Hafnium-175 is a useful radioisotope for numerous applications; however, its evaluated half-life ($70\pm 2\mathrm{days}$) has a large uncertainty. To enable a new measurement of the half-life, ${}^{175}\mathrm{Hf}$ was produced via proton irradiation of natural lutetium and chemically purified. The ${}^{175}\mathrm{Hf}$ sample was counted approximately once a month with three high-purity germanium detectors for 13 months ($\sim 5.5$ half-lives). A ${}^{133}\mathrm{Ba}$ standard was counted in an identical manner to quantify systematic uncertainties over the measurement period. The measured ${}^{175}\mathrm{Hf}$ half-life is $69.90\pm 0.07$ days, in agreement with the evaluated value, but with significantly reduced uncertainty.

We study the $\alpha +\alpha +{}^3\mathrm{He}$ cluster structure of ${}^{11}\mathrm{C}$ within the microscopic cluster model. The calculations essentially reproduce the energy spectra for both negative and positive parity states, particularly the $3/2_3^{-}$ state near the $\alpha +\alpha +{}^3\mathrm{He}$ threshold. We also calculate the isoscalar monopole, electric quadrupole transition strengths, and root-mean-square radii for the low-lying states. These results suggest that the $3/2_3^{-}, 1/2_2^{-}$, and $5/2_3^{-}$ states have a well-developed $\alpha +\alpha +{}^3\mathrm{He}$ cluster structure. The analysis of the generator coordinate method wave functions indicates the dilute gaslike nature for the $3/2_3^{-}, 1/2_2^{-}$, and $5/2_3^{-}$ states, suggesting that they could be candidates for the Hoyle-analog state. Furthermore, it is found that the $5/2_2^{+}$ and $5/2_3^{+}$ states may possess a linear chain structure.

In the context of relativistic heavy-ion collisions, we explore the stochastic and dissipative relaxational dynamics of a nonconserved order parameter in a $\lambda {\phi }^4$ interaction. The cutoff of the theory is provided by the lattice spacing chosen for our numerical simulations. As a consequence, observables become dependent on that scale. We consider a possible first-order phase transition and an evolution close to a critical point. We demonstrate that using a lattice counterterm restores the expected behavior of the mean, variance, and kurtosis: the mean and the variance become lattice spacing independent, and we recover the correct expectation value of the mean, the growth of the variance with the correlation length, and the expected minimum in the kurtosis. Our findings hold true in equilibrium and during the dynamical relaxation, and therefore mark an important step towards a fully fluctuating fluid dynamical setup.

In this paper, we introduce a novel Ansatz for generalized parton distributions (GPDs), named GSAMA24. This Ansatz aims to provide a more accurate and comprehensive description of the internal structure of hadrons by incorporating advanced parametrizations and fitting techniques. We compare the performance of the GSAMA24 Ansatz with three established models: the extended Regge (ER), modified Gaussian (MG), and M-HS22 Ansatz. The GSAMA24 Ansatz is designed to address limitations observed in previous models by offering improved flexibility in the $t$ dependence and skewness parameter $\xi$. Our analysis involves fitting the GSAMA24 Ansatz to experimental form factor data and evaluating its predictive power against the ER, MG, and M-HS22 models. The comparison is based on key metrics such as the accuracy of form factor predictions, the consistency with known GPD properties, and the computational efficiency of the fitting process. Results indicate that the GSAMA24 Ansatz provides a superior fit to the experimental data, particularly in the high momentum transfer region, where it outperforms the ER and MG models. Additionally, the GSAMA24 Ansatz demonstrates better agreement with the theoretical expectations of GPD behavior compared to the M-HS22 model. These findings suggest that the GSAMA24 Ansatz is a promising tool for future studies of hadronic structure and could significantly enhance our understanding of the spatial and momentum distributions of quarks and gluons within hadrons.

In this work we improve on several aspects of the computation of the (anti)neutrino charged-current multinucleon cross section carried out in Phys. Rev. C 83, 045501 (2011) and Phys. Rev. C 102, 024601 (2020). Most importantly, we implement a consistent treatment of the nucleon self-energy in the $W^{\pm }N\to N^{\prime }\pi$ amplitude entering the definition of the two-particle two-hole (2p2h) cross section, and estimate the source of uncertainty of our model due to a simplified treatment of the $\mathrm{\Delta }$ self-energy. Our new predictions are around 40% higher than previously. We show comparisons for the inclusive lepton double-differential cross sections, with no pions in the final state, measured by MiniBooNE on carbon and by T2K on carbon and oxygen. In all cases, we find an excellent reproduction of the experiments, and in particular, the neutrino MiniBooNE data is now well described without requiring a global 90% rescaling of the flux. In addition, we take the opportunity of this revision to discuss in detail several important issues of the calculation of the 2p2h cross section, delving into the microscopic dynamics of the multi-nucleon mechanisms. The improved treatment presented in this work provides realistic first-step emitted two-nucleon final-state momentum configurations, beyond the approximation of phase-space distributions. Finally, we also show that these new 2p2h results are now closer to those obtained by the Lyon group in Phys. Rev. C 80, 065501 (2009) and Phys. Rev. C 84, 055502 (2011), which can be now accommodated within the uncertainties of our scheme, thus ending a longstanding discrepancy between both sets of theoretical predictions.

We propose a semi-empirical formula (SEF) for calculating the nuclear matrix elements (NMEs) for two-neutrino double-β decay. The SEF's dependence on the proton and neutron numbers, the pairing, isospin, and deformation properties of the initial and final nuclei is inspired by the insights offered by nuclear many-body methods and trends in experimental data. Compared with the previous phenomenological and nuclear models, the SEF yields the best agreement with the experimental NMEs. Its stability and predictive power are cross validated, and predictions are provided for nuclear systems of experimental interest.

In this study experiments were performed at bremsstrahlung end-point energies of 10–23 MeV with the beam from the MT-25 microtron (Joint Institute for Nuclear Research, Dubna) using the γ-activation technique. The experimental values of relative yields, cross sections per equivalent quantum and flux-averaged cross sections were compared with theoretical results obtained on the basis of TALYS-2.0 code with the standard parameters and the combined model of photonucleon reactions. Including isospin splitting in the combined model of photonucleon reactions allows describing experimental data on reactions with proton escape in the energy range from 15 to 23 MeV. Therefore, taking into account isospin splitting is necessary for a correct description of the decay of the giant dipole resonance.

The multinucleon transfer (MNT) process in low-energy heavy ion collisions can be utilized to produce unknown nuclei far beyond the stability line. However, the reaction products exhibit broad angular and energy distributions, which could lower the experimental detection efficiency. We present a classical approach that employs a parametrized angular distribution to describe the complex issue. By analyzing limited experimental data on the angular distribution, we propose a three-parameter formula to calculate the angular distribution and identify the dependencies of the parameters. We also discuss the sensitivity of these parameters within this method. A comprehensive comparison with microscopic models and experimental data across a wide range of conditions is conducted. The proposed formula offers an efficient and straightforward way to determine the angular distribution of MNT products.

This is an addendum to the article “Dielectron production in proton-proton and proton-lead collisions at $\sqrt{s_{\mathrm{NN}}}=5.02\mathrm{TeV}$” published in [Phys. Rev. C 102, 055204 (2020)]. We update the extracted charm cross section at midrapidity given in Table III and Fig. 4 (left) of the original publication with the fragmentation fractions of charm quarks in $pp$ collisions published in [Phys. Rev. D 105, L011103 (2022)].

This work establishes the time-dependent relativistic Hartree-Fock (TD-RHF) model with spherical symmetry. The time-dependent integral differential Dirac equations are solved by expanding Dirac spinors on the spherical Dirac Woods-Saxon (DWS) basis. The numerical verification demonstrates the high conservation qualities for both the total binding energy and the particle number, as well as the time-reversal invariance of the system, which ensures the precision and reliability of the newly developed TD-RHF model. Subsequently, the isoscalar giant monopole resonance (ISGMR) mode of ${}^{208}\mathrm{Pb}$ is investigated using the RHF Lagrangian PKO1. The constrained energy of the ISGMR calculated by PKO1 is found to be in close agreement with the experimental data, and the strength function is similar to the results given by the relativistic Hartree-Fock plus random phase approximation. Based on the advantage of the TD-RHF model that avoids complicated calculations of the residual interactions, the ISGMR mode of ${}^{208}\mathrm{Pb}$ is calculated by 12 relativistic effective Lagrangians. The results indicate that the value of the incompressibility of nuclear matter $K_{\infty }$ constrained by relativistic effective Lagrangians is in the range of 237–246 MeV, which is lower than the previous investigations based on the relativistic models.

In this project, we systematically investigate and evaluate the performance and predictive power of refined nuclear-mass models with tree-based machine learning methods, including the model-repair capabilities applied to the “bare” mass-model calculations. Combining six theoretical models with five machine-learning algorithms, the refined model accuracies are illustrated based on available experimental masses and a physics-based feature space. The root-mean-square (rms) deviations between the physics-model calculations and the available experimental data range from the maximum, about 2.46 MeV, to the minimum, about 0.29 MeV. Significant improvements can be obtained for the refined theoretical models in the interpolation predictions of nuclear masses. The rms values of describing experimentally known nuclei can reach a high level (e.g., falling to about 0.16 MeV, crossing the accuracy of 0.20 MeV) in the combinations between theoretical mass models and machine learning algorithms. It is found that the model-prediction capabilities can be rearranged after they are refined by different machine learning algorithms, indicating the different abilities of picking up the missing “physics.” The residual between the “bare” mass model and experimental data usually presents a nonrandom pattern, revealing the model deficiency to some extent, while, after refining the theoretical model by machine learning, the residuals exhibt a uniform distribution. The model-repair capabilities of five data-driven machine-learning algorithms applied to six physically based nuclear-mass models are evaluated. In addition, based on optimal combinations of bare mass-models and machine-learning algorithms, the extrapolation predictions and model-repair abilities are validated and briefly discussed.

The chiral magnetic effect (CME) is a phenomenon in which electric charge is separated by a strong magnetic field from local domains of chirality imbalance in quantum chromodynamics. The CME-sensitive, azimuthal correlator difference $\mathrm{\Delta }\gamma$ between opposite-sign (OS) and same-sign (SS) charged hadron pairs is contaminated by a major physics background proportional to the particle elliptic anisotropy ($v_2$). The CME signal, on the other hand, contributes to the difference in the pair elliptic anisotropies between OS and SS pairs ($\mathrm{\Delta }{v}_{2,\mathrm{pair}}$). We investigate $\mathrm{\Delta }{v}_{2,\mathrm{pair}}$ and find its sensitivity to CME to be similar to that of the $\mathrm{\Delta }\gamma$ observable.

We study the hadronic light-by-light scattering contribution to the energy interval $1S\text{−}2S$ in muonium. Various amplitudes of interaction of a muon and an electron are constructed, in which the effect of hadronic scattering of light by light is determined using the transition form factor of two photons into a meson. Their contributions to the particle interaction operator in the case of $S$ states are obtained in integral form, and their contributions to the energy spectrum are obtained in numerical form. The contributions of pseudoscalar, scalar, and axial vector mesons are taken into account.

The emergence and stability of static hexadecapole deformations as well as the impact in the development of dynamic deformation due to collective motion considering quadrupole-hexadecapole coupling are studied for a selected set of radium, thorium, uranium, and plutonium isotopes, using the Gogny Hartree-Fock-Bogoliubov and generator coordinate method frameworks. Sizable hexadecapole deformations are found to play a significant role in the ground and excited states of nuclei in the neighborhood of ${}^{238}\mathrm{U}$. For each of the studied isotopic chains, it is shown that a region with small negative hexadecapole deformation, just below the neutron magic number $N=184$, remains stable once zero-point quadrupole-hexadecapole fluctuations are taken into account. A transition is predicted, with increasing mass number, from a regime in which the quadrupole and hexadecapole degrees of freedom are interwoven to a regime in which they are decoupled, accompanied by an enhanced shape coexistence in the more neutron-rich sectors of the isotopic chains. It is also shown, that quadrupole-hexadecapole configuration mixing brings a nontrivial additional correlation energy gain comparable to the quadrupole correlation energy itself.

Multinucleon transfer reactions ${}^{204,207}\mathrm{Hg}, {}^{235,238}\mathrm{U}+{}^{198}\mathrm{Pt}$ at incident energy 8 MeV/nucleon are simulated by using the improved quantum molecular dynamics model. Symmetric system with neutron-rich but unstable projectile ${}^{207}\mathrm{Hg}$ provides the largest production cross sections for $N=126$ neutron-rich nuclei. For the other three projectiles, ${}^{238}\mathrm{U}$ provides the advantage in the production of unknown $N=126$ neutron-rich nuclei with $Z<76$ due to the neutron excess and the small slope of the cross sections as the function of atomic number, which mainly originates from the projectilelike fragments produced in the massive transfer process. The entrance channel effects of neutron excess of projectiles and mass asymmetry of two collision partners, as well as the exchange of nucleons, manifest themselves in the net transfer of a few nucleons, massive transfer and the variation of production probabilities of $N=126$ neutron-rich nuclei with impact parameters. The comparisons of four reactions suggest that the available ${}^{238}\mathrm{U}$ projectile is a better choice for the productions of these new neutron-rich nuclei with $N=126$.

We theoretically investigate quasiparticle properties of a neutron immersed in an alpha condensate, which is one of the possible states of dilute symmetric nuclear matter. The resonant $p$-wave neutron-alpha scattering, which plays a crucial role in forming halo nuclei, is considered. This system is similar to a Bose polaron near the $p$-wave Feshbach resonance that can be realized in cold-atomic experiments. Calculating the self-energy within the field-theoretical approach, we give an analytical formula for the effective mass of a polaronic neutron as a function of alpha condensation density. Moreover, two adjacent neutrons in a medium, each of which behaves like a stable polaron having an enhanced effective mass, can form a bound dineutron, with the help of ${}^{1}S_0$ neutron-neutron attraction. This is in contrast to the case of the vacuum, where a dineutron is known to be unbound. Our result is useful for understanding many-body physics in astrophysical environments as well as the formation of multinucleon clusters in neutron-halo nuclei.

The dynamics of $N/Z$ and mass equilibration are investigated in the reactions ${}^{112}\mathrm{Sn}+{}^{239}\mathrm{Pu}$ (${\mathrm{E}}_{\mathrm{c}.\mathrm{m}.}=500\mathrm{MeV}$) and ${}^{124}\mathrm{Sn}+{}^{239}\mathrm{Pu}$ (${\mathrm{E}}_{\mathrm{c}.\mathrm{m}.}=490$ and 510 MeV) by employing the isospin-dependent quantum molecular dynamics model. It is found that $N/Z$ and mass equilibration take place at different collision stages. The $N/Z$ relaxation is observed in the approaching phase (from first contact to deepest contact) with a very short time, whereas interestingly we find for the first time that mass equilibration only takes place in the separation phase (from the deepest contact to reseparation), both of which are explained by investigating the dynamical asymmetry between the approaching and separation phases. The mass equilibration could also be clarified with a dynamical potential energy surface. Our results provide new insight into the equilibration dynamics of quantum systems.