Based on relativistic mean field theory for atomic nuclei, we compute the mass radius and other radii associated with the energy momentum tensor for dozens of spin-0 nuclei across the nuclear chart. We also compute the D-term of these nuclei, the forward limit of the gravitational form factor $D(t=0)=D$. The dependence on the neutron number $N$ is systematically studied for calcium (Ca), nickel (Ni), zirconium (Zr), tin (Sn), and lead (Pb) isotopes. Remarkably, $\left|D\right|$ does not monotonically increase with $N$. Instead, it exhibits local maxima and minima when $N$ equals a magic number and even a submagic number. This results in characteristic kinks in the mass, scalar, tensor, and shear radii of these isotopes. Our work for the first time elucidates the strong sensitivity of the various mechanical properties of nuclei to the nuclear shell structure.

The production cross sections of 23 fission fragments in the mass range $71\le A\le 141$ have been measured in the ${}^{12}\mathrm{C}+{}^{193}\mathrm{Ir}$ reaction at $E_{\mathrm{lab}}=83.99\pm 0.013, 80.99\pm 0.007$, and $74.82\pm 0.026\mathrm{MeV}$ using the recoil-catcher activation technique followed by offline $\gamma$-ray spectroscopy. The mass and charge distributions of the fission fragments have been analyzed to study the isotopic and isobaric yield distributions. The mass dispersion parameter (${\sigma }_A^2$) for iodine isotopes is found to be $4.66\pm 0.82, 4.04\pm 0.52$, and $3.13\pm 0.39$ at $E_{\mathrm{lab}}=83.99\pm 0.013, 80.99\pm 0.007$, and $74.82\pm 0.026\mathrm{MeV}$, respectively. The charge dispersion parameter (${\sigma }_Z$) for iodine isotopes is estimated to be 0.862, 0.799, and 0.709 at the respective energies. It has been observed that the fission fragment mass distribution displays well-described Gaussian functions, consistent with compound-nucleus fission. The variance of the fission-fragment mass distribution has been analyzed as a function of compound-nucleus temperature and found to increase exponentially with it. The variance is strongly influenced by entrance-channel mass asymmetry, highlighting the role of entrance-channel parameters. The present study also explores a linear dependence of mass variance on the deformation parameter (${\beta }_2$) of the target nuclei at the same excitation energy for ${}^{12}\mathrm{C}+{}^{193}\mathrm{Ir}$ and ${}^{12}\mathrm{C}+{}^{169}\mathrm{Tm}$ systems.

The collective structure of low-lying states in the $N=50$ nucleus ${}^{92}\mathrm{Mo}$ $(Z=42)$ has been investigated through sub-barrier Coulomb excitation using the CHICO2 device coupled to the $\gamma$-ray energy tracking in-beam nuclear array (GRETINA). Quadrupole and octupole collective properties are measured for the $2_1^{+}$, $2_2^{+}$, $2_3^{+}$, $2_4^{+}$, and $3_1^{-}$ states. The spectroscopic quadrupole moment for the $2_1^{+}$ state is measured to be $Q_s=0.23\left(8\right)e\mathrm{b}$, showing a weakly deformed oblate nature in good agreement with recent state-of-the-art Shell-Model calculations. A modest reduced electric-octupole transition strength of $B(E3;3_1^{-}\to 0_1^{+})=15\left(3\right)\mathrm{W}.\mathrm{u}.$ is obtained, in disagreement with the literature, revealing an emerging tension in the strength of octupole collectivity for the $N=50$ nuclei between historic $(e,e^{\prime })$ and $(p,p^{\prime })$ experiments and more recent experiments utilizing Coulomb excitation and lifetime plus branching-ratio data.

Quantum computing is increasingly offering concrete solutions toward the simulation of nuclear structure, with the potential to overcome the exponential scaling that limits classical diagonalization methods in large spaces. A particularly efficient encoding scheme, based on collective like-nucleon pairing modes, reduces the qubit requirements by half and avoids the nonlocal operator strings of standard fermion-to-qubit mappings. While this quasiparticle framework provides accurate results for semimagic nuclei, it does not adequately describe open-shell systems where proton-neutron correlations become important. In this work, we apply Brillouin-Wigner perturbation theory to systematically improve the quasiparticle description of open-shell nuclei in the $sd$ shell, reaching an energy relative error below $0.2\%$ compared with the nuclear shell model. Furthermore, to make the effective Hamiltonian suitable for quantum simulation, we introduce a mean-field Hartree-Fock approximation of the nonquasiparticle resolvent, achieving ground-state energies typically within $2\%$ of the exact shell-model result. This represents a systematic improvement over the bare quasiparticle Hamiltonian while remaining within the reach of near-term quantum devices.

This study investigates nuclear responses to two-body external fields, interpreted as double-phonon excitations, within the subtracted second random-phase approximation (SSRPA) for ${}^{16}\mathrm{O}$ and ${}^{40}\mathrm{Ca}$. To clarify the underlying characteristics of these modes, Hartree–Fock and SSRPA with the diagonal approximation are first examined. The resulting strength distributions are nearly identical, indicating that residual interactions in the one-particle–one-hole (1p-1h) sector contribute only weakly. This behavior contrasts with that of one-body excitations, where coupling between 1p-1h and two-particle–two-hole (2p-2h) configurations is essential for generating collectivity. In the full SSRPA calculation, which incorporates the residual interaction among 2p-2h configurations, the strength distributions are substantially modified. The double isoscalar $0^{+}$ and $2^{+}$ modes show pronounced redistribution, with peaks shifted to lower energies and additional strength emerging at higher energies, whereas the double isovector $1^{-}$ mode shifts predominantly to higher energies due to a largely repulsive interaction, resulting in a resonance around twice the peak energy of the single giant dipole resonance. Analysis of single transition amplitudes reveals that low-lying resonances are formed coherently through constructive neutron-neutron, proton-proton, and neutron-proton configurations, while high-lying resonances are dominated by neutron-proton configurations, reflecting their higher state density. These results demonstrate that double-phonon excitations cannot be described by simple folding of one-body responses; a fully microscopic treatment of 2p-2h mixing, as provided by SSRPA, is essential.

Half-lives of yrast excited states in ${}^{94}\mathrm{Pd}$ were measured using isomeric decay spectroscopy. The experiment was performed at Radioactive Isotope Beam Factory, where ${}^{94}\mathrm{Pd}$ ions were produced via in-flight fragmentation of a ${}^{124}\mathrm{Xe}$ beam impinging on a ${}^9\mathrm{Be}$ target. These ions were implanted into the GARi active stopper array, and isomeric delayed $\gamma$ rays were detected with the IDATEN fast-timing array consisting of 48 ${\mathrm{LaBr}}_3$(Ce) detectors. The half-lives were determined using the generalized centroid difference method, yielding the $T_{1/2}$ values of $\le 15$ ps, 13(11) ps, $\le 13$ ps, 693(72) ps, and $\le 19$ ps for the $\left(2_1^{+}\right), \left(4_1^{+}\right), \left(6_1^{+}\right), \left(8_1^{+}\right)$, and $\left({10}_1^{+}\right)$ states, respectively. Reduced transition probabilities were deduced from the measured half-lives and discussed in the context of shell-model calculations employing the JUN45 effective interaction. The results indicate that ${}^{94}\mathrm{Pd}$, with $N=Z+2$, lies in a transitional regime between the $N=Z$ isoscalar-pairing domain (${}^{92}\mathrm{Pd}$) and the $N=50$ isovector-dominated region (${}^{96}\mathrm{Pd}$).

A framework for computing $\gamma$-ray feeding probabilities in nuclear decay schemes based on absorbing Markov chains is presented. In this approach, excited nuclear states are treated as transient states and long-lived levels as absorbing states, allowing feeding fractions to be obtained exactly from the transition matrix. Experimental uncertainties are propagated via Monte Carlo sampling from Dirichlet distributions, which naturally maintains the physical constraint of unit normalization for branching-ratio vectors. This framework is applied to the key $E_r=92$ keV resonance in the ${}^{25}\mathrm{Mg}(p,\gamma ){}^{26}\mathrm{Al}$ reaction $(E_x=6398 \mathrm{keV})$, which governs the production of ${}^{26}\mathrm{Al}$ in hydrogen-burning environments. Combining multiple experimental datasets within a Hierarchical Bayesian framework, a ground-state feeding probability of $f_0=0.68\pm 0.06\left(1\sigma \right)\pm 0.13\left(2\sigma \right)$ is found, and the dominant $\gamma$-decay transitions contributing to its uncertainty are identified. The formalism reproduces traditional cascade calculations while providing analytic sensitivity information and a transparent uncertainty decomposition. This approach offers a general and computationally efficient tool for propagating nuclear-structure uncertainties to astrophysical reaction rates and can be readily extended to other nuclei.

The electrostatic field strength inside heavy nuclei far exceeds the famous Schwinger critical field strength and most intense laser fields available nowadays. Under such an extreme electric field, the quantum electrodynamics (QED) effect dominated by vacuum polarization in the nuclear system turns out to dramatically enhance the nuclear decay probability against $\alpha$-decay, cluster radioactivity, and proton radioactivity by several times to even dozens of times, resulting in the reduced stability of nuclei. And it can even push the proton drip line toward the less proton-rich side. These extraordinary QED effects thus establish nuclear systems as a novel platform for probing strong-field QED physics.

High-spin states in the neutron-deficient nucleus ${}_{61}{}^{131}\mathrm{Pm}_{70}$ have been investigated using the Jurogam 3 $\gamma$-ray spectrometer. This is the lightest promethium isotope with known excited states. The proton intruder $h_{11/2}$ rotational structure has been extended to both higher and lower spin, and its unfavored-signature partner identified. This rotational structure is established down to a presumed $I^{\pi }=5/2^{-}$ bandhead of the $\pi h_{11/2}\left[532\right]5/2^{-}$ Nilsson orbital, which is also expected to form the ground state of this deformed nucleus. Systematic comparisons are made with cranked shell-model calculations.

We investigate the finite-temperature evolution of microscopic free-energy corrections in nuclear fission, focusing on pairing and shell effects near scission. The analysis is based on a finite-temperature BCS treatment combined with the Strutinsky method and is performed for representative deformation points along the fission path. Both pairing and shell contributions exhibit regular thermal attenuation, but their deformation dependencies differ substantially. In particular, pairing remains strongly deformation dependent in the scission region, and its free-energy contribution differs markedly between the constant and surface-dependent pairing-strength prescriptions. The shell correction near scission is also significant at low temperature and is progressively suppressed with increasing excitation energy. These results support the interpretation of odd-even staggering in fragment charge yields as a manifestation of pairing correlations surviving into the strongly deformed prescission configuration. They also show that pairing and shell effects should be treated separately in finite-temperature dynamical calculations, with distinct deformation- and temperature-dependent attenuation laws.

We study deformed neutron halo nuclei in the mass region $40<A<90$ and their soft electric dipole $\left(E1\right)$ excitations based on the deformed relativistic Hartree-Bogoliubov theory in continuum. Three candidates, ${}^{43}\mathrm{Si}$, ${}^{69}\mathrm{Ti}$, and ${}^{75}\mathrm{Cr}$, are selected for detailed analysis. Unique features are identified in the decoupled densities of possible $s$- and $p$-wave deformed halo nuclei in this mass region, which are influenced by large high-$l$ configurations. It is shown that the dipole response is a highly sensitive observable to detect the halo component of the single-particle wave function in deformed halo nuclei, and it helps identify the configuration and the magnitude of deformation for halo nuclei in the $40<A<90$ mass region. Experimental confirmation of the dipole strength in the low-energy region is highly desirable to explore possible deformed halo candidates in the medium-heavy mass region.

We extend previous halo effective field theory analyses of low-energy elastic scattering of ${}^3\mathrm{He}\text{−}{}^4\mathrm{He}$, including the ${\frac{7}{2}}^{-}$ $f$-wave resonance as an explicit degree of freedom. The presence of this resonance necessitates a changing power counting scheme depending on the kinematic region. Therefore, we construct a theory uncertainty model at the partial wave amplitude level, allowing us to generate a sophisticated theory covariance matrix that captures the way the theory error structure changes as energy increases. We then perform a Bayesian analysis and simultaneously estimate the joint posterior distributions of the effective range theory parameters and the parameters that characterize the effective field theory truncation uncertainty. We compare two different analyses: no $f$-wave interactions for data up to $E_{\text{max}}=2.6$ MeV and including $f$-wave interactions for data up to $E_{\text{max}}=5.5$ MeV. The inferred breakdown scales in each analysis are consistent with previous work. We find that $f$-wave interactions are needed to describe data for $E_{\mathrm{lab}}\gtrsim 3.6$ MeV.

The present study provides an extension to our recent work on the vector (V) electromagnetic single-nucleon current and associated response functions, both for unpolarized situations and in situations where the target nucleon is polarized. Here the axial-vector (A) single-nucleon current matrix element is developed in detail and the full set of vector and axial-vector currents is used to obtain the electroweak VV, AA, and VA response functions. Only the unpolarized case is studied in the present work. The general forms for all of these elements are developed together with various approximation schemes in which numerical studies are provided to indicate where these approximations may be expected to be valid. The results of this work provide the basis for a deeper understanding of the roles played by the various single-nucleon form factors in weak interaction reactions on free nucleons and when using the standard “prescription for nuclear physics” in reactions involving nucleons in nuclei.

Neutrino processes are important in the modeling of supernova explosions, proto-neutron star evolution, and binary neutron star mergers. We study neutrino production and absorption in proto-neutron star and supernova matter and direct Urca neutrino emission of neutron star matter in the framework of the random phase approximation (RPA). As interactions, we employ the recent extended Skyrme parametrization Sky3s whose effective masses and spin-dependent terms were adjusted to microscopic calculations, and the SLy4 parametrization that was used in previous calculations of neutrino rates. The rates obtained for Sky3s differ from those for SLy4 by up to one order of magnitude for some processes and energy regions. We also determine the electron, muon, and proton fractions that lead to a stationary composition of matter for a density above the direct Urca threshold, and find that with Sky3s the standard $\beta$ equilibrium condition is not as badly violated at finite temperature as predicted in the literature. There are also minor differences between the full RPA and the common Landau approximation, but they are probably not significant for astrophysical simulations. We conclude that it would be worthwhile to repeat the calculation of neutrino rates for the use in astrophysical simulations, and the corresponding simulations, with several and better constrained interactions than SLy4, such as Sky3s.

High-spin states of ${}^{125}\mathrm{I}$ have been populated using the ${}^{122}\mathrm{Sn}({}^7\mathrm{Li},4n){}^{125}\mathrm{I}$ reaction at a beam energy of 44 MeV. Four three-quasiparticle rotational bands originating from neutron alignment were observed. A pair of nearly degenerate positive-parity doublet bands is assigned the $\pi g_{7/2}\otimes \nu h_{11/2}^2$ configuration and proposed as candidate chiral doublet bands. Another positive-parity band and a negative-parity band are assigned the $\pi g_{7/2}\otimes \nu {(g_{7/2}/d_{5/2})}^2$ and $\pi g_{7/2}\otimes \nu h_{11/2}(g_{7/2}/d_{5/2})$ configurations, respectively. These interpretations are supported by the adiabatic and configuration-fixed constrained triaxial relativistic-mean-field and multiparticle plus rotor model calculations.

In this study, we investigate the impact of the effective nucleon mass and the existence of the dineutron and the tetraneutron on the thermodynamic properties and nuclear composition by constructing new equations of state. Our results indicate that the model with a larger effective nucleon mass slightly alters the nuclear composition in neutron-rich environments primarily due to differences in the symmetry energy: the mass fractions of unbound neutrons, protons, and heavy nuclei increase. The impact on the thermodynamic properties is negligible, except for the chemical potentials. On the other hand, multineutron states become prominent at high densities in neutron-rich environments, leading to a substantial reduction in the unbound neutron fraction. This depletion lowers the chemical potential of unbound neutrons, which in turn reduces the abundance of neutron-rich nuclei. Consequently, the number of unbound protons increases, leading to a corresponding rise in proton chemical potential. These shifts in chemical potentials promote the formation of heavy nuclei with larger mass and proton numbers. Ultimately, this compositional shift results in a lower free energy, primarily driven by the emergence of these heavy nuclei.

Per-trigger yields of ${\pi }^0\text{−}\mathrm{hadron}$ correlations were measured in semicentral Pb-Pb collisions at $\sqrt{s_{\mathrm{NN}}}=5.02\text{TeV}$ in ALICE at the CERN Large Hadron Collider. The reconstructed ${\pi }^0\to \gamma \gamma$, with a transverse momentum of $11\mathrm{GeV}/c<p_{\mathrm{T}}\left({\pi }^0\right)<14\mathrm{GeV}/c$, is used as the trigger particle to calculate yields of associated charged particles on the near- and away-side. The photons are reconstructed using the ALICE Electromagnetic Calorimeter, and the charged particles are measured in the ALICE central barrel within a pseudorapidity range of $\left|\eta \right|<0.8$. The yields are reported relative to the orientation of the ${\pi }^0$ with the second-order event plane and are background subtracted using the reaction-plane fit method. The data give an indication of a suppression of the associated charged-particle yields near $p_{\mathrm{T}}\approx 2\mathrm{GeV}/c$ when comparing out-of-plane to in-plane trigger particles. At associated charged-particle $p_{\mathrm{T}}>3$ GeV/$c$, no significant event-plane dependence is observed within uncertainties. The results are compared with predictions from the JEWEL model, which implements jet energy loss in an expanding medium. JEWEL predicts no significant modification of either the near- or away-side associated yields, independent of whether medium recoils are included. The observed behavior may indicate the presence of additional energy-loss mechanisms beyond those governed by path-length dependence.

Background: The $N=80$ isotones offer an important opportunity for studying nuclear structure evolution and the interplay between single-particle motion and collective behavior near the $N=82$ shell closure. Although the nuclear shell model is a powerful and predictive framework, progress for the open-shell nuclei has been limited by the rapidly increasing configuration-space dimensions and the lack of a reliable effective interaction.

Purpose: To construct a feasible shell-model Hamiltonian capable of describing the $N=80$ even-even isotonic chain with $Z=50–74$, and to investigate their underlying low-lying configurations.

Methods: Full-configuration-interaction shell-model calculations are performed in a model space that includes the proton and neutron orbitals $0g_{7/2}, 1d_{5/2}, 1d_{3/2}, 2s_{1/2}$, and $0h_{11/2}$. The effective interaction is derived by optimizing the monopole and multipole components of the realistic interactions, reducing the number of independent parameters to eight via the principal component analysis approach. Further analysis is carried out using the nucleon-pair approximation of the shell model.

Results: The calculation reproduces excitation energies and electromagnetic properties for known $N=80$ isotones and provides predictions for ${}^{150}\mathrm{Yb}, {}^{152}\mathrm{Hf}$, and ${}^{154}\mathrm{W}$ near the proton drip line, including a level inversion between the yrast ${18}^{+}$ and ${20}^{+}$ states in ${}^{154}\mathrm{W}$. It further reveals a systematic evolution of the low-lying structures with increasing proton number.

Conclusions: The $N=80$ isotones exhibit coexistence of multiple configurations: the yrast $0^{+}–4^{+}$ states are (generalized-)seniority-dominated for lower-$Z$ nuclei, becoming increasingly vibrational-like with growing valence proton number, while the yrast $6^{+}–{10}^{+}$ states undergo transitions among neutron seniority-2, proton seniority-2, and proton-neutron coupled configurations along the isotonic chain, driven by proton-neutron interactions and the evolution of the proton Fermi surface. The analysis of the predicted level inversion in ${}^{154}\mathrm{W}$ highlights the essential role of the isoscalar spin-aligned proton-neutron correlation.