We report precision mass measurements of ${}^{74-76}\mathrm{Sr}$ performed with the TITAN multiple-reflection time-of-flight mass spectrometer. This marks a first-time mass measurement of ${}^{74}\mathrm{Sr}$ and gives increased mass precision to both ${}^{75}\mathrm{Sr}$ and ${}^{76}\mathrm{Sr}$, which were previously measured using storage ring and Penning trap methods, respectively. This completes the $A=74$, $T=1$ isospin triplet and gives increased precision to the $A=75$, $T=1/2$ isospin doublet, which are both the heaviest experimentally evaluated triplets and doublets to date. The new data allow us to evaluate coefficients of the isobaric multiplet mass equation for the first time at $A=74$ and with increased precision at $A=75$. With increased precision of ${}^{75}\mathrm{Sr}$, we confirm the recent measurement reported by CSRe that was used to remove a staggering anomaly in the doublets. New ab initio valence-space in-medium similarity renormalization group calculations of the $T=1$ triplet are presented at $A=74$. We also investigate the impact of the new mass data on the reaction flow of the rapid proton capture process in type I x-ray bursts using a single-zone model.

In this investigation, we compute the nuclear matrix elements (NMEs) relevant to the light neutrino-exchange mechanism governing neutrinoless double beta ($0\nu \beta \beta$) decay in ${}^{136}\mathrm{Xe}$. Our method is based on the nonclosure approach within the interacting nuclear shell model framework. This approach considers the genuine effects arising from the excitation energies of the first 200 states for each spin-parity of the intermediary nucleus ${}^{136}\mathrm{Cs}$. All computations are performed using the effective shell model Hamiltonian GCN5082. To understand the impact of nuclear structure on $0\nu \beta \beta$ decay, we explore the dependence of the NME on various factors, including the number of intermediate states and their spin-parity characteristics. We identify an optimal closure energy of approximately 3.7 MeV for the $0\nu \beta \beta$ decay of ${}^{136}\mathrm{Xe}$ that reproduces the nonclosure NME using the closure approach. The calculated total NME for the light neutrino-exchange $0\nu \beta \beta$ decay of ${}^{136}\mathrm{Xe}$ is 2.06 with the CD-Bonn short-range correlation. These results can be valuable for future experimental investigations into the $0\nu \beta \beta$ decay of ${}^{136}\mathrm{Xe}$.

Background: In an earlier experiment by one of us and collaborators, we measured the evaporation residue cross sections for the ${}^{37}\mathrm{Cl}+{}^{68}\mathrm{Zn}$ fusion reaction near the Coulomb barrier in the energy range of $E_{\mathrm{c}.\mathrm{m}.}=61.38$–89.97 MeV [Phys. Rev. C 102, 064606 (2020)]. The enhancement in the measured sub-barrier fusion cross sections has been understood in terms of distinct intrinsic degrees of freedom of the colliding nuclei, but a complete understanding of the phenomenon has yet to emerge.

Purpose: In the present work, we aim to theoretically analyze the decay of ${}^{105}\mathrm{Ag}^{*}$ compound nucleus in the energy range $E_{\mathrm{c}.\mathrm{m}.}=61.38–89.97\mathrm{MeV}$ using the dynamical cluster-decay model (DCM). We first intend to examine the sub-barrier and above barrier fusion phenomena. Next objective is to investigate the role of deformations on the preformation structure. Finally, we attempt to scrutinize the noncoplanarity effects.

Methods: Quantum mechanical fragmentation theory is employed to calculate the fusion evaporation cross sections, ${\sigma }_{\mathrm{fus}.}$, for the reaction ${}^{37}\mathrm{Cl}+{}^{68}\mathrm{Zn}$, using the one-parameter fitting, viz. the neck length parameter ($\mathrm{\Delta }R$). This parameter, which fixes both preformation and penetration paths, varies smoothly with the temperature of the compound nucleus in both below- and above-barrier energy regions. A systematic approach is made by first considering only spherical and then quadrupole (${\beta }_{2i}$) deformed fragments with corresponding optimum (${\theta }_i^{\mathrm{opt}.}$) orientations using the coplanar ($\mathrm{\Phi }=0^{\circ }$) configuration. As a next step, deformations up to hexadecapole (${\beta }_{2i}\text{−}{\beta }_{4i}$) and associated compact orientations (${\theta }_{ci}$) are taken into account with the use of noncoplanar ($\mathrm{\Phi }\ne 0^{\circ }$) degree of freedom.

Results: For the best fitted $\mathrm{\Delta }R$, the role of spherical and temperature independent ${\beta }_{2i}$ deformations are explored with hot-compact configuration. The DCM calculated fusion evaporation cross sections are compatible with the experimental data. Further, investigation of spherical, ${\beta }_{2i}$ ($T=0$)-static and ${\beta }_{2i}$ ($T\ne 0$)-dynamic deformations are performed at the highest $E_{\mathrm{c}.\mathrm{m}.}=90.0\mathrm{MeV}$ energy. Finally, a comparative study of the decay path is done by including the noncoplanar configurations as well.

Conclusions: The addition of deformations modifies the radii of the decaying fragments and hence their orientations which in turn impact the Coulomb, proximity, and angular momentum-dependent potentials. Thus, the structural information contained in the compound nucleus optimizes as per the minimized fragments in the resulting fragmentation potential. Along with deformations, angular momentum also plays a crucial role in determining the preformation probability and barrier characteristics of the decay fragments. Thus, preformation and penetration probabilities, which ultimately determine fusion cross-sections, get modified for different configurations of the decaying fragments.

The production mechanism of light nuclei in heavy-ion collisions is vital to understanding the intricate details of nucleon-nucleon interactions. The coalescence of nucleons is a well-known mechanism that attempts to explain the production mechanism of these light clusters. This work investigates the formation mechanism of these nucleon clusters with a combination of coalescence and femtoscopy of nucleons and nuclei. It is achieved by appending a coalescence and correlation afterburner (CRAB) to the SMASH transport model. To have a proper view of the anisotropy of light nuclei clusters, a mean-field approach to SMASH is applied. The anisotropic coefficients of various light nuclei clusters are calculated and compared to experimental measurements. To incorporate hydrodynamics into the picture, the anisotropic measurements are completed in a hybrid SMASH$+$vHLLE mode. In both approaches, the femtoscopy of nucleons and light nuclei is performed, reported with CRAB, and compared to the latest experimental measurements. An insight into cluster formation time is drawn by extracting the emission source size with the Lednický-Lyuboshits model.

The two-particle momentum correlation between the omega-baryon ($\mathrm{\Omega }$) and ${}^4\mathrm{He}\left(\alpha \right)$ in high-energy heavy ion collisions is explored. Such correlations as an alternative source of information can help us further understand the interaction between $\mathrm{\Omega }$ and nucleons ($N$). $\mathrm{\Omega }\alpha$ potentials in the single-folding potential approach are constructed by employing two different available $\mathrm{\Omega }N$ interactions in the ${}^{5}S_2$ channel, i.e., one is based on the (2 $+$ 1)-flavor lattice QCD simulations near the physical point by the HAL QCD Collaboration, and the other is based on meson exchanges with an effective Lagrangian, where in the latter case the effect of coupled channels is considered. It is found that the correlation functions at small source size depend on the potential model used. This implicitly means that, in high density nuclear medium, the $\mathrm{\Omega }\alpha$ momentum correlation could carry information on the feature of $\mathrm{\Omega }N$ interactions. Moreover, by extracting the scattering length and the effective range from obtained $\mathrm{\Omega }\alpha$ potentials, the correlation functions are calculated within the Lednicky-Lyuboshits (LL) formalism. It is shown that, since the $\mathrm{\Omega }\alpha$ has a large interaction range, the LL formula leads to different results at small source sizes.

The nuclear structures of ${}^7\mathrm{Li}$ ($\alpha +n+n+p$) and ${}^7\mathrm{Be}$ ($\alpha +p+p+n$) are studied within the microscopic cluster model, in which the clustering fragments, e.g., triton, ${}^3\mathrm{He}$, and even the single nucleons around the core are studied in the ${}^7\mathrm{Li}$ and ${}^7\mathrm{Be}$ systems. We obtain the energy spectra and wave functions of ${}^7\mathrm{Li}$ and ${}^7\mathrm{Be}$, and the calculated energy spectra of the ground states and some of the excited states are consistent with experimental data. To investigate the cluster-formation probabilities, we calculate the reduced-width amplitudes of various binary partitions. The results show that the $\alpha +t{(}^3\mathrm{He})$ cluster structure is dominant in the low-lying states of ${}^7\mathrm{Li}$ (${}^7\mathrm{Be}$), including the ground state and the three lowest excited states. In some higher states around the single-particle thresholds, the components of $\mathrm{core}+N$ structures, namely ${}^6\mathrm{Li}+n$ and ${}^6\mathrm{He}+p$ in ${}^7\mathrm{Li}$ and ${}^6\mathrm{Li}+p$ in ${}^7\mathrm{Be}$, are significantly enhanced.

The influences of triaxial dynamics on the anomalous $E2$ transitional behaviors in the interacting boson model (IBM) is comprehensively examined without symmetry restrictions. Specifically, different triaxial schemes in the IBM is analyzed using a general procedure for deriving triaxial rotor modes based on two distinct approaches. The results indicate that the $B\left(E2\right)$ anomaly feature, characterized by $B_{4/2}=B(E2;4_1^{+}\to 2_1^{+})/B(E2;2_1^{+}\to 0_1^{+})<1.0$, can occur in all triaxial schemes due to strong band-mixing effects. This finding is further tested in describing the available data for ${}^{172}\mathrm{Pt},{}^{168,170}\mathrm{Os}$ and ${}^{166}\mathrm{W}$ using the model constructed upon the extended consistent-$Q$ formula, providing a simple theoretical explanation of the depressed $B_{4/2}$ values observed in the experiments.

A convolutional neural network (CNN) is employed to investigate nuclear mass. By introducing the masses of neighboring nuclei and the paring effects at the input layer of the network, local features of the target nucleus are extracted to predict its mass. Then, through learning the differences between the experimental nuclear masses and the predicted nuclear masses by the WS4 model, a new global-local model (CNN-WS4) is developed, which incorporates both the global nuclear mass model and local features. Due to the incorporation of local features, the CNN-WS4 model achieves high accuracy on the training set. When extrapolating for newly emerged nuclei, the CNN-WS4 also exhibits appreciable stability, thereby demonstrating its robustness.

The cross sections for the ${}^{12}\mathrm{C}(\gamma ,\alpha ){}^8\mathrm{Be}\to 3\alpha$ reaction have been successfully measured using exclusive coincidence between three $\alpha$ particles, minimizing Compton background. Sequential breakup kinematics are evident, and the cross sections are presented as locally averaged histogram values. Theoretical Fresco Continuum Discretized Coupled Channel-Coupled Reaction Channels (CDCC-CRC) calculations reproduce the experimental data, showing that the process involves electromagnetic coupling to both ${}^8\mathrm{Be}^{0^{+}}$ and ${}^8\mathrm{Be}^{2^{+}}$ states. This study confirms that the ${}^{12}\mathrm{C}(\gamma ,\alpha ){}^8\mathrm{Be}\to 3\alpha$ reaction proceeds via a sequential mechanism, crucial for understanding its significance in radiotherapy dosimetry.

We investigate the pre-equilibrium dipole response in the charge-asymmetric reaction ${}^{40}\mathrm{Ca}+{}^{152}\mathrm{Sm}$, of recent experimental interest, at several beam energies within the range $[5,11]\approx 10A$ MeV and different collision centralities. By employing Skyrme-like effective interactions for the nuclear mean field, we probe the role of the different ingredients performing theoretical calculations based on the time-dependent Hartree-Fock approach or a semiclassical transport model that also includes two-body correlations. A comparative analysis between these approaches allows us to disentangle the role of deformation effects in the entrance channel from the ones associated with structure details of genuine quantal nature on the dipole emission. Moreover, we also investigate the impact of the occurrence of residual two-body collisions on the reaction dynamics. This study contributes to the understanding of the microscopic processes that determine the complex dynamics of low-energy heavy-ion collisions along the fusion-fission path, which is relevant to superheavy-element synthesis, unraveling interesting connections with the characteristics of the nuclear effective interaction and the associated equation of state.

Self-consistent mean-field methods with Skyrme-type effective interactions and semiclassical approximations, such as the Thomas-Fermi approach and its extensions are particularly well-suited for describing in a thermodynamically consistent way the various phases of the dense matter present in the interior of neutron stars. These methods have been applied to predict the composition of the different regions, including the inner crust constituted by nuclear clusters coexisting with free neutrons and electrons. Because of the computational cost, the energy is typically calculated for a few selected average baryon number densities, and the results are interpolated to obtain the pressure numerically. However, this may introduce systematic errors in the calculations of the global structure of a neutron star and its dynamical evolution. In this paper, we show how the full equation of state can be consistently calculated within the same framework by deriving exact formulas for the chemical potentials and for the pressure that can be easily implemented in existing computer codes. These formulas are applicable to both catalyzed and accreted crusts. We discuss in each case the suitable conditions to impose to determine the composition. Numerical examples are also presented and discussed. Results from refined calculations of the BSk24 equation of state for the inner crust of nonaccreted neutron stars and the corresponding adiabatic index are provided.

Precise mass measurements of refractory nuclei produced by multinucleon transfer reactions of $\mathrm{a}{}^{136}\mathrm{Xe}$ beam and ${}^{\mathrm{nat}}\mathrm{Ir}$ target were conducted at the KISS (KEK Isotope Separation System) facility, using a multireflection time-of-flight mass spectrograph. The study encompasses ions with mass numbers $A=188,189,190,192$, and atomic numbers $Z=74–79$. Our findings show good agreement between the evaluated masses, excluding ${}^{192}\mathrm{Re}$, and known values, within the specified error margins. The assessment includes the reevaluation of the rejected mass value for ${}^{189}\mathrm{W}$ in the AME2020 atomic mass evaluation. The determined atomic mass of ${}^{189}\mathrm{W}$ aligns closely with previously reported values obtained through direct mass measurements using the GSI storage ring ESR and $\beta$-decay $Q$-value measurements. The flat $S_{2\mathrm{n}}$ pattern between ${}^{189}\mathrm{W}$ and ${}^{190}\mathrm{W}$ was interpreted as a result of a shape transition at $N=116$ according to Hartree-Fock-Bogoliubov calculations with the SV-min parametrization. Additionally, the updated mass value for ${}^{192}\mathrm{Re}$ also suggests a shape transition at $N=117$, consistent with previous studies.

Within the framework of Lanzhou quantum molecular dynamics transport model, the neutron-skin thickness and its impact on the nuclear dynamics induced by low-energy antiprotons are investigated thoroughly. The correlation of the neutron-skin thickness and stiffness of symmetry energy is implemented into the transport model via the Fermi distributions of the proton and neutron density profiles. It is found that antiprotons are predominantly annihilated in the subsaturation density region ($0.4{\rho }_0–0.8{\rho }_0$). The isospin ratios of free neutrons to protons (n/p) and charged pion yields (${\pi }^{-}/{\pi }^{+}$) in collisions of antiprotons on ${}^{48}\mathrm{Ca}$ and ${}^{208}\mathrm{Pb}$ are analyzed systematically for extracting the symmetry energy in the domain of subsaturation densities. The n/p ratio is sensitive to the stiffness of symmetry energy in the low-density region, and a soft symmetry energy leads to the larger n/p ratio, in particular, with decreasing the beam momentum. However, the ${\pi }^{-}/{\pi }^{+}$ ratio weakly depends on the symmetry energy.

The chiral magnetic effect (CME) in heavy-ion collisions reflects the local violation of $\mathcal{P}$ and $\mathcal{C}P$ symmetries in strong interactions and manifests as electric charge separation along the direction of the magnetic field created by the wounded nuclei. The experimental observables for the CME, such as the ${\gamma }_{112}$ correlator, the $R_{{\mathrm{\Psi }}_2}\left(\mathrm{\Delta }S\right)$ correlator, and the signed balance functions, however, are also subject to non-CME backgrounds, including those from resonance decays. A previous study showed that the CME observables are affected by the diagonal component of the spin density matrix, the ${\rho }_{00}$ for vector mesons. In this work, we study the contributions from the other elements of the spin density matrix using a toy model and a multiphase transport model. We find that the real part of the ${\rho }_{1-1}$ component, $\mathrm{Re}{\rho }_{1-1}$, affects the CME observables in a manner opposite to that of the ${\rho }_{00}$. All three aforementioned CME observables show a linear dependence on $\mathrm{Re}{\rho }_{1-1}$ in the model calculations, supporting our analytical derivations. The rest elements of the spin density matrix do not contribute to the CME observables. The off-diagonal terms in the spin density matrix indicate spin coherence and may be nonzero in heavy-ion collisions due to local spin polarization or spin-spin correlations. Thus, $\mathrm{Re}{\rho }_{1-1}$, along with ${\rho }_{00}$, could play a significant role in interpreting measurements in search of the CME.

A covariant relativistic approach based on the Vlasov equation is applied to the study of infinite asymmetric nuclear matter. We use several Walecka-type hadronic models and obtain the dispersion relations for the longitudinal modes. The isovector and isoscalar collective modes are determined for a wide range of densities as a function of isospin asymmetry and momentum transfer within a set of 11 relativistic mean field models with different nuclear matter properties. Special attention is given to beta-equilibrium matter. It is shown that the possible propagation of isoscalar- and isovector-like modes depends directly on the density dependence of the symmetric nuclear matter equation of state and of the symmetry energy, with a stiff equation of state favoring the propagation of isoscalar-like collective modes at high densities, and a stiff symmetry energy defining the behavior of the isovector-like modes which propagate for densities below two times saturation density. The coupling of the nuclear modes to the electron plasmon is also discussed.

The goal of this work is to treat few-body nuclear systems using the adiabatic hyperspherical representation, to test an alternative approach to treat both bound and continuum states and compare the results to other techniques often used in nuclear calculations. This method is utilized to solve the $N$-body Schrödinger equation for the three- and four-body systems, treating both ${}^6\mathrm{He}$ and ${}^7\mathrm{He}$ nuclei. A simplified central potential model for the ${}^4\mathrm{He}-n$ interaction is used in conjunction with a spin-dependent three-body interaction to reproduce ${}^6\mathrm{He}$ bound-state and resonance properties as well as properties for the ${}^8\mathrm{He}$ nucleus in its ground state. With this Hamiltonian, bound and scattering states for both ${}^6\mathrm{He}$ and ${}^7\mathrm{He}$ nuclei are computed. For the ${}^6\mathrm{He}$ system, the electric quadrupole transition between the $0^{+}$ and $2^{+}$ state is investigated. For the ${}^7\mathrm{He}$ system, ${}^6\mathrm{He}+n$ elastic scattering is investigated along with the four-body recombination process ${}^4\mathrm{He}+n+n+n\to {}^6\mathrm{He}+n$ and breakup process ${}^6\mathrm{He}+n\to {}^4\mathrm{He}+n+n+n$. An application of the adiabatic hyperspherical representation to a five-body description of ${}^8\mathrm{He}$ is also presented with the prospects of studying four neutrons in the scattering continuum that interact with a core nucleus.

The finite-temperature phase structures for neutron-proton superfluidity in asymmetric nuclear matter are investigated, with a particular focus on the angular dependence of the pairing gap induced by the ${}^{3}SD_1$ nucleon-nucleon interaction. This angular dependence of the pairing gap results in the Cooper pair momentum in the Fulde-Ferrell-Larkin-Ovchinnikov (FFLO) state exhibiting exactly two distinct stable orientations: one orthogonal (FFLO-ADG-O) and the other parallel (FFLO-ADG-P) to the symmetry axis of the pairing gap. The FFLO-ADG-O state dominates at low asymmetries, while the FFLO-ADG-P state prevails at high asymmetries. Additionally, this analysis of normal-superfluid phase separation reveals that the angular dependence of the pairing gap eliminates phase separation in the low-asymmetry regime, whereas the Cooper pair momentum effectively suppresses phase separation at high asymmetries. These two mechanisms act in concert to significantly prevent the occurrence of normal-superfluid phase separation across the entire phase diagram, ensuring the stability of the homogeneous superfluid state over a broad range of asymmetries. These results provide new insights into the interplay between the angular dependence of the pairing gap and the stability of superfluidity in asymmetric nuclear matter.

High-spin states of the odd-odd ${}^{136}\mathrm{Pr}$ nucleus have been investigated using the ${}^{100}\mathrm{Mo}({}^{40}\mathrm{Ar},1p3n)$ reaction with the JUROGAM II $\gamma$-ray spectrometer. Many new transitions and levels were identified in addition to the confirmation of most previously known transitions and levels. The high statistics of the present data set allowed the multipolarity assignments for many transitions to be established, which were previously assigned tentatively. Possible configuration assignments for the bands above the $I^{\pi }=6^{+}$ isomer are analyzed within the tilted axis cranking covariant density functional theory framework, and the experimental energy spectra and ratios of reduced transition probabilities are reproduced fairly well. A complete picture of the band structure of this nucleus is established. In particular, the effect of the neutron $h_{9/2}$ and $f_{7/2}$ intruder orbitals involved in the configurations of the decoupled bands is discussed in detail.

The reactions of $p +{}^{12}\mathrm{C}$ with triangular $3\alpha$ structure and spherical structure with incident energies ranging from 5 to 200 MeV/nucleon are simulated by the extended-quantum-molecular-dynamics (EQMD) model together with the GEMINI decay process. This paper presents the incident energy dependence of the branching ratios of fragment production and multiplicity, as well as the associated event information entropy. The results indicate that the triangular $3\alpha {}^{12}\mathrm{C}$ has an extra branching ratio for the quasielastic reaction compared to the spherical ${}^{12}\mathrm{C}$. This peculiarity of the branching ratios of the triangular $3\alpha {}^{12}\mathrm{C}$ appears as a small dent in the curves of the event information entropy (both the fragment information entropy and the multiplicity information entropy). Therefore, we propose that the event information entropy could be a probe for detecting the $\alpha$-cluster structure.