Here we report on the measurements of the $\gamma$-ray strength functions and nuclear level densities of ${}^{112,114}\mathrm{Sn}$ performed for the first time at the 9-MV Tandem accelerator facilities at Horia Hulubei Institute for Physics and Nuclear Engineering using the Oslo method. We extract thermodynamic properties and gross and fine properties of the pygmy dipole resonance for systematic comparison in the chain of Sn isotopes. The results are compared with microscopic models implemented in the TALYS reaction code and the fully microscopic quasiparticle-phonon model for the underlying nuclear structure of the dipole strength in ${}^{112,114}\mathrm{Sn}$. The quasiparticle-phonon model results show the importance of complex configurations to the low-energy dipole response in the pygmy dipole resonance energy region. The experimental data are further included in the cross section and reaction rate calculations for the $(n,\gamma )$ reaction of the $p$-process nuclei ${}^{112,114}\mathrm{Sn}$ showing a significant increase in reaction rates at high temperatures compared to existing nuclear databases.

The intranuclear cascade model is improved to explain the spectra of light charged particles from the reaction of 230-MeV/u α particles on an aluminum target. This model features α inelastic scattering and the processes of knockout and indirect pickup in addition to projectile fragmentation. To reproduce the different spectral shapes of various particles, three important assumptions are introduced: (i) the breakup channel ratios have impact-parameter dependence; (ii) there is repulsion between the cluster and the target nucleus; and (iii) the particles undergo forward-biased deflection when escaping the target. Consequently, the calculations reproduce all the spectra of α, ${}^3\mathrm{He}$, triton, deuteron, and proton with high accuracy. The roles of projectile fragmentation and target fragmentation, knockout, and indirect pickup are discussed.

Inclusive electron scattering cross sections off a hydrogen target at a beam energy of 10.6 GeV have been measured with data collected from the CLAS12 spectrometer at Jefferson Laboratory. These first absolute cross sections from CLAS12 cover a wide kinematic area in invariant mass $W$ of the final state hadrons from the pion threshold up to 2.5 GeV for each bin in virtual photon four-momentum transfer squared $Q^2$ from 2.55 to $10.4{\mathrm{GeV}}^2$ owing to the large scattering angle acceptance of the CLAS12 detector. Comparison of the cross sections with the resonant contributions computed from the CLAS results on the nucleon resonance electroexcitation amplitudes has demonstrated a promising opportunity to extend the information on their $Q^2$ evolution up to 10 ${\mathrm{GeV}}^2$. Together these results from CLAS and CLAS12 offer good prospects for probing the nucleon parton distributions at large fractional parton momenta $x$ for $W<2.5$ GeV, while covering the range of distances where the transition from the strongly coupled to the perturbative regimes is expected.

We analyze the $\gamma p\to {\eta }^{\prime }p$ process within the framework of an isobar model. This model works well in energies from the process threshold $W_{\mathrm{thr}}=1.897\text{GeV}$ up to approximately $2.4\text{GeV}$, which is why we focus on the description of this region only. We construct the amplitude as a sum of tree-level Feynman diagrams with exchanges of proton and nucleon resonances in the $s$ and $u$ channels and $\rho$ and $\omega$ mesons in the $t$ channel. We include also the contact current in order to make the total amplitude gauge invariant. The free parameters of our models were fitted to data on differential cross section and photon-beam asymmetry. We identified the $N\left(1875\right)3/2^{-}, N\left(1895\right)1/2^{-}, N\left(1900\right)3/2^{+}, N\left(2100\right)1/2^{+}$, and $N\left(2120\right)3/2^{-}$ states as the most important ones to get a good description of data. The exchanges of spin-3/2 fields were introduced in the consistent formalism. We show three different models: in two of them we assume pseudoscalar coupling in the strong vertex (one is fitted on cross sections only, the other one is fitted on all data), and in the third model we include the pseudovector coupling in the strong vertex but the data prefer the pseudoscalar coupling as it leads to lower ${\chi }^2$. We compare our models with data and comment on the roles of individual resonances for reliable data description. We give also predictions for the recoil-proton polarization asymmetry and target polarization asymmetry.

Multireference density functional theory (MR-DFT) has been a pivotal method for studying nuclear low-lying states and neutrinoless double-beta ($0\nu \beta \beta$) decay. However, quantifying their theoretical uncertainties has been a significant challenge due to the computational demands. This study introduces a subspace-projected covariant density functional theory (SP-CDFT), which efficiently emulates MR-CDFT calculations for nuclear low-lying states. This approach leverages the eigenvector continuation method combined with the quantum-number projected generator coordinate method, based on a relativistic energy density functional (EDF). We apply SP-CDFT to investigate the correlations among the physical quantities of nuclear matter, nuclear low-lying spectroscopy, and the nuclear matrix elements (NMEs) of $0\nu \beta \beta$ decay in the two heaviest candidate nuclei. Our findings reveal generally strong correlations between the NMEs of $0\nu \beta \beta$ decay and the excitation energy of the $2_1^{+}$ state, as well as the $E2$ transition strength, although these correlations vary significantly among nuclei. This work also paves the way for refining nuclear EDF parameters using spectroscopic data.

The resonant structure of the proton-unbound nucleus ${}^{18}\mathrm{Na}$ has been studied via knockout reactions of a ${}^{20}\mathrm{Mg}$ beam on a ${}^9\mathrm{Be}$ target. Three resonant states in ${}^{18}\mathrm{Na}$ are identified through the invariant-mass reconstruction of ${}^{17}\mathrm{Ne}+1p$ events, including the $1_1^{-}$ ground state with one-proton decay energy of 1.38(2) MeV. In comparison with the low-lying states in the mirror neutron-rich nucleus ${}^{18}\mathrm{N}$, the $1_1^{-}$ ground state and $2_1^{-}$ excited state with $\pi {\left(1d_{5/2}\right)}^3$ $\otimes$ $\nu 1p_{1/2}$ configurations in ${}^{18}\mathrm{Na}$ likely correspond to different proton seniorities, $\nu =3$ and 1, respectively, while the $0_1^{-}$ and $1_2^{-}$ states with $\pi {\left(1d_{5/2}\right)}^2\left(2s_{1/2}\right)$ $\otimes$ $\nu 1p_{1/2}$ configuration show obvious Thomas-Ehrman shifts. With the more-precise atomic mass of ${}^{18}\mathrm{Na}$, the one-neutron separation energy $S_n\left({}^{19}\mathrm{Na}\right)=20.31\left(2\right)\mathrm{MeV}$ is derived. Based on the systematics of the differences in experimental one-neutron separation energy in the isotopic chains from $Z=9$ to 12, the shell effects at $N=8$ for proton-rich nuclei are discussed.

The isoscaling behavior of intermediate-mass fragments has been investigated in reactions involving ${}^{14}\mathrm{N},{}^{20}\mathrm{Ne}+{}^{112,116,124}\mathrm{Sn}$ at 18–30 MeV/nucleon at K500 superconducting cyclotron facility, VECC. In all cases, the isoscaling property is clearly observed, and the isoscaling parameters $\alpha$ and $\beta$ have been extracted. The systematic evolution of the isoscaling parameters with respect to difference in isospin composition and excitation energy has been studied. The nuclear temperature was extracted using the double isotope ratio method. The coefficient of the symmetry energy term in the nuclear equation of state, $C_{\mathrm{sym}}$, was derived from the extracted values of isoscaling parameter and nuclear temperature. The values obtained are approximately 24–17 MeV, for $E^{*}/A$ = 2.1–2.8 MeV. The inconsistency of $C_{\mathrm{sym}}$ at $E^{*}/A$ = 1.8 MeV, compared to the decreasing trend of $C_{\mathrm{sym}}$ for $E^{*}/A>$ 2 MeV, could be due to the reduction or vanishing of multifragmentation at this energy.

The collective flow of double-strangeness ${\mathrm{\Xi }}^{-}$ baryons and its sensitivity to the equation of state (EoS) of dense nuclear matter are investigated in $\mathrm{Au}+\mathrm{Au}$ collisions at $\sqrt{s_{\mathrm{NN}}}=4$–10 GeV using a pure hadronic transport model (AMPT-HC). By simulating semicentral collisions $(b=4–8.5 \mathrm{fm})$ with soft $(K_0=230 \mathrm{MeV})$ and stiff $(K_0=380 \mathrm{MeV})$ EoS parameterizations, we analyze the central evolution of compression density, ${\mathrm{\Xi }}^{-}$ production mechanisms, and collective flow observables. The results demonstrate that ${\mathrm{\Xi }}^{-}$ production, concentrated in the midrapidity region, exhibits stronger sensitivity to the EoS stiffness than single-strangeness hadrons, owing to its dependence on multistep strangeness-exchange processes in high-density regions. The directed flow $\left(v_1\right)$ and elliptic flow $\left(v_2\right)$ of ${\mathrm{\Xi }}^{-}$ further reveal distinctive EoS-driven dynamics: a stiff EoS generates stronger anisotropic pressure gradients during compression, leading to a pronounced $v_1$ slope at midrapidity and enhanced $v_2$ at high transverse momenta $(p_T>1.0\mathrm{GeV}/c)$. These observables, complementary in probing cumulative yields and intensive kinematics, highlight ${\mathrm{\Xi }}^{-}$ as a unique probe of the high-density EoS near the QCD phase boundary. The findings underscore the critical role of ${\mathrm{\Xi }}^{-}$ collective flow in constraining the nuclear matter EoS at suprasaturation densities.

We present an ab initio calculation of nuclear $\beta$ decay within the framework of nuclear lattice effective field theory (NLEFT), employing auxiliary-field quantum Monte Carlo methods to solve the nuclear many-body problem. Our approach combines next-to-next-to-leading order two- and three-body chiral interactions with one- and two-body axial current operators, all consistently derived in chiral effective field theory. Low-energy constants are determined exclusively from nucleon-nucleon scattering phase shifts and few-body observables for systems with $A\le 3$. Using these interactions and transition operators, we perform two-channel Monte Carlo simulations to compute the $\beta$-decay matrix element for ${}^6\mathrm{He}$, obtaining results in reasonable agreement with experimental measurements. To address the Monte Carlo sign problem, we implement a perturbative expansion around a leading-order Hamiltonian with approximate Wigner-SU(4) symmetry. This systematic approach provides a foundation for extending NLEFT simulations to precision studies of weak processes in medium-mass nuclei.

We analyze the impact of the $\sigma$-cut potential on the properties of pure nucleonic neutron star matter containing an antikaon condensate within the relativistic mean field model. The UCIb and UCIc RMF models, which have been recently proposed and well-constrained, are utilized to explore the composition and structure of neutron stars with an antikaon condensate. The antikaon condensation component of the equation of state is determined based on experimental data from $K^{-}$ atomic and kaon-nucleon scattering. The $\sigma$-cut potential, influencing the stiffness of the equation of state at high densities, is governed by a free parameter $f_s$ that is constrained by observational data. Our analysis shows that for all values of $f_s$, neutron star configurations with antikaon condensates can exceed $2M_{\odot }$ in all cases. The calculated global properties of neutron stars with antikaon condensates, including mass and radius, are found to be in good agreement with other theoretical, and observational data.

With the help of a semiclassical kinetic theory, a new collision kernel is proposed, which simultaneously conserves the energy-momentum tensor and the spin tensor of a relativistic fluid of spin-1/2 particles irrespective of the frame and matching conditions, even when relaxation time is momentum dependent. The relativistic Boltzmann's equation is solved using this new collision kernel that will lead to the transport coefficients with general definitions for the frame and matching conditions. The results indicate the expected existence of Barnett-like effect and the nonexistence of Einstein–de Haas–like effects. For the first time, a local collision kernel is being proposed that can be used to construct relativistic spin hydrodynamics along the line of Bemfica-Disconzi-Noronha-Kovtun (BDNK) formulation, which may lead to a first-order stable and causal theory.

In this paper, ${\beta }^{-}$ and $\beta$-delayed neutron decays of ${}^{46,47}\mathrm{Cl}$ are reported from an experiment carried out at the National Superconducting Cyclotron Laboratory using the Beta Counting System. The half-lives of both ${}^{46}\mathrm{Cl}$ and ${}^{47}\mathrm{Cl}$ were extracted. Based on the delayed $\gamma$-ray transitions observed, the level structure of $N=28$ ${}^{46}\mathrm{Ar}$ was determined. Completely different sets of excited states above the first $2^{+}$ state in ${}^{46}\mathrm{Ar}$ were populated in the ${}^{46}\mathrm{Cl}$ $\beta 0n$ and ${}^{47}\mathrm{Cl}$ $\beta 1n$ decay channels. Two new $\gamma$-ray transitions in ${}^{47}\mathrm{Ar}$ were identified from the very weak ${}^{47}\mathrm{Cl}$ $\beta 0n$ decay. Furthermore, ${}^{46}\mathrm{Cl}$ $\beta 1n$ and ${}^{47}\mathrm{Cl}$ $\beta 2n$ were also observed to yield different population patterns for levels in ${}^{45}\mathrm{Ar}$, including states of different parities. The experimental results allow us to address some of the open questions related to the delayed neutron emission process. For isotopes with large neutron excess and high $Q_{\beta }$ values, delayed neutron emission remains an important decay mode and can be utilized as a powerful spectroscopic tool. Experimental results were compared with shell-model calculations using the FSU and $V_{\mathrm{MU}}$ effective interactions.

We develop a dynamical model to describe critical fluctuations in heavy-ion collisions, incorporating the baryon diffusion current and chiral condensate as dynamical degrees of freedom, to address their nontrivial scale separation. The model couples fluctuations of the chiral condensate $\sigma$ with baryon density fluctuations $n$ and the diffusion current $\nu$ based on a second-order stochastic diffusion equation with a finite relaxation time of the baryon diffusion ${\tau }_{\mathrm{R}}$. We analyze the spacetime evolution and these correlation functions of the fluctuations in a one-dimensionally expanding background. We confirm that an appropriate relaxation time ${\tau }_{\mathrm{R}}$ ensures causality. We show that propagating waves with finite ${\tau }_{\mathrm{R}}$ split into two modes at the critical temperature due to a rapid change of kinetic coefficients. In the correlation functions, we find that dynamical $\sigma$ blurs the structure and peak around the critical temperature. With finite ${\tau }_{\mathrm{R}}$, the effect of the critical fluctuations persists longer into the later stages of the evolution. These findings suggest the importance of dynamical effects of the chiral condensate and baryon diffusion current in identifying critical-point signals in heavy-ion collisions, where the scale separation is nontrivial.

This paper reports measurements of the transverse energy per unit pseudorapidity ($d{E}_T/d\eta$) produced in Au+Au collisions at $\sqrt{s_{{}_{NN}}}=200\mathrm{GeV}$, performed with the sPHENIX detector at the Relativistic Heavy Ion Collider (RHIC). The results cover the pseudorapidity range $\left|\eta \right|<1.1$ and constitute the first such measurement performed using a hadronic calorimeter at RHIC. Measurements of $d{E}_T/d\eta$ are presented for a range of centrality intervals and the average $d{E}_T/d\eta$ as a function of the number of participating nucleons, $N_{\mathrm{part}}$, is compared to a variety of Monte Carlo heavy-ion event generators. The results are in agreement with previous measurements at RHIC, and feature an improved granularity in $\eta$ and improved precision in low-$N_{\mathrm{part}}$ events.

Background: In deep-inelastic collisions of heavy nuclei, reaction products with a wide range of mass and charge are produced. Such collisions been considered as a possible way to produce superheavy nuclei, as an alternative to fusion reactions. To provide reliable theoretical predictions, it is desired to develop microscopic approaches that correctly and accurately describe nucleon transfer processes in dissipative collisions of heavy nuclei.

Purpose: The purpose of the present work is (1) to investigate the mechanism of nucleon transfers in dissipative collisions of two heavy nuclei, and (2) to explore possible pathways to produce neutron-rich heavy nuclei, through detailed theoretical analyses of fluctuations and correlations in nucleon transfers in ${}^{208}\mathrm{Pb}+{}^{208}\mathrm{Pb}$ reactions.

Methods: Three-dimensional time-dependent Hartree-Fock (TDHF) calculations are performed for the collisions of ${}^{208}\mathrm{Pb}+{}^{208}\mathrm{Pb}$ at $E_{\text{c.m.}}=832$, 936, and 1040 MeV, using the Skyrme SLy4d energy density functional. To calculate fluctuations and correlations in nucleon transfers, we employ the stochastic mean-field (SMF) theory, and the results are compared with another theoretical framework currently available, the time-dependent random phase approximation (TDRPA). Primary and secondary production cross sections are calculated with the SMF theory combined with a statistical model, GEMINI $++$ .

Results: Using information of nucleon flow across a neck of colliding nuclei in TDHF calculations, we solve quantal diffusion equations for fluctuations and correlations in nucleon transfers based on the SMF theory. From the SMF calculations, we obtain the time evolution of diffusion coefficients as well as fluctuations and correlations in nucleon transfers for a range of initial orbital angular momenta. We compare the results of the SMF calculations with those of TDRPA, showing that TDRPA tends to predict substantially larger fluctuations and correlations in strongly damped collisions of heavy nuclei, which exhibit complex initial angular momentum dependence, while the SMF results provide almost constant (stable) values. Using the obtained fluctuations and correlations, we calculate primary and secondary production cross sections for the ${}^{208}\mathrm{Pb}+{}^{208}\mathrm{Pb}$ collisions. From the results, we find that both lighter and heavier reaction products as compared to ${}^{208}\mathrm{Pb}$ are produced for a wide region in the $N\text{−}Z$ plane as primary products, thanks to the quantal diffusion mechanism in the dissipative collisions. However, we show that cross sections for production of heavy nuclei with $Z\gtrsim 90$ or $N\gtrsim 135$ are washed out due to secondary particle evaporation and/or fission processes. On the other hand, we find that there remain sizable cross sections for production of neutron-rich nuclei along $N=126$ with $Z<82$, even after secondary disintegration processes. We demonstrate that the secondary production cross sections depend weakly on incident energies, but lower (higher) energy is slightly preferred for production of nuclei with smaller (larger) atomic numbers as compared to $Z=82$.

Conclusions: Based on the microscopic SMF calculations, it has been shown that deep-inelastic collisions of heavy nuclei, such as ${}^{208}\mathrm{Pb}+{}^{208}\mathrm{Pb}$ examined in this study, can be a promising means to produce neutron-rich heavy nuclei along $N=126$. Discrepancies between the SMF and TDRPA approaches are left unsolved for future investigations.

Source functions are obtained from $p-p$ and $d-\alpha$ correlation functions by applying the Richardson-Lucy (RL) deblurring to the Koonin-Pratt (KP) equation. To prevent the fitting of noise in the correlation function, total-variation (TV) regularization is employed, which has been effective in ordinary image restoration. TV alone cannot ensure the normalization of the source functions. To ensure the latter, we propose a maximum-entropy-regularized RL algorithm (MEM-RL). We outline the MEM-RL formalism and optimization strategy for the KP equation, demonstrating its effectiveness on both simulated and experimental data, including the $p-p$ and $d-\alpha$ correlation functions.

The nucleon matrix elements (NMEs) associated with quark chromomagnetic dipole moments (cMDMs) play a crucial role in determining the $\mathit{CP}$-odd pion-nucleon couplings induced by quark chromoelectric dipole moments. In recent years, it has been argued that the NMEs of cMDMs can be related to the third moment of the nucleon's higher-twist (specifically, twist-3) parton distribution function (PDF) $e\left(x\right)$, which can, in principle, be measured through dihadron production in semi-inclusive deep inelastic scattering processes. By applying the spin-flavor expansion to the cMDM operators in the large-$N_c$ limit, where $N_c$ is the number of quark colors, we show that the NMEs receive contributions not only from the twist-3 PDF $e\left(x\right)$ but also from an additional, previously neglected nucleon form factor. Incorporating constraints from the spin-flavor expansion, recent experimental data on $e\left(x\right)$, as well as model calculations of $e\left(x\right)$, we estimate the NMEs of the cMDM operators. Our analysis indicates that the NMEs are dominated by the nucleon form factors, and the cMDM contributions to pion-nucleon couplings can be comparable to those from the quark sigma terms.