{}^3\mathrm{He})$ and hypernuclei $\left({}_{\mathrm{\Lambda }}^3\mathrm{H}\right)$ in $\sqrt{s_{NN}}=3–200\mathrm{GeV} \mathrm{Au}+\mathrm{Au}$ collisions. For tritons, calculations with a Gaussian wave function reproduce experimental spectra and yield ratios across this energy range. For the hypertriton, the model predictions are highly sensitive to the assumed wave function. This sensitivity is strongest at low collision energies and in low-multiplicity environments, implying that such conditions are particularly valuable for probing hypernuclear structure.

Based on an extended nuclear statistical equilibrium model, we investigate the properties of nonaccreted crusts of young and warm neo-neutron stars, i.e., of finite-temperature inhomogeneous dense matter in beta equilibrium. An interesting feature is the appearance, in the deep inner crust, of an extensive and almost pure layer of neutron-rich light nuclei that extends up to the density of the transition to homogeneous matter. Most probably, this layer emerges due to translational degrees of freedom of the nuclei. If confirmed, it will significantly impact the transport and elastic properties of the crust and its crystallization process. Then we demonstrate that our inner crust is stable with respect to the diffusion of ions, which is in contrast with some of the predictions made in the literature for cold crusts. Finally, we show that clusterization completely exhausts the density instabilities that affect subsaturated nuclear matter.

Fission product yields (FPY) constitute critical infrastructure data for a wide range of nuclear applications. Accurately predicting FPY remains a significant challenge both experimentally and theoretically. Drawing inspiration from recent advancements in Bayesian neural networks within nuclear physics, as demonstrated by Wang et al. [Phys. Rev. Lett. 123, 122501 (2019)], we propose a physics-guided approach utilizing a multilayer perceptron that achieves highly accurate predictions of nuclear fission yields. The engineering and analysis of the network validate the robustness of this physics-driven neural network methodology for FPY. This approach also provides uncertainty quantification for the predicted yields. These findings underscore the effectiveness of machine learning in nuclear FPY prediction, enhancing the accuracy and reliability of theoretical models, and offering valuable insights for experimental scientists.