High-precision measurements of nuclear decay energies can reveal rare low-Q transitions with enhanced sensitivity to the absolute neutrino mass. Using the JYFLTRAP double Penning trap and the PI-ICR technique, the electron-capture Q value of ${}^{113}$Sn was determined with an eightfold improvement in precision over the previous evaluation. Combining the new mass result with known excited states in ${}^{113}$In identifies two energetically allowed low-Q electron-capture branches. In particular, an allowed transition to the 1029.650-keV state has $Q{*}_{EC}=9.60(20)$ keV and lies close to the L-shell binding energies. Atomic and nuclear calculations show enhanced spectral sensitivity near the endpoint, making this decay an interesting complementary system for future direct neutrino-mass studies.

[Phys. Rev. C 114, 035501] Published Thu Sep 10, 2026

Photons and dileptons produced in high energy nuclear collisions contain undistorted information about the conditions at their point of emission, such as the local temperature, flow velocity, and chemical potential. Using state of the art modeling of the collision dynamics, which reproduce hadronic spectra, the authors find good agreement with measurements by the STAR Collaboration at the Relativistic Heavy Collider, but differ from measurements by the PHENIX Collaboration in terms of magnitude but not shape. This work shows that the multimessenger approach to heavy-ion collisions previously used at higher energy is amenable to baryon-rich environments at lower temperatures, and paves the way for more comprehensive studies of the QCD phase diagram.

[Phys. Rev. C 114, 034902] Published Tue Sep 08, 2026

An enhanced Full-Potential Linear Augmented Plane Wave (FLAPW) method is introduced which incorporates the small Dirac components of valence states—specifically the 6p1/2 semicore states—in actinide solids such as Ac, Th, ThO${}_2$, and UO${}_2$. By accounting for these small components, it is demonstrated that the valence electron density at the nucleus increases by a factor of 2.4 to 4.3, correcting standard approximations in computational physics that omit significant valence electron density near the atomic nucleus. These refined relativistic Dirac calculations offer improved theoretical precision for nuclear phenomena such as internal conversion, Mossbauer spectroscopy, and electron bridge effects, providing foundational electronic structure insights relevant to technologies like ${}^{229}$Th-based solid-state nuclear clocks.

[Phys. Rev. C 114, 034601] Published Thu Sep 03, 2026

We have demonstrated a new way to reveal the electrical ‘fingerprint’ left by a single nuclear decay. When a radioactive atom implanted just beneath a surface decays, its products can eject a shower of secondary electrons from the surrounding material. Often undetected by conventional laboratory instruments, these electrons can create a substantial background in experiments that rely on precise electron counting. To study this process, we use a microscopic glass sphere suspended by laser light as a highly isolated charge detector with sub-electron charge sensitivity. We pair the sphere with a conventional scintillation detector that records the emitted radiation. By matching the timing of the two signals, we can link each charge change to a specific decay. We found that one alpha decay can knock more than 100 electrons from a material’s surface, while beta decays release far fewer. Measuring these electrical fingerprints one decay at a time could help experiments searching for rare events, including future sterile neutrino searches, to distinguish genuine signals from electrons released by radioactive impurities near detector surfaces.

[Phys. Rev. C 114, 034602] Published Thu Sep 03, 2026

Nuclear effective field theories (EFTs) have had enormous impact on ab initio nuclear physics, yet many open questions remain regarding their development and application. This work studies Chiral EFT in a strictly RG-invariant formulation and applies it to the process of deuteron electrodisintegration, extending the reach of such calculations from static properties to breakup processes that probe a larger range of physics. To achieve this, the Lorentz Integral Transform (LIT) method is extended such that all subleading corrections, including those to the electromagnetic current operator, are included in perturbation theory, reaching second order in the EFT expansion. Finding good agreement with available data, this perturbative LIT framework paves the way for similar studies involving heavier nuclei.

[Phys. Rev. C 114, 024004] Published Mon Aug 31, 2026

Discovering new isotopes begins with knowing where to look. Predicting rare-isotope production is difficult because different nuclear-mass models can give substantially different results, making the planning of experiments uncertain. This work introduces a Bayesian-inspired model-averaging framework that combines abrasion–ablation calculations based on 12 nuclear mass tables into one statistically weighted prediction. Experimental data for krypton-78 and xenon-124 are used to determine which calculations are more reliable, and the resulting trends are transferred to molybdenum-92 and samarium-144 projectiles. The method provides predicted cross sections together with uncertainty estimates, giving a more reliable basis for selecting primary beams and estimating yields. Applied to proton-rich fragmentation at FRIB, the approach identifies several promising candidates for new-isotope searches with expected production rates above one event per day. It can help researchers plan experiments more effectively and explore still-unknown regions of the nuclear chart.

[Phys. Rev. C 114, 024603] Published Thu Aug 06, 2026

Variational methods employing symmetry-breaking intrinsic states offer alternative ways to tackle large-scale shell model calculations. While the latter provides a unified picture of the rotational motion and shell structure, the former has been known to provide a good approximation for the description of nuclear deformation. However, in such approaches, it is generally difficult to fully capture the effects of pairing correlations, for example in the backbending phenomena where the collective rotational motion is significantly disturbed. In this paper, the binding energies of levels coming from large-scale shell-model calculations are exactly reproduced using a discrete set of non-orthogonal Slater determinants, thus verifying their relevance for describing pairing properties as demonstrated in the ground-state band of 48Cr and the ground state of 78Ni, which is at the limit of conventional shell-model calculations. These results constitute a firm proof of the Broeckhove-Deumens theorem on the completeness property of non-orthogonal wave functions in realistic shell-model calculations.

[Phys. Rev. C 114, 014327] Published Wed Jul 22, 2026

The authors present both qualitative and quantitative advances in extracting transport coefficients and other parameters for the quark-gluon plasma formed in heavy ion collisions. The manuscript uses extensive data sets from all four of the original RHIC experiments to calibrate the input to a full 3-dimensional simulation based on relativistic hydrodynamics. The authors consider both a large system (Au+Au) as well as several small systems (d+Au, p+Au and ${}^3$He+Au). The success in describing small systems provides strong support for the hydrodynamic paradigm, and also helps resolve a long-standing puzzle between STAR and PHENIX measurements in such systems.

[Phys. Rev. C 114, 014905] Published Wed Jul 15, 2026

This work addresses the important issue of the determination of the superfluid neutron fraction in the inner crust of neutrons stars. Knowing this fraction is important to understand if the inner crust can provide enough angular momentum to drive observed pulsar glitches. The paper presents, for the first time, fully self-consistent Hartree-Fock-Bogoliubov calculations of the flow of superfluid neutrons through the periodic lattice of nuclear clusters, which show that the superfluid fraction can reach 90% and support a sufficient superfluid angular momentum reservoir to drive pulsar glitches.

[Phys. Rev. C 114, 015802] Published Mon Jul 06, 2026

A key goal in nuclear astrophysics is explaining the abundance patterns of the elements in combination with observational astrophysical data and nuclear reaction networks. Although two nuclear reaction pathways—the slow ($s$ process) and rapid ($r$ process) neutron capture processes—are known to produce many heavy elements beyond iron, a process at intermediate neutron densities (the $i$ process) has been proposed. This process is an additional pathway that occurs in some stellar environments to explain observed elemental abundances. In this work, the authors utilized a ${}^{88}$Br beam that was implanted within a $\gamma$-ray total absorption spectrometer to produce the compound nucleus ${}^{88}$Kr through $\beta$ decay. The authors measured the constrained neutron radiative capture on ${}^{87}$Kr, showing that it plays an important role in the production of Rb in the conditions of the $i$ process. In addition, the results significantly reduce the uncertainty in the rate of this reaction by determining the $\gamma$-ray strength function in the compound nucleus ${}^{88}$Kr. This work demonstrates that reducing experimental uncertainties in a single neutron-capture reaction can significantly affect comparisons with theoretical predictions of element abundance patterns.

[Phys. Rev. C 113, 065801] Published Mon Jun 01, 2026

New density-functional-theory calculations describe the radioactive decay of tritium bound to graphene, offering a way to model experiments that could open cleaner windows onto neutrino mass.

[Phys. Rev. C 113, 054607] Published Wed May 13, 2026

To overcome the challenge of synthesizing nuclei of superheavy elements (SHEs) beyond $Z=118$, the authors developed a new calculation method using the dinuclear system model. The novel approach consistently and microscopically derives all necessary structure inputs—including nuclear masses, fission barriers, and level density parameters—from finite-temperature covariant density functional theory. After validating the method against data for nobelium and flerovium isotopes, the approach provides meaningful predictions for the production of $Z=120$ isotopes, which should be useful for planning future SHE synthesis experiments.

[Phys. Rev. C 113, 054604] Published Thu May 07, 2026

The authors introduce a perturbation theory quantum Monte Carlo (PTQMC) method to compute high-order many-body perturbative corrections. The approach avoids exponential scaling inherent to conventional constructions of high-rank excitation operators. Benchmark calculations for the Richardson pairing model reproduce exact many-body perturbation-theory calculations up to 16th order even in strongly divergent regimes. The results are relevant for future applications of PTQMC to realistic nuclear matter and finite nuclei, as well as for the systematic assessment of perturbative uncertainties in $ab$-$initio$ nuclear theory.

[Phys. Rev. C 113, L051302] Published Mon May 04, 2026

The neutron electric dipole moment (nEDM) is a key probe of $CP$ violation and physics beyond the Standard Model. Experimental sensitivity scales with the applied electric field, making higher fields essential for improved measurements. A 1994 proposal to perform an nEDM experiment in superfluid ${}^4$He suggested several potential advantages, including in-situ production of ultracold neutrons with reduced loss and the possibility of higher electric fields. Here, the authors report the outcome of a comprehensive program to develop the high-voltage and electrode system for such an experiment, including new insights into relevant physical phenomena and detailing selected technical solutions with their corresponding experimental demonstrations. The results demonstrate the necessary technology for operation at electric fields up to $E=75$ kV/cm, compared with $E\approx 10$ kV/cm in recent nEDM experiments—a major step toward significantly enhanced sensitivity.

[Phys. Rev. C 113, 045503] Published Thu Apr 30, 2026

Radiative strength functions (RSFs) are crucial inputs for statistical nuclear reaction codes but are difficult to calculate because they require wave functions of highly excited states. The authors used large-scale shell model calculations to identify a key result of the energy-localized Brink-Axel hypothesis: the shape of the RSF evolves smoothly with wave-function energy. Combined with an efficient Lanczos strength-function method, this insight leads to a practical new approach for computing RSFs which was validated for ${}^{24}$Mg and provided novel results for ${}^{56}$Fe. The method is expected to simplify RSF calculations while motivating the use of energy-dependent RSFs in modern reaction codes.

[Phys. Rev. C 113, 044327] Published Wed Apr 29, 2026

The importance of quadrupole degrees of freedom has long been a hallmark of nuclear structure studies, while octupole degrees of freedom become increasingly important as proton and neutron numbers increase. This work introduces a microscopic collective Hamiltonian built upon multidimensionally constrained covariant density functional theory, incorporating both axial and triaxial quadrupole and octupole modes and their mutual couplings. As an example application, the complex excitation spectrum of ${}^{152}$Sm is well reproduced, along with a good replication of $E0$, $E1$, and $E2$ transitions. The unifying microscopic collective Hamiltonian proposed here is relevant for achieving a microscopic description of shape coexistence in nuclei and their associated excitation modes.

[Phys. Rev. C 113, 044328] Published Wed Apr 29, 2026

Located just beyond the $Z=28$ proton-shell closure, the odd-$N$ zinc isotopes ($Z=30$) provide a sensitive testing ground for the evolution of neutron orbitals through their low-lying states. The authors report high-precision Penning-trap mass measurements of the ground and first isomeric state in ${}^{75}$Zn at ISOLTRAP, with both states populated via the decay of ${}^{75}$Cu inside a Penning trap. Earlier work had identified only a single long-lived state in ${}^{75}$Zn and assigned its mass to the ground state. The new measurements show that the previously observed state is instead the first isomeric state, restoring a smooth trend in the two-neutron separation energies and supporting a ground-state spin-parity assignment of $J^{\pi }=1/2^{-}$. The results of the new high-precision measurements also provide benchmarks for improving theoretical models in this region of rapidly evolving nuclear structure.

[Phys. Rev. C 113, 044321] Published Mon Apr 27, 2026

Optical potentials are necessary for modeling scattering and reactions, but are challenging to derive rigorously; practitioners often resort to phenomenology instead. Inspired by other recent work, this paper investigates a key input into optical potentials, the off-shell densities, here computed in the $ab$-$initio$ no-core shell model. The authors find these densities are well approximated by a handful of separable terms, with the number of needed terms depending only upon the number of protons and neutrons. Such insights will likely influence the future development of both phenomenological and first-principles optical potentials.

[Phys. Rev. C 113, 044323] Published Mon Apr 27, 2026

Accurate modeling of nuclear reactions is relevant to understanding the structure and dynamics of atomic nuclei, as well as for nuclear science applications and for understanding how nuclei are created in the universe. The authors generalize the reduced basis method, a physics-based emulator used for elastic scattering, to coupled-channels equations for nuclear reactions. They apply the method to neutron scattering on ${}^{48}$Ca and ${}^{208}$Pb and show that the calculated elastic and inelastic cross sections match those obtained using traditional accurate methods. Because emulators can offer a fast and reliable alternative to the exact solution of several scattering problems in nuclear physics, and because many reactions can be cast as a coupled-channels problem, the new developments will have significant impact on future research.

[Phys. Rev. C 113, 044623] Published Mon Apr 27, 2026

The efficient production of neutron-rich nuclei has been a challenge and is a central theme at current and future rare-isotope facilities. Nuclides with high neutron excess can be reached by transferring multiple neutrons from the target to the projectile and/or by stripping protons from the projectile in multinucleon transfer reactions. Beam energies range from the Coulomb barrier to Fermi energies, about 15–35 MeV/nucleon. The authors analyze two reactions, ${}^{86}$Kr+${}^{86}$Ni and ${}^{86}$Kr+${}^{124}$Sn, each previously measured at 15 MeV/nucleon at the MARS recoil separator at the Texas A&M Cyclotron Institute. Systematic comparisons with calculations from two well-known models followed by a deexcitation description provide significant insight into the reaction mechanisms and indicate that multiple charge-exchange channels, along a diagonal `southeast’ path in the nuclear chart, offer an efficient route to neutron-rich nuclides.

[Phys. Rev. C 113, 034621] Published Fri Mar 27, 2026

Quantum computers offer new ways to solve the nuclear many-body problem, but realistic applications remain out of reach. Computations on a position-space lattice are promising as they exploit the short-range nature of nuclear forces. Using a local effective field theory Hamiltonian with two- and three-nucleon forces, this paper analyzes the resources required to compute ground states using adaptive variational algorithms. Demonstrations for the deuteron and helium-3 illustrate how such approaches may scale toward future quantum computations of nuclei.

[Phys. Rev. C 113, 034321] Published Tue Mar 24, 2026

Experimental data on hyperon-nucleon interactions are scarce even though measurements of hyperon-nucleon scattering have been performed since the 1960s. This work takes advantage of ${10}^{10}$ $J/\psi$ particles produced at an $e^{+}{e}^{-}$ collider to extract unique hyperon-nucleon cross sections. Following the decay $J/\psi \to {\mathrm{\Sigma }}^{+}{\overline{\mathrm{\Sigma }}}^{-}$, the experiment tracked the nearly monoenergetic hyperons through the collider beam pipe and their interactions with bound neutrons in the pipe. Cross sections for two final states are extracted with $>3\sigma$ sensitivity. These results should aid theory progress on hyperon-nucleon interactions and may be useful in constraining hyperons in the equation of state of neutron star cores.

[Phys. Rev. C 113, L032201] Published Mon Mar 23, 2026

Predicting the low-energy, two-nucleon ($NN$) forces directly from quantum chromodynamics (QCD), the underlying theory of strong interactions, remains a challenge for theory. The authors present a high-statistics, technically sophisticated lattice QCD calculation of $p$-$n$ and $n$-$n$ scattering amplitudes at equal (heavy) pion and kaon masses of 714 MeV and find that deuteron and di-neutron bound states do not exist. The results help diagnose a long-standing disagreement in the literature regarding the methods used to determine the $NN$ spectra and amplitudes with such calculations. The work represents a significant step toward deriving nuclear physics from first principles.

[Phys. Rev. C 113, 024002] Published Tue Feb 17, 2026

This work presents an extensive theoretical and numerical study of charged few-nucleon systems ($pd$, $dd$, and $p$-${}^3$He bound states and scattering) in the framework of pionless effective field theory (EFT) up to next-to-leading order (NLO). The authors treat the Coulomb interaction nonperturbatively, while NLO interactions, including three-body forces and a four-body force, are treated in perturbation theory. Special attention is given to renormalization issues. Only a mild cutoff dependence is seen, consistent with the expectations of power counting in pionless EFT. The results hold significant promise for $ab$-$initio$ studies of charged-particle scattering at very low energies, with applications to reactions of astrophysical interest.

[Phys. Rev. C 113, 024001] Published Fri Feb 13, 2026

Benchmarking simulation codes for electron transport and scattering in matter is a crucial step for estimating uncertainties in precision measurements in $\beta$ decay and other applications. This work reports the measurement and the quantitative analysis of backscattering probabilities of electrons in the energy range 0.1 to 3.4 MeV where experimental data are scarce. Using a setup for precise identification of backscattered events impinging on a YAP:Ce scintillator, the authors achieved meaningful agreement between simulations and experimental data covering a large range of energies and large incident angles. The results should help mitigate the usually large relative uncertainties considered for electron backscattering probabilities. Reaching an improved understanding of the systematic uncertainties at the percent level, compared to the previous 10% level, promises to be of high value to the community engaged in precision $\beta$ spectroscopy.

[Phys. Rev. C 113, 025501] Published Mon Feb 09, 2026

The ${}^{12}$C($\alpha$,$\gamma$)${}^{16}$O reaction sets the carbon-to-oxygen ratio after core helium burning and strongly influences late stellar evolution. Because direct measurements near $E\approx 300$ keV are not available, this work combines existing experimental constraints in a Bayesian analysis to determine a well-defined range for the astrophysical factors $S_{E1}$(300 keV) and $S_{E2}$(300 keV). The resulting $S$(300 keV) range has important implications for the final outcomes of massive stars, including the formation of heavy black-hole remnants relevant to gravitational-wave observations.

[Phys. Rev. C 113, 025803] Published Mon Feb 09, 2026

Nuclear moments are fundamental nuclear characteristics such as whether an individual nuclear state is deformed, or whether the nucleus carries its angular momentum as a collective whole or as individual nucleons with contributions from both their orbital motion and their intrinsic spin. However, calculations of nuclear moments have long been carried out mostly for certain classes of nuclei rather than seamlessly across an entire region. The authors report comprehensive calculations of spectroscopic magnetic dipole and electric quadrupole moments in odd-$N$, even-$Z$ nuclei with their code HFODD. The calculations cover gadolinium to osmium nuclei, ranging from near-spherical to well-deformed nuclei, within nuclear density functional theory with the Skyrme functional UNEDEF1. Comparison with experimental data for 82 states without parameter adjustment demonstrates that the study captures the main features of magnetic dipole and electric quadrupole moments. The holistic approach to an entire region of the nuclear chart provides valuable insight into the evolution of the underlying nuclear structure and will help guide future fine-tuning of the functionals.

[Phys. Rev. C 113, 024306] Published Thu Feb 05, 2026

The thorium isotopes exhibit a transition from symmetric to asymmetric fission. To study this transition, the authors carry out a systematic investigation of fission modes across the thorium isotopic chain, based on state-of-the-art microscopic models. They show that it is strongly correlated with rapid changes in the configuration of the nucleus at scission as the thorium isotopes become more neutron-rich. Furthermore, they find that the change in configuration is driven by a deformed shell closure for krypton and strontium isotopes which dominate the light asymmetric fragment yields. This work can point the way toward finding other isotopic chains where such fission-mode transitions occur.

[Phys. Rev. C 113, 024601] Published Mon Feb 02, 2026

Synthesizing neutron-rich superheavy elements such as those near the $N=152$ shell closure is experimentally challenging and requires reliable guidance from nuclear theory. This work reports on the multinucleon transfer (MNT) reaction ${}^{238}$U+${}^{238}$U to synthesize neutron-rich ${}^{244}$U. The authors use a semi-classical approach based on solving a master equation, the DNS-sysu model, to obtain the fragment distribution probability. Using a multidimensional analysis of the correlations among the scattering angle, the kinetic energy, and the angular momentum, the authors focus on how these physical parameters influence the optimal detection angle for ${}^{244}$U production. They find that the optimal production kinematic window corresponds to peripheral collisions with high angular momentum and kinetic energy, at a scattering angle near those for grazing collisions. The results can help guide experiments toward optimizing the detection geometry for MNT experiments to synthesize and detect ${}^{244}$U and similar neutron-rich actinides, which are important to better understand the evolution of nuclear stability near the predicted “island of stability” of superheavy elements.

[Phys. Rev. C 113, L021601] Published Mon Feb 02, 2026

This work is a new and impressive example for the potential of $\gamma$-ray-tagged neutron-adding transfer reactions at high beam velocities. By tuning the desired angular momentum transfer, this reaction allows selecting specific neutron configurations and complements spectroscopic information from the more common neutron-removal and low-energy ($d$,$p$) transfer reactions. The experiment selectively populated excited states in ${}^{47}$Ca—a neighbor of the doubly magic ${}^{48}$Ca nucleus—based on $\ell \ge 3$ neutron configurations following one-neutron pickup by ${}^{46}$Ca from a ${}^{12}$C target, and recorded their decay with the GRETINA detector array. The experimental results demonstrate that the $\ell =3$ spectroscopic strength is rather fragmented, in contrast to shell-model calculations, which predict it to be strongly concentrated in only a few states. The work not only suggests opportunities for a modern ($d$,$p$) measurement to complement the present selective high-$\ell$ data but more generally introduces $\gamma$-ray-tagged neutron-adding transfer reactions as a complementary tool for exploring neutron single-particle excitations.

[Phys. Rev. C 113, 014328] Published Thu Jan 29, 2026

The authors present new results for nuclear shape evolution and phase transitions from a comprehensive microscopic calculation based on the projected Hartree-Fock-Bogolyubov plus generator coordinate method. They identify, in particular, the microscopic origins of the symmetries originally suggested by algebraic or geometric models. The calculations show that by taking ${}^{134}$Ba as the reference and varying the $Q\cdot Q$ strengths involving the quasi-SU(3) partners ($1g_{9/2}$,$2d_{5/2}$) and ($1h_{11/2}$,$2f_{7/2}$), one can reproduce the relevant IBM symmetries and the shape-critical behavior symmetries. The work also identifies a line, in a visual representation of the transitions between the symmetries, with $Q_s(2_1^{+})$ equal to zero dividing states indicative of prolate and oblate nuclear shapes.

[Phys. Rev. C 113, 014327] Published Wed Jan 28, 2026

During fission, a heavy nucleus splits into two hot fragments that cool by emitting particles. To simulate this cooling process, the angular momentum distribution of the fragments is required. Historically, this has been described using simplified phenomenological models. In this work, advanced quantum-mechanical methods are used to predict, for the first time, the angular momentum distributions of all fragments observed experimentally. The calculations confirm a pronounced sawtooth pattern in the average angular momentum as a function of fragment mass, consistent with recent measurements. Moreover, substantial variations are predicted for isobaric nuclei, indicating that simplified models are not sufficiently accurate. The generated data are an important input for fission modeling based on robust quantum-mechanical methods, an effort relevant for fundamental science and technology.

[Phys. Rev. C 113, 014612] Published Wed Jan 28, 2026

Many precision tests of the Standard Model require controlled understanding of nuclear structure. An example is precise knowledge of nuclear charge radii, which can be obtained from the x-ray spectra of muonic atoms. Such spectra themselves have important corrections, such as the induced nuclear polarization. This Letter presents a simple yet reliable collection of formulas to compute the nuclear polarization for light to medium-mass nuclides. These formulas encode information across bound-state QED, nuclear reactions, and hadronic interactions, and aim at providing better constraints in interpreting key experiments.

[Phys. Rev. C 113, L011301] Published Wed Jan 14, 2026

Precision knowledge of the neutron lifetime is important in predicting the cosmological abundance of helium following the Big Bang, the flux of solar neutrinos, and the influence of beyond-standard-model theories with new massive particles on electroweak interactions. However, the neutron lifetime puzzle—the several-standard-deviation discrepancy between the neutron storage “bottle” experiments and the neutron decay “beam” experiments—limits a confident extraction of the experimental lifetime. This work addresses a previously unquantified systematic effect in the beam experiments, the loss of trapped protons due to charge exchange with molecular hydrogen in the residual gas. These new results, using the BL2 experimental apparatus at NIST, provide direct information on the effects of charge exchange of protons and show that this effect is not responsible for the observed difference in lifetime from the two measurement techniques, concluding that the neutron lifetime puzzle remains.

[Phys. Rev. C 112, 065501] Published Fri Dec 12, 2025

Atomic nuclei within an isobaric multiplet have rather similar structure, and studying $\beta$ decay between these nuclei is a powerful spectroscopy tool. An international team of researchers reports on a large amount of nuclear structure data for several nuclei near the proton dripline: ${}^{64}$Se, its isobar multiplet neighbor ${}^{64}$As, and ${}^{63}$Ge. ${}^{64}$Se is the heaviest $T_z=-2$ nucleus that both $\beta$ decays and has a stable mirror partner $T_z=+2$. The experiment used fragmentation from a high-intensity ${}^{78}$Kr beam at the RIKEN Nishina Center in Japan and recorded in addition to $\beta$-delayed $\gamma$ rays also decay protons from states above the separation energy. The comprehensive spectroscopy led to new insights on the isobaric mass multiplet equation for the $A=64$ $T=2$ system, the heaviest multiplet where these studies are possible, and found good mirror symmetry. In also measuring the half-life of ${}^{64}$Se and revisiting the idea of the anti-analog state originally discussed for the $A=56$ system half a century ago, the work brings detailed nuclear decay studies very close to the proton drip line.

[Phys. Rev. C 112, 054319] Published Thu Nov 20, 2025

Phenomenological nuclear reaction models primarily rely on data from stable isotopes. It is uncertain how these models would perform when applied to reactions involving unstable, exotic isotopes the data of which are crucial for astrophysics, medicine, and energy applications. To address this challenge, the authors introduce a microscopic optical potential, derived from the Feshbach formalism and informed by the valence shell model. The work presents an innovative self-consistent, iterative approach for calculating the nonlocal Green’s function, forging a direct and systematic link between nuclear structure and reaction theory. Applied to $n{+}^{24}$Mg elastic scattering, the new optical potential yields close agreement with experimental data, demonstrating a powerful and necessary tool for modeling reactions away from the valley of stability.

[Phys. Rev. C 112, 054606] Published Thu Nov 13, 2025

This work develops a fully microscopic framework for neutron-induced reactions to describe direct and one-step pre-equilibrium processes. The authors combine the noniterative finite-amplitude method (FAM) with the distorted-wave Born approximation (DWBA). The resulting FAM-QRPA+DWBA formalism employs the Skyrme effective interaction to derive quasiparticle random-phase approximation (QRPA) equations, which leads to a consistent and parameter-free treatment of neutron inelastic scattering to both discrete and continuum states. Applied to the ${}^{208}$Pb($n$,$n\prime$) reaction, the method accurately reproduces measured differential and double-differential cross sections across 7–25 MeV without empirical adjustments. The calculated spin distributions of residual nuclei agree with combinatorial 1p–1h systematics, demonstrating that the noniterative FAM-QRPA+DWBA approach provides an efficient and predictive tool for modeling neutron-induced reactions within a unified microscopic framework.

[Phys. Rev. C 112, 054607] Published Thu Nov 13, 2025

Describing reactions with deformed nuclei remains a challenging task. The article proposes a microscopic method to consistently calculate cross sections and construct optical potentials for such systems, using symmetry breaking and restoration techniques. The formalism builds Green’s functions and self-energies from multiple reference states, with sum rules that allow truncation of the many-body space, overall reducing computational time. Applied to neutron scattering on ${}^{24}$Mg, the approach reproduces cross sections and demonstrates a promising path toward systematic microscopic optical potentials for heavy and deformed nuclei.

[Phys. Rev. C 112, L051602] Published Thu Nov 13, 2025

Photons in high-energy probe beams that pass through their intended target can be “reused” for making promising nuclides in nuclear medicine, new experiments show.

[Phys. Rev. C 112, 054603] Published Fri Nov 07, 2025

This work describes the first calculation of a nuclear matrix element for the two-neutrino double-beta transition ($2\nu \beta \beta$ ${}^{48}$Ca${\to }^{48}$Ti) within a recently developed theory framework, no-core configuration-interaction based on density-functional theory (DFT-NCCI). The authors build on a tested approach, and explicitly include nuclear deformation. A clever choice of the single-particle wave functions reduces the computational effort. The result obtained for this transition is complementary to those obtained in other nuclear frameworks, giving confidence in modeling this very rare process with DFT-NCCI. This is not only relevant for modeling $2\nu \beta \beta$ decay in heavier nuclei within a unified formalism but is also highly relevant for modeling the $0\nu \beta \beta$ decay process for which nuclear matrix elements differ significantly between various approaches.

[Phys. Rev. C 112, 055502] Published Thu Nov 06, 2025

Sum rules for electromagnetic transitions offer valuable insight into atomic nuclei. The Thomas-Reiche-Kuhn (TRK) sum rule on electric dipole transitions, for instance, directly reflects the exchange components of the nuclear force. These sum rules can be efficiently computed as expectation values of moment operators. In this work, the authors perform $ab$ $initio$ calculations of the multipole response of closed-shell nuclei from ${}^4$He to ${}^{78}$Ni using various chiral two- and three-nucleon interactions. The moment operators are evolved with the in-medium similarity renormalization group (IMSRG) to incorporate key ground-state correlations. Applying this method, the TRK sum rule for ${}^{16}$O and ${}^{40}$Ca agrees well with experiment, demonstrating an advance over competing many-body methods. This framework thus provides a benchmark for other $ab$ $initio$ calculations of integrated nuclear response properties.

[Phys. Rev. C 112, 054303] Published Wed Nov 05, 2025

$Ab$ $initio$ no-core shell model calculations do well in reproducing experimental energies. Observables with radial dependences, however, such as radii and electric quadrupole moments and transitions, are particularly affected by large-distance tails of the nuclear wave function. Such observables are generally in poorer agreement with experiment and are much more sensitive to the choice of model space. The work in these two papers shows that dimensionless ratios of such observables are significantly less sensitive to the model space and agree better with data. Thus, if one can measure at least one observable, one can make a reliable prediction for the others. Moreover, these dimensionless ratios provide $ab$ $initio$ insight into the nuclear quadrupole deformation.

[Phys. Rev. C 112, 044318] Published Thu Oct 23, 2025

$Ab$ $initio$ no-core shell model calculations do well in reproducing experimental energies. Observables with radial dependences, however, such as radii and electric quadrupole moments and transitions, are particularly affected by large-distance tails of the nuclear wave function. Such observables are generally in poorer agreement with experiment and are much more sensitive to the choice of model space. The work in these two papers shows that dimensionless ratios of such observables are significantly less sensitive to the model space and agree better with data. Thus, if one can measure at least one observable, one can make a reliable prediction for the others. Moreover, these dimensionless ratios provide $ab$ $initio$ insight into the nuclear quadrupole deformation.

[Phys. Rev. C 112, 044319] Published Thu Oct 23, 2025

The ${}^4$He nucleus, for historical reasons often called the $\alpha$ particle, has a large binding energy but it lacks stable excited states. Experimental data suggest a $0^{+}$ resonance about 0.4 MeV above the $p$-${}^3$H threshold with a width comparable to that energy. The authors carry out a benchmark calculation which locates a shallow bound excited state in ${}^4$He near that threshold when they switch off the Coulomb interaction. As they gradually re-introduce it, the excited state crosses the threshold and eventually becomes a resonant state. Comparisons of resonant energy and width show significant discrepancies with $R$-matrix analyses from experimental data. However, using universal concepts, the authors conclude that the existence of this state is not a consequence of a particular interaction between the constituent protons and neutrons but is due to a discrete scale invariance that constrains the spectrum of the $N$-body system, thus demonstrating a connection to the universal behavior of systems with four nucleons.

[Phys. Rev. C 112, 044001] Published Wed Oct 01, 2025

Fusion reactions are the most complex reaction processes during the collision of two nuclei, their cross sections spanning several orders of magnitude. The authors expand a previous analysis of heavy-ion fusion, applying a recently proposed universal function for fusion cross sections. By scaling both energy and cross sections according to characteristics of the Coulomb barrier, the authors essentially take into account the influence of the Coulomb interaction between the two nuclei as they fuse. The approach reproduces fusion excitation functions rather well, even in the energy region below the Coulomb barrier, while highlighting individual reaction characteristics as one compares many fusion systems. The success in identifying simple scaling laws for universal representations of a large body of fusion data may motivate future work including predicting unmeasured fusion cross sections.

[Phys. Rev. C 112, 034612] Published Wed Sep 17, 2025

Machine learning (ML) is rapidly becoming an important technique in nuclear physics. However, applying machine learning reliably requires quantifying the uncertainty in an ML model, which can be computationally very expensive, requiring multiple runs of training. Researchers at Lawrence Livermore National Laboratory have, for the first time in nuclear physics, implemented a method to combine training data features with biases also selected from the training data features, which allow for simultaneous fitting and uncertainty quantification. When applied to nuclear binding energies, the new method not only successfully quantifies the errors, but in particular signals when the ML model is extrapolated too far from data and becomes unreliable. This heralds a new ability to extrapolate data to extreme conditions, with reduced computational resources, yet without compromising our knowledge of how trustworthy the extrapolation is.

[Phys. Rev. C 112, 034317] Published Mon Sep 15, 2025

The study of low-lying energy levels in odd-$A$ heavy nuclei provides important information regarding the ordering of Nilsson single-particle states, and thus the evolution of shell structure in the heavy-mass region. In the present work, the authors used the observation of pile-up traces from conversion electrons following the $\alpha$-decay events of ${}^{247}$Md to identify a new isomeric state of ${}^{243}$Es, which has a half-life as short as 5 microseconds. This result, which constitutes the first observation of an isomeric decay in $Z=99$ Es isotopes, led to a significant rearrangement of the level scheme of ${}^{243}$Es. This cutting-edge $\alpha$-decay spectroscopy using digital pulse-shape analysis promises to open a new avenue for exploring isomerism in other transfermium isotopes.

[Phys. Rev. C 112, 034315] Published Fri Sep 12, 2025

Knowing the correct ground-state spin of neutron-rich nuclei is crucial for the interpretation of $\beta$-decay data and nuclear structure, but experimental information is often scarce. Using a novel laser excitation scheme specifically developed for this work the authors measured the ground-state spin and magnetic dipole moment of the short-lived nucleus ${}^{61}$Cr at ISOLDE-CERN with high-resolution resonance ionization laser spectroscopy. The hyperfine spectrum of ${}^{61}$Cr revealed a ground-state spin of $I=1/2$, contradicting the previously adopted value of $I=(5/2)$. This, together with the value of the magnetic dipole moment and advanced theoretical calculations characterizes the ${}^{61}$Cr ground-state configuration as dominated by an unpaired $p_{1/2}$ neutron coupled to intruder neutron 2p-2h excitations, placing this Cr isotope at the “western” entrance to the $N=40$ island of inversion. The nature of the results holds promise for a deeper understanding of nuclear structure in a region that harbors shell and shape evolution.

[Phys. Rev. C 112, L031301] Published Tue Sep 02, 2025

Electron-capture reactions on iron-group nuclei are relevant in the late stages of the evolution of massive stars, but their rates are highly sensitive to the detailed Gamow-Teller (GT) strength distributions. Using a combination of experimental facilities at the NSCL at MSU including high-resolution $\gamma$ coincidences the authors measured the GT strength via a charge-exchange reaction from a triton beam. The work demonstrates that low-lying states play important roles in certain stellar environments, emphasizing the importance of coincident high-resolution $\gamma$-ray spectroscopy to obtain accurate electron-capture rates.

[Phys. Rev. C 112, 024615] Published Fri Aug 22, 2025

The ${}^{14}$N$+n$ reaction plays a significant role in various nuclear science scenarios: it is thought to be one of the main neutron poisons during $s$-process nucleosynthesis; it provides insight for nuclear security for atmospheric nuclear weapons testing; and it is needed for simulating neutron transport through a variety of materials. Yet, for ${}^{14}$N$+n$, only one high-sensitivity measurement has been available, but its experimental details were incomplete. To cross-check existing nuclear evaluations, the authors carried out comprehensive neutron transmission measurements from 0.1 to 12 MeV neutron energy at the nELBE facility in Dresden-Rossendorf, Germany, and combined them with detailed $R$-matrix studies. The cross sections are in good agreement with previous data over much of the energy range with the key exception of the lowest-energy resonance at a neutron energy of 433 keV. In addition to providing strong confirmation of the role of ${}^{14}$N in influencing the $s$ process, this work improves confidence in the present ENDF/B nuclear evaluation and promises improvements for future evaluations of related ${}^{14}$N$+n$ cross sections.

[Phys. Rev. C 112, 025805] Published Wed Aug 20, 2025

Recent observations of red giant stars in a globular cluster in the outer halo of the Milky Way revealed a puzzling anomaly in the abundance of chemical elements that cannot be explained by common cluster evolution models. The authors use nuclear resonance fluorescence, a powerful method for determining the spins and parities of astrophysically relevant nuclear resonances, to selectively photoexcite several low-lying levels in ${}^{31}$P that would be challenging to access with traditional reaction techniques. Using the TUNL High-Intensity Gammaray Source, the authors unambiguously determined the orbital angular momentum transfers of two previously unobserved resonances at $E_r^{\mathrm{c}.\mathrm{m}.}=18.7$ keV and 50.5 keV. The measured thermonuclear reaction rate differs by about an order of magnitude from earlier estimates at temperatures of $T\le 200$ MK relevant for globular cluster nucleosynthesis. The new results put crucial constraints on the reaction mechanism correcting assumptions from previous work and could have broader implications for nucleosynthesis in certain stellar populations.

[Phys. Rev. C 112, 025804] Published Fri Aug 15, 2025

First principles calculations of nuclear binding and excitation energies have been a dramatic success of the recent era of nuclear structure calculations. Much more challenging have been long-range observables such as radii, in part because the standard harmonic oscillator basis functions fall off too quickly. This work repairs the radial densities by introducing the known exponential tail, leading to much better agreement. As both binding energies and radii are key inputs in constraining theory, this approach may help address a long-standing gap in our fundamental models.

[Phys. Rev. C 112, 024317] Published Tue Aug 12, 2025

The nucleon-nucleon interaction is studied in chiral effective field theory on the lattice. For the first time isospin-breaking effects, charge-independence breaking as well as charge-symmetry breaking, and the two-pion exchange interaction up to next-to-next-to-next-to leading order are included on the lattice. A high-quality description of the two-nucleon phase-shift and mixing-angle parameters is achieved up to 200 MeV/$c$ relative momentum. The deuteron properties are accurately reproduced. The work provides a promising basis to apply lattice effective field theory to nuclear many-body problems.

[Phys. Rev. C 112, 014009] Published Tue Jul 29, 2025

Nuclei are often viewed as drops of nuclear matter, but we also know that $\alpha$ clusters can play an important role in nuclear structure. A relativistic mean-field calculation of ${}^{16}$O, constraining the radius and thus the density, shows a change from a mostly homogeneous constitution to a dilute gas-like structure of four $\alpha$ particles. Such a phase transition, which is also sensitive to the effect of temperature, could have implications both for the structure of finite nuclei as well as nuclear matter in astrophysical scenarios.

[Phys. Rev. C 112, 014311] Published Thu Jul 10, 2025

Increasing the strength of the isovector spin-orbit potential in mean-field calculations can reconcile the PREX and CREX measurements of the neutron skin thicknesses in ${}^{208}$Pb and ${}^{48}$Ca. The authors demonstrate this within a relativistic mean-field framework by exactly recasting the Dirac equation into a Schrödinger-like form, allowing a clear identification and manipulation of the various components of the effective potential. However, they show that such modifications undermine well-established shell-model phenomenology, particularly the ordering of spin-orbit partners. Although by itself this approach cannot resolve the CREX-PREX dilemma in a consistent way, the results underscore that the ongoing tension offers a valuable opportunity to advance our understanding of the nuclear dynamics.

[Phys. Rev. C 112, 014310] Published Tue Jul 08, 2025

The inner crust of neutron stars is known to form exotic inhomogeneous phases, described as “pasta” phases. They are expected to affect observational properties of neutrons stars, such as pulsar glitches. This requires an accurate description of neutron pairing effects between free neutrons and their interaction with lattice nuclei that determines the band structure. The manuscript presents a generalization of the finite-temperature coordinate-space Fermi operator expansion method for Hartree-Fock-Bogoliubov band theory calculations. The method produces results with high accuracy, providing a promising tool for the simulation of the pasta phases in the inner crust of neutron stars.

[Phys. Rev. C 112, 015804] Published Tue Jul 08, 2025

Nuclear breakup reactions provide crucial insights into nuclear structure, but modeling them accurately has been hampered by numerical instabilities. This work solves a long-standing computational problem in the Ichimura-Austern-Vincent model by introducing a hybrid technique that achieves stable, accurate calculations. Validated through calculations for the deuteron and ${}^6$Li, the method significantly outperforms traditional approaches. This advance enables reliable theoretical predictions of breakup processes, providing the nuclear physics community with an improved tool for interpreting experiments at modern facilities.

[Phys. Rev. C 112, 014609] Published Wed Jul 02, 2025

The size of the atomic nucleus is a fundamental observable, for which laser spectroscopy of atomic hyperfine transitions can measure the changes in mean-square charge radii as neutrons are added or removed. This work reports an extensive set of results from collinear resonance ionization spectroscopy at ISOLDE-CERN on ground- and isomeric states of indium ($Z=49$) isotopes, almost spanning the complete valence space between the neutron-shell closures $N=50$ and 82. Whereas the new results largely agree with literature values within experimental and atomic-factor uncertainties, the authors find intricate variations in the odd-even staggering of the nuclear charge radii. This work shows how the breadth of data can serve as a benchmark for nuclear theory, suggesting directions for further improvements.

[Phys. Rev. C 111, 064325] Published Thu Jun 26, 2025

A major thrust of twenty-first century electron scattering at the present CEBAF at JLab and at the future Electron Ion Collider (EIC) at BNL is the determination of generalized parton distributions (GPDs), which describe the full 3D quark and gluon structure of the proton and of atomic nuclei. The authors have carried out a comprehensive study of a new, yet-unmeasured process, double deeply virtual Compton scattering (DDVCS), at both CEBAF and EIC, which can access GPDs without restrictions that are present in current measurements. For example, they show the sensitivity of DDVCS cross-section asymmetries to the chiral-even proton GPDs from different model predictions. The insights gained from the systematic analysis promise significant benefit to next-generation experiments designed to study the full 3D quark and gluon structure of hadrons.

[Phys. Rev. C 111, 065205] Published Tue Jun 24, 2025

Fusion of the two heavy hydrogen isotopes deuterium with tritium is important for future energy production. The authors attempt to reproduce an early experimental result by Arthur J. Ruhlig (published in the Physical Review in 1938, but not cited until 2023) that suggested Ruhlig had observed the so-called “DT” reaction, ${}^3$H($d$,$n$)${}^4$He in a secondary reaction (see figure). In the present work the authors use modern experimental techniques to repeat the experiment, and they indeed observe DT fusion and measure the reaction rate. In addition to giving insights into the historic nuclear fusion experiment, the technique used could have applications in checking triton stopping powers in deuterium-containing fusion targets.

[Phys. Rev. C 111, 064618] Published Fri Jun 20, 2025

The stellar carbon-nitrogen-oxygen nuclear reaction cycle (CNO cycle) converts four protons to an $\alpha$ particle providing most of the energy in massive main sequence stars and in stars in more advanced stages. It also affects the nucleosynthesis output of these stars and ultimately the chemical evolution of galaxies. The present manuscript reports on a new cross-section measurement for the ${}^{13}$C($p$,$\gamma$)${}^{14}$N reaction—the second proton capture reaction in the CNO cycle—performed at the Felsenkeller shallow-underground laboratory in Dresden, Germany. The new data are consistent with recent results reported by the LUNA Collaboration and are about 20\% lower than previous literature data. The newly calculated reaction rate is systematically lower than assumed so far for temperatures up to 10 GK, a result that should have an impact on stellar model calculations and CNO cycle nucleosynthesis.

[Phys. Rev. C 111, 064611] Published Wed Jun 11, 2025

Nuclear reactors create copious amounts of antineutrinos, but calculating their spectrum is challenging because one must understand in great detail both the available nuclear data and which physics contributions are relevant. Accurate new experiments have shown a 5% neutrino deficit in the detected flux known as the “reactor antineutrino anomaly”, and an excess at 5 to 7 MeV. The authors explore the effect of one particular and so far not fully appreciated input, the ratio of fission yield from an isomeric state to the total yield, known as the isomeric yield ratio (IYR) and which reflects different endpoint energies of the antineutrino spectra. Examining newly evaluated IYRs, the authors find that the values for certain isotopes significantly increase the antineutrino spectrum around and above 7 MeV with a 50% or greater increase at higher energies. The sensitivity study in this work identifies the need for accurate experimental data, especially for key fission products, to fully understand the observed discrepancies between measured and calculated antineutrino spectra.

[Phys. Rev. C 111, L061601] Published Wed Jun 11, 2025

The authors present the first dynamical fission model calculation of fission in the sub-lead region in which the mass yields and total kinetic energies arise from the calculations. The Langevin code developed by the authors reproduces the fragment mass and total kinetic energy distributions with remarkable accuracy for the reactions ${}^{36}$Ar + ${}^{144}$Sm $\Rightarrow$ ${}^{180}$Hg and ${}^{36}$Ar + ${}^{154}$Sm $\Rightarrow$ ${}^{190}$Hg at various excitation energies, with deviations of the calculated results from experiment that do not exceed the experimental uncertainties. The study also clarifies the role of shell effects due to multi-chance fission at excitation energies of 30–50 MeV, where these effects are not well known. The present work confirms the five-dimensional Langevin approach as a reliable tool to predict fission process observables.

[Phys. Rev. C 111, 054620] Published Tue May 20, 2025

Measuring how efficiently an isotope captures neutrons of various energies both confirms and refutes some surprising recent results.

[Phys. Rev. C 111, 034613] Published Tue Mar 18, 2025

How shapes of heavy nuclei evolve as their valence nucleon shells are filled continues to be a nuclear physics research frontier. The authors populated high-spin isomers in very-neutron-rich $A\approx 190$ Hf-Ta-W nuclei with the pioneering fragmentation of a ${}^{198}$Pt primary beam at the NSCL. The collective level structure deduced from the subsequent $\gamma$ decay of stopped isomeric fragments using the A1900 spectrometer and GRETINA array points to a sudden transition from axially prolate shapes in the lighter Ta isotopes to a strong triaxial shape for the ${}^{189}$Ta nucleus ($Z=73$, $N=116$; 8 neutrons more than stable ${}^{181}$Ta). The results suggest that the prolate-oblate shape boundary has been reached in this previously inaccessible region of neutron-rich nuclei. They are also an important experimental benchmark for nuclear theory to describe nuclear structure and shape evolution far from stability.

[Phys. Rev. C 111, L031301] Published Tue Mar 18, 2025

The probabilities of an excited atomic nucleus to emit particles and $\gamma$ rays provide important information on the nuclear level density as well as the $\gamma$-ray strength function. These statistical quantities are important to model nuclear reactions including the complex nucleosynthesis networks that have formed the elements that exist today. But these emission probabilities are hard to come by in the laboratory. The authors demonstrate how they have achieved this challenging task with a new experimental approach, by exciting the stable, doubly magic nucleus ${}^{208}$Pb in inelastic proton scattering on a hydrogen gas-jet target inside the Experimental Storage Ring (ESR) at the GSI facility, and by detecting the lead (Pb) beamlike ions instead of the emitted $\gamma$ rays or neutrons. Such measurements in inverse kinematics in a storage ring are free from complications by, e.g., competing reactions or energy loss in a fixed target. Here, the ${}^{208}$Pb beam passes the low-density hydrogen target a million times per second, restoring the luminosity in the regime of the thin target that preserves pristine excitation-energy resolution and particle identification capability, and enables outstanding detection efficiencies. The present results along with improvements under development promise future results for many short-lived nuclei of interest in astrophysics and nuclear science applications.

[Phys. Rev. C 111, 024614] Published Tue Feb 18, 2025

Because processes involving charged leptons are expected to conserve flavor, any evidence of muon-to-electron conversion is recognized as an important signal to constrain physics beyond the Standard Model. Whereas most experiments so far have assumed elastic transitions for muon-to-electron conversion, this paper shows how inelastic transitions which leave the nucleus in an excited state would allow for more probes of new physics. Such transitions can modify the near-endpoint spectrum of conversion electrons, to which the underlying flavor-symmetry violating operator is sensitive. The authors find that ${}^{27}$Al, the target of ongoing muon-to-electron conversion experiments, is an excellent isotope choice to observe inelastic transitions.

[Phys. Rev. C 111, 025501] Published Fri Feb 07, 2025

Many spherical nuclei exhibit a collective, low-lying octupole excitation. This paper analyzes such a state in the doubly magic nucleus ${}^{208}$Pb and traces the properties back to coherent scattering of high-angular momentum proton-neutron pairs that are fully aligned. A large fragmentation of the particle-hole wave function, together with its coherence, which is shown to be a generic property of the lowest-energy eigenstate, lead to a constructive accumulation of interaction strength. This insight into the shell-model underpinnings of such otherwise well-characterized collective nuclear states may help explain the ubiquity of their appearance.

[Phys. Rev. C 111, L021301] Published Wed Feb 05, 2025

$\beta$ decays provide important tests of the Standard Model, but the precision is limited by model dependencies and small but crucial corrections such as isospin breaking. By comparing theoretical and experimental ratios of mirror decays, the authors find cancellation of many of the model dependencies, allowing constraints on the remaining corrections and ultimately on possible new physics.

[Phys. Rev. C 111, 015501] Published Mon Jan 13, 2025

${}^{100}$Sn is often regarded as the holy grail of nuclear structure studies as it is the heaviest proton-bound nucleus with equal numbers of protons and neutrons; and with $N=Z=50$ it is also expected to be doubly magic. Aside from the proximity to the proton dripline, the region of the nuclear chart near ${}^{100}$Sn also harbors nuclei at the end of the $rp$ process which powers x-ray bursts on the surface of accreting neutron stars. The nuclear mass is a telltale observable for nuclear structure studies and nuclear astrophysics. Just three neutrons heavier than ${}^{100}$Sn, ${}^{103}$Sn had been identified as an outlier with a seriously irregular mass deduced from its $\beta$-decay $Q$ value and the decay-daughter mass. An international research team performed high-precision Penning-trap mass measurements of ${}^{103}$Sn at the Facility for Rare Isotope Beams (FRIB). Their measured mass value is more than an order of magnitude more precise than that of a previous storage ring measurement. The team’s reported result reestablishes the smoothness of the nuclear mass surface and provides reevaluated values for the masses of several other important isotopes connected to ${}^{103}$Sn via decays.

[Phys. Rev. C 111, 014314] Published Thu Jan 09, 2025

Expected to be doubly magic, ${}^{100}$Sn is the heaviest proton-bound, self-conjugate ($N=Z$) nucleus. Its mass and those of nearby nuclei are key to understanding nuclear structure and reactions near the proton dripline, including neutron-star-surface nucleosynthesis. The mass of ${}^{103}$Sn, previously an outlier due to a discrepant $\beta$-decay measurement, was precisely determined by an international team at CERN ISOLDE using multireflection time-of-flight mass spectrometry, their results agreeing well with those from another, complementary technique at FRIB. This new value enables re-evaluating the masses of five parent nuclei connected via decays. Comparing their results with theory calculations, the authors recovered a smooth trend of the local nuclear mass surface for tin, tellurium, and xenon isotopes, with possible impact on nuclear structure and astrophysics. Insights into ISOL target and source performances also suggest a path toward improved production of lighter tin isotopes for future studies.

[Phys. Rev. C 111, 014315] Published Thu Jan 09, 2025

The equation of state (EOS) of isospin-asymmetric nuclear matter plays a crucial role in many different realms of modern physics, from nuclear structure and heavy-ion reaction dynamics to the modeling of compact stellar objects. The author presents an in-depth comparison of calculations based on an improved transport model with heavy-ion collision data at intermediate energies. Accurate constraints on several features of the nuclear effective interaction, namely nucleon effective masses, in-medium elastic nucleon-nucleon cross-sections, and EOS can be extracted. This study paves the way toward comprehensive analyses that combine constraints derived from various EOS-sensitive physical phenomena.

[Phys. Rev. C 110, 064911] Published Mon Dec 23, 2024

Color deconfinement and chiral-symmetry restoration have long been predicted by QCD theory. Color deconfinement in the form of a nearly perfect fluid of quarks was reported by all four RHIC experiments in 2005. Now, the PHENIX Collaboration details two-pion Lévy-stable Bose-Einstein correlation data in Au+Au collisions at the top RHIC energy. They report a significant reduction of the mass of the $\eta \prime$ meson in hot and dense hadronic, color-confining matter. This implies a second transition in QCD by the return of the so-called prodigal Goldstone boson—a specific kind of partial chiral-symmetry restoration—and calls for further, challenging experimental studies, aiming at direct measurements of identified $\eta \prime$ spectra in high-energy heavy-ion collisions.

[Phys. Rev. C 110, 064909] Published Fri Dec 20, 2024

A realistic description of the equation of state of nuclear matter is of paramount importance for understanding neutron-star structure and astrophysical phenomena. The authors perform benchmark $ab$ $initio$ calculations for nuclear matter with several modern chiral interactions using three diagrammatic methods: coupled-cluster theory, self-consistent Green’s functions, and many-body perturbation theory. They obtain robust predictions for the equation of state of both pure neutron matter and symmetric nuclear matter, especially for soft chiral potentials. The very good agreement between different techniques, in particular between the nonperturbative coupled-cluster and Green’s functions methods, suggests that these many-body approaches can reach high accuracy, and uncertainties on the equation of state are mostly related to the nuclear interaction.

[Phys. Rev. C 110, 054322] Published Fri Nov 22, 2024

This paper presents a new detailed study of magnetic moments and form factors of nuclei with mass number $A$ up to 10, based on $ab$-$initio$ approaches and chiral effective field theory. The results of quantum Monte Carlo calculations for elastic magnetic form factors show excellent agreement with experimental data out to momentum transfers $q\approx 3$ fm${}^{-1}$. Benchmarking such electroweak current models against available data over a wide range of kinematics allows for accurate predictions, which are very important to disentangle signals of new physics from nuclear physics effects.

[Phys. Rev. C 110, 054316] Published Mon Nov 18, 2024

This manuscript introduces a fresh theory perspective on nuclear fission. The typical approach to fission uses collective coordinates with, e.g., the potential energy derived from semiclassical microscopic-macroscopic models or from density functional theories. The novel approach is based on the configuration-interaction framework, which has been successful for calculating energies and spectroscopic properties, along with the generator-coordinate method introduced by Hill and Wheeler. Here the total wavefunction is represented by a superposition of Slater determinants characterized by the collective coordinate along the fission path. As an important new step, configurations with finite momenta are taken into account. With Kohn’s reaction theory to treat barrier penetration assuming a Gaussian-shaped barrier, the authors show that including the finite momentum configurations leads to a more stable and more accurate solution. This method, while applied to fission here, could be useful for other systems involving interacting fermions.

[Phys. Rev. C 110, 054610] Published Mon Nov 18, 2024

The authors propose a new approach for the calculation of nuclear-dependent corrections to superallowed $\beta$ decays based on effective field theory (EFT). The calculation is timely given the observation in recent years of a 2–3 $\sigma$ anomaly in the test of the first row of the Cabibbo-Kobayashi-Maskawa matrix. Within a comprehensive assessment, the authors methodically develop a master formula for superallowed $\beta$ decays, paving the way for $ab$-$initio$ nuclear many-body computations of nuclear-structure-dependent corrections. The results show promise for state-of-the-art extractions of $V_{ud}$ from nuclear processes with controlled uncertainty quantification, and for using precision $\beta$-decay experiments to search for physics beyond the standard model.

[Phys. Rev. C 110, 055502] Published Mon Nov 18, 2024

Vortices such as smoke rings in air are familiar features in hydrodynamics. They appear when fast-moving local currents are embedded in the larger medium. This paper reports on results of realistic simulations of relativistic heavy-ion collisions using relativistic fluid dynamics. The work highlights the formation of a novel toroidal vortex ring structure which could manifest itself in the polarization of the $\mathrm{\Lambda }$ hyperon. This proposed new observable is argued to have great potential as a probe of hydrodynamic behavior in small collision systems, and of early-time dynamics in general. The predictions made in this work can be tested by experiments performed at current heavy-ion colliders such as RHIC at BNL and the LHC at CERN, as well as by future fixed-target experiments to be carried out at the LHC.

[Phys. Rev. C 110, 054908] Published Fri Nov 15, 2024

Accurate computation of nuclear radii is surprisingly challenging. By decomposing the contributions into orbital occupations and radial wave functions, the authors tease out a sensitive dependence upon the details of the pairing force, providing an improved description of the radii of stable calcium isotopes. Measurements of the radii of neutron-deficient calcium isotopes would help further constrain these insights.

[Phys. Rev. C 110, 054315] Published Thu Nov 14, 2024

The $\gamma$-ray strength function is an important input into Hauser-Feshbach calculations of neutron capture in compound nuclear reactions. Experiments suggest an enhancement of the strength function at low energy, but this enhancement has not been reproduced in models of heavy nuclei as conventional shell-model methods become computationally intractable. Using shell-model Monte Carlo methods, the authors have successfully reproduced the low-energy enhancement (LEE) for magnetic dipole transitions in neodymium isotopes, while also illuminating the role of the scissors and spin-flip modes in these $M1$ transitions. If the LEE persists in heavy neutron-rich nuclei, thus significantly enhancing the radiative neutron-capture rates of nuclei near the neutron drip line, it would likely have profound effects on $r$-process nucleosynthesis.

[Phys. Rev. C 110, 054313] Published Wed Nov 13, 2024

The state-of-the-art in the modeling and analysis of relativistic heavy-ion collisions involves multistage approaches to simulate the evolving strongly interacting matter and uses Bayesian analysis to obtain statistically relevant physical quantities. This work features a (3+1)D model applied to collision energies lower than those considered so far to explore the full range of the RHIC beam energy scan. This enables an exploration of the behavior of QCD at large baryon chemical potentials. The results of such comprehensive and systematic phenomenological studies have promise to advance knowledge of QCD in extreme conditions.

[Phys. Rev. C 110, 054905] Published Wed Nov 13, 2024

When the conditions are right, the energy released in a downward electronic transition in an atom can excite its atomic nucleus, potentially creating a path to controlling excited nuclear quantum states. Among these processes, nuclear excitation by electron capture (NEEC) stands out as the only one that has not yet been unambiguously confirmed by experiment, despite theoretical proposals spanning nearly half a century. The authors propose using intense femtosecond laser pulses on clusters of ${}^{235}$U atoms, demonstrating that with suitable laser parameters, the 76.7-eV nuclear isomer in ${}^{235}$U is almost entirely (more than 99.9%) excited via NEEC. The long, 26-minute lifetime of the isomer allows for efficient detection and diminishes atomic processes disturbing the detection. An experimental confirmation would represent a robust and conclusive verification of this elusive phenomenon.

[Phys. Rev. C 110, L051601] Published Tue Nov 12, 2024

The treatment of particle correlations and the description of clusters in the nuclear medium are important aspects that need to be better understood in the theoretical description of nuclear matter and the simulation of heavy-ion collisions. The authors propose a novel treatment of clustering for transport calculations based on a mechanism that suppresses cluster formation due to the Pauli principle via a medium-dependent cutoff in the momentum distribution of the clusters. The impact of clusters on the dynamics of unstable nuclear matter is clearly seen, and a `distillation’ mechanism is observed that affects the distribution of clusters between the low- and high-density regions. Although the approach has room for improvements, it captures the essential physics, and promises to have an impact on the further development of the field.

[Phys. Rev. C 110, L031601] Published Mon Sep 16, 2024

The nature of dark matter is one of the outstanding problems in particle physics and cosmology. To assist in the search for dark matter (DM), the authors examine the most general interactions between weakly interacting massive particles (WIMPs), assumed to be spin-1/2 fermions, and isotopes of the lightest nuclei, hydrogen and helium, using chiral effective field theory for a wide range of masses and coupling constants. The authors conclude that the scalar nuclear response functions are much greater than the others and severely constrained by the existing limits provided by experiments. The present study could be extended to other possible types of DM interactions, lighter DM candidates or heavier nuclei, such as lithium, argon, and xenon, currently widely used in dark matter detectors.

[Phys. Rev. C 110, 034002] Published Fri Sep 06, 2024

The proton dripline demarcates the nuclear landscape on the neutron-deficient side. A measurement at the SIS/FRS facility at GSI in Darmstadt, Germany of the anatomy of the immediate breakup of fragile ${}^{21}$Al into ${}^{20}$Mg + proton has now established that ${}^{21}$Al is unbound against proton emission in its ground state. The result thus places ${}^{21}$Al as the first Al isotope beyond the proton dripline. Its precise, negative proton separation energy will be a benchmark for nuclear structure models that treat nuclei as open quantum systems.

[Phys. Rev. C 110, L031301] Published Tue Sep 03, 2024

Lattice QCD calculations at finite temperature and zero or small baryon chemical potential have shown that there is no phase transition separating quasi-free quarks and those confined in baryons. Quarkyonic matter is a hypothetical state where quarks and baryons can coexist in a single Fermi sphere; quarks occupy the low momenta levels, hadrons the high momenta ones. This paper puts forward the idea that normal nuclear matter may, in fact, be quarkyonic and that the existence of this exotic phase may already have been seen in current electron-nucleus scattering data.

[Phys. Rev. C 110, 025201] Published Mon Aug 05, 2024

Experiments at the Joint European Torus make the case for using gamma rays to determine the fusion reaction rate in a magnetically confined plasma.

[Phys. Rev. C 110, 014625] Published Tue Jul 30, 2024

$Ab$-$initio$ calculations of atomic nuclei have revolutionized nuclear structure physics. Yet challenges remain, not least the reliable calculation of nuclear radii. In a concurrent development, modern machine-learning algorithms have excelled in a variety of computational tasks such as pattern recognition and interpolation. The authors have applied artificial neural networks (ANNs) to the extrapolation of no-core shell model calculations to infinite model spaces, effectively circumventing their computational limitations. In particular, the results show that min-max normalization, a common technique in machine learning, leads to the best results for radii. These advances offer hope that the ANN architecture is capable of handling other observables such as electromagnetic moments and transition strengths.

[Phys. Rev. C 110, 014327] Published Thu Jul 25, 2024

Atomic nuclei near mass 80 with approximately equal numbers of protons and neutrons are known to be strongly deformed while different shapes coexist in the same nucleus. These phenomena have challenged nuclear models but are also an opportunity to test the advances in theoretical approaches. The authors perform $ab$-$initio$ coupled-cluster calculations for even-even nuclei near neutron-deficient ${}^{80}$Zr, including calculations of $B(E2)$ transitions, using chiral $NN$ and $NNN$ forces. The results adequately describe shape coexistence even if they cannot unambiguously determine ground-state shapes. The calculations are a significant step forward in mass number for $ab$-$initio$ computations of deformed nuclei.

[Phys. Rev. C 110, L011302] Published Wed Jul 24, 2024

Recent observations by the ATOMKI Collaboration of anomalies in electron-positron pair production following proton capture on light nuclides has led to the postulation of a new boson with mass around 17 MeV. Here a team of scientists from the United States, Canada, and France presents the most detailed microscopic calculations to date of the proton capture reactions, and is unable to find a conventional explanation for the anomalies. While these calculations do not confirm the existence of the so-called X17 boson, they provide strong motivation for continued and independent experiments to investigate the ATOMKI results. Further refinements of the calculations may provide theoretical constraints for future data.

[Phys. Rev. C 110, 015503] Published Wed Jul 10, 2024

Nucleosynthesis during the Big Bang (BBN) can produce the lightest elements, including lithium, but the observed abundance of lithium in old stellar populations is much less than that predicted from BBN. To solve this so-called “lithium puzzle”, it had been postulated that a previously unobserved resonance in ${}^7$Be could deplete lithium through resonant proton capture on ${}^6$Li and thus account for the deficit. The authors performed a detailed study using information from all possible reactions that could be influenced by such a state, utilizing the stringent constraint imposed by the unitarity of the scattering matrix. They conclude that the postulated $3/2^{+}$ state in ${}^7$Be is highly unlikely, but they also suggest that additional radiative capture data are required to solve lingering discrepancies.

[Phys. Rev. C 110, 015802] Published Tue Jul 09, 2024

Nuclear masses are among the most significant observables to elucidate nuclear structure and its evolution with proton and neutron number as well as nucleosynthesis in the cosmos. This is especially so in exotic nuclei where masses will be among the first observables measured for new nuclei. Yet, such measurements are extremely difficult due to the short lifetimes and low production yields at rare isotope beam facilities. The present work describes the Rare-RI Ring facility, an isochronous storage ring at RIKEN, and the first commissioning measurements to establish its capabilities. The full identification of each ion before injection into the storage ring and the measurement time of about 1 ms are excellently suited for measuring masses of the most exotic nuclei, promising a breakthrough in the precision mass spectrometry of extremely rare short-lived radionuclides.

[Phys. Rev. C 110, 014310] Published Wed Jul 03, 2024

The ${}^{22}$Ne + $\alpha$ reaction has significant impact at the end of the core helium burning phase in red giant stars. Radiative $\alpha$ capture, ($\alpha$,$\gamma$), heats the plasma while the ($\alpha$,$n$) reaction provides neutrons for the weak $s$ process; their interplay determines the efficiency of the latter as a neutron source. The authors measure the strength of the resonance at $E_{\alpha ,\text{lab}}=830$ keV in the ${}^{22}$Ne($\alpha$,$n$)${}^{25}$Mg reaction. This resonance dominates the reaction rate for both the ${}^{22}$Ne($\alpha$,$n$)${}^{25}$Mg reaction and the competing ${}^{22}$Ne($\alpha$,$\gamma$)${}^{26}$Mg radiative capture at temperatures larger than 0.25 GK. As a crucial step, the authors characterize the stilbene neutron detector, where relevant information on the neutron energy is retained, and evaluate the possible sources of neutron background in their measurement. The results significantly improve the characterization of the astrophysically impactful 830 keV resonance.

[Phys. Rev. C 110, 015801] Published Wed Jul 03, 2024

Understanding nuclear properties away from the stability line and near the limits of the nuclear landscape relies heavily on theoretical calculations, because many unstable nuclei are difficult to reach in experiments. The authors apply two machine learning (ML) models to assess their performance in predicting nuclear mass excesses using available experimental data and a physics-based feature space. The models successfully reproduce known physical relationships and demonstrate a robust capability for extrapolation far beyond the training and test regions, offering results comparable to the model calculations. Incorporating techniques that enhance the interpretability of the ML models highlights their potential as powerful nuclear physics tools.

[Phys. Rev. C 109, 064322] Published Tue Jun 25, 2024

The authors perform rigorous Bayesian inference on a variety of measurements in relativistic Pb-Pb collisions at the LHC using a comprehensive multistage model combining QCD-based initial states with viscous hydrodynamics and a hadronic afterburner. In particular, they extracted systematic constraints on the temperature dependence of shear and bulk viscosities of quark-gluon plasma that are significantly more precise due to improved physical models and statistical methods. For the range of plasma temperature probed in heavy-ion collisions, they find that the specific bulk viscosity demanded by the data is strongly non-zero and temperature-dependent, whereas the specific shear viscosity shows a much weaker temperature dependence that is indistinguishable from a constant value even with improved statistical analysis. Importantly, the authors showcase the application of transfer learning to efficiently explore a range of model uncertainties wider than had been considered previously. This work represents a substantial advancement in constraining the shear and bulk viscosities of strongly interacting matter.

[Phys. Rev. C 109, 065207] Published Thu Jun 20, 2024

A chiral effective field theory (EFT) description of the nuclear interaction contains a power counting to organize the order-by-order contributions of the strong-interaction dynamics to nuclear observables. The truncation of the EFT expansion at finite order induces errors in predicted nucleon-nucleon scattering observables. These errors are correlated across scattering energies and angles, which robust uncertainty quantification needs to account for. This work reports a Bayesian analysis for neutron-proton scattering in a so-called $\mathrm{\Delta }$-full version of chiral EFT. The authors employ Gaussian processes to learn about the correlation structure of the truncation errors and find that the effective number of neutron-proton scattering data is reduced by approximately a factor of 4 due to the correlation structure of the EFT truncation error (shown in the figure for differential cross sections). The results are important for analyzing the predictive capabilities in $ab$-$initio$ nuclear theory.

[Phys. Rev. C 109, 064003] Published Tue Jun 18, 2024

Properties of neutron stars such as their masses and radii arise from the characteristics of highly asymmetric nuclear matter (with many more neutrons than protons) which is not accessible in experiments. The authors consider a family of neutron-star equations of state characterized by a nontrivial behavior of nuclear matter at high densities, including a steep rise and then decline (i.e., a sharp peak) in the speed of sound with density, which is compatible with ultraheavy neutron stars up to 2.5 solar masses. The symmetry-energy expansion is then applied to obtain equations of state applicable to the almost symmetric nuclear matter created in heavy-ion collisions in the laboratory. The authors find that the description incorporating a sharp peak in the speed of sound profile aligns well with experimental data. The systematic approach opens promising perspectives for further investigations bridging the physics of neutron stars and heavy-ion collisions.

[Phys. Rev. C 109, 065803] Published Mon Jun 17, 2024

This work studies the structure and dynamics of the inner crust of neutron stars where nuclear matter is expected to form slabs or so-called pasta phases. The authors report a first fully self-consistent calculation of the structure of the Coulomb lattice of nuclei immersed in a sea of dripped neutrons, taking fully into account, and on the same footing, both the band structure and superfluid effects. They employ a real-time method to extract the collective masses of a slab and of protons, which in turn quantify the conduction-neutron number density and the neutron effective mass, known as the entrainment effect. The results agree with recent self-consistent band calculations without superfluidity and demonstrate that the neutron effective mass is substantially reduced up to about 42% in the slab phase; superfluidity slightly enhances this anti-entrainment effect. The current one-dimensional formalism can be extended to two and three dimensions once the computational challenges of parallelization have been successfully addressed. This gives hope that the controversial situation concerning the entrainment effects in the inner crust of neutron stars can be resolved.

[Phys. Rev. C 109, 065804] Published Mon Jun 17, 2024

A first-of-its-kind measurement reveals the energy spectrum of the neutrons produced during the fission of plutonium, a common nuclear fuel component.

[Phys. Rev. C 109, 064611] Published Thu Jun 13, 2024

Microscopic optical potentials based on realistic nucleon-nucleon interactions are important for describing the scattering phenomenology involving nuclei far away from the valley of nuclear stability. The authors construct a new optical potential by combining the relativistic Brueckner-Hartree-Fock theory with a microscopic description of the density profile of the target nucleus. The new model provides good reproduction of proton scattering data on five target nuclei, opening up interesting perspectives for applications to exotic nuclei, including setting up a reliable framework to investigate isospin effects in nuclear structure from a scattering perspective.

[Phys. Rev. C 109, 064603] Published Mon Jun 03, 2024