We propose an algebraic approach to elucidate the dynamic characteristics of triaxial rotor modes in nuclei by mapping a triaxial rotor Hamiltonian to the interacting boson model one within a finite-$N$ framework. Our method unveils striking features not observed in conventional modes, exemplified by the $B\left(E2\right)$ anomaly, characterized by $B(E2;4_1^{+}\to 2_1^{+})/B(E2;2_1^{+}\to 0_1^{+})<1$. Using specific examples, we demonstrate that the peculiar properties of low-lying states in both neutron-rich and neutron-deficient Os nuclei can be comprehensively understood through the proposed Hamiltonian, which incorporates both rigid and soft triaxial rotor modes. This algebraic method not only offers fresh insights into triaxial dynamics but also showcases its capability in uncovering emergent exotic collective modes in nuclear structure.

The low-energy nuclear structure and two-neutrino double-$\beta$ ($2\nu \beta \beta$) decay are studied within the interacting boson model (IBM) that is based on the nuclear energy density functional (EDF). The IBM Hamiltonian describing the initial and final even-even nuclei, and the interacting boson fermion-fermion Hamiltonian producing the intermediate states of the neighboring odd-odd nuclei are determined by the microscopic inputs provided by the self-consistent mean-field (SCMF) calculations employing a relativistic EDF and a separable pairing force. Sensitivities of the low-lying structure and $2\nu \beta \beta$-decay properties to the pairing strength are specifically analyzed. It is shown that the SCMF calculations with decreased and increased pairing strengths lead to quadrupole-quadrupole interaction strengths in the IBM that are, respectively, significantly enhanced and reduced in magnitude. When the increased pairing is adopted, in particular, the energy levels of the excited $0^{+}$ states are lowered, and the predicted $2\nu \beta \beta$-decay nuclear matrix elements (NMEs) increase in magnitude systematically. The mapped IBM employing the increased pairing force generates effective NMEs and half-lives that are in a reasonable agreement with the experimental data for the ${}^{76}\mathrm{Ge}\to {}^{76}\mathrm{Se}, {}^{82}\mathrm{Se}\to {}^{82}\mathrm{Kr}$, and ${}^{100}\mathrm{Mo}\to {}^{100}\mathrm{Ru}$ decays in particular, whereas the calculation with the standard pairing strength is adequate to provide an overall good description of the effective NMEs in agreement with data.

Excited states of ${}^{122}\mathrm{Xe}$ populated via ${\beta }^{+}$ and electron capture (EC) decay of ${}^{122}\mathrm{Cs}$ have been studied with $\gamma$-ray spectroscopy using the $8\pi$ spectrometer at the TRIUMF Isotope Separator and Accelerator facility. Two sets of data were collected to optimize the signal-to-background ratio for decays of the ground ($t_{1/2}=21.2$ s) and isomeric ($t_{1/2}=3.7$ min) states of ${}^{122}\mathrm{Cs}$. The data collected have enabled the observation of 520 transitions and 191 levels, including eight new excited $0^{+}$ states in ${}^{122}\mathrm{Xe}$. The $\gamma \text{−}\gamma$ angular correlations have been analyzed that permitted the assignment or restriction of the spins for 66 levels. The $E2/M1$ multipolarity mixing ratios for 38 $\gamma$-ray transitions were also extracted from these analyses. Low-spin members of the $0_2^{+}, 0_3^{+}, 0_4^{+}$, and $K^{\pi }=4^{+}$ bands are assigned, as well as suggested $K^{\pi }=2_2^{+}$ and $K^{\pi }=2_3^{+}$ bandheads. Combined with previous results for high-spin states, rotational bands built on a newly assigned $K^{\pi }=3_1^{-}$ state and its $4_1^{-}$ signature partner, the $5_2^{-}$ and its $6_2^{-}$ signature partner, are suggested. The results for the positive-parity bands are compared with a model using a general Bohr Hamiltonian derived from a mean-field theory based on the UNEDF0 energy-density functional that displays good overall agreement.

We present exact relations between the diffusion coefficients or conductivities, ${\kappa }_{q{q}^{\prime }}/T={\sigma }_{q{q}^{\prime }}$, of strongly interacting matter. We show that once the diagonal entries are known in two different charge representations, the off-diagonal coefficients are functions of the diagonal entries once isospin symmetry applies. As an important example, we infer the conductivities on the basis of available calculations from lattice quantum chromodynamics and argue that these computations suffer under the approximations made to achieve them. Further, we argue that the representation of the conductivities with respect to the conserved quark flavors may deliver more insight into the chemical composition of strongly interacting matter.

We discuss the electron and muon neutrino and antineutrino double-differential cross sections on carbon in the quasielastic as well as in the multinucleon and one pion production channels. By projecting them in the transferred momentum—transferred energy plane and in the neutrino energy—lepton scattering angle plane, as well as by performing simple considerations on the position of the quasielastic and Delta peaks and on their broadening, we explain the surprising dominance of the muon neutrino and antineutrino cross sections over the electron ones in particular kinematical conditions.

We present a systematic study on the structural properties of odd-$Z$ superheavy nuclei with proton numbers $Z=117,119$, and neutron numbers $N$ increasing from $N=170$ to the neutron dripline within the framework of axially deformed relativistic Hartree-Bogoliubov theory in continuum. The results are compared with those of even-even superheavy nuclei with proton numbers $Z=118$ and 120. We analyze various bulk properties of their ground states, including binding energies, quadrupole deformations, root-mean-square radii, nucleon separation energies, and $\alpha$-decay energies. The coexistence of competing prolate and oblate or spherical shapes leads to abrupt changes in both quadrupole deformations and charge radii as functions of neutron numbers. Compared to even-even nuclei, the odd-mass ones exhibit a more complicated transition picture, in which the quantum numbers of $K^{\pi }$ of the lowest-energy configuration may change with deformation. This may result in the change of angular momentum in the ground-state to ground-state $\alpha$ decay and thus quench the decay rate in odd-mass nuclei. Moreover, our results demonstrate a pronounced proton shell gap at $Z=120$, instead of $Z=114$, which is consistent with the predictions of most covariant density functional theories. Besides, large neutron shell gaps are found at $N=172$ and $N=258$ in the four isotopic chains, as well as at $N=184$ in the light two isotopic chains with $Z=117$ and $Z=118$, attributed to the nearly degenerate $3d$ and $4p$ spin-orbit doublet states due to the presence of bubble structure.

Nuclear Coulomb excitation is often calculated using a semiclassical (SC) approach, where the projectile follows classical trajectories and excites the target nucleus through a time-dependent Coulomb interaction. While the validity of the SC approach has been well established for electric quadrupole ($E2$) transitions, its accuracy for higher-order multipole transitions remains insufficiently benchmarked. In this paper, we compare Coulomb excitation cross sections for higher-order multipole transitions calculated using the SC approach with those obtained through a quantum mechanical (QM) approach, where the projectile is described by wave functions. For $E2$ transitions, the excitation cross sections from both approaches are of the same order of magnitude, consistent with existing validations. However, for higher-order multipole transitions, the SC approach yields significantly higher cross sections, deviating possibly by orders of magnitude from the QM results. This discrepancy underscores the necessity of the QM approach for accurate calculations of the Coulomb excitation cross sections. The failure of the SC approach is explained through using the Wentzel-Kramers-Brillouin approximation.

Employing the neural network framework, we obtain empirical fits to the electron-scattering cross sections for carbon over a broad kinematic region, extending from the quasielastic peak through resonance excitation to the onset of deep-inelastic scattering. We consider two different methods of obtaining such model-independent parametrizations and the corresponding uncertainties: based on the bootstrap approach and the Monte Carlo dropout approach. In our analysis, the ${\chi }^2$ defines the loss function, including point-to-point and normalization uncertainties for each independent set of measurements. Our statistical approaches lead to fits of comparable quality and similar uncertainties of the order of 7%. To test these models, we compare their predictions to test datasets excluded from the training process and theoretical predictions obtained within the spectral function approach. The predictions of both models agree with experimental measurements and theoretical calculations. We also perform a comparison to a dataset lying beyond the covered kinematic region, and find that the bootstrap approach shows better interpolation and extrapolation abilities than the one based on the dropout algorithm.

Analyses for the NICER data indicate that there is no significant variation of compact star radii within the mass range of 1.4 to 2.0 solar masses. Yamamoto et al. [Phys. Rev. C 108, 035811 (2023)] concluded recently that “this feature cannot be reproduced by the hadronic matter due to the softening of the equation of state (EoS) by hyperon mixing, suggesting the possible existence of quark phases in neutron-star interiors.” Using a collection of 162 purely nucleonic, hyperonic, and quarkish EoSs from the CompOSE database and some other works, we verify that hyperons indeed lead to a significant difference in radii of stars of 1.4 and 2.0 solar masses, which diminishes in the presence of quarks. We compare the shapes of the mass-radius curves and show that hyperons and quarks in the neutron star cores prefer a particular curve shape with backbending. It is argued that the shape is controlled by the density dependence of the nuclear symmetry energy. We draw attention to the existence of a class of purely hadronic relativistic mean-field EoSs with scalar-field dependent hadron masses and coupling constants that satisfy the known constraints on the EoSs including the analyses of the new NICER data and the above requirement of insignificant variation of the neutron star radii.

A simple analytic expression of the three-body wave function describing the system $\left(\alpha \alpha n\right)$ in the ground state ${\frac{3}{2}}^{-}$ of ${}^9\mathrm{Be}$ is obtained. In doing this, it is assumed that the $\alpha$ particles interact with each other via the $S$-wave Ali-Bodmer potential including the Coulomb term, and the neutron-$\alpha$ forces act only in the $P$-wave state. This wave function is constructed by trial and error method via solving in this way a kind of inverse problem when the two-body $\alpha \alpha$ potential is recovered from a postulated three-body wave function. As a result, the wave function is an exact solution of the corresponding three-body Schrödinger equation for experimentally known binding energy and for the $\alpha \alpha$ potential whose difference from the Ali-Bodmer one is minimized by varying the adjustable parameters on which the postulated wave function depends.

High-spin states of ${}^{133}\mathrm{Cs}$ have been studied using the fusion-evaporation reaction ${}^{130}\mathrm{Te}({}^7\mathrm{Li},4n){}^{133}\mathrm{Cs}$ at a beam energy of 32 MeV. The previously reported level scheme of ${}^{133}\mathrm{Cs}$ is extended and modified with the addition of nearly 30 new $\gamma$ transitions. A pair of nearly degenerate positive-parity doublet bands are identified and assigned the same $\pi d_{5/2}\otimes \nu h_{11/2}^{-2}$ configuration. The properties of both bands show general agreement with the fingerprints of chiral rotation, and thus the bands are suggested as candidate chiral doublet bands. This interpretation is also supported by the particle rotor model calculations. In addition, the high-$j$ intruder $\pi h_{11/2}$ band is extended to the $27/2^{-}$ state. A new decoupled $\mathrm{\Delta }I=2$ sequence and a weak positive-parity band with magnetic dipole $\left(M1\right)$ transitions are observed. The former is tentatively assigned the $\pi d_{5/2}{h}_{11/2}^2$ configuration. Meanwhile, the systematic studies of the $\pi d_{5/2}$, $\pi g_{7/2}$, and $\pi h_{11/2}$ bands in odd-$A$ Cs isotopes are also discussed in the present work.

The influence of different nuclear surface energy coefficients $\gamma$ on the process of proton radioactivity is systematically studied within the Coulomb and proximity potential formalism. We investigate the proximity potential Guo 2013 formalism with 13 different versions of the coefficient $\gamma$ for the description of 44 experimental half-lives of proton emitters in the ground and isomeric states. It has been observed that the four versions, namely Guo 2013 (original), Guo 2013 (set 1), Guo 2013 (set 2), and Guo 2013 (set 3), exhibit the lowest rms deviations (approximately $\sigma =0.4733$) when compared to the experimental data. The detailed investigation of the known proton decay processes indicate that the decrease in the strength of nuclear surface tension improves the agreement between the experimental data and the calculated values of proton radioactivity half-lives. In addition, our results reveal that the apparent deviation does not follow a continuous behavior around $Z=68$. In fact, by decreasing the strength of the surface energy coefficient $\gamma$ compared to its calculated value from the original proximity potential (Guo 2013) for lighter mass regions $(Z<68)$ and increasing it for heavier ones $(Z>68)$, we observe significantly improved agreement with experimental data $(\sigma =0.453)$. A discussion about the role of nuclear surface tension coefficients in the experimental information of proton emitters in the ground state and the isomeric state is also presented.

Background: Nuclear deformation provides a crucial characteristic of nuclear structure. Conventionally, the quadrupole deformation length of a nucleus, ${\delta }_2$, has often been determined based on a macroscopic model through a deformed nuclear potential with the deformation length ${\delta }_2^{\left(\mathrm{pot}\right)}$, which is determined to reproduce the nuclear scattering data. This approach assumes ${\delta }_2={\delta }_2^{\left(\mathrm{pot}\right)}$ although there is no theoretical foundation.

Purpose: We clarify the relationship between ${\delta }_2$ and ${\delta }_2^{\left(\mathrm{pot}\right)}$ for high-energy heavy-ion scattering systematically to evaluate the validity of the conventional approach to determine the nuclear deformation.

Method: The deformation lengths for the ${}^{12}\mathrm{C}$ inelastic scattering by ${}^{12}\mathrm{C}$, ${}^{16}\mathrm{O}$, ${}^{40}\mathrm{Ca}$, and ${}^{208}\mathrm{Pb}$ targets at $E/A=50$–400 MeV are examined. First, we perform microscopic coupled-channel (CC) calculations to relate ${\delta }_2$ of the deformed density into the inelastic scattering cross section. Second, we use the deformed potential model to determine ${\delta }_2^{\left(\mathrm{pot}\right)}$ so as to reproduce the microscopic CC result. We then compare ${\delta }_2^{\left(\mathrm{pot}\right)}$ with ${\delta }_2$.

Results: We find that ${\delta }_2^{\left(\mathrm{pot}\right)}$ is about 20–40% smaller than presumed ${\delta }_2$, showing strong energy and target dependence. Further analysis, which considers higher-order deformation effects beyond the derivative model, reveals that ${\delta }_2^{\left(\mathrm{pot}\right)}$ is still about 15–35% smaller than ${\delta }_2$.

Conclusion: Our results suggest that one needs to be careful when the deformed potential model for the high-energy heavy-ion scattering is used to extract the nuclear deformation. The conventional approach may underestimate the deformation length ${\delta }_2$ systematically.

Multiparticle cumulants method can be used to reveal long-range collectivity in small and large colliding systems. The four-particle symmetric cumulant $s{c}_{2,4}\left\{4\right\}$, three-particle asymmetric cumulant $a{c}_2\left\{3\right\}$, and the normalized cumulants $ns{c}_{2,4}\left\{4\right\}$ and $na{c}_2\left\{3\right\}$ from the transverse momentum conservation and flow are calculated. The interplay between the two effects is also investigated. Our results are in a good agreement with the recent ATLAS measurements of multiparticle azimuthal correlations with the subevent cumulant method, which provides insight into the origin of collective flow in small systems.

We investigate the impact of baryon stopping on the temporal evolution of electromagnetic fields in vacuum at low-energy Au+Au collisions with $\sqrt{s_{NN}}=4–20\mathrm{GeV}$. Baryon stopping is incorporated into the Monte Carlo Glauber model by employing a parametrized velocity profile of participant nucleons with nonzero deceleration. The presence of these decelerating participants leads to noticeable changes in the centrality and $\sqrt{s_{NN}}$ dependence of electromagnetic fields compared to scenarios with vanishing deceleration. The influence of baryon stopping differs for electric and magnetic fields, also exhibiting variations across their components. We observe slight alteration in the approximate linear dependency of field strengths with $\sqrt{s_{NN}}$ in the presence of deceleration. Additionally, the longitudinal component of the electric field at late times becomes significant in the presence of baryon stopping.

Deep inelastic scattering from nuclear targets probes the parton distribution functions (PDFs) in nuclei. Comparisons of the PDFs from heavy nuclei and the deuteron show deviations that demonstrate a nontrivial nuclear dependence to these distributions, referred to as the EMC effect. A global analysis of the world's data on the EMC effect reveals tensions between different extractions. Precise measurements at Jefferson Lab, studying the dependence on both the quark momentum fraction, $x$, and nuclear mass, show systematic discrepancies among experiments, making the extraction of the A dependence of the EMC effect sensitive to the selection of datasets. By comparing various methods and assumptions used to calculate radiative corrections, we have identified differences that, while not large, significantly impact the EMC ratios and show that using a consistent radiative correction procedure resolves this discrepancy, leading to a more coherent global picture and allowing for a more robust extraction of the EMC effect for infinite nuclear matter.

In 2018, the E12-17-003 experiment was conducted at the Thomas Jefferson National Accelerator Facility (JLab) to explore the possible existence of an $nn\mathrm{\Lambda }$ state in the reconstructed missing mass distribution from a tritium gas target [K. N. Suzuki et al., Prog. Theor. Exp. Phys. 2022, 013D01 (2022); B. Pandey et al., Phys. Rev. C 105, L051001 (2022)]. As part of this investigation, data were also collected using a gaseous hydrogen target, not only for a precise absolute mass scale calibration but also for the study of $\mathrm{\Lambda }/{\mathrm{\Sigma }}^0$ electroproduction. This dataset was acquired at $Q^2\simeq 0.5$ ${(\mathrm{GeV}/c)}^2$, $W=2.14$ GeV, and ${\theta }_{\gamma \mathrm{K}}^{\mathrm{c}.\mathrm{m}.}\simeq 8^{\circ }$. It covers forward angles where photoproduction data are scarce and a low-$Q^2$ region that is of interest for hypernuclear experiments. On the other hand, this kinematic region is at a slightly higher $Q^2$ than previous hypernuclear experiments, thus providing crucial information for understanding the $Q^2$ dependence of the differential cross sections for $\mathrm{\Lambda }/{\mathrm{\Sigma }}^0$ hyperon electroproduction. This paper reports on the $Q^2$ dependence of the differential cross section for the $e+p\to e^{\prime }+K^{+}+\mathrm{\Lambda }/{\mathrm{\Sigma }}^0$ reaction at $0.2–0.8$ ${(\mathrm{GeV}/c)}^2$, and provides comparisons with the currently available theoretical models.

Nuclear shape and orientation degrees of freedom are incorporated into the calculation of the double-folding nuclear potential within the relativistic mean-field (RMF) formalism. The quadrupole deformations (${\beta }_2$), nuclear densities, and the effective nucleon-nucleon ($NN$) interaction potential are obtained using the RMF approach for the hybrid, ${\mathrm{NL3}}^{*}$, and NL3 parametrizations. The calculated quadrupole deformations are included in the target densities through the nuclear radius. The deformation and orientation-dependent microscopic nuclear potentials are further employed to obtain fusion barrier characteristics and cross sections for 12 even-even heavy-ion reactions with doubly magic spherical ${}^{16}\mathrm{O}$ and ${}^{48}\mathrm{Ca}$ as projectiles along with deformed targets from different mass regions. The results obtained for the relativistic R3Y $NN$ potential are compared with those of the Reid version of the nonrelativistic M3Y $NN$ potential as well as with the available experimental data. A decrease in the barrier height and increase in the cross-section is observed upon the inclusion of target quadrupole deformations in the nuclear density distributions at the target orientation angles, ${\theta }_2\le {58}^{\circ }$ for the R3Y $NN$ potential and at ${\theta }_2\le {60}^{\circ }$ for the M3Y $NN$ potential. On comparing the ${\theta }_2$-integrated cross section calculated using M3Y and R3Y $NN$ potentials with spherical and deformed densities, one observes that the deformed densities and the relativistic R3Y $NN$ potential obtained for the hybrid parameter set provide better agreement with the available experimental data for all the considered reactions. Moreover, the modifications in the characteristics of the fusion barrier and hence in the cross section with the inclusion of nuclear shape degrees of freedom and orientations are found to become more prominent in reactions forming heavier compound nuclei. This implies that the inclusion of nuclear deformations and orientation in the calculation of the microscopic nuclear potential within the RMF formalism is crucial to provide a reliable description of the sub-barrier nuclear fusion dynamics, especially in the heavy and superheavy mass regions.

The $p$ process nucleosynthesis is responsible for the synthesis of 35 neutron-deficient nuclei from ${}^{35}\mathrm{Se}$ to ${}^{196}\mathrm{Hg}$. An important input that can affect the modeling of this process is the nuclear level density at the relevant excitation energies of the nuclei involved in the reaction network. The oslo method has been extensively used for the measurement of level densities in excitation energies of several MeV. In this work, Bayesian optimization has been used in order to estimate the 95% credible intervals for the parameters of two level-density models optimized on the oslo data. These uncertainties are then propagated on the cross sections of ($p,\gamma$) reactions leading to the compound nuclei ${}^{105,106}\mathrm{Pd}$ and ${}^{105,106}\mathrm{Cd}$ inside the astrophysically relevant energy range. Imposing constraints in this region of the isotopic chart is important for network calculations involving the nearby $p$ nuclei ${}^{102}\mathrm{Pd}$ and ${}^{106}\mathrm{Cd}$. We discuss the reduction of the range of cross sections due to the uncertainties arising from the level-density data compared to the range of the six default level-density models available in talys and we highlight the need for level-density data inside the astrophysically relevant energy ranges.