In this article, the surface tension and stability of quark matter modified by the vector interaction in a strong magnetic field are investigated in the quasiparticle model with the multiple reflection expansion. The self-consistent thermodynamic treatment of the chemical-potential-dependent quark mass is maintained by the effective bag function, which depends on both the chemical potential and the magnetic field. It is found that the vector interaction could enlarge the surface tension in both the parallel and transverse directions with respect to the magnetic field. In a stronger magnetic field region, the presence of the vector repulsive interaction leads to an increase in transverse surface tension with the magnetic field strength, which is opposite to the vanishing value without repulsive interaction in the previous work. Consequently, it is concluded that a moderate-intensity magnetic field is required for the formation of a quark-matter bubble with the vector interaction. Finally, it is demonstrated that the vector interaction slightly reduces the stability of quark matter.

Using $(10087\pm 44)\times {10}^{6}J/\psi$ events collected with the BESIII detector operating at the BEPCII storage ring in 2009, 2012, 2018, and 2019, we perform a search for the reaction ${\mathrm{\Xi }}^{0}n\to \mathrm{\Lambda }\mathrm{\Lambda }X$, where $X$ denotes any additional final particles. Given the highly suppressed phase space for producing extra pions, the $X$ consists of either nothing or a photon, corresponding to the processes ${\mathrm{\Xi }}^{0}n\to \mathrm{\Lambda }\mathrm{\Lambda }$ and ${\mathrm{\Xi }}^{0}n\to \mathrm{\Lambda }{\mathrm{\Sigma }}^0\to \mathrm{\Lambda }\mathrm{\Lambda }\gamma$. The ${\mathrm{\Xi }}^0$ comes from the decay of $J/\psi \to {\mathrm{\Xi }}^0{\overline{\mathrm{\Xi }}}^0$, while the neutron originates from material of the beam pipe. A signal is observed for the first time with a statistical significance of $6.4\sigma$. The cross section for the reaction ${\mathrm{\Xi }}^0+{}^9\mathrm{Be}\to \mathrm{\Lambda }+\mathrm{\Lambda }+X$ is measured to be $(43.6\pm 10.5_{\text{stat}}\pm 11.1_{\text{syst}})\mathrm{mb}$ at $P_{{\mathrm{\Xi }}^0}\approx 0.818\mathrm{GeV}/c$, where the first uncertainty is statistical and the second systematic. No significant $H$-dibaryon signal is observed in the $\mathrm{\Lambda }\mathrm{\Lambda }$ final state.

The in-medium nucleon-nucleon cross section and the cluster production are key ingredients in transport models for heavy-ion collisions. They have been constrained by the comparison of predictions of the AMD transport model to experimental data of ${}^{20}\mathrm{Ne}+{}^{12}\mathrm{C}$ at 50 MeV/nucleon [C. Frosin et al., Phys. Rev. C 107, 044614 (2023)], tuning the related parameters in the framework of a Bayesian inference. Experimental data have been collected with four blocks of the FAZIA setup. A large dataset of observables has been included in the analysis. The prior distribution of the examined parameters was chosen on the basis of the existing literature. The posterior distribution indicates a trend towards a larger number of collisions per event with respect to the previously used simulations.

We study the influence of the nuclear equation of state (EOS) on collective observables—the directed ($v_1$) and elliptic flow ($v_2$) of nucleons and light clusters—in heavy-ion collisions at gigaelectronvolt energies energies using the parton-hadron-quantum-molecular dynamics (PHQMD) approach. A novel development in this work is the inclusion of a momentum-dependent nucleon potential in the PHQMD in addition to the static, density-dependent Skyrme interaction. This enables three distinct EOS scenarios: two static (“soft” and “hard,” differing in compressibility) and a soft, momentum-dependent EOS calibrated to $pA$ elastic scattering data. In PHQMD, clusters form during the entire heavy-ion collision via nucleon interactions and are identified using the minimum spanning tree (MST) algorithm, including additional deuteron production from hadronic kinetic reactions. We find a strong EOS sensitivity in proton and cluster rapidity and $p_T$ distributions: soft and soft momentum-dependent EOS yield similar results, markedly different from the hard EOS. Softening the EOS reduces proton yields at midrapidity while enhancing light-cluster production. The EOS also affects flow observables differently for nucleons and clusters. For protons, a soft momentum-dependent potential increases slightly the magnitude of $v_1$ and $v_2$ relative to the hard EOS, whereas cluster flows are nearly similar. The soft momentum-dependent EOS provides an overall good agreement with experimental data from HADES and FOPI Collaborations while the soft EOS is not in line with the data. A scaling of $v_2$ with cluster mass number $A$ is observed at midrapidity for low $p_T$, which breaks at higher $p_T$. Finally, we examine the sensitivity of flow observables to deuteron production mechanisms. Deuterons formed via MST clustering exhibit different flow patterns from those produced by coalescence at freeze-out, indicating that flow harmonics may help discriminate between cluster formation scenarios.

The formalism of particle number projection on a spatial domain for mean-field wave functions with pairing is revisited to account for the common situation where incomplete, finite-dimensional basis is used. The restriction to a spatial domain implies that the symmetry operators used in projection are always nonunitary and this property requires a specific treatment not considered in traditional approaches. Some deficiencies of previous implementations presented in the literature are highlighted and the correct implementation taking into account the nonunitary character of the symmetry operators in finite-dimensional spaces is presented. It is shown that the present formalism has the right limit in the well-known case of zero pairing, whereas some of the other implementations do not satisfy this basic requirement. By using a simple one-dimensional model, I illustrate the differences in the results obtained with both the correct methods and the incorrect one in the study of particle number distribution probability.

We evaluate pairwise correlations using ground-state wave functions for ${}^4\mathrm{He}$ and ${}^6\mathrm{He}$ obtained by ab initio no-core shell model calculations with the Daejeon16 nucleon-nucleon interaction plus Coulomb interaction, to characterize the structures of these two systems. We demonstrate that two-nucleon spatial correlations, specifically the pair-number operator $r^0$ and the square-separation operator $r^2$ projected on two-body spin $S$ and isospin $z$ components encode important details of the halo structure of ${}^6\mathrm{He}$. We also analyze the single-particle state occupancies and the two-body state occupancies for the ground state of ${}^4\mathrm{He}$ and ${}^6\mathrm{He}$. Our results indicate that the two valence neutrons in the ground state of ${}^6\mathrm{He}$ dominantly form a spin-singlet configuration. The rms pair separations between core nucleons and halo neutrons of ${}^6\mathrm{He}$ are, on average, about 80% larger than pair separations within the swollen and off-centered “$\alpha$ core.” We show that this off-centering effect is primarily responsible for the observed increase in point-proton radius $r_p$ in ${}^6\mathrm{He}$ relative to ${}^4\mathrm{He}$.

The measurement of fragmentation cross sections for nuclei up to ${}^{56}\mathrm{Fe}$ on light elements found in the human body (e.g., H, C, and O) is of fundamental importance for particle therapy (PT) and radioprotection in space (RPS), as well as for advancing cosmic-ray physics. These measurements can significantly improve the accuracy of dose calculations for patients during PT treatments and for astronauts exposed to cosmic radiation during deep-space missions. Among the many ions of interest, ${}^{16}\mathrm{O}$ is used in PT and is the most abundant species within the HZE component of cosmic rays. This paper presents the results of angular nuclear fragmentation cross sections for the production of He, Li, Be, B, C, and N nuclei in the interaction of a $400\mathrm{MeV}/\mathrm{nucleon}$ ${}^{16}\mathrm{O}$ beam with a hydrogen and polyethylene target. The fragmentation on the hydrogen was measured by combining the results on polyethylene with recent measurements on a graphite target. While the fragmentation on hydrogen is fundamental for improving nuclear interaction models, allowing more accurate predictions of dose distributions in PT and RPS, polyethylene has proven to be a promising shielding material in radiation protection models. The data analyzed were collected in 2021 at the GSI Helmholtz Center for Heavy Ion Research facility in Darmstadt (Germany) by the FOOT Collaboration. All results were compared with different Monte Carlo models for light ion fragmentation physics in the energy range of interest implemented in FLUKA and Geant4.

To investigate the mechanism of $\alpha$-particle production, energy-angle correlations of the emitted $\alpha$ particles have been measured for the ${}^6\mathrm{Li}+{}^{93}\mathrm{Nb}$ system at energies around the Coulomb barrier. Results of three-body Monte Carlo simulations for breakup are in good agreement with the measured experimental energy-angle correlations. This is in contrast to the observation involving ${}^7\mathrm{Li}$ projectile, where breakup simulation failed to reproduce the experimental data. Comparison of the data with two different semiclassical prescriptions for the optimum $Q$ value leads to conflicting results, so no firm conclusion could be extracted from this comparison. Instead, fully quantum-mechanical calculations, employing the continuum-discretized coupled-channels (CDCC) method for the elastic breakup component and the Ichimura-Austern-Vincent (IAV) for the nonelastic one, reproduce the present experimental data rather well. The present study highlights the complexity of weakly bound projectile interactions and emphasizes the importance of more such studies for a comprehensive understanding.

For the spectroscopy of nucleon resonances at the total energies from the ${\eta }^{\prime }$-meson production threshold to 2.32 $\mathrm{GeV}$, photon beam asymmetries of the reaction $\gamma p\to {\eta }^{\prime }p$ were measured together with total and differential cross sections by analyzing the two decay modes ${\eta }^{\prime }\to \gamma \gamma$ and ${\pi }^0{\pi }^0\eta$. New constraints for amplitude decomposition were given by the first-time result of photon beam asymmetries at $E_{\gamma }>1.84 \mathrm{GeV}$ and the most precise data of differential cross sections to date at extremely backward ${\eta }^{\prime }$ angles. The possibility of a larger coupling constant of the ${\eta }^{\prime }$-nucleon system to the $N\left(2250\right)$ resonance was implied in the partial wave analyses using the present data.

Within the shell-model framework, we have derived a new effective interaction from the realistic N3LO interaction to provide an accurate description of the nuclear structure properties of even-even nuclei with $50\le Z, N\le 82$, in the ${}^{132}\mathrm{Sn}$ mass region. We validate our theoretical framework and the reliability of the new effective interaction by comparing the calculated energy levels, $E2$ transition rates, and magnetic dipole moments with experimental data. Special attention is devoted to the evolution of collectivity; an in-depth study of the quadrupole properties of different nuclei in this region reveals the presence of triaxial $\gamma$ bands.

The Woods-Saxon (WS) potential, a well-established model describing the central mean field potential in atomic nuclei, plays a critical role in studies of nuclear structure and nuclear reactions. Currently, research on the WS potential primarily focuses on the forward problem, solving for wave functions given the potential, whereas the inverse problem of inferring WS potential parameters from wave functions remains underexplored. In this work, three WS central potential parameters, the depth $V_0$, radius $R_0$, and diffuseness $a_0$ are selected. Corresponding wave functions are calculated using the WS potential model, and a Gaussian process emulator is trained, achieving a coefficient of determination $R^2=0.99$, and the mean absolute error is 0.0015 on the test set. The wave functions associated with $V_0=-50$ MeV, $R_0=3.5$ fm, $a_0=0.45$ fm are treated as experimental evidence. Using Bayesian analysis, we obtain posterior distributions for the parameters, $V_0=-50.{30}_{-5.27}^{+5.00}$ MeV, $R_0=3.{56}_{-0.06}^{+0.07}$ fm, $a_0=0.{43}_{-0.04}^{+0.04}$ fm. The central values of the posterior distributions agree closely with the true values, and the full distributions encompass the target WS potential parameters. This demonstrates that Bayesian inference can successfully invert WS parameters from theoretical wave functions, thereby offering a robust new approach for potential inversion and for exploring complex nuclear systems such as exotic nuclei and high-energy scattering processes.

The neutron radiative capture reaction ${}^{17}\mathrm{O}(n,\gamma ){}^{18}\mathrm{O}$ plays a pivotal role in both nuclear structure studies and astrophysical nucleosynthesis, particularly in the formation of elements during hydrostatic and explosive stellar environments. We calculated the ${}^{17}\mathrm{O}(n,\gamma ){}^{18}\mathrm{O}$ cross section within the Skyrme Hartree-Fock potential model and analyzed electric dipole $E1$ transitions to both positive- and negative-parity states below the α-decay threshold in ${}^{18}\mathrm{O}$. Our cross sections are significantly different from the data available in commonly used libraries. We further investigate the impact of the new calculated cross section on weak $r$-process nucleosynthesis using large-scale reaction network calculations across a wide range of electron fractions and entropies. Our results show that the ${}^{17}\mathrm{O}(n,\gamma ){}^{18}\mathrm{O}$ reaction rate significantly influences the production of first $r$-process peak elements, such as strontium, under specific astrophysical conditions. This study highlights the importance of accurate nuclear data for light isotopes in modeling heavy-element synthesis and provides updated reaction rates for future nucleosynthesis simulations.

A multinucleon transfer reaction with a ${}^{136}\mathrm{Xe}$ beam and a gold-backed ${}^{176}\mathrm{Yb}$ target populated isomers in $N=108{}^{178}\mathrm{Yb}$ and ${}^{179}\mathrm{Lu}$. The single decay from the $t_{1/2}=203$(16) ns isomer in ${}^{178}\mathrm{Yb}$ to the $I^{\pi }=4^{+}$ level in the ground-state band suggests a $I^{\pi }=4^{-}$ assignment, and multiquasiparticle calculations associate this state with the $K^{\pi }=4^{-}, {\nu }^2(1/2\left[510\right],9/2\left[624\right])$ configuration. At least two isomers were observed in ${}^{179}\mathrm{Lu}$. One likely couples the $K^{\pi }=4^{-}$ configuration found in ${}^{178}\mathrm{Yb}$ to the $9/2\left[514\right]$ quasiproton orbital to form a $K^{\pi }=17/2^{+}$ level ($t_{1/2}=1.0\left(4\right)\mu \mathrm{s}$) which primarily decays into the rotational band based on the 9/2[514] state. A second isomer was observed to decay into this same band, but at higher energy and spin. Based on its feeding pattern, its similarity to an isomer found in ${}^{181}\mathrm{Ta}$, and a multiquasiparticle calculation, it is proposed to correspond to a $K^{\pi }=29/2^{-}$ state based on the $\pi 9/2\left[514\right]{\nu }^2(9/2\left[624\right],11/2\left[615\right])$ configuration. An analysis of the reduced hindrance factors for negative-parity, two-quasineutron isomers in the rare-earth region is presented as well.

Nuclear lattice effective field theory (NLEFT) is an efficient ab initio tool for solving nuclear many-body systems using the imaginary-time projection technique, where the preparation of trial states is essential for substantially reducing the computational cost required to achieve the desired numerical precision. It has been challenging in forming optimal multireference trial states using multiple Slater determinants within auxiliary-field-based quantum Monte Carlo frameworks like NLEFT. In this work, we develop a novel sampling method for efficiently incorporating such multireference trial states into NLEFT calculations. We applied the optimized trial state to ${}^7\mathrm{Li}$ and ${}^8\mathrm{Li}$, finding overall improvements in calculated energies, electromagnetic properties, and transitions compared to results obtained without these optimizations. Our approach provides a reliable foundation for accurately simulating nuclear ground and low-lying excited states within the NLEFT framework.

Background: The complex scaling method (CSM) has been successfully used to describe many-body resonances as eigenvalues of the complex-scaled Hamiltonian in an appropriate $L^2$ basis representation. Its scope has subsequently been extended to many-body continuum states, strength functions, and scattering observables. However, a general framework that incorporates time evolution within the same CSM framework has not yet been established.

Purpose: We formulate a time-evolution formalism as a natural extension of the CSM based on the extended completeness relation (ECR), and apply it to the electric dipole ($E1$) excitation of ${}^6\mathrm{He}$ in order to clarify how an initially correlated three-body configuration evolves into continuum states.

Methods: Time evolution is described by a complex-scaled time-evolution operator represented with the ECR. The formalism is first tested in a simple two-body model through comparison with a direct numerical solution of the time-dependent Schrödinger equation. It is then applied to the $E1$ excitation of ${}^6\mathrm{He}$ in an $\alpha +n+n$ three-body model, and the density distributions are analyzed in different Jacobi coordinate systems.

Results: The present formalism reproduces the wave-packet evolution obtained in the direct time-dependent calculation. In the application to ${}^6\mathrm{He}$, the initial $E1$-excited state exhibits a correlated configuration and evolves into spatially extended continuum states. The time evolution of the density distributions indicates the coexistence of sequential decay through a core-neutron subsystem and direct breakup.

Conclusions: The present formalism extends the scope of the CSM from spectral and scattering observables to real-time continuum dynamics, and provides a unified framework that connects initial-state correlations, continuum structure, and decay dynamics in weakly bound nuclei.

Physics-informed neural networks (PINNs) have emerged as a powerful tool for solving differential equations, yet their application to nuclear scattering has been hindered by the oscillatory, nondecaying nature of scattering wave functions. In this work, I demonstrate that exterior complex scaling (ECS) transforms scattering boundary conditions into exponentially decaying waves suitable for neural network solutions, enabling PINNs to solve nuclear reaction problems for the first time. I develop a driven-equation formulation where the source term is confined to the real axis, avoiding the need to analytically continue nuclear potentials into the complex plane. The method is validated on nucleon-nucleus scattering ($\mathrm{n}+{}^{40}\mathrm{Ca}$ at $E_{\text{lab}}=20\mathrm{MeV}$) with 21 partial waves, achieving phase shift accuracy of $\mathrm{\Delta }\delta \lesssim 0.1^{\circ }$ for the strongly absorbed channels ($\ell \le 4$) and $\mathrm{\Delta }\delta \le 0.{60}^{\circ }$ for all channels up to $\ell =10$, when compared with conventional solvers. I further demonstrate the approach on heavy-ion scattering (${}^6\mathrm{Li}+{}^{208}\mathrm{Pb}$ at 40 MeV) with 41 partial waves and strong Coulomb effects, where an auto-adaptive anchor warm-down for weak-source channels yields a mean $S$-matrix accuracy of $\left|\mathrm{\Delta }\right|S_{\ell }\left|\right|\approx 3\times {10}^{-3}$ across the full angular momentum range, including the absorption-to-transparency transition region. This work establishes the foundation for extending PINNs to inverse problems where end-to-end differentiability enables direct fitting of optical potential parameters, coupled-channel reactions, and few-body scattering, where traditional grid methods face exponential scaling.

Central ${}^{136,124}\mathrm{Xe}+{}^{124,112}\mathrm{Sn}$ collisions from INDRA data are analyzed using a Bayesian inference on light nuclei multiplicities to estimate the thermodynamical parameters and in-medium modification of the cluster self-energies within a relativistic mean-field model. An excellent description of experimentally measured abundances of H and He isotopes is obtained. We examine two possible modeling of in-medium effects as an increased in-medium effective mass or an increased vector repulsion. We show that these physical pictures cannot be discriminated by the data. In both cases, the temperature dependence of the meson couplings leads to a faster weakening of the light cluster abundances with temperature than previous studies predicted. Possible systematic errors due to out-of-equilibrium effects affecting the experimental abundances are considered by repeating the Bayesian inference with reduced information. The abundance prediction of the species excluded from the constraint is well compatible with the experimental data, suggesting that there is no a priori need of accounting for nonequilibrium effects or finite state interactions that potentially affect the deuteron yield.

Measurement of particle emission source is a fundamental objective of femtoscopy in high-energy nuclear collisions. Conventional analyses rely on Gaussian parametrizations of pair emission sources, which makes the extraction of single-particle emission sources challenging, particularly for rare particles. Here, we introduce a novel statistical reconstruction method that allows extracting information of the target source relative to a data-constrained reference source instead of the Gaussian assumption. The correlation function is expressed as an ensemble average over the single-particle-conditioned correlation kernel, defined as the particle-by-particle contribution to the correlation function conditioned by the target particles. For particles with rare yields, the particle-by-particle distribution of this kernel can be transformed into event-by-event extraction and becomes experimentally accessible, enabling a direct statistical reconstruction of the emission source of single particles, instead of inferring a pair source. We apply this method to reconstruct $J/\psi$ source via $p\text{−}J/\psi$ correlations, using HAL QCD-derived $NJ/\psi$ potentials in $\sqrt{s}=13.6$ TeV $pp$ collisions simulated with EPOS4HQ. The reconstructed source reproduces the key characteristics and this new approach achieves a systematic uncertainty of approximately $13\%$ based on EPOS4 simulation.

Two pairs of doublet bands with opposite parities have been identified in ${}^{118}\mathrm{I}$ via in-beam $\gamma$-ray spectroscopy techniques. The present experimental energy levels and reduced transition probabilities indicate that they are two distinct chiral doublet bands with the $\pi g_{9/2}^{-1}\otimes \nu h_{11/2}$ and $\pi h_{11/2}^1\otimes \nu h_{11/2}$ configurations, respectively. This interpretation is further supported by the constrained triaxial covariant density functional theory and triaxial particle rotor model calculations. The present work reports the observation of multiple chiral doublet bands based on different configurations involving only intruder orbitals.