The degeneracy of chiral partners is an ideal signal for measuring the restoration of the spontaneously broken chiral symmetry in QCD. In this work we investigate the observability of the $\varphi$ - $f_1\left(1420\right)$ degeneracy in the J-PARC E16 experiment, which measures dielectrons emitted from 30-GeV pA collisions. We for this purpose make use of an effective Lagrangian approach, which naturally incorporates the broken charge-conjugation symmetry in nuclear matter and the ensuing anomaly-induced mixing between vector and axial-vector mesons, to compute the spectral function relevant for the experimental measurement. The real-time dynamics of the pA collision is obtained from a transport simulation. Including experimental background and resolution effects on top of that, we find that a signal of the $\varphi$ - $f_1\left(1420\right)$ mixing can be observed at around 2.5 $\sigma$, with the Run2 statistics planned for the J-PARC E16 experiment with an ideal mixing strength.

We perform a detailed study of the $\mathrm{{\rm Y}}$-, ${\eta }_b$-, and $B_c$-nucleus systems in momentum space to calculate the bound-state energies and the corresponding coordinate-space radial wave functions. The attractive strong potentials for the meson-nucleus systems are calculated from the Lorentz scalar mass modifications of these mesons in nuclear matter in the local density approximation in the nucleus. The downward shift of the meson masses may be regarded as a signature of partial restoration of chiral symmetry in a nuclear medium applied in the present study in an empirical sense, because the origin of the negative mass shift in this study is not directly related to the chiral symmetry mechanism. Furthermore, as an initial and realistic study, the $B_c^{\pm }\text{−}{}^{12}\mathrm{C}$ bound states are studied for the first time, with the effects of self-consistently calculated Coulomb potentials in ${}^{12}\mathrm{C}$ (when the $B_c^{\pm }$ mesons are absent).

Angular momentum projection plays a key role in studying quantum many-body systems with rotational invariance such as atomic nuclei. With given quantum numbers $JM$, one can generate $2J+1$ angular momentum projected states labeled with $-J\le K\le J$ from a deformed Slater determinant. Usually, a nuclear wave function with $K$ mixing can be expressed as a superposition of all these $2J+1$ projected states, where the coefficients can be obtained by solving the generalized eigenvalue equation. In this Letter, we report a new fundamental feature that the frequently discussed $K$ mixing in the angular momentum projected nuclear wave function can be safely removed. Strikingly, we found that such nuclear wave function with $K$ mixing can always be well approximated by a single projected state with any given $K$. This simplification can further improve methods related to angular momentum projection in chemistry, atomic, and nuclear physics, particularly offering significant advantages in dealing with high-spin states.

Background: The coexistence of various structures, such as diverse shapes and cluster structures, is a fundamental property of atomic nuclei. In neutron-rich nuclei, a $\mathrm{core}+n$ structure can compete with nuclear deformation due to the small neutron separation energy. A neutron-rich carbon isotope, ${}^{17}\mathrm{C}$, exemplifies the appearance of the deformation and the $\mathrm{core}+n$ decoupling in its spectrum, which is desirable for a deeper understanding of the coexistence phenomena in neutron-rich nuclei.

Purpose: We aim to describe and understand this coexistence phenomenon in the low-lying levels of ${}^{17}\mathrm{C}$ in a unified manner considering explicitly the degrees of freedom of both the quadrupole deformation and the relative motion between a ${}^{16}\mathrm{C}$ core and a valence neutron.

Method: We adopt the generator coordinate method (GCM) with the antisymmetrized molecular dynamics (AMD) to describe various configurations. We superpose various basis wave functions generated by the energy variation by imposing two types of constraints: one incorporating the degree of the quadrupole deformation and the other taking care of the relative motion between a ${}^{16}\mathrm{C}$ core and a valence neutron.

Results: We find that the experimental energy level is well reproduced by the present method, including both deformed and ${}^{16}\mathrm{C}+n$ configurations. The ground $3/2^{+}$ and second excited $5/2^{+}$ states exhibit a triaxially deformed shape, while the main component of the first excited $1/2^{+}$ state is a ${}^{16}\mathrm{C}(0^{+}$) core plus an $s$-wave neutron configuration. The tail of the valence neutron is significantly improved by including the ${}^{16}\mathrm{C}+n$ basis functions explicitly.

Conclusion: The explicit inclusion of both the quadrupole deformation and the relative motion between a core and a valence neutron is essential to describe the coexistence phenomena observed in neutron-rich nuclei in the $\mathrm{AMD}+\mathrm{GCM}$ framework.

This study proposes a theoretical model for studying the spin characteristics and angular correlations of fission fragments of heavy nuclei. The mechanisms of spin formation, including the influence of transverse vibrations, are considered and the relationship between the anisotropy of the angular distribution and the correlation coefficient is revealed. The theoretical predictions are compared with experimental data and various models developed by other research groups.

Di-hadron and di-jet correlation measurements in proton-nucleus ($p+A$) and electron-nucleus collisions are widely motivated as sensitive probes of novel, nonlinear quantum chromodynamices saturation dynamics in hadrons, which are particularly accessible in the dense nuclear environment at low values of Bjorken-$x$ ($x_{\mathrm{A}})$. Current measurements at the BNL Relativistic Heavy Ion Collider (RHIC) and the CERN Large Hadron Collider (LHC) observe a significant suppression in the per-trigger yield at forward rapidities compared to that in proton-proton collisions, nominally consistent with the “mono-jet” production expected in a saturation scenario. However, the width of the azimuthal correlation remains unmodified, in contradiction to the qualitative expectations from this physics picture. I investigate whether the construction of these observables leaves them sensitive to effects from simple nuclear shadowing as captured by, for example, universal nuclear parton distribution function (nPDF) analyses. I find that modern nPDF sets, informed by recent precision measurements sensitive to the shadowing of low-$x_{\mathrm{A}}$ gluon densities in LHC and other data, can describe all or the majority of the di-hadron/jet suppression effects in $p+A$ data at both RHIC and the LHC, while giving a natural explanation for why the azimuthal correlation width is unmodified. Notably, this is achieved via a $(x_{\mathrm{A}},Q^2)$-differential suppression of overall cross sections only, without requiring additional physics dynamics which alter the interevent correlations.

We study how the nuclear symmetry energy slope affects the properties of hadron-quark pasta phases and their sizes in massive hybrid stars ($>2M_{\odot }$). We utilize the relativistic mean-field model with a density-dependent isovector coupling constant fitted by varying values of the symmetry energy slope $L$ to describe the hadronic matter, while the quark matter is described by a modified MIT bag model with vector interactions. We construct the hadron-quark phase transition using the energy minimization method and compare with the Gibbs construction in the hybrid star. We find that the massive hybrid stars generally tend to have a hadron-quark pasta phase core rather than a pure quark core for most values of $L$, except in some special cases where they have a small pure quark core. Furthermore, we show that the mass and size of the pasta phase core are strongly influenced by the symmetry energy. The radius associated with the onset of pasta phases is also influenced by the symmetry energy. Additionally, we also evaluate the effects of the surface tension $\sigma$, the bag constant $B$, and the vector interaction $G_V$.

We evaluated the cross section per unit volume for the absorption and emission of neutrinos and antineutrinos in hot stellar matter under the influence of a strong magnetic field. The system considered consists of neutrons, protons, electrons, and positrons in $\beta$-equilibrium and charge neutrality. Two different models for the equation of state (EoS) were employed: the first assumes noninteracting particles, while the second uses the Hartree-Fock approximation with the Skyrme interaction. The cross-section evaluation was performed self-consistently with the EoS. We analyzed densities up to $\approx 2.5{\rho }_0$, where ${\rho }_0$ represents the nuclear saturation density, focusing on a system with a magnetic field intensity of $B={10}^{18}$ G and a temperature of $T=15$ MeV. Our results show that neutrino absorption is the dominant reaction. Furthermore, we found that the interplay between the EoS and the cross-section calculation is crucial. Due to the presence of the magnetic field, the cross section exhibits an asymmetric behavior depending on the direction of the (anti)neutrino absorbed or emitted relative to the magnetic field. This asymmetry favors the flux of (anti)neutrinos (anti)parallel to the magnetic field.

In our recent publication [H. Zhang, T. Li, and X. Wang, Phys. Rev. Lett. 133, 152503 (2024)], we demonstrate that the interaction between hydrogenlike thorium-229 ions (${}^{229}\mathrm{Th}^{89+}$) and contemporary intense lasers can access a highly nonlinear and nonperturbative regime of light-nucleus interaction. This interaction enables highly efficient nuclear isomeric excitation of ${}^{229}\mathrm{Th}$, achieving an excitation probability exceeding 10% per nucleus per femtosecond laser pulse. In this paper, we significantly expand on our previous work by providing a detailed theoretical framework, extended numerical results, and comprehensive analysis. We emphasize that the role of the electron is crucial in enhancing light-nucleus interactions, particularly through a nuclear hyperfine mixing effect. We also show that the nuclear isomeric excitation can be further optimized to approximately 90% per nucleus per pulse.

We determine the onset of quarkyonic matter corresponding to values of temperature and baryon chemical potential at which the quark phase space density becomes one. At zero temperature for baryon chemical potentials below the mass of the Λ baryon, only nucleons contribute to the quark density. This is different at finite temperature, where all baryons, mesons and their resonances can be excited and thus add quarks to the phase space. The probability density to find a quark inside a hadron is determined using the Yukawa ansatz of the IdylliQ model of quarkyonic matter. We estimate separately the magnitude of the various contributions of nucleons, Δ baryons, pions as well as further hadrons and resonances. The uncertainty in the parametrization of the probability density to find a quark inside a nucleon is spanned by assuming that at zero temperature the transition density to quarkyonic matter is between one and three times that of nuclear matter. Various predictions for a possible critical point associated with the chiral phase transition are found close to the point at which the line of the deconfinement transition and the curve associated with the transition to quarkyonic mqatter intersect. These considerations provide an estimate for the region in the quantum chromodynamics phase diagram where quarkyonic matter may be found.

The observation of mass-asymmetric fission in the neutron-deficient sublead region has dramatically expanded the region of mass-asymmetric fission in the nuclide chart, and has led to intense experimental and theoretical investigations. The mechanism for this asymmetric fission mode in this mass region is still not fully understood. To investigate the systematic evolution of the mass-asymmetric fission modes with increasing excitation energy and varying neutron numbers of the neutron-deficient nuclei, the fission-fragment mass distributions have been measured in fissions of the excited compound nuclei ${}^{176,186}\mathrm{Pt}$ formed by fusion of ${}^{32}\mathrm{S}+{}^{144,154}\mathrm{Sm}$ over a wide excitation energy range. The fission-fragment mass distributions of ${}^{176,186}\mathrm{Pt}$ can be described by two main fission modes at all the measured energies, that is one mass-symmetric and one mass-asymmetric fission based on triple-Gaussian fits. In addition, the gef model was used to provide a general prediction for the present paper. The available experimental systematics for the fission of neutron-deficient Pt isotopes suggests that the proton shell of the fragments dominates the mass-asymmetric fission mode, with the most probable proton number being $Z_{\mathrm{L}}\approx 35$ for the light fragments and $Z_{\mathrm{H}}\approx 43$ for the heavy ones.

We develop a generative model for the nuclear matter equation of state at zero net baryon density using the Gaussian process regression method. We impose first-principles theoretical constraints from lattice quantum chromodynamics and hadron resonance gas at high- and low-temperature regions, respectively. By allowing the trained Gaussian process regression model to vary freely near the phase transition region, we generate random smooth crossover equations of state with different speeds of sound that do not rely on specific parametrizations. We explore a collection of experimental observable dependencies on the generated equations of state, which paves the groundwork for future Bayesian inference studies to use experimental measurements from relativistic heavy-ion collisions to constrain the nuclear matter equation of state.

We investigate the signal of the chiral magnetic effect (CME) in $\mathrm{Au}+\mathrm{Au}$ collisions and isobar collisions of ${}_{44}{}^{96}\mathrm{Ru}+{}_{44}{}^{96}\mathrm{Ru}$ and ${}_{40}{}^{96}\mathrm{Zr}+{}_{40}{}^{96}\mathrm{Zr}$ in the newly developed chiral anomaly transport module based on the state-of-the-art model “a multiphase transport.” Our numerical simulation results for the ratio charge correlation $\mathrm{\Delta }\gamma$ in $\mathrm{Ru}+\mathrm{Ru}$ and $\mathrm{Zr}+\mathrm{Zr}$ collisions are close to the latest experimental data. The simulation shows that the CME signal is larger in $\mathrm{Ru}+\mathrm{Ru}$ collisions than that in $\mathrm{Zr}+\mathrm{Zr}$ collisions, while the background is smaller, and the upper limit of the CME signal is $15\%$ in the isobar collisions.

Excited states in ${}^{251}\mathrm{Md}$ have been populated by decay of an isomeric state at $E_x\approx 1174$ keV and studied via delayed $\gamma$-ray spectroscopy. We observe the population of two rotational bands, one of which we identify as the Nilsson $\pi \frac{7}{2}\left[514\right]$ ground-state band and the other we propose is based on the $\pi \frac{9}{2}\left[624\right]$ configuration. From the observed decay pattern, we suggest that the isomer spin parity is ${\frac{23}{2}}^{+}$, with the three-quasiparticle configuration $\pi \frac{7}{2}\left[514\right]\otimes {\{\nu \frac{7}{2}\left[624\right]\otimes \nu \frac{9}{2}\left[734\right]\}}_{K^{\pi }=8^{-}}$. We compare our results to theoretical predictions of the single- and multi-quasiparticle structure of ${}^{251}\mathrm{Md}$.

Background: The development of future nuclear reactors using fast neutrons necessitates nuclear data with low uncertainties over a wide range of neutron energies above 1 MeV. For ${}^{235}\mathrm{U}$, reliable experimental data on prompt fission neutron energy distributions are scarce in this region, and improved measurements are needed.

Purpose: We aim to measure the prompt fission neutron spectra (PFNS) in the ${}^{235}\mathrm{U}(n,f)$ reaction as a function of incoming neutron energy between 1 and 600 MeV.

Methods: The double time-of-flight technique was used at the Los Alamos Neutron Science Center to measure incoming and prompt fission neutrons energies. The data were measured relative to the very well known ${}^{252}\mathrm{Cf}\left(\mathrm{sf}\right)$ PFNS.

Results: Prompt fission neutrons with energies between 0.186 and 11.5 MeV were measured over the full range of incoming neutron energies with uncertainties in the PFNS mean energy below 0.8%. There are discrepancies between the data and the evaluations JEFF3.3, ENDF/B VIII.1, and JENDL-5.

Conclusions: The low uncertainties can lead to significant constraints on evaluations over the range of interest for applications, below 25 MeV.

Background: The high complexity of deuteron-nucleus interactions is due to (i) a variety of reactions induced by nucleons that follow the deuteron breakup (BU), owing to the deuteron weak binding energy, and (ii) the specific stripping and pickup direct reactions (DRs) in addition to the statistical processes of preequilibrium emission (PE) and evaporation from the compound nucleus (CN). Moreover, an update of the limited experimental deuteron database is needed, and there is an incomplete theoretical framework for deuteron activation analysis.

Purpose: Accurate new measurements of low-energy deuteron-induced reaction cross sections for natural Mo target are intended to enhance the related database and provied a consistent account of BU, DR, PE, and CN involved reaction mechanisms.

Methods: The activation cross sections for ${}^{91–97,99,101}\mathrm{Tc}$ residual nuclei in deuteron-induced reactions on Mo were measured by the stacked-foil technique and high-resolution gamma spectrometry using the U-120M cyclotron of the Center of Accelerators and Nuclear Analytical Methods (CANAM) infrastructure of the Nuclear Physics Institute of the Czech Academy of Sciences (NPI CAS), at energies up to 20 MeV, and using the Neutrons for Science (NFS) SPIRAL2/GANIL facility at energies up to 40 MeV, where a single-foil technique and a dedicated transport system were used for short-lived isotopes. Their extended analysis, including all available data for deuteron interactions with Mo isotopes up to 50 MeV, considered every process from elastic scattering until CN evaporation, with particular attention paid to BU and DR mechanisms.

Results: The newly measured activation excitation functions have improved substantially the deuteron database for molybdenum, which is a major constituent of large-scale facilities using deuteron beams. Concurrent analysis of all available data has brought forward questions concerning their consistentcy.

Conclusions: The suitable description of nuclear mechanisms involved within deuteron-induced reactions on Mo, especially the BU and DR processes, is validated by overall agreement of the calculated and measured cross sections including the new data at low energies. The analysis of many isomeric-state activation data in this work provides also a quite useful analysis of the CN+PE spin distribution effects.

The dipole cross-section behavior for protons and nuclei is analyzed with and without considering the heavy quark masses in the Bjorken variable $x$ using the Kharzeev-Levin-Nardi (KLN) model of low $x$ gluon distributions. The color glass condensate (CGC) effects in the color dipole model are influenced by the heavy quark masses in the Bjorken variable $x$ at $Q^2<Q_s^2$. These nonlinear saturation effects will be observable in the Large Hadron Electron Collider (LHeC) and the Electron-Ion Collider (EIC) at very small $x$ values.

We investigate the two-proton ($2p$) emission from ${}^{16}\mathrm{Ne}$ with the time-dependent ${}^{14}\mathrm{O}+p+p$ three-body calculations. Two $0^{+}$ resonances are suggested to participate. For the $0_1^{+}$ resonance, the true emission of the spatially localized two protons is dominant, if the single-particle $s_{1/2}$ resonance locates above the $2p$ energy. By evaluating a time-evolution probability, the $0_2^{+}$ resonance is suggested at $\cong 3$ MeV from the $2p$ threshold. The inclusion of $0_2^{+}$ resonance makes the true-$2p$ emission more dominant in the time-dependent calculations.

The study of nuclei at finite temperature is of immense interest for many areas of nuclear astrophysics and nuclear-reaction science. A variety of ab initio methods are now available for computing the properties of nuclei from interactions rooted in quantum chromodynamics, but applications have largely been limited to zero temperature. In the present work, we extend one such method, the in-medium similarity renormalization group (IMSRG), to finite temperature. Using an exactly solvable schematic model that captures essential features of nuclear interactions, we show that the FT-IMSRG can accurately determine the energetics of nuclei at finite temperature, and we explore the accuracy of the FT-IMSRG in different parameter regimes, e.g., strong and weak pairing. In anticipation of FT-IMSRG applications for finite nuclei and infinite matter, we discuss differences arising from the choice of working with the canonical and the grand-canonical ensembles. In future work, we will apply the FT-IMSRG with realistic nuclear interactions to compute nuclear structure and reaction properties at finite temperature, which are important ingredients for understanding nucleosynthesis in stellar environments, or modeling reactions of hot compound nuclei.