I investigate ${}^{12}\mathrm{C}$, particularly the four kinds of the $0^{+}$ bands with various types of the $3\alpha$ configurations. These states are obtained in the variation of the multiple bases of the antisymmetrized molecular dynamics, where the bases are optimized simultaneously in the variation of the total energy. In the $0_2^{+}$ Hoyle state and the $0_3^{+}$ linear-chain state, I confirm a mixture of the $\alpha$-cluster breaking of the $s$-wave configuration with contributions from the spin-orbit force, while the $0_4^{+}$ state exhibits a relatively pure $3\alpha$ cluster state characterized by a large radius. The $2_{2-4}^{+}$ and $4_{2-4}^{+}$ states also tend to be the pure $3\alpha$ cluster states. The monopole transitions between the $0_2^{+}$ and $0_4^{+}$ bands exhibit large values, suggesting breathing mode of the $3\alpha$ states in the $0_4^{+}$ band. This conclusion aligns with the predictions of the $3\alpha$ models with an $\alpha$ condensate and also with a neural network, although the order of the $0_3^{+}$ and $0_4^{+}$ bands is reversed in the present results due to the attraction of the spin-orbit force.

The kink observed in the nuclear charge radius of Sn isotopes around neutron number $N=82$ is investigated within the relativistic mean-field framework using the $\mathrm{NL}{3}^{*}$ parameter set. It is shown that the small components of the Dirac spinors for the neutron single-particle states near the Fermi level play a crucial role in forming the kink through their contribution to the proton central potential. In particular, the significant differences between the radial parts of the small components of spin-orbit partner states make neutrons with $j=l-1/2$ more efficient in increasing the nuclear charge radius than those with $j=l+1/2$. However, the effect induced by the small components alone does not fully account for the magnitude of the kink observed in Sn isotopes.

Background: The study of the structure of odd-mass nuclei in regions characterized by the interplay of multiple particle-hole configurations represents a major challenge in nuclear structure physics. The odd-mass niobium isotopes ($Z=41$), located near the $N=60$ region, are of particular interest due to the occurrence of shape coexistence and quantum phase transitions.

Purpose: This work aims to investigate the structure of the ${}^{93-103}\mathrm{Nb}$ isotopes using the intrinsic-frame formalism of the interacting boson-fermion model with configuration mixing (IBFM-CM). The goal is to determine the nuclear shapes and explore the phenomena of shape coexistence, configuration crossing, and quantum phase transitions.

Method: We employ the intrinsic formalism of the IBFM-CM, which includes both 0p-0h (regular) and 2p-2h (intruder) configurations interacting with the unpaired nucleon. This approach provides a self-consistent framework to study energy surfaces, shape coexistence, and intruder bands for both positive- and negative-parity states. A realistic Hamiltonian for niobium, determined in previous studies, is adopted.

Results: The formalism is applied to the ${}^{93-103}\mathrm{Nb}$ isotopes for both positive- and negative-parity bands. A detailed analysis of the mean-field energy surfaces has been performed, including axial energy curves, triaxial energy surfaces in the $\beta \text{−}\gamma$ plane, and the corresponding equilibrium deformation parameters. The results reveal clear evidence of configuration coexistence and crossing along the isotopic chain.

Conclusions: We have applied the recently developed intrinsic-state formalism of the IBFM-CM using a realistic Hamiltonian for a chain of niobium isotopes. The existence of crossing configurations has been demonstrated around $N=60$, corresponding to a quantum phase transition previously identified in the Sr and Zr isotopic chains. Furthermore, we find that the presence of an unpaired nucleon in Nb influences the abruptness of the quantum phase transition, underscoring the sensitivity of the structural evolution to single-particle degrees of freedom.

We use the light front quark model to investigate the form factors in the $e^{+}{e}^{-}\to B\overline{B}$ collision proceses with $B=\mathrm{\Lambda },\mathrm{\Sigma }$ and $\mathrm{\Xi }$. These form factor behaviors are calculated based on the Bethe-Salpeter formalism with $q^{+}>0$ to effectively account for nonvalence contributions. We show that our results of the $q^2$-dependent form factors closely match the BESIII data. In particular, we obtain that $|G_{\mathrm{eff}}|=(0.921,0.098,0.189$) and $R=|\frac{G_E}{G_M}|=(0.97,0.89,0.936)$ for $e^{+}{e}^{-}\to \mathrm{\Lambda }\overline{\mathrm{\Lambda }}, {\mathrm{\Sigma }}^{+}{\mathrm{\Sigma }}^{-},{\mathrm{\Xi }}^{+}{\mathrm{\Xi }}^{+})$ with $q^2=(5.74,6.0,7.0){\mathrm{GeV}}^2$.

Covariant density functionals have been successfully applied to the description of finite nuclei and dense nuclear matter. These functionals are often constructed by introducing density dependence into the nucleon–meson couplings, typically through functions that depend only on the vector, i.e., proper baryon density. In this work, we employ a Bayesian framework to investigate how different parametrizations, characterized by distinct functional forms and by their dependencies on vector and scalar densities, affect the properties of dense matter and compact stars. Our analysis demonstrates that although all considered parametrizations yield broadly comparable inferences, the differences in the equation of state and the symmetry energy remain significant at suprasaturation densities, reflecting the sensitivity to the chosen functional form of the density dependence. We find that allowing the nuclear saturation properties in the isoscalar channel, including the skewness coefficient $Q_{\mathrm{sat}}$, to be freely adjusted provides adequate flexibility for the current modeling of nuclear and neutron-star matter. In contrast, the isovector channel requires further refinement, with freedom extended at least up to the curvature coefficient $K_{\mathrm{sym}}$ to capture variations in the symmetry energy and particle composition at high densities. This work advances prior studies by implementing a rational-function parametrization of the density dependence, informed and constrained by multimessenger astrophysical observations.

We present the two-pion exchange contributions to the nucleon-nucleon interaction up to next-to-next-to-next-to leading order (${\mathrm{N}}^3\mathrm{LO}$) in covariant baryon chiral perturbation theory. Both one-loop and two-loop diagrams are calculated with the spectral functional regularization. We show that the phase shifts for partial waves with total angular momentum $3\le J\le 5$ are in better agreement with the partial wave analysis from the Nijmegen or the SAID group than their ${\mathrm{N}}^2\mathrm{LO}$ counterparts. In addition, the relativistic chiral force exhibits better convergence than its nonrelativistic counterpart, suggesting the importance of relativistic corrections.

This study systematically investigates the influence of nuclear $\alpha$ clustering on transport properties using an extended quantum molecular dynamics model for the ${}^{16}\mathrm{O}+{}^{197}\mathrm{Au}$ and ${}^{16}\mathrm{O}+{}^{40}\mathrm{Ca}$ collision systems. The results show that different $\alpha$-cluster configurations of ${}^{16}\mathrm{O}$ lead to differences in the extracted system temperature $T$ and density $\rho$, with a tendency toward the ordering tetrahedral $>$ square $>$ kite $>$ chain. The sensitivity to the initial configurations is reduced in the heavier ${}^{16}\mathrm{O}+{}^{197}\mathrm{Au}$ system. The dependence of the shear viscosity $\eta$ and the viscosity-to-entropy density ratio $\eta /s$ on the initial $\alpha$-cluster structure is weaker, owing to the fact that $\eta$ and $\eta /s$ reflect the combined contributions of both temperature $T$ and density $\rho$.

I study the event-by-event fluctuation and rapidity decorrelation of the mean transverse momentum $\left[p_T\right]$, which has recently been proposed as a sensitive probe of the equation of state at finite baryon density. The investigation reveals that, in a baryon-rich medium, the event-by-event fluctuation of the mean transverse momentum is driven by the combined effects of energy-density and net-baryon-density fluctuations. Consequently, the rapidity dependence of this observable provides a promising handle to probe the three-dimensional structure of both energy and baryon density profiles. Previous studies have shown that $\left[p_T\right]$ decorrelation with rapidity is largely insensitive to shear and bulk viscosity; however, its dependence on baryon diffusion, another key transport coefficient in baryonic matter, has not been explored. I find that baryon diffusion has a negligible impact, establishing this observable as a robust probe of the equation of state. Furthermore, I present predictions for identified hadrons and observe a pronounced splitting in the rapidity decorrelation of mean transverse momentum between protons and antiprotons, indicating different transverse flow dynamics for baryons and antibaryons.

Dissipative processes are pivotal for understanding the hydrodynamic evolution of hot and dense quantum chromodynamics (QCD) matter created in relativistic nuclear collisions. The interplay of multiple conserved charges—net baryon, strangeness, and electric charge—is of particular interest. We simulate the longitudinal hydrodynamic evolution with the three diffusion currents in a hydrodynamic model with a lattice-QCD-based equation of state, neos-4d, and estimate rapidity distributions including diffusive corrections to the phase-space distribution in the presence of multiple charges, which ensure charge conservation at particlization. We determine the response of particle yields at midrapidity to changes in the diagonal and off-diagonal conductivities. Inversely, we find that most components of the conductivity matrix can be constrained experimentally using identified particle multiplicities at different collision energies.

We study $\mathrm{\Xi }{-}^4\mathrm{He}$ ($\alpha$) momentum correlation functions in high-energy nuclear collisions to investigate the nature of the $\mathrm{\Xi }N$ interactions. We employ the folding $\mathrm{\Xi }\alpha$ potential based on the lattice QCD $\mathrm{\Xi }N$ interactions to compute the correlation function. The $\mathrm{\Xi }\alpha$ potential supports a Coulomb-assisted bound state ${}_{\mathrm{\Xi }}^5\mathrm{H}$ in the ${\mathrm{\Xi }}^{-}\alpha$ channel, while the ${\mathrm{\Xi }}^0\alpha$ channel is unbound. To examine the sensitivity of the correlation function to the nature of the $\mathrm{\Xi }\alpha$ interaction, we vary the potential strength, simulating stronger and weaker interactions. The result of the correlation function is sensitive to the existence of the bound state in the ${\mathrm{\Xi }}^0\alpha$ channel, and the characteristic behavior of the bound state also remains in the ${\mathrm{\Xi }}^{-}\alpha$ correlation with the Coulomb interaction. The effect of the repulsive core of the $\mathrm{\Xi }\alpha$ potential can be found in the correlation from the small source as a distinctive dip in the intermediate momentum region.

We study finite-volume (FV) corrections to determinations of $g_A$ via lattice quantum chromodynamics (QCD) using analytic results and numerical analysis. We observe that $SU\left(2\right)$ heavy Baryon chiral perturbation theory does not provide an unambiguous prediction for the sign of the FV correction, which is not surprising when one also considers large-$N_c$ constraints on the axial couplings. We further show that nonmonotonic FV corrections are naturally allowed when one considers either including explicit $\mathrm{\Delta }$-resonance degrees of freedom or one works to higher orders in the chiral expansion. We investigate the potential impact of these FV corrections with a precision study of $g_A$ using models of FV corrections that are monotonic and nonmonotonic. Using lattice QCD data that is approximately at the 1% level of precision, we do not see significant evidence of nonmonotonic corrections. Looking forward to the next phase of lattice QCD calculations, we estimate that calculations that are between the 0.1% and 1% level of precision may be sensitive to these FV artifacts. Finally, we present an update of the CalLat prediction of $g_A$ in the isospin limit with subpercent precision, $g_A^{\mathrm{QCD}}=1.2674\left(96\right)$.

The higher-twist formalism is used at $O\left({\alpha }_s^2\right)$ to compute all possible medium-induced single-scattering emission kernels for an incoming highly energetic and virtual quark traversing the nuclear environment. The effects of the heavy-quark mass scale are taken into account [Phys. Rev. C 94, 054902 (2016)] both in the initial state as well as in the final state, along with interactions involving both in-medium Glauber gluons and quarks [Nucl. Phys. A 793, 128 (2007)], as well as coherence effects [Phys. Rev. C 105, 024908 (2022)]. As this study is a continuation of our work on medium-induced photon production [Phys. Rev. C 112, 025204 (2025)], the general factorization procedure for $e\text{−}A$ deep-inelastic scattering is still used. An incoming quark energy loss in the nuclear medium yields four possible scattering kernels ${\mathcal{K}}_i$ with the following final states: (i) $q+g$; (ii) $g+g$; and (iii) $q+{\overline{q}}^{\prime }$, where the quark $q$ may have a flavor different from the antiquark ${\overline{q}}^{\prime }$; and (iv) $q+q^{\prime }$, where, again, $q$ may have a flavor different from $q^{\prime }$. The collisional kernels include full phase factors from all nonvanishing diagrams and complete first-order derivative in the longitudinal direction ($k^{-}$) as well as second-order derivative in the transverse momentum ($k_{\perp }$) gradient expansion. Furthermore, in-medium parton distribution functions and the related jet transport coefficients have a hard transverse-momentum dependence (of the emitted quark or gluon) present within the phase factor.

Background: Constraining the nuclear matter equation of state (EoS) from neutron star observations is one of the main subjects in nuclear physics today. Most studies are based on the Tolman-Oppenheimer-Volkoff equation, which describes a star in spherical hydrostatic equilibrium in general relativity. In general, however, neutron stars rotate rapidly and the structure of neutron stars can be affected by rotation, especially in millisecond pulsars. To better constrain the nuclear EoS, it is important to describe neutron star structure taking into account the effects of rotation in a fully relativistic manner.

Purpose: In this study, we investigate the internal structure of neutron stars under the influence of rotation. We explore correlations between rotational effects and EoS parameters, based on fully general relativistic calculations of rapidly rotating neutron stars.

Methods: We consider the standard class of neutron stars with cores composed of neutrons, protons, electrons, and muons ($npe\mu$ matter), surrounded by the crust. For the EoS, we employ Skyrme-type energy density functionals for $npe\mu$ matter and the conventional Baym-Pethick-Sutherland (BPS) EoS for the inner and outer crusts. To account for the rotational effects, we employ a method proposed by Komatsu, Eriguchi, and Hachisu (the KEH method), which provides stable solutions for axially symmetric rotating equilibrium configurations.

Results: Using five different Skyrme-type EoS parameter sets, we find that the maximum angular frequency achievable by rotating neutron stars, as calculated via the KEH method, varies depending on the stiffness of the equation of state. We confirm that an increase in the rotating frequency leads to an overall increase in both the mass and radius along the $M\text{−}R$ curve, consistent with earlier studies. By performing calculations for three frequently referenced neutron stars, we further examine how the changes in mass and radius correlate with the nuclear matter properties at saturation density. Our results suggest that the often-quoted 716 Hz rotational constraint may require a more conservative interpretation when accounting for realistic stellar deformation effects.

Conclusions: To place stringent constraints on the nuclear EoS based on observational data, it is sometimes essential to account for the effects of rotation in neutron star models. In particular, the influence of rotation becomes increasingly significant at higher spin frequencies and cannot be neglected in rapidly rotating systems with $\nu \gtrsim 400\mathrm{Hz}$.

We study the order-by-order expansion of the energy per particle of asymmetric nuclear matter up to twice saturation density in chiral effective field theory (EFT) within a Bayesian framework. For this, we develop a two-dimensional Gaussian process (2D GP) that is trained using many-body perturbation theory results based on chiral two- and three-nucleon interactions from leading to next-to-next-to-next-to-leading order (${\mathrm{N}}^3\mathrm{LO}$). This allows for an efficient evaluation of the equation of state (EOS) and thermodynamic derivatives with EFT truncation uncertainties. After benchmarking our 2D GP against Bayesian uncertainties for pure neutron matter and symmetric matter, we study the energy per particle, pressure, and chemical potentials of neutron star matter in $\beta$ equilibrium including EFT uncertainties. We investigate the phase diagram of neutron-rich matter from neutron- to proton-drip and to the uniform phase, including surface and Coulomb corrections. Based on this, we construct EOSs for the inner crust of neutron stars that are consistent with the chiral EFT results for uniform matter at ${\mathrm{N}}^3\mathrm{LO}$.

We perform ab initio calculations of three-point mass differences in the odd- and even-mass ${}^{39-49}\mathrm{Ca}$ isotopes to probe nuclear superfluidity via empirical neutron pairing gaps. We also quantify the sensitivity of those gaps to the parameters of the interaction at mean-field level. Recent studies employing accurate chiral nuclear interactions have found these gaps to be too small. We show that experimental values can be reproduced at mean-field level by substantially increasing the attraction of the singlet $S$-wave two-nucleon contact interaction, but doing so induces an unphysical bound state of the dineutron. The sensitivity of these predictions to the full calibration of the nuclear interaction is then studied by performing Bayesian posterior sampling in a delta-full chiral effective field theory at third chiral order. We find that pairing gaps remain largely unaffected, leaving the explanation of nuclear superfluidity as a future task for improved many-body modeling and refined interactions at higher chiral orders.

The intruder bands in Sn isotopes, built on the 2p-2h excitation across the $Z=50$ proton shell gap, are well-known examples of shape coexistence near the neutron mid-shell region. Spectroscopic signatures for shape coexistence include enhanced $E0$ transitions between the $0^{+}$ band heads. However, the underlying shape coexistence and mixing has been unclear because lifetime information for the excited $0^{+}$ states was incomplete in ${}^{118}\mathrm{Sn}$. We thus present here the first measurement of the $0_3^{+}$ lifetime in ${}^{118}\mathrm{Sn}$ using the fast-timing technique following thermal-neutron capture. The observed enhancement in ${\rho }^2(E0;0_3^{+}\to 0_2^{+})$ of 150(30) milliunits provides compelling indications for multiple shape coexistence in ${}^{118}\mathrm{Sn}$. Additionally, three distinct shapes in ${}^{116,118,120}\mathrm{Sn}$ naturally emerged in theoretical calculations based on the quantum-number-projected generator coordinate method employing a relativistic energy density functional.

The low-energy nuclear isomeric state of ${}^{229m}\mathrm{Th}$ provides a unique bridge between nuclear and atomic physics, enabling applications such as nuclear clocks and precision metrology. However, efficient and controllable production of ${}^{229m}\mathrm{Th}$ remains a major experimental challenge. We propose an efficient scheme to produce the ${}^{229m}\mathrm{Th}$ in storage rings (SRs) and electron beam ion traps (EBITs), using a cascade decay pathway. Highly charged ions are excited to higher nuclear states via nuclear excitation by inelastic electron scattering (NEIES) and nuclear excitation by electron capture (NEEC), followed by radiative or internal conversion cascades that populate the isomer. Our calculations demonstrate that, under typical SRs and EBITs conditions, optimized indirect excitation pathways significantly enhance ${}^{229m}\mathrm{Th}$ production rate. In particular, NEIES can provide an enhancement of up to four orders of magnitude through cascade deexcitation at high energies, while NEEC can contribute an additional enhancement of up to several tens of times. Such a significant increase in the ${}^{229m}\mathrm{Th}$ yield rate would facilitate its application in various nuclear photonics fields, especially in the development of atomic nuclear clocks.

Spontaneous ternary fission into medium-mass fragments is investigated within the self-consistent Hartree-Fock-plus-BCS method using the SLy6 Skyrme interaction with delta pairing. This work complements our previous study in the actinide region by extending it to two superheavy systems: ${}^{296}\mathrm{Lv}$ for its anticipated collinear tripartition involving two tin fragments, and ${}^{288}120$, examined in various equatorial (triangularlike) partitions that may emerge from the predicted superoblate shape of its second minimum. In the collinear case of ${}^{296}\mathrm{Lv}$, the calculated energy surfaces reveal no additional energy barrier associated with the chosen ternary channel. We quantify its dynamical suppression from the competition with the predominant binary decay by applying a simple Langevin-type model of overdamped motion with constant damping and temperature. Under assumptions designed to yield an upper bound, we find the tripartition probability per binary decay to be of the order of ${10}^{-6}$, larger than the corresponding predictions for actinides within the same approach. In the case of ${}^{288}120$, we compute the energy maps for several $A_1+2\times A_2$ symmetric triangular configurations. The resulting barrier heights, above 10 MeV, although lower than in simplified approaches, remain large enough to suppress these ternary modes.