Currently, the neutron-proton asymmetry $[I=(N-Z)/A]$ term in various mass formulas, such as that of the symmetry or Wigner energy, usually behaves according to its even power or absolute value based on the charge independence of the nucleon-nucleon ($NN$) interaction. In this study, the $I^3$ term is introduced into the classical liquid drop (LD) model to perform the deviations of the mass evaluations away from the previous assumption, if the isospin symmetry of the $NN$ interaction is not conserved. On one hand, the mass difference between mirror nuclei is explored with a slightly improved accuracy by considering the $I^3$ term in the LD formula. On the other hand, the evaluated data of nuclear mass from various models are mapped into the LD formula, along with a specific focus on the coefficients of $I$-related terms. It is readily found that the obvious deviations between various mass formulas come from the symmetry energy plus the higher order term $I^3$ especially for neutron-rich nuclei. Finally, the slope parameters of the symmetry energy coefficient and the symmetry energy at $\rho =2{\rho }_0/3$, with ${\rho }_0$ being the nuclear saturation density, are extracted for the nuclear equation of state with/without the $I^3$ term in the mass formula of finite nuclei.

The convergence properties of spectroscopic factors in the ab initio no-core shell model are hereby investigated. For this, we consider nuclear energies and spectroscopic factors in $A=6$ and 7 isotopes, using the chiral forces ${\mathrm{NNLO}}_{\mathrm{opt}}$ and ${\mathrm{N}}^3\mathrm{LO}$. While low-lying spectrum energy demonstrates remarkable convergence with the increase of model space within the no-core shell model, the spectroscopic factor exhibits no definitive convergence trend and seems independent of the employed nuclear interaction. The use of spectroscopic factors issued from the no-core shell model to calculate cross sections of knockout reactions might then be questionable. The results are compared with that of the standard shell model and ab initio Monte Carlo calculations.

We evaluate the leading exchange corrections to the helium-4 gravitational form factors (GFFs) to momenta of the order of the nucleon mass. We use both the K-harmonic method with simple pair nucleon potential, and a Jastrow trial function using the Argonne $v_{14}$ potential, to evaluate the helium-4 GFFs. The exchange current contributions include the pair interaction, plus the seagull and the pion exchange interactions, modulo the recoil corrections. To estimate the off-shellness of the pion nucleon coupling in this momenta range, we discuss the results using either the pseudoscalar (PS) or pseudovector (PV) pion-nucleon couplings. When the PV coupling is used, the pair diagram contribution is higher order in the nonrelativistic expansion. The results for the helium-4 A-GFF are comparable to those given by the impulse approximation, especially for the PS coupling using both the K-harmonic method and variational method. The exchange current contributions with the PS coupling for the charge form factor of helium-4, yield better agreement with the existing data over a broad range of momenta, especially when the Argonne $v_{14}$ potential including the D-wave admixture is used.

The formations of the $K\left(\overline{K}\right), D\left(\overline{D}\right)$, and $B\left(\overline{B}\right)$ meson-nucleus bound states in ${}^{16}\mathrm{O}, {}^{40}\mathrm{Ca}, {}^{90}\mathrm{Zr}, {}^{197}\mathrm{Au}$, and ${}^{208}\mathrm{Pb}$ nucleus are investigated using the quark meson coupling model. The model relies on a mean field description of non-overlapping nucleon bags bound by the self-consistent interactions of scalar ($\sigma , \delta$) and vector ($\omega , \rho$) mesons with the (anti)quarks inside the bags, which is further extended to explore the properties of nuclei. We estimate the meson-nucleus bound state energies by solving the Klein-Gordon equations with the real potentials calculated self-consistently within the model, using a coordinate space approach. The calculations are carried out for different nuclear interactions. The effects of Coulomb interaction are considered in the present study for the charged mesons. Our study indicates the formation of rather deeply bound $B$-mesic states at the very central region of the nuclei, compared to the $D$ and $K$ mesons, offering a more promising probe to explore subtle nuclear medium effects. The investigations of such bound states are of particular interest for the upcoming $\overline{\mathrm{P}}\mathrm{ANDA}$ at FAIR, J-PARC-E29, and JLab experiments.

Systematical calculations are performed to study the effects of different effective nucleon-nucleon ($NN$) interactions on $\alpha$-decay half-life and extracted $\alpha$-cluster preformation probability. Within the double-folding model, both the nonrelativistic M3Y-type and the relativistic R3Y-type $NN$ interactions are involved and different methods to include the medium effect into the interactions are also introduced. The differences of the effective $NN$ interactions as well as their corresponding nuclear potentials and total $\alpha$-core potentials are analyzed in detail, and then their impacts on the $\alpha$-decay half-lives are discussed. By fitting the experimental decay half-lives of $\alpha$ emitters throughout the nuclide chart, three kinds of common $\alpha$-cluster preformation probability for even-even, odd-$A$, and odd-odd parent nuclei are extracted within two usual strategies. The obtained values are consistent with previous results and the medium effect on the $\alpha$-cluster preformation probability is further discussed. Under the extracted preformation probability, the theoretical $\alpha$-decay half-lives are in good agreement with the experimental data.

The proton transfer processes in multinucleon transfer reactions of ${}^{58}\mathrm{Ni}+{}^{208}\mathrm{Pb}$ and ${}^{71}\mathrm{Ni}+{}^{208}\mathrm{Pb}$ at incident energies of about 1.1 Bass barrier are investigated by using the improved quantum molecular dynamics model. A strong inverse multinucleon transfer effect is observed in the reaction ${}^{58}\mathrm{Ni}+{}^{208}\mathrm{Pb}$. The relative height of the Fermi surface between two colliding nuclei dominates the direction of proton transfer in quasielastic and deep-inelastic collision processes. By analyzing the correlation between the charge distributions and the contact time of the reaction partners, we find that the deep-inelastic collision processes of the neutron-deficient system ${}^{58}\mathrm{Ni}+{}^{208}\mathrm{Pb}$ have obvious advantages for producing the transtarget elements far from Pb. Up to 14 protons can be transferred from ${}^{58}\mathrm{Ni}$ to ${}^{208}\mathrm{Pb}$, resulting in a final cross section of the order of ${10}^{-4}$ mb.

We investigate charged-hadron production in relativistic heavy-ion collisions of asymmetric systems within a nonequilibrium-statistical framework. Calculated centrality-dependent pseudorapidity distributions for p-Pb collisions at $\sqrt{s_{\text{NN}}}=5.02$ and 8.16 TeV are compared with data from the Large Hadron Collider. Our approach combines a relativistic diffusion model with formulations based on quantum chromodynamics while utilizing numerical solutions of a Fokker-Planck equation to account for the shift and broadening of the fragmentation sources for particle-production with respect to the stopping (net-baryon) rapidity distributions. To represent the centrality dependence of charged-hadron production in asymmetric systems over a broad region of pseudorapidities, the consideration and precise modeling of the fragmentation sources, along with the central gluon-gluon source, is found to be essential. Specifically, this results in an inversion of the particle-production amplitude from backward to forward dominance when transitioning from central to peripheral collisions, in agreement with recent ATLAS and ALICE p-Pb data at $\sqrt{s_{\text{NN}}}=5.02\mathrm{T}\mathrm{e}\mathrm{V}$.

The radius parameters of single-particle potentials are important in theories of direct nuclear reactions where single-particle degrees of freedom are involved. Based on a separation energy prescription, we constrain the radius parameters of single-particle potentials of Woods-Saxon forms, $r_0$, using Hartree-Fock calculations with 122 sets of Skyrme interactions for the valence nucleons in the ground states of atomic nuclei. These $r_0$ values are used in the analysis of $(d,{}^3\mathrm{He})$ and ${(}^3\mathrm{He},d)$ reactions with the distorted wave Born approximation. The single-proton spectroscopic factors obtained from $(d,{}^3\mathrm{He})$ reactions agree very well with those from $(e,e^{\prime }p)$ reactions, and the reduction factors of the single-proton spectroscopic factors with respect to results of configuration mixing shell model calculations also agree well with the systematics of reduction factors found in other types of nuclear reactions. The $r_0$ values for nuclei with charge numbers $10\le z\le 20$ are found to be around 1.34 fm rather than the traditionally widely used 1.25 fm.

Background: Experiments involving nuclear reactions in a storage ring offer exceptional possibilities for precise measurements in inverse kinematics. These experiments provide excellent angular and energy resolution by particle spectroscopy, in addition to high luminosities. However, the extremely low-pressure environment maintained in the storage rings poses significant difficulties for experiments employing detectors or any outgassing material in the ring.

Purpose: We investigate nuclear reactions in inverse kinematics using the storage-ring technique. The reactions were induced by scattering of a ${}^{20}\mathrm{Ne}$ beam off a hydrogen target at an energy of 50 MeV/u.

Method: A beam of fully stripped ${}^{20}\mathrm{Ne}$ ions was injected into the ESR storage ring at an energy of 50 MeV/u. The beam interacted with an internal hydrogen gas-jet target. An ultrahigh vacuum compatible detector setup was installed around the gas jet inside the ring to measure the recoiling particles generated by nuclear reactions.

Results: Multiple reaction channels were observed during the experiment. In particular, we present the results from studies on elastic and inelastic scattering, as well as the neutron transfer reaction ${}^{20}\mathrm{Ne}(p,d){}^{19}\mathrm{Ne}^{*}$. The experimental data were compared to calculations that took into account the most significant excited states, using a coupled-reaction channel approach. A very good agreement with the experimental data was achieved.

Conclusions: The present results are the first demonstration of the investigation transfer reactions using detectors directly installed in the ring. This provides an important proof-of-principle for prospective studies with far-from-stability radioactive beams in the future.

The ${}^{17}\mathrm{O}(n,\alpha ){}^{14}\mathrm{C}$ and ${}^{17}\mathrm{O}(\alpha ,n){}^{20}\mathrm{Ne}$ reactions compete to determine the level of neutron recycling that occurs following neutron absorption by the ${}^{16}\mathrm{O}(n,\gamma ){}^{17}\mathrm{O}$ reaction during $s$-process nucleosynthesis. Yet, because of large inconsistencies in the absolute cross section of the ${}^{17}\mathrm{O}(n,\alpha ){}^{14}\mathrm{C}$ reaction, this process retains a large uncertainty. To resolve the inconsistencies in past experimental data, a multichannel $R$-matrix analysis was used to fit ${}^{14}\mathrm{C}(\alpha ,\alpha ){}^{14}\mathrm{C}$ data, thereby constraining the partial widths of the two lowest energy resonances and thus the resonant ${}^{17}\mathrm{O}(n,\alpha ){}^{14}\mathrm{C}$ cross section. A detailed uncertainty analysis, using Bayesian methods, has been performed resulting in an updated reaction rate. Recommendations are given to further improve the cross section determination using this method.

The equation of state (EOS) in the limit of infinite symmetric nuclear matter exhibits an equilibrium density, $n_0\approx 0.16{\mathrm{fm}}^{-3}$, at which the pressure vanishes and the energy per particle attains its minimum, $E_0\approx -16\mathrm{MeV}$. Although not directly measurable, the nuclear saturation point $(n_0,E_0)$ can be extrapolated by density-functional theory (DFT), providing tight constraints for microscopic interactions derived from chiral effective-field theory (EFT). However, when considering several DFT predictions for $(n_0,E_0)$ from Skyrme and relativistic mean field (RMF) models together, a discrepancy between these model classes emerges at high confidence levels that each model prediction's uncertainty cannot explain. How can we leverage these DFT constraints to rigorously benchmark nuclear saturation properties of chiral interactions? To address this question, we present a Bayesian mixture model that combines multiple DFT predictions for $(n_0,E_0)$ using an efficient conjugate prior approach. The inferred posterior distribution for the saturation point's mean and covariance matrix follows a normal-inverse-Wishart (NIW) class, resulting in posterior predictives in the form of correlated, bivariate $t$ distributions. The DFT uncertainty reports are then used to mix these posteriors using an ordinary Monte Carlo approach. At the 95% credibility level, we estimate $n_0\approx 0.157\pm 0.010{\mathrm{fm}}^{-3}$ and $E_0\approx -15.97\pm 0.40\mathrm{MeV}$ for the marginal (univariate) $t$ distributions. Combined with chiral EFT calculations of the pure neutron matter equation of state, we obtain bivariate normal distributions for the nuclear symmetry energy and its slope parameter evaluated at $n_0$: $S_v\approx 32.0\pm 1.1\mathrm{MeV}$ and $L\approx 52.6\pm 8.1\mathrm{MeV}$ (95%), respectively. Our Bayesian framework is publicly available, so practitioners can readily use and extend our results.

The cross sections of the ${}^{70}\mathrm{Ge}(n,2n){}^{69}\mathrm{Ge}, {}^{72}\mathrm{Ge}(n,\alpha ){}^{69\mathrm{m}}\mathrm{Zn}, {}^{72}\mathrm{Ge}(n,p){}^{72}\mathrm{Ga}, {}^{73}\mathrm{Ge}(n,n\alpha ){}^{69\mathrm{m}}\mathrm{Zn}, {}^{73}\mathrm{Ge}(n,np/d){}^{72}\mathrm{Ga},{}^{73}\mathrm{Ge}(n,p){}^{73}\mathrm{Ga},{}^{74}\mathrm{Ge}(n,\alpha ){}^{71\mathrm{m}}\mathrm{Zn},{}^{74}\mathrm{Ge}(n,np/d){}^{73}\mathrm{Ga}$, and ${}^{76}\mathrm{Ge}(n,2n){}^{75}\mathrm{Ge}$ reactions have been experimentally determined via the activation technique, relative to the ${}^{27}\mathrm{Al}(n,\alpha ){}^{24}\mathrm{Na}$ reference reaction in the energy range between 14.0 and 18.9 MeV. The quasi-monoenergetic neutron beams were produced via the ${}^3\mathrm{H}(d,n){}^4\mathrm{He}$ reaction at the neutron beam facilities of NCSR “Demokritos” (Greece) and the accelerator for metrology and neutron applications in external dosimetry (AMANDE) of the Institute of Radiation Protection and Nuclear Safety (IRSN, France). After each irradiation, the samples' induced radioactivity was measured via $\gamma$-ray spectroscopy using HPGe detectors. Isotopically enriched Ge targets were utilized for all cross-section measurements, yielding more accurate cross-section results in comparison with the more widely used natural ones. Finally, theoretical calculations were performed via the empire 3.2.3 code, employing a coherent set of input parameters for the successful reproduction of all the aforementioned reaction channels.

The structure of the dense-matter equation of state is essential for the phenomenology of neutron stars. In this work, I relate the thermodynamic properties to the average speed of sound in the interior of a star. I study the consequences of the vanishing of the trace anomaly. In particular, I show that if the trace anomaly vanishes in the centers of maximally massive neutron stars, the speed of sound likely exceeds its conformal value and exhibits nonmonotonic behavior. I also find that the additional assumption of positive definiteness of the trace anomaly naturally induces a local peak of the speed of sound at densities realized in the cores of neutron stars. I also reanalyze the stability condition for hybrid neutron stars. Possible implications for the dense matter equation of state and the phenomenology of neutron stars are also discussed.

We analyze the ${}^{115}\mathrm{In}\beta$-decay energy spectrum through the spectral moment method (SMM), previously introduced in the context of ${}^{113}\mathrm{Cd}\beta$ decay. The spectral moments ${\mu }_n$ are defined as averaged $n\mathrm{th}$ powers of the $\beta$ particle energy, characterizing the spectrum normalization ($n=0$) and shape ($n\ge 1$) above a given threshold. For ${}^{115}\mathrm{In}$, we consider three independent datasets characterized by different thresholds. We also consider three nuclear model calculations with two free parameters: the ratio of axial-vector to vector couplings, $r=g_{\mathrm{A}}/g_{\mathrm{V}}$, and the small vector-like relativistic nuclear matrix element (NME), $s=s$-NME. By using the most recent of the three datasets, we show that the first few spectral moments can determine $(r,s)$ values in good agreement with those obtained by full-fledged experimental fits. We then work out the SMM results for the other datasets. We find that, although $g_{\mathrm{A}}$ quenching is generally favored, the preferred quenching factors may differ considerably depending on the chosen experimental data and nuclear models. We discuss various issues affecting both the overall normalization and the low-energy behavior of the measured and computed spectra, and their joint effects on the experimentally quoted half-life values. Furthermore, ${}^{115}\mathrm{In}\beta$-decay data at the lowest possible energy threshold appear to be crucial to clarify these issues.

Excited states of the neutron-rich nucleus ${}^{157}\mathrm{Sm}$ were populated through the ${\beta }^{-}$ decay of ${}^{157}\mathrm{Pm}$, which has a tentatively assigned ground-state spin and parity of $J^{\pi }=(5/2^{-})$. Over 30 levels have been observed, 16 of which are new, and over 45 new $\gamma$-ray transitions have been placed in the level scheme. An evolution in the ground-state configurations for $N=95$ nuclei from $5/2^{-}\left[523\right]$ (Er/Yb), to $5/2^{+}\left[642\right]$ (Dy), to $3/2^{-}\left[521\right]$ (Sm/Gd) can be explained based on increasing deformation from $Z=70$ to $Z=62$ and the fact that these three orbitals are energetically close to each other at deformations near ${\beta }_2\approx 0.25–0.3$. Tentative spin and parity assignments are made for most of the states below 1500 keV based on the decay properties of the levels and using excitation-energy systematics of the various orbitals observed in $N=95$ nuclei.

We employ a microscopic method to study how isospin affects the fission potential of ${}^{240}\mathrm{Pu}$. Our approach uses constrained Hartree-Fock theory (CHF) which allows us to separately investigate the isoscalar and isovector properties of the nuclear energy density functional (EDF). By analyzing the isoscalar and isovector components of the EDF along the fission path we can assess the isovector contribution to fission barriers. We study this effect for the fully adiabatic path to scission. The isovector component of the fission potential is found to increase in magnitude as the nucleus evolves towards scission, exemplifying the importance of stringent constraints on the isovector sector of the nuclear EDF for reliable predictions of fission properties.

We report the mass measurements of neutron-rich isotopes produced via spontaneous fission of ${}^{252}\mathrm{Cf}$ using a multireflection time-of-flight mass spectrograph. The mass of ${}^{155}\mathrm{Ce}$ is determined experimentally for the first time. A discrepancy between the experimental and literature values was found for the mass of ${}^{127}\mathrm{Sb}$, which was previously deduced through indirect measurements. In comparison with several theoretical predictions, both the values and the trend of the mass excesses of ${}^{152\text{–}155}\mathrm{Ce}$ cannot be consistently explained. The wide-range and simultaneous mass measurements of the multireflection time-of-flight mass spectrograph enable us to crosscheck the existing mass data, and the conflict between the measured time-of-flight ratio and the extracted mass would imply the necessity of re-examining them.

The evolution of a relativistic heavy-ion collision is typically understood as a process that transmutes the initial geometry of the system into the final momentum distribution of observed hadrons, which can be described via a cumulant expansion of the initial distribution of energy density and is represented at leading order as the well-known eccentricity scaling of anisotropic flow. We extend this framework to include the contribution from initial momentum-space properties, as encoded in other components of the energy-momentum tensor. We confirm the validity of the framework in state-of-the-art hydrodynamic simulations of large and small systems. With this framework, it is possible to separate the effects of early time dynamics from those of final-state evolution, even in the case when the distribution of energy does not fully determine subsequent evolution, as for example, in small systems. Specifically, we answer the question of when and how azimuthal correlations from the initial state survive to the final state. In very small systems such as $p\text{−}p$, for example, initial momentum degrees of freedom dominate over energy. Thus, even if the system forms a quark-gluon plasma that is well described by hydrodynamics, the usual hydrodynamic picture of the transmutation of initial geometry to final momentum anisotropy is broken. Nevertheless, we show that the hydrodynamic response to the full energy-momentum tensor can be well understood in a similar manner as larger systems. Additionally, this framework elucidates the generic features of the system's evolution that are responsible for the impressive success of hydrodynamic simulations, but which may still hold even in cases where hydrodynamics is not applicable.