Nuclear potentials are known to exhibit a considerable degree of scheme dependence. For one- and two-pion exchange nucleon-nucleon (NN) potentials, unitary ambiguities start showing up at the level of the leading relativistic corrections to the dominant static contributions. However, for the three-pion exchange potential, scheme-dependent contributions are expected to appear already at the static level. Here we analyze the leading and subleading chiral $3\pi$-exchange NN potentials using the method of unitary transformation. In line with the expectations, our results for selected classes of contributions differ from those obtained by Kaiser using $S$-matrix matching. We present analytical expressions for the $3\pi$-exchange potential, which are off-shell consistent with the interactions used by the Bochum group, and discuss the numerical importance of the observed differences.

The development of systematic effective field theories (EFTs) for nuclear forces and advances in solving the nuclear many-body problem have greatly improved our understanding of dense nuclear matter and the structure of finite nuclei. For global nuclear calculations, density functional theories (DFTs) have been developed to reduce the complexity and computational cost required in describing nuclear systems. However, DFT often makes approximations and assumptions about terms included in the functional, which may introduce systematic uncertainties compared to microscopic calculations using EFTs. In this work, we investigate possible avenues of improving nuclear DFT using nonlinear relativistic mean-field (RMF) theory. We explore the impact of RMF model extensions by fitting the nonlinear RMF model to predictions of nuclear matter and selected closed-shell nuclei using four successful chiral EFT Hamiltonians. We find that these model extensions are impactful and important in capturing the physics present within chiral Hamiltonians, particularly for charge radii and neutron skins of closed-shell nuclei. However, there are additional effects that are not captured within the RMF model, particularly within the isoscalar sector of RMF theory. Additional model extensions and the reliability of the nonlinear RMF model are discussed.

The electromagnetic properties of low-lying states in ${}^{70}\mathrm{Ge}$ were investigated via multistep Coulomb excitation of a ${}^{70}\mathrm{Ge}$ beam impinging on a ${}^{208}\mathrm{Pb}$ target at the ATLAS facility of the Argonne National Laboratory. A total of 27 transitional elements and six diagonal matrix elements coupling 11 low-lying states were extracted from the measured cross sections. These were used to calculate reduced transition probabilities, spectroscopic quadrupole moments, and rotational invariant shape parameters, providing enhanced precision and expanding on previous studies. The experimental data were compared within several theoretical frameworks, including the generalized triaxial rotor model, configuration-interaction shell-model calculations, and computations within the combined frameworks of relativistic density functional theory and the five-dimensional collective Hamiltonian. The results demonstrate a good agreement with the experimental data and, in conjunction with calculations using a two-state mixing model, support significant triaxiality and strong mixing between the $0_1^{+}$ and $0_2^{+}$ states. This results in the magnitudes of their respective quadrupole deformations $[{\beta }_{\mathrm{rms}}\left(0_1^{+}\right)=0.228\left(3\right)$, ${\beta }_{\mathrm{rms}}\left(0_2^{+}\right)=0.273\left(1\right)]$ being more similar than previously observed. The implications of these results for understanding the complex shape coexistence phenomena, the role of triaxiality, and shape evolution along the Ge isotopic chain are discussed.

A thermodynamically consistent description of induced fission pathways in the superheavy nucleus ${}^{296}\mathrm{Lv}$ is presented within the framework of nuclear energy-density functional theory. Using self-consistent finite-temperature Hartree-Fock-Bogoliubov calculations with the Skyrme-type energy-density functional ${\mathrm{SkM}}^{*}$, we derive and compare effective potentials corresponding to different thermodynamic processes—isothermal ($T=\text{const}$), isentropic ($S=\text{const}$), and isoenergetic ($E=\text{const}$)—as functions of quadrupole deformation and excitation energy. At the same amount of excitation energy the isoenergetic description predicts the highest fission barrier and the largest damping factor. The suppression of the isoenergetic fission barrier is analyzed by examining how the driving force changes with increasing excitation energy and by studying the contribution of the nonpotential term to the effective potential. Within the framework of the three thermodynamic schemes considered, the different behavior of temperature and entropy along the fission pathway is also emphasized. A transition of the effective level-density parameter from a deformation-sensitive quantity at low excitation energies to a nearly constant value at high energies is observed, in line with the Fermi-gas model expectations.

In this work, we study the charged hadron anisotropic flow coefficients $v_n$ (up to $n=12$) using high-statistics event-by-event simulations of $\mathrm{Pb}+\mathrm{Pb}$ collisions at $\sqrt{s_{\mathrm{NN}}}=5.02$ and $5.36$ TeV, employing the IP-Glasma $+$ MUSIC $+$ UrQMD hybrid approach. The power spectra of anisotropic flow coefficients ($v_n\left\{2\right\}$ vs $n$) are compared with the ALICE measurements from central to 50% centrality. To understand the various sources contributing to the high-order $v_n$ coefficients, we analyze the nonlinear mode coefficients for high-order anisotropic flow coefficients using different approximations and make comparisons with available measurements.

We make order-by-order predictions of neutron-deuteron total cross sections up to next-to-next-to-leading order in pionless effective field theory. Using Bayesian methods, we infer a posterior distribution for the breakdown scale. The result shows a mode near 100 MeV, and a combined analysis with neutron-proton scattering further sharpens the inference, placing the mode close to the pion mass scale, consistent with the expected range of pionless effective field theory.

The $M1$ transition strengths between excited $2^{+}$ states of the neutron-rich, radioactive nuclide ${}^{132}\mathrm{Te}$ was studied through direct lifetime measurements using the Doppler-shift attenuation method in a two-neutron transfer reaction on a ${}^{130}\mathrm{Te}$ target. An unambiguous identification of the lowest-lying mixed-symmetry $2^{+}$ state was achieved on the basis of the large $B(M1;2_2^{+}\to 2_1^{+})=0.18\left(2\right){\mu }_{\mathrm{N}}^2$ transition strength. Results are compared to the shell model, and the analysis of both data and calculations unambiguously identifies the second-excited $2^{+}$ state of ${}^{132}\mathrm{Te}$ as the one-quadrupole phonon mixed-symmetry state of this isotope. A lowering of the energy and $B(M1;2_{\mathrm{ms}}^{+}\to 2_1^{+})$ strength within the $N=80$ isotones toward the $Z=50$ shell closure is observed, which occurs along with the lowering of the $E2$ collectivity approaching the magic proton shell.

Background: α decay remains one of the most fundamental decay modes in heavy nuclei, and its study provides crucial insights into nuclear structure, shell effects, and deformation properties. Plutonium isotopes, situated in a transitional region of the actinide chain, serve as an important testing ground for understanding the interplay between shell closures and deformation effects on decay dynamics.

Purpose: The present work aims to provide a comprehensive microscopic investigation of ground-state α-decay properties of plutonium nuclei within the preformed cluster-decay model (PCM), with a focus on identifying the structural factors that govern decay half-lives and their systematics across the isotopic chain.

Methods: Our analysis encompasses 24 isotopes of plutonium ($Z$ = 94) with mass numbers ranging from $A$ = 220 to $A$ = 244. Using the Proximity 1988 nuclear potential and optimizing the neck-length parameter, we aim to enhance predictive precision. The Wentzel-Kramers-Brillouin approximation is employed to compute the penetration probability, a critical factor in determining α-decay half-lives. The study extracts and analyses several essential decay parameters: barrier height ($V_B$), barrier position ($R_B$), preformation probability ($P_0$), and penetration probability ($P$), linking them to underlying nuclear structure features.

Results: The accuracy of the model is first verified by comparing predictions with experimentally known α emitters. Excellent agreement is observed for a broad range of isotopes, namely, ${}^{220-230,236,238-240,242,244}\mathrm{Pu}, {}^{216-219,221-228,230,232,233,235,236,238}\mathrm{U}, {}^{212-230,232}\mathrm{Th}, {}^{209-211,214-224,226}\mathrm{Ra}$, and ${}^{210,212-220,222}\mathrm{Rn}$. This confirms the robustness and applicability of the PCM approach in modeling α-decay phenomena. The study extends beyond known α emitters to offer theoretical predictions for isotopes lacking experimental confirmation. Notable candidates for future experimental observation due to strong theoretical signatures for ${}^{231,232,234}\mathrm{Pu}, {}^{220,234}\mathrm{U}, {}^{208,212}\mathrm{Ra}$, and ${}^{204-209,211}\mathrm{Rn}$. These predictions broaden the PCM utility in identifying promising α emitters in less-explored regions. Furthermore, certain nuclei show significant hindrance to α decay, likely due to unfavorable barriers or structural conditions, such as ${}^{233,235,237,241,243}\mathrm{Pu}, {}^{229,231,237,239,240}\mathrm{U}, {}^{231,233-236}\mathrm{Th}, {}^{213,225,227-232}\mathrm{Ra}$, and ${}^{221,223-228}\mathrm{Rn}$, which are predicted to be poor α emitters. In addition to these, we revealed crucial structural correlations for both $P_0$ and $P$, showing marked enhancement at $N=128$ parent nuclei, indicating highly favorable conditions for α decay, underscoring the dominant role of shell closures in α-decay dynamics. In addition to the well-established spherical magic number $N=126$, our study also identifies signatures of enhanced stability at new neutron numbers, notably $N=134$ and $N=144$ for Pu, $N=144$ for U, $N=124$ for Ra, and $N=122$ for Rn, suggesting the emergence of deformed shell closures in these regions. And also, plutonium isotopes exhibit significant deformation, which strongly affects barrier characteristics and decay rates, which is less pronounced for lighter actinide chains. To further validate our approach, we computed the standard deviation between the calculated α-decay half-lives and the available theoretical as well as experimental data, providing a quantitative measure of the model's accuracy.

Conclusions: This study reinforces the PCM framework as a powerful tool for understanding α-decay mechanisms from a microscopic perspective. The model successfully reproduces experimental systematics and extends predictive capabilities to nuclei lacking experimental data. The significant influence of shell closures, particularly at $N=126$ daughter nuclei, and the role of nuclear deformation are central to explaining observed decay behaviors. Plutonium isotopes serve as critical test cases for examining shell evolution and structural transitions, situated in a region where α decay begins to compete with alternative decay modes.

Theoretical description of collective nuclear excitations and astrophysically relevant processes require methods going beyond the random phase approximation (RPA) or Tamm-Dancoff approximation (TDA), which are limited to one-particle–one-hole (1p-1h) configurations. In this work, we introduce the second Tamm-Dancoff approximation (STDA) based on the relativistic nuclear energy density functional, which also incorporates two-particle–two-hole (2p-2h) configurations, providing a more comprehensive description of nuclear excitations. Within the relativistic STDA (RSTDA), we implement the subtraction method, which is essential to avoid double counting of correlations and provide realistic description of excited states. Using the DD-PC1 parametrization of the relativistic point-coupling interaction, in the first application of the RSTDA we investigate the properties of isoscalar monopole and quadrupole transitions in ${}^{16}\mathrm{O}$. The analysis reveals the important role of complex configurations in centroid energies, transition strength distributions, and the fine structure of nuclear response. By resolving the fragmentation and spreading of excitation strength, the RSTDA enables accurate description of experimental spectra.

We propose a novel procedure for computing overlaps and matrix elements in the $M$-scheme $SD$-pair shell model. Our approach demonstrates that calculating the overlap or matrix element of a one- or two-body operator between two $N$-pair states requires, at most, $N!(N+1)!/2^N$ products of one-pair overlaps. We also establish an upper bound on the number of independent one-pair overlaps involved. A major advantage of this method is its inherent parallelizability: the one-pair overlaps needed for $N$-pair overlaps or matrix elements can be computed independently, enabling efficient parallelization to significantly accelerate the overall computation.

This study investigates the short-range nuclear matrix elements (NMEs) for the light-neutrino exchange mechanism of $\beta \beta$ decay using the microscopic interacting boson model (IBM-2). The NMEs are calculated with both Argonne and CD-Bonn short-range correlations, and the coupling, that is currently not well constrained, is estimated from charge-independence breaking terms. Our results are compared with those obtained using the proton-neutron quasiparticle random-phase approximation and the nuclear shell model (NSM). We find that the short-range NMEs calculated with IBM-2 and NSM are remarkably similar, particularly for heavier nuclei. The effect of the short-range component on the half-life estimates of neutrinoless $\beta \beta$ decay is also examined, demonstrating its relevance for interpreting experimental results. This study highlights the impact of short-range contributions, derived from chiral effective field theory ($\chi \mathrm{EFT}$), on nuclear matrix element calculations within the IBM-2 framework. While the IBM-2 model is not derived from $\chi \mathrm{EFT}$, the inclusion of $\chi \mathrm{EFT}$-based short-range operators provides valuable insight into the role of short-distance physics in $0\nu \beta \beta$ decay. These findings emphasize the importance of incorporating short-range effects to better understand and constrain theoretical uncertainties, even within phenomenological models.

High-spin states of ${}^{81}\mathrm{Br}$ were populated using the ${}^{82}\mathrm{Se}(\alpha ,\mathit{\text{p}}4\mathit{n})$ reaction. One positive-parity band and four negative-parity bands were observed. Based on the experimental characteristics of these bands, a pair of nearly degenerate three-quasiparticle bands with negative parity are interpreted as chiral doublet bands based on the $\pi {(f_{5/2},p_{3/2})}^{-5}\pi g_{9/2}^2$ configuration. The third three-quasiparticle band is interpreted as a pseudospin partner band, thereby forming pseudospin-chiral triplet bands in ${}^{81}\mathrm{Br}$. The interpretation was supported by the relativistic density functional theory and the multiparticle plus rotor model calculations. The present work suggests a new chiral configuration in the nuclear system and reports the first observation of pseudospin-chiral triplet bands with a pure proton configuration.

The moving orientation effect (MOE) in nuclear collisions has been investigated through barrier distributions. To this end, the experimental barrier distributions for systems with a spherical medium-mass target nucleus (${}^{90}\mathrm{Zr}$) and two different deformed projectiles, ${}^{24}\mathrm{Mg}$ and ${}^{28}\mathrm{Si}$, with prolate (${}^{24}\mathrm{Mg}$) and oblate (${}^{28}\mathrm{Si}$) deformations, were analyzed within the framework of coupled-channels (CC) calculations. It is observed that the MOE is mainly driven by the nuclear rotational coupling of the moving projectiles in the field of stationary, heavy, and spherical target. The change in the shape of barrier distribution due to the MOE depends on the ground-state deformations, that is, the quadrupole (${\beta }_2$) and hexadecapole (${\beta }_4$) deformations of the deformed projectiles. A reduction in fusion cross sections for free orientations with respect to frozen cases was observed, which is more in the case of prolate than the oblate deformations irrespective of the value and the sign of ${\beta }_4$. This is primarily because the effective rotational energy is larger for the prolate than the oblate shapes. These results may have a direct bearing to the nuclear collisions for synthesis of superheavy elements involving nearly spherical target and axially deformed projectile.

The objective of present study is to explore the influence of breakup of weakly bound nuclei on fusion reactions induced by ${}^7\mathrm{Li}$ on light- and medium-mass targets ${}^{16}\mathrm{O}$, ${}^{27}\mathrm{Al}$, ${}^{28}\mathrm{Si}$, and ${}^{64}\mathrm{Ni}$ in above-barrier energy region. Continuum discretized coupled-channel calculations have been carried out to compute the total fusion (TF) and complete fusion (CF) cross sections using computer code fresco. It is found that inclusion of breakup couplings in the calculations enhance the agreement between data and TF cross sections. Also noticed that CF cross sections are suppressed with respect to TF cross sections for all the systems except ${}^7\mathrm{Li}+{}^{16}\mathrm{O}$ reaction, however, the degree of suppression is very small in comparison to that observed in reactions involving heavy targets. To obtain a clear systematic of CF suppression with target mass, calculations have been compared with UFF curve on the same scale and also a suppression factor ($\mathrm{S}{\mathrm{F}}_{\mathrm{CF}}$) has been estimated for each system. No suppression for ${}^{16}\mathrm{O}$ target is seen while for ${}^{27}\mathrm{Al}$ and ${}^{28}\mathrm{Si}$ CF cross sections are suppressed by 3% and around 6% suppression in CF is noticed for ${}^{64}\mathrm{Ni}$. Further, the estimated suppression factors have been compared with the calculated $\mathrm{S}{\mathrm{F}}_{\mathrm{CF}}$ for reactions involving medium- and heavy-mass targets (available in literature) and it exhibit that CF suppression factor increases initially with ${\mathrm{A}}_T$ and finally achieve a constant value (around 30%) for heavy-mass targets.

Recent measurements by various experiments in ultraperipheral collisions have observed spin-interference in ${\rho }^0$ photoproduction, marking a breakthrough in Fermi-scale quantum interference experiments. Building on this, the STAR Collaboration extended the measurement to hadronic heavy-ion collisions, where significant rescattering effects on ${\rho }^0$ mesons were expected. In this study, we investigate how these rescattering effects influence the measurement of spin-interference. By embedding ${\rho }^0$ mesons produced via photoproduction, modeled by the vector-meson dominance model, into the ultrarelativistic quantum molecular dynamics framework, we estimate the impact on the $cos2\varphi$ and $cos4\varphi$ modulations, where $\varphi$ is the angle between ${\rho }^0$ and one of the daughters' (${\pi }^{\pm }$) transverse momenta. The results indicate a significant suppression of the $cos2\varphi$ modulation, while the $cos4\varphi$ modulation remains largely unaffected, which provides insight for understanding the difference due to rescattering effects between experimental measurements and theoretical predictions for ${\rho }^0$ photoproduction in heavy-ion collisions.

We present a theoretical investigation of photonuclear tomography as a novel technique for probing the internal structure of nuclei. In this approach, ultraperipheral heavy-ion collisions (UPCs) serve as a source of intense fluxes of virtual photons, which induce coherent production of vector mesons. By analyzing the probabilities and cross sections of these photon-induced processes, we propose a methodology for reconstructing the spatial distribution of nucleons within the nucleus. Our framework provides a systematic way to access information on the nuclear geometry probed in UPCs, offering new opportunities for studies of nuclear structure using particle production as a probe. Numerical calculations for selected examples illustrate the feasibility and potential of this method.

The abundance of elements heavier than iron produced via the astrophysical rapid-neutron-capture process depends sensitively on the atomic mass of the involved nuclei as well as the behavior of a few special types of nuclear isomers called “astromers.” High-precision mass measurements of ${}^{119}\mathrm{Cd}$ and ${}^{119}\mathrm{Ag}$ and their respective isomeric states have been performed with the phase-imaging ion cyclotron resonance (PI-ICR) method with a precision of $\delta m/m\approx {10}^{-8}$ using the Canadian Penning trap. The ground-state mass excess, as well as the excitation energy, agrees with recent Penning trap measurements from JYFLTRAP. Network calculations using these new measurements have revealed that, contrary to previous expectations, ${}^{119m}\mathrm{Ag}$ behaves as an astromer, which significantly affects the population of ${}^{119}\mathrm{Ag}$.

An experimental investigation of ${}^{105}\mathrm{Pd}$ has revealed, for the first time, the existence of two wobbling bands, both having one phonon configuration and originating from excitation, which is the wobbling from the yrast band with the $h_{11/2}$ quasineutron fully aligned with the short axis, and from an excited band with the same quasineutron but with less alignment along the short axis. These observations have been drawn from the measured ratios of the interband and intraband γ-transition rates. Model calculations based on the triaxial projected shell model (TPSM) approach have been performed and are found to be in good agreement with the experimental energies and relative transition probabilities. The analysis of the TPSM results provides an insight into the nature of the observed structures at a microscopic level.

Transport coefficients in the Langevin equation are essential for the dynamical analysis of nuclear fission. Two primary methods for calculating these coefficients exist: macroscopic and microscopic. Here we study the fission of ${}^{236}\mathrm{U}$ using a five-dimensional Langevin equation with a Cassini shape parametrization to examine how the choice of transport coefficients affects the distributions of fission fragment mass, quadrupole $\left({\beta }_2\right)$, octupole $\left({\beta }_3\right)$, and total kinetic energy. The results indicate that microscopic transport coefficients generate fragments with a broader range of deformation, which improves the agreement with experimental mass distributions for asymmetric fission modes. This improvement is found to be primarily due to the microscopic inertia tensor. To assess the effectiveness of the five-dimensional parametrization, the results are compared with those from lower-dimensional calculations. The Cassini parameter set $\{\alpha ,{\alpha }_1,{\alpha }_3,{\alpha }_4,{\alpha }_6\}$ is shown to properly describe both mass asymmetry and superlong symmetric fission. Furthermore, a rare type of hot fission is observed for heavy fragment masses of $134\pm 2$, characterized by a superelongated, neck-shaped light fragment.

High-energy neutron emission from the reactions of ${}^{40}\mathrm{Ar}$ and ${}^{20}\mathrm{Ne}$ on a natural copper target at $E_{\mathrm{inc}}/A=400$ to 600 MeV is studied, examining a possible signature of nucleon-nucleon short-range correlations (SRCs) in the high-energy/high-momentum tails in the neutron spectra, using available experimental datasets of Iwata et al. [Phys. Rev. C 64, 054609 (2001)]. Semirelativistic antisymmetrized molecular dynamics (SrAMD) is utilized with a three-nucleon collision (3NC) term, in which each nucleon is boosted with Fermi motion plus an empirical high-momentum tail (HMT) in the collision process, where the HMT is closely related to SRC. High-energy/high-momentum tails observed above the projectile velocity at forward angles in the experimental neutron spectra, which are commonly observed in Iwata et al.'s datasets, are attributed to originate from non-physics-related origins. Those at ${\theta }_{\mathrm{lab}}\ge {60}^{\circ }$ are started below the projectile velocity and attributed to originate from physics-related processes, since these can be reproduced by the SrAMD simulations with HMTs in the Fermi boost. This observation suggests that the high-energy/high-momentum tails are affected by the short-range correlations and may characterize the nature of SRCs that appear in the heavy-ion collisions, though the experimental data quality in accuracy and statistics makes it difficult to make conclusive remarks. Although the positive correlation between HMTs in the Fermi boost and the enhancement of the high-energy/high-momentum tails in the neutron spectra is observed, no flattening of the momentum spectra in the $K^4$-weighted representation of neutron cross section $K^{4}d{\sigma }^2/dKd\mathrm{\Omega }$ is observed in the SrAMD simulations.