The $1/2^{-}$ resonances in ${}^{13}\mathrm{C}$ are investigated to search for the Hoyle-analog state. In order to treat the resonances located around the $3\alpha +n$ threshold, the analytic continuation in the coupling constant has been combined with the real-time evolution method. We show that the observed $1/2^{-}$ resonances are mainly $p_{3/2}$-dominant states such as the ${}^9\mathrm{Be}(3/2^{-})+\alpha$ channel, and no Hoyle-analog ${}^{12}\mathrm{C}\left(0_2^{+}\right)+p_{1/2}$ state exists below 10 MeV.

The clustering of nucleons is a fundamental phenomenon with broad implications for nuclear physics and astrophysics. In this work, we employ a microscopic in-medium few-body approach to systematically investigate the formation and dissolution of light clusters (deuteron, ${}^3\mathrm{H}, {}^3\mathrm{He}, \alpha$ particle) embedded in nuclear medium. The medium-modified cluster structures under the Pauli blocking and the picture of Mott transitions in nuclear medium are discussed in detail. We find that the weakly bound deuteron survives to higher densities as compared with the more compact $\alpha$ particle in symmetric nuclear matter, with its rms radius expanding markedly prior to its dissolution. Moreover, the Mott density of the $\alpha$ particle is slightly lower in neutron-rich matter than in symmetric matter. These results may provide useful constraints for the formation of light clusters at nuclear surface and the cluster yields in intermediate-energy heavy-ion collisions.

A search for a $\beta$-delayed fission ($\beta \mathrm{DF}$) decay branch of isomerically pure samples of ${}^{178}\mathrm{Au}^g$ and ${}^{178}\mathrm{Au}^m$ was performed at the ISOLDE-CERN facility. Two complementary detection systems capable of registering $\alpha$ decays and fission fragments, the ISOLDE Decay Station and the ASET (Alpha SETup), were used. Despite very high statistics of produced ${}^{178}\mathrm{Au}$ nuclei, no fission fragments were detected. Upper limits of $\beta \mathrm{DF}$ probabilities of $P_{\beta \mathrm{DF}}\left({}^{178}\mathrm{Au}^g\right)<1.11\left(2\right)\times {10}^{-8}$ and $P_{\beta \mathrm{DF}}\left({}^{178}\mathrm{Au}^m\right)<9.7\left(2\right)\times {10}^{-9}$ were determined. Corresponding lower limits of $\beta \mathrm{DF}$ partial half-lives were deduced as well, and the results are discussed in the context of experimental systematics of $\beta \mathrm{DF}$ in the neutron-deficient region of the nuclear chart.

A systematic theoretical investigation of the quadrupole and octupole collective properties across the Gd isotopic chain is performed employing a quadrupole-octupole axially symmetric model. These nuclei recently attracted significant attention following the revelation that the maximum octupole collectivity in this region is located at ${}^{150}\mathrm{Gd}$. The model parameters are optimized by fitting to the low-lying positive and negative-parity energy levels, as well as to known $E0, E1, E2$, and $E3$ transition strengths. Our primary objective is a simultaneous and unified description of quadrupole and octupole collectivity across the even-even Gd nuclei in the $84\le N\le 96$ range, a region that includes the transition from spherical to rotational nuclear shapes. The results show a smooth evolution of the quadrupole deformation, highlighted by a distinct jump at the well-known $N=90$ critical point. The enhancement of quadrupole deformation is also correlated with the loss of non-zero octupole deformation, which is reported only for the lightest ${}^{148,150}\mathrm{Gd}$ nuclei. This translates into a fair agreement with the measured $E3$ strength, predicting a maximum $B\left(E3\right)$ value for the ${}^{152}\mathrm{Gd}$ isotope.

Background: This work presents a study of the combined influence of nuclear deformation and nonlocality on cross sections of 20 $(\alpha ,n)$ reactions relevant to $\gamma$-process nucleosynthesis in the mass range $69\le A\le 197$. Earlier works employing the TALYS global $\alpha –\mathrm{OMP}$ reproduced data trends using a nine-parameter potential that captures broad systematics but omits deformation and nonlocality. The present study evaluates how the explicit inclusion of these effects impacts the predictive performance of semimicroscopic models.

Purpose: The purpose of this work is to investigate, within a unified and physically motivated framework, the combined influence of nuclear deformation and nonlocality on $(\alpha ,n)$ reaction cross sections relevant to $p$-process nucleosynthesis and to assess their role in achieving quantitative agreement with experimental data.

Methods: We extend a previously developed semimicroscopic $\alpha$-nucleus optical model potential ($\alpha –\mathrm{OMP}$) based on a double-folding real interaction supplemented with a repulsive core. Nuclear deformation is included through couplings to collective states using ${\beta }_2$ and ${\beta }_4$ deformation parameters, while Pauli-type nonlocality is modeled with a Gaussian Perey–Buck kernel. Systematic calculations are performed using this framework for 20 $(\alpha ,n)$ reactions.

Results: Nuclear deformation is found to significantly reduce the Coulomb barrier and enhance sub-barrier reaction probabilities, particularly for well-deformed nuclei. The inclusion of nonlocality further refines the wave-function profile and improves the agreement with experimental cross sections. The best performance is obtained when both deformation and nonlocality are included simultaneously, yielding the lowest deviations across the nuclear chart.

Conclusions: The analysis indicates that nuclear deformation and nonlocality contribute meaningfully to the description of $(\alpha ,n)$ reactions at astrophysical energies. Their combined treatment leads to improved physical consistency and predictive performance relative to global parametrizations. This framework thus represents a constructive step toward structure-informed $\alpha –\mathrm{OMP}$ developments for future astrophysical applications.

We report a precise measurement of ${}^{216}\mathrm{Po}$ half-life using the PandaX-4T liquid-xenon time-projection chamber (TPC). ${}^{220}\mathrm{Rn}$, emanating from a ${}^{228}\mathrm{Th}$ calibration source, is injected to the detector and undergoes successive $\alpha$ decays, first to ${}^{216}\mathrm{Po}$ and then to ${}^{212}\mathrm{Pb}$. The PandaX-4T detector measures the five-dimensional (5D) information of each decay, including time, energy, and three-dimensional position. Therefore, we can identify the ${}^{220}\mathrm{Rn}$ and ${}^{216}\mathrm{Po}$ decay events and pair them exactly to extract the lifetime of each ${}^{216}\mathrm{Po}$. With a large data set and high-precision ${}^{220}\mathrm{Rn}\text{−}{}^{216}\mathrm{Po}$ pairing technique, we measure the ${}^{216}\mathrm{Po}$ half-life to be $143.7\pm 0.5$ ms, which is the most precise result to date and agrees with previously published values. The leading precision of this measurement demonstrates the power of the 5D calorimeter and the potential of exact parent-daughter pairing in the xenon TPC.

We demonstrate a statistical method to describe the fragment formation in rapidly expanding nuclear matter. The production of light nuclei in central collisions of ${}^{132}\mathrm{Sn}+{}^{124}\mathrm{Sn}$ and ${}^{108}\mathrm{Sn}+{}^{112}\mathrm{Sn}$ at 270 MeV/nucleon has been studied in the framework of the statistical model with the hypothesis of local equilibrium. The model suggests that the nuclei are formed at subnuclear density from the dynamically produced baryons, which can be subdivided into the local highly excited clusters. The nucleation takes place inside these clusters during the matter expansion, when the clusters enter the phase coexistence region of the nuclear liquid-gas phase transition. This process is described within the microcanonical version of the statistical multifragmentation model (SMM) as a decay of hot clusters into final nuclei. We emphasize the importance of studying nucleosynthesis in this energy range because of the expected change of the fragmentation mechanisms, which was also observed in previous experiments. There is a qualitative agreement with the recent experimental data obtained in these reactions at the Radioactive Isotopic-Beam Factory (RIKEN).

It has been assumed that nuclear modification does not exist in the longitudinal-transverse structure-function ratio $R_N=F_L^N/\left(2x{F}_1^N\right)$ in lepton deep inelastic scattering. This assumption is widely used in obtaining structure functions of the “nucleon” from nuclear data such as the deuteron ones. However, nuclear modifications do exist theoretically at least in medium- and large-$x$ regions because nucleons in a nucleus move in any direction, which is not necessarily the longitudinal direction of the virtual-photon or weak-boson momentum in lepton scattering. Because of this transverse motion, the nucleon's transverse and longitudinal structure functions should mix with each other in nuclei with the mixture probability proportional to the nucleon's transverse momentum squared ${\vec{p}}_T^2/Q^2$. In this work, numerical results are explicitly shown regarding such nuclear modifications in the deuteron. These nuclear modifications are important for determining precise structure functions of the nucleon. Furthermore, modifications of $R_N$ should be investigated also at small $x$ by the future electron-ion collider to find interesting gluon dynamics in nuclei. Hopefully, this nuclear effect of $R_N$ could be found by future experimental measurements at lepton accelerator facilities.

Vector meson photoproduction is an important probe of nuclear structure. Light vector mesons are most sensitive to $\mathrm{low}\text{−}x$ structure, as long as they are not too light for perturbative QCD calculations. The ${\rho }^{\prime }$ is of interest as an intermediate mass state (between the $\rho$ and $J/\psi$) that is easier to detect than the $\varphi$. Using HERA data on proton targets, we make projections for lead/gold targets in ultraperipheral collisions (UPCs) at the CERN Large Hadron Collider and the BNL Relativistic Heavy Ion Collider, and for $ep$ and $eA$ collisions at a future electron-ion collider (EIC). We compare the UPC projections with ALICE data, and constrain the branching ratio divided by the square of the photon-${\rho }^{\prime }$ coupling. The data prefer large couplings and small branching ratio, probably less than 25%. The photon-meson coupling predicted by generalized vector meson dominance does not fit the data. The HERA $ep$ and ALICE UPC $e\mathrm{Pb}$ data exhibit very similar $4\pi$ mass spectra, indicating that, if the system is composed of two resonances, the products of their photon couplings with their four-pion branching ratios are similar. The predicted rates are high for both UPCs and the EIC. The ${\rho }^{\prime }\to {\pi }^{+}{\pi }^{-}{\pi }^{+}{\pi }^{-}$ decay can be observed at the EIC with high efficiency. In $ep$ collisions at the highest energy, the forward B0 detector is needed to observe this channel down to the lowest achievable $\mathrm{Bjorken}\text{−}x$ values.

Bayesian model mixing (BMM) is a statistical technique that can combine constraints from different regions of an input space in a principled way. Here we extend our BMM framework for the equation of state (EOS) of strongly interacting matter from symmetric nuclear matter to asymmetric matter, specifically focusing on zero-temperature, charge-neutral, $\beta$-equilibrated matter. We use Gaussian processes (GPs) to infer constraints on the neutron-star matter EOS at intermediate densities from two different microscopic theories: chiral effective-field theory ($\chi \mathrm{EFT}$) at baryon densities around nuclear saturation, $n_B\sim n_0$, and perturbative QCD at asymptotically high baryon densities, $n_B⩾20n_0$. The uncertainties of the $\chi \mathrm{EFT}$ and pQCD EOSs are obtained using the BUQEYE truncation error model. We demonstrate the flexibility of our framework through the use of two categories of GP kernels: conventional stationary kernels and a nonstationary changepoint kernel. We use the latter to explore potential constraints on the dense matter EOS by including exogenous data representing theory predictions and heavy-ion collision measurements at densities $⩾2n_0$. We also use our EOSs to obtain neutron-star mass-radius relations and their uncertainties. Our framework, whose implementation will be available through a GitHub repository, provides a prior distribution for the EOS that can be used in large-scale neutron-star inference frameworks.

High-energy, heavy-ion collisions can create local domains of chirality-imbalanced quarks, reflecting the topological features of quantum chromodynamics. The chiral magnetic effect (CME) predicts an electric charge separation of quarks in such topological domains along the magnetic field ($\vec{B}$) generated by the passing of two high-$Z$ nuclei. We use a correlation observable $\mathrm{\Delta }{\gamma }^{112}$ between charged meson pairs to detect the CME-induced charge separation and a novel event shape selection (ESS) method to mitigate the background effects related to elliptic flow ($v_2$). The ESS method classifies events based on the emission pattern of final-state particles and determines $\mathrm{\Delta }{\gamma }_{\mathrm{ESS}}^{112}$ from the zero-flow limit. We reconstruct the $\vec{B}$ field direction from the spectator nucleons, which minimizes backgrounds unrelated to the collective motion of the system. In this work, we report the measurements of $\mathrm{\Delta }{\gamma }^{112}$ and a background indicator $\mathrm{\Delta }{\gamma }^{132}$ in $\mathrm{Au}+\mathrm{Au}$ collisions from the Brookhaven National Laboratory Relativistic Heavy Ion Collider (RHIC) Beam Energy Scan phase II and at the top RHIC energy. After background suppression, $\mathrm{\Delta }{\gamma }_{\mathrm{ESS}}^{132}$ aligns with zero, and $\mathrm{\Delta }{\gamma }_{\mathrm{ESS}}^{112}$ is reduced to no more than 20% of $\mathrm{\Delta }{\gamma }^{112}$. We observe a finite residual charge separation with $2.5\sigma , 3\sigma$, and $3.2\sigma$ significance in the 20–50% centrality range of $\mathrm{Au}+\mathrm{Au}$ collisions at 11.5, 14.6, and 19.6 GeV. The results at 17.3 and 27 GeV also show positive values but with a lower significance of $1.3\sigma$ and $1.1\sigma$, respectively. The corresponding $\mathrm{\Delta }{\gamma }_{\mathrm{ESS}}^{112}$ values at 7.7, 9.2, and 200 GeV are consistent with zero within uncertainties.

We present an ab initio study of the correlation between nuclear matrix elements (NMEs) of $0\nu \beta \beta$ decay and nucleon-nucleon scattering phase shifts in the ${}^{1}S_0$ channel. Starting from 34 statistically weighted interactions derived from chiral effective field theory, we apply the valence-space in-medium similarity renormalization group to calculate NMEs in the four experimentally relevant isotopes. Comparing with the ${}^{1}S_0$-channel phase shifts given from each interaction, in all cases we observe a strong correlation for scattering energies above approximately 75 MeV. From a global sensitivity analysis, enabled by newly developed machine-learning emulators, we find that $0\nu \beta \beta$ NMEs indeed depend primarily on the $C_{1S0}$ low-energy constant, which is associated with phase shifts in that partial wave. These results provide the first clear correlation between $0\nu \beta \beta$ decay NMEs and a measured observable, and have already been shown to reduce the total uncertainty of the NME in ${}^{76}\mathrm{Ge}$ by $\approx 25\%$. This correlation will serve as a crucial component in ongoing and future refinements of ab initio uncertainty estimates for $0\nu \beta \beta$ decay.

New developments have been brought to our energy-, spin-, and parity-dependent nuclear level densities based on the microscopic combinatorial method. Our new calculation is based on the BSkG3 mean-field model [Grams et al., Skyrme-Hartree-Fock-Bogoliubov mass models on a 3D mesh: III. From atomic nuclei to neutron stars, Eur. Phys. J. A 59, 270 (2023)] which relies on a three-dimensional coordinate-space representation of the nucleus, allowing for the spontaneous breaking of ground-state rotational, axial, and reflection symmetry. In particular, we now account for the impact of possible triaxial deformation of nuclear ground states on the level density. This has two effects on our calculations: the additional freedom of the single-particle levels affects the intrinsic level density while the absence of a rotational symmetry axis results in a larger collective correction. The present model reproduces the experimental $s$- and $p$-wave neutron resonance spacings with a degree of accuracy comparable to that of the best global models available. It is also shown that the model gives a reliable extrapolation at low energies where experimental data on the cumulative number of levels can be extracted. The predictions are also in good agreement with the experimental data extracted from the Oslo method. Total level densities for more than 8500 nuclei are made available in a table format for practical applications. For the nuclei for which experimental $s$-wave spacings and enough low-lying states exist, renormalization factors are provided to reproduce simultaneously both observables. The same combinatorial method is used to estimate the nuclear level densities at the fission saddle points of actinides and at the shape isomer deformation. Finally, the new nuclear-level densities are applied to the calculation of radiative neutron capture cross sections and compared with those obtained with our previous combinatorial model.

The centroid-shift method was used to determine half-lives of excited levels in ${}^{204}\mathrm{Pb}$ and ${}^{206}\mathrm{Pb}$. For the states with $I^{\pi }={12}^{+}$, ${17}^{-}$, and ${19}^{-}$ in ${}^{204}\mathrm{Pb}$, values of $T_{1/2}=4.9\left(3\right)$, 3.9(3), and 0.9(3) ns, respectively, were determined. The half-life of the $I^{\pi }=9^{-}$ level in ${}^{206}\mathrm{Pb}$ was measured to be 1.1(3) ns. In ${}^{204}\mathrm{Pb}$, the ${12}^{+}$ state arises from two neutron holes in the $i_{13/2}$ subshell, while the ${17}^{-}$ and ${19}^{-}$ levels are built on $\nu (i_{13/2}^{-3},p_{1/2}^{-1})$ and $\nu (i_{13/2}^{-3},f_{5/2}^{-1})$ four-neutron-hole configurations, respectively. The $9^{-}$ state in ${}^{206}\mathrm{Pb}$ results from a $\nu (i_{13/2}^{-1},f_{5/2}^{-1})$ excitation. The transition probabilities for the decay of these isomeric levels are reasonably consistent with the expected single-particle values, and these states are described well by shell-model calculations using the kshell code with the KHHE interaction.

This study employs the post-form distorted wave Born approximation (DWBA) within a fully quantum mechanical framework to probe the Coulomb breakup dynamics of one-neutron halo nuclei interacting with heavy targets. A novel first-order perturbative Fourier transform method is developed in momentum space to evaluate the transition amplitude, enabling efficient computation of exclusive and inclusive observables for light and deformed medium-mass systems, such as ${}^{11}\mathrm{Be}$ and ${}^{31}\mathrm{Ne}$, respectively. Validated against the full-order Coulomb wave Born approximation, which captures higher-order effects at low energies, the Fourier transform method demonstrates robust accuracy across high beam energies. This analytic approach bridges perturbative simplifications with exact dynamics, and may offer a versatile tool for extracting electromagnetic response and astrophysical capture rates from exotic beam facilities.

EPOS4 is based on a sophisticated (recently significantly improved) parallel-primary-scattering scenario followed by a hydrodynamic expansion, for all collision systems, from small ones such as proton-proton $\left(pp\right)$ to large ones such as lead-lead (PbPb). Having already reported on identified particle spectra in recent publications (providing information about radial flow), I discuss here the multiplicity dependence of multiparticle cumulants and flow harmonics, to better understand collectivity in small systems. The model is not particularly tuned for flow results, but it is a “general purpose” approach, trying to accommodate various types of observables with the same model.

We investigate the appearance of quark degrees of freedom in dense isospin-symmetric nuclear matter. We employ the parity doublet model to incorporate chiral dynamics. Specifically, we contrast quarkyonic matter, in which quarks occupy states above the nucleon Fermi surface, with baryquark matter, in which quarks populate states inside the nucleonic Fermi sea. We find that while baryquark matter is generally energetically favored over quarkyonic matter, the self-consistent treatment of the momentum-space shell reveals that purely hadronic matter provides the lowest free energy up to densities well beyond nuclear saturation. Consequently, the contribution of quarks is not relevant within the model's domain of applicability, even though chiral symmetry becomes restored. This demonstrates that the onset of quark degrees of freedom and the restoration of chiral symmetry need not coincide.

The evolution of the collectivity of tellurium isotopes from midshell towards $N=82$ is currently based mainly on properties of the first excited $2^{+}$ states. To extend structural information in this isotopic chain, in particular with respect to the balance of microscopic, seniority-type, and collective excitations, electric quadrupole transition strengths from $4^{+}$ states need to be considered. An experiment was performed to determine the $4_1^{+}$ lifetime of ${}^{132}\mathrm{Te}$ via the recoil-distance Doppler-shift method at the University of Cologne tandem accelerator. The isotope of interest was populated in the two neutron-transfer reaction ${}^{130}\mathrm{Te}$(${}^{18}\mathrm{O},{}^{16}\mathrm{O}$)${}^{132}\mathrm{Te}^{*}$. The $E2$ decay transition strength has been determined to be $B(E2;4_1^{+}\to 2_1^{+})=9.3\left(10\right)\text{W.u.}$ This value differs from literature data but compares favorably to shell model calculations.

In this study we examine the impact of the initial stage and dynamical evolution on final-state observables in heavy-ion collisions. For this goal we develop a novel approach, $\mathrm{EPOSir}+\mathrm{PHSDe}$, which employs energy-conserving multiple parallel scattering approach, accommodating factorization and saturation (EPOS) initial conditions as the starting point for parton and hadron evolution within the parton-hadron-string dynamics (PHSD) microscopic transport approach. By examining the space-time evolution of matter in this model and comparing to EPOS (which starts with an $S$-matrix approach for parallel scatterings for the initial conditions and uses a hydrodynamic evolution for the quark-gluon plasma stage with the UrQMD as afterburner) and PHSD (which starts with primary high-energy $NN$ scattering realized via the LUND string model and continues with fully microscopic transport dynamics for strongly interacting partonic and hadronic matter), we identify the key differences in the final particle distributions among the three approaches. Our analysis focuses on rapidity, transverse momentum spectra, and flow harmonics $v_2$ for $\mathrm{Au}+\mathrm{Au}$ collisions at the invariant energy of $\sqrt{s_{NN}}=200$ GeV. We find a dominant influence of dynamical evolution over the initial conditions on the final observables.

Hadronic resonances, with lifetimes of a few $\mathrm{fm}/c$ are key tools for studying the hadronic phase in high-energy collisions. This work investigates resonance production in pp collisions at $\sqrt{s}=13.6\mathrm{TeV}$ and in Pb-Pb collisions at $\sqrt{s_{NN}}=5.36\mathrm{TeV}$ using the EPOS4 model. The EPOS4 model provides the capability of switching the Ultrarelativistic Quantum Molecular Dynamics (UrQMD) ON or OFF, allowing the study of final-state hadronic interactions in the hadronic phase. Although this study is primarily focused on understanding the production of hadronic resonances, we also investigate the production of strange and nonstrange hadrons in relation to rescattering, regeneration, baryon-to-meson production, and strangeness enhancement, using transverse momentum ($p_{\mathrm{T}}$) spectra and particle ratios. Rescattering effects and strangeness enhancement play an important role in the low-$p_{\mathrm{T}}$ region, where soft, nonperturbative processes dominate particle production. At intermediate $p_{\mathrm{T}}$, the baryon-to-meson yield ratios show an enhancement, and the strong mass-dependent radial flow observed for baryons in the most central Pb-Pb collisions reflects the interplay between hadronization dynamics and collective effects. The average $p_{\mathrm{T}}$ scaled with the reduced hadron mass (i.e., the mass divided by the number of valence quarks) is examined, revealing a deviation from a linear trend for short-lived resonances, attributed to hadronic phase effects. By analyzing the yield ratios of short-lived resonances to stable hadrons in pp and Pb-Pb collisions, the time duration ($\tau$) of the hadronic phase as a function of average charged multiplicity is estimated. The results show that $\tau$ increases with increasing multiplicity and system size, also exhibiting a nonzero value for high-multiplicity pp collisions. It is found that the production of baryons such as nonstrange ($p$), strange ($\mathrm{\Lambda }$), and multistrange ($\mathrm{\Xi }$, $\mathrm{\Omega }$) in the most central Pb-Pb collisions is influenced by competing processes of strangeness enhancement and baryon-antibaryon annihilation. Comparing these findings with measurements at energies available at the CERN Large Hadron Collider offers valuable insights into the underlying dynamics of the hadronic phase and their production dynamics.