Mono-energetic neutrinos from kaon decay at rest (KDAR) provide a unique opportunity to investigate nuclear weak transition strengths under fixed kinematic conditions. In this work, we study charged-current KDAR neutrino-induced reactions on ^12 C at an incident energy of E_ν≃ 236 MeV, focusing on a multipole-resolved analysis of nuclear transition strengths. The transition strengths are decomposed according to spin and parity, and separated into longitudinal and transverse components as well as vector and axial-vector contributions. In particular, the multipole dependence reveals a clear transition from collective to single-nucleon dynamics with increasing excitation energy. The present results demonstrate that KDAR neutrino-induced reactions provide direct access to multipole-dependent nuclear transition strengths that are otherwise difficult to isolate in flux-averaged measurements.

We investigate coherent elastic neutrino–nucleus scattering (CEνNS) induced by pion–decay–at–rest (πDAR) and kaon–decay–at–rest (KDAR) neutrinos, with emphasis on the transition from strict coherence to the diffractive regime. Organizing CEνNS observables in terms of the dimensionless variable qR, we show that πDAR measurements remain confined to the near–coherent region for all nuclei, whereas KDAR neutrinos (E_ν=236 MeV) extend the kinematics into qR≳1, where recoil spectra develop genuine shape sensitivity to the nuclear weak form factor. Using representative light, medium–mass, and heavy nuclei (^12C, ^40Ca, ^48Ca, and ^208Pb), we examine relevant cross sections and quantify the statistical sensitivity to the neutron skin thickness achievable at a JSNS^2–like facility. For a total exposure of 10 ton·year and realistic KDAR fluences, projected 1σ sensitivities reach ΔR_np^ (1 σ) ≃0.09–0.02 fm for ^48Ca and ≃0.07–0.02 fm for ^208Pb as the fluence increases. These sensitivities are competitive with, and complementary to, parity–violating electron–scattering measurements such as CREX and PREX, while relying on an electroweakly clean neutral–current probe with distinct systematic uncertainties. Our results establish KDAR–based CEνNS as a quantitatively robust and complementary avenue for probing neutron skins and nuclear weak densities beyond the coherent limit.

We present a systematic study of halo characteristics in the neutron-rich isotopes 28-32Ne within the deformed relativistic Hartree-Bogoliubov theory in continuum (DRHBc). Microscopic density distributions are analyzed in coordinate space, momentum space, and reaction observables to establish a quantitative and locally defined criterion for halo identification in medium-mass nuclei. The DRHBc densities reveal a pronounced neutron extension in 31Ne. A phenomenological analysis based on deformed Woods-Saxon fits shows a clear isotopic anomaly in the surface diffuseness parameter, with a value of about 1.1 fm for 31Ne, significantly larger than those of neighboring isotopes. The anomalously large diffuseness is therefore treated as the primary phenomenological halo signature, whereas the reduced fitted radius parameter is used only as a supporting consequence of the chosen normalization and tail-sensitive fit. Helm-model form-factor analysis demonstrates that deformation contributes to geometric smearing but does not fully account for the extended spatial structure, as reflected in the enhanced difference between microscopic and folded rms radii. Glauber reaction cross section calculations further confirm a robust relative enhancement of the interaction cross section for 31Ne that persists across reasonable nucleon-nucleon interaction prescriptions. These complementary analyses consistently identify 31Ne as the most prominent halo candidate within the 28-32Ne isotopic chain, while 32Ne exhibits intermediate features and 29Ne shows no clear halo signature. The present framework provides a practical and quantitative approach for identifying halo phenomena in deformed, neutron-rich nuclei beyond the light-mass region.

Electron-capture (EC) rates in medium-mass nuclei are governed by Gamow–Teller (GT) strength distributions and provide important input for stellar weak-interaction processes. In this work, we investigate the deformation dependence of the GT strengths and stellar EC rates in selected medium-mass nuclei in and near the pf shell, namely ^48Ti, ^56Ni, ^60Zn, and ^64Ge. The GT^(+/-) strength distributions are calculated in the deformed quasiparticle random-phase approximation (DQRPA) on a single-particle basis obtained by the Skyrme SGII interaction, while the stellar EC rates are evaluated from the resulting B(GT^+) strengths using the standard phase-space formalism. The potential-energy curves are used to identify shape softness and possible shape coexistence in the nuclei under consideration. We find that deformation strongly modifies the GT strength distributions by changing the centroid energies, resonance splitting, and fragmentation patterns. In particular, a pronounced shape dependence of the GT^(+/-) strengths is found for ^56Ni and ^64Ge, whereas ^60Zn is characterized by a favoured prolate minimum and ^48Ti exhibits a soft near-spherical/prolate landscape. By contrast, the corresponding EC rates are generally much less sensitive to deformation than the differential GT response itself, except at low temperatures and low densities where the low-lying GT^+ strength becomes decisive because of the negative EC Q-value in the electron phase space. Available charge-exchange data for ^48Ti and ^56Ni are used as benchmarks of the model predictions. The present results provide microscopic constraints on the role of deformation and shape coexistence in stellar weak rates for selected medium-mass nuclei, including proton-rich isotopes near the N = Z line.

The intrinsic structure of ^12C remains a longstanding challenge in self-consistent mean-field approaches, as different density functional theory calculations predict either spherical or deformed ground-state configurations. In this work, we investigate the interplay between the spin–orbit interaction, pairing correlations, and quadrupole deformation in ^12C within the Skyrme–Hartree–Fock–Bogoliubov framework. By systematically varying the strengths of the spin–orbit interaction and the pairing interaction, we analyze the evolution of potential energy curves, single-particle shell structure, and occupation probabilities. For the normal spin–orbit strength, the spherical configuration remains remarkably robust against variations in the pairing strength. When the spin–orbit interaction is reduced, the shell structure around the Fermi surface becomes softened, allowing pairing correlations to play a decisive role in stabilizing an oblate intrinsic shape. These results demonstrate that, in ^12C , the spin–orbit interaction controls the onset of deformation, whereas pairing correlations determine whether deformation is realized. It means that Gamow–Teller transition strengths might be highly sensitive to these structural changes and thus provide a valuable probe of the underlying intrinsic configuration.

Rodeo filtering applies R ancilla-assisted energy interrogations. If all measurements are deferred, a static realization requires n_s+R active qubits for an n_s-qubit system, whereas mid-circuit measurement and reset allow one ancilla to be recycled and reduce the width to n_s+1 without changing the ideal filter. We demonstrate this compression for a trapped-spectrum input to model neutron–proton scattering. A static R=10 circuit on IonQ Forte-1 uses 12 active qubits, while a dynamic circuit on IBM Aachen uses only three, a 75% reduction. The controlled interleaved IBM scan gives ΔE_c=-0.017±0.507, comparable to the static result -0.568±0.694. Mapping these centers through the finite-confinement modified effective range expansion (MERE) gives 𝒦_3.7=p_0,3.7 =0.13419±0.00020 fm^-1 for IonQ and 0.13435±0.00015 fm^-1 for the interleaved IBM scan, both consistent with the exact value 0.13436 fm^-1. Both implementations retain complete four-configuration support and therefore reproduce the exact 4×4 effective-space level by sample-based quantum diagonalization. Three IBM batches nevertheless expose run-dependent center variations beyond finite-shot fluctuations, while the postselection attenuation is more stable. Ancilla recycling therefore makes the rodeo width independent of R, freeing qubits for the nuclear register while preserving a finite-confinement scattering input, but exchanges spatial resources for mid-circuit latency and repeatability requirements.

We investigate the Gamow-Teller (GT) transition strength distributions in the light carbon isotopes ^12,14,16C within the framework of the deformed quasiparticle random-phase approximation (DQRPA). Nuclear deformation is explicitly incorporated through Skyrme Hartree-Fock mean-field calculations combined with the QRPA formalism. The residual particle-hole (p-h) and particle-particle (p-p) interactions are derived from Brückner G-matrix calculations based on the CD-Bonn potential, and their impact on the low-lying GT strengths is systematically examined by varying the corresponding interaction strengths. We find that nuclear deformation, associated with a reduced spin-orbit strength, plays a significant role in interpreting the GT strength distribution of ^12C. In contrast, the calculated GT^(-) strength distribution of ^14C in the spherical limit reproduces the essential features of the experimental (p,n) charge-exchange data. The case of ^16C reveals additional high-lying GT strength associated with deformation-induced configuration mixing.

We study the evolution of total binding energy (TBE), mean field energy, and pairing energy of Pb, Hg, and Ar isotopes, as a function of the nuclear deformation. As for the nuclear model, we exploit a deformed relativistic Hartree-Bogoliubov theory in continuum (DRHBc), and a deformed Skyrme Hartree-Fock plus BCS model. It is found that the dependence of pairing energy on the deformation is strongly correlated to that of the mean field energy, which is obtained by subtracting the pairing energy from the TBE; in other words, the energy minimum characterized by a large negative mean field energy has a smaller negative pairing energy or, equivalently, a smaller positive pairing gap, while a stronger pairing energy is found in the region away from the minimum of the total energy. Consequently, the two energies show an antisymmetric feature in their deformation dependence, although the energy scales are very different. Moreover, since the pairing energy has a negative sign with respect to to the pairing gap, the evolution of mean field energy follows closely that of the pairing gap. This implies that the pairing energy (or pairing gap) and the mean field energy "talk to each other" and work together along the potential energy curve to determine the energy minimum and/or the local minimum.

We investigate the Gamow-Teller (GT) transition strength distributions of strongly deformed nuclei, Mg-24,Mg-26, as well as of O-18. The calculations are performed within a deformed quasiparticle random-phase approximation which explicitly includes the deformation degree of freedom in the Skyrme-Hartree-Fock and random-phase approximation calculations. The residual particle-particle (p-p) interaction as well as the particle-hole (p-h) interaction are extracted from Bruckner G-matrix calculations. The residual interaction dependence of the low-lying GT strength of these strongly deformed nuclei is examined by changing the strength of the residual p-p and p-h interactions. We have found that the low-lying GT peaks are quite similar in energy to those found in spherical N = Z and N = Z+2 nuclei near magic shells, but the configurations of Mg-24,Mg-26 are largely mixed by the pairing correlations and the deformation. Our results are compared with the experimental GT (+/-) transition data by (t, He-3) and (He-3, t) reactions and are found to reproduce the main features of GT strength distributions.

We calculate muon-neutrino (ν_μ) scattering off ^12C via charged current (CC) by exploiting the 236 MeV ν_μ from the kaon-decay-at-rest (KDAR). In this energy region, since both inelastic scattering below the quasielastic (QE) region and the QE scattering contribute simultaneously, we combine the inelastic scattering obtained by the QRPA and the QE scattering obtained by distorted wave born approximation (DWBA) based on the relativistic mean field (RMF) theory. We compare the results to the data from MiniBooNE. Further, since the KDR ν_μ CC scattering may have angle dependence of outgoing muon, we investigate the differential angular dependent cross section in the ν_μ-^12C scattering and compare to the results by ν_e-^12C scattering. These results could be useful for the calibration of the forthcoming KDAR neutrino cross section experiments.

We study the evolution of the total binding energy (TBE) and pairing energy of Pb, Hg and Ar isotopes, as a function of the nuclear deformation. As for the nuclear model, we exploit a deformed relativistic Hartree-Bogoliubov theory in the continuum (DRHBc), and a deformed Skyrme Hartree-Fock plus BCS model. It is found that the dependence of pairing energy on the deformation is strongly correlated to that of the mean field energy, which is obtained by subtracting the pairing energy from the TBE; in other words, the energy minimum characterized by a large negative mean field energy has a smaller negative pairing energy or, equivalently, a smaller positive pairing gap, while a stronger pairing energy is found in the region away from the minimum of the total energy. Consequently, the two energies show an anti-symmetric feature in their deformation dependence, although the energy scales are very different. Moreover, since the pairing energy has a negative sign with respect to to the pairing gap, the evolution of mean field energy follows closely that of the pairing gap. This implies that the pairing energy (or pairing gap) and the mean field energy talk to each other and work together along the potential energy curve to determine the energy minimum and/or the local minimum.

We investigate the effects of residual tensor force (TF) and pairing force on the Gamow-Teller (GT) transitions in four magic nuclei, Ca-48, Zr-90, Sn-132 and Pb-208. The TF is taken into account by using the Br & uuml;ckner G-matrix theory with the charge-dependent (CD) Bonn potential as the residual interaction of charge-exchange quasiparticle random phase approximation (QRPA). We found that particle-particle (p-p) tensor interaction does not affect the GT transitions because of the closed shell nature in the nuclei, but repulsive particle-hole (p-h) residual interaction for the p-h configuration of spin-orbit partners dominates the high-lying giant GT states for all of the nuclei. It is also shown that appreciable GT strengths are shifted to a lower energy region by the attractive p-h TF for the same j(pi) = j(nu) configuration, and produce the low-lying GT peak about 2.5 MeV in Ca-48. Simultaneously, in Zr-90 and Sn-132, the low-energy GT strength appears as a lower energy shoulder near the main GT peak. On the other hand, the shift of the low-lying GT state is not seen clearly for Pb-208 because of the strong spin-orbit splitting of high j orbits, which dominates the GT strength.

Recent experiments using advanced laser spectroscopy technique revealed that the charge radii of neutrondeficient gold (Au) isotopes exhibit significant changes in ground state deformation: odd-even shape staggering in the N = 98-100 region and abrupt change of charge radii from N = 108. In this study, we examine the abnormal evolution of the nuclear charge radii. To understand the nuclear structure underlying this phenomenon, we exploit the deformed relativistic Hartree-Bogoliubov theory in continuum (DRHBc). The significant change in mean-squared charge radii (delta(r2)) turns out to originate from nuclear shape transitions between prolate deformation and small oblate deformation due to the shape coexistence possibility. We elucidate the nuclear shape evolution by analyzing the evolution of occupation probability for single-particle states. In addition, the abrupt kink structure in the nuclear charge radius of lead (Pb) isotopes near the N = 126 shell is also investigated and reproduced quite well.

The mass table in the deformed relativistic Hartree–Bogoliubov theory in continuum (DRHBc) with the PC-PK1 density functional has been established for even-Z nuclei with 8≤Z≤120, extended from the previous work for even–even nuclei (Zhang et al. (DRHBc mass table collaboration), At. Data Nucl. Data Tables 144, 101488 (2022)). The calculated binding energies, two-nucleon and one-neutron separation energies, root-mean-square (rms) radii of neutron, proton, matter, and charge distributions, quadrupole deformations, and neutron and proton Fermi surfaces are tabulated and compared with available experimental data. A total of 4829 even-Z nuclei are predicted to be bound, with an rms deviation of 1.433 MeV from the 1244 mass data. Good agreement with the available experimental odd–even mass differences, α decay energies, and charge radii is also achieved. The description accuracy for nuclear masses and nucleon separation energies as well as the prediction for drip lines is compared with the results obtained from other relativistic and nonrelativistic density functional. The comparison shows that the DRHBc theory with PC-PK1 provides an excellent microscopic description for the masses of even-Z nuclei. The systematics of the nucleon separation energies, odd–even mass differences, pairing energies, two-nucleon gaps, α decay energies, rms radii, quadrupole deformations, potential energy curves, neutron density distributions, and neutron mean-field potentials are discussed.

We investigate the Gamow-Teller (GT) transition strength distributions of {strongly} deformed nuclei, $^{24,26}$Mg, as well as of $^{18}$O. The calculations are performed within a deformed quasi-particle random phase approximation (DQRPA) which explicitly includes the deformation degree of freedom in the Skyrme-Hartree-Fock (SHF) and RPA calculations. The residual particle-particle ($p-p$) interaction as well as the particle-hole ($p-h$) interaction are extracted from Br\"uckner $G$-matrix calculations. The {residual interaction} dependence of the low-lying GT strength of these strongly deformed nuclei is examined by changing the strength of the residual $p-p$ and $p-h$ interactions. We have found that the low-lying GT peaks are quite similar in energy to those found in {spherical} $N=Z$ and $N=Z+2$ nuclei near magic shells, but the configurations {of $^{24,26}$Mg are largely mixed by} the pairing correlations and the deformation. Our results are compared to the experimental GT $(\pm)$ transition data by ($t$, $^3$He) and ($^{3}$He, $t$) reactions, {and found to reproduce the main features of GT strength distributions.

We investigate the symmetry energy in relation with the two-proton and two-neutron separation energies using different nuclear mass data. For this aim, we exploit the deformed relativistic Hartree-Bogoliubov theory in the continuum (DRHBc), FRDM2012, and & Oslash;2020 data. First, we study the two-proton and two-neutron separation energies in Pb and Ca isotopes by subtracting the contribution of Coulomb energy. They show a strong correlation with neutron number as well as with the neutron skin thickness. By taking the relative difference of both separation energies, we derive the symmetry energy from Ca and Pb isotopes. Since the nuclear surface contributes to the symmetry energy, we deduce the volume symmetry energy by subtracting the surface contribution using several mass models. The obtained symmetry energy coefficient, asym, is 20.0-22.7 MeV for Pb isotopes and 18.7-19.3 MeV for Ca isotopes from the DRHBc mass table data, while the results from other mass tables are 19.6-22.1 (20.7-22.3) MeV for Pb isotopes and 18.9-19.0 (19.6-19.7) MeV for Ca isotopes from & Oslash;2020 (FRDM2012) data. The volume contribution to the asymmetry coefficient, avsym, which depends on the ratio of the surface to the volume energy coefficients, as/av,is also provided for each mass model. Since the ratio as/av is determined neither by nuclear theory nor by experimental data, we have investigated avsym by using the ratio as/av as a free parameter, and have obtained avsym = 27.0 MeV, almost irrespective of nuclear model and isotopic chain, with the ratio as/av constrained as as/av = 1.10-1.13.

We examined the shape staggering of relative charge radii in 180−186Hg isotopes, which was first measured in 1977 and recently confirmed using advanced spectroscopy techniques. To understand the nuclear structure underlying this phenomenon, we employed the deformed relativistic Hartree–Bogoliubov theory in continuum (DRHBc). Our analysis revealed that the shape staggering can be attributed to nuclear shape transition in the Hg isotopes. Specifically, we demonstrated that prolate shapes of 181,183,185Hg lead to an increase in the charge radii compared to oblate shapes of 180,182,184,186Hg isotopes. We explained the nuclear shape staggering in terms of the evolution of occupation probability (OP) of ν1i13/2, ν1h9/2, π1h9/2, and π3s1/2 states. Additionally, we clarified the kink structure of the charge radii in the Hg isotopes near N=126 magic shell does not come from the change of the OP of π1h9/2 state, but mainly by the increase of the OPs of ν1i11/2 and ν2g9/2 states.

We report the present status of the feasible constraints from nuclear physics on the ambiguity in the neutrino reactions applied to the astrophysics. With the advance of the multi-messenger astrophysics, neutrinos become an important probe for exploring the stellar evolution and the primordial universe. But paucity of experimental data relevant to the neutrino reaction may bring about some uncertainties on the interpretation of the observational data. We discuss the plausible uncertainty and the possible approaches to overcome those ambiguities from prospect of the nuclear physics, which has been accumulating relevant data for a couples of decades.

We investigate the tensor force (TF) effect on the Gamow-Teller (GT) transition strength distributions in Ca-42, Ti-46 and O-18, which are known to have strong low-energy GT states, so called, the low energy super GT (LeSGT) transition, peculiar to the nuclei retaining a neutron number N = Z + 2. The TF is explicitly taken into account in the pairing channels of the residual interaction on top of the mean field described by a deformed Woods-Saxon potential. The pairing matrix elements (PMEs) comprising isoscalar and isovector parts, which consistently describe both the ground and the GT excited states, are calculated by the Bruckner G-matrix based on the charge dependent (CD) Bonn potential. By switching on and off the TF in the PMEs, we deduce meaningful correlations between the TF and the GT strength distributions. It is found that the attractive TF affects not only the ground state but also plays a crucial role of shifting the main GT peak to low-excitation energy region leading to the LeSGT.