APS Editor in Chief, Randall D. Kamien, discusses the importance and impact of journal reviewers.

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.

Understanding the interplay between the intrinsic shape of nuclei and the dynamics of their low-lying collective states is one of the most pressing challenges in contemporary nuclear structure physics. Within the framework of the generator coordinate method with a Gogny interaction, this paper highlights the important role of hexadecapole deformation in several isotopes of the rare earth region. These features could also have an impact on the evaluation of neutrinoless double-$\beta$ decay nuclear matrix elements and on heavy ion collision dynamics. The study highlights that the physics touched by considering the hexadecapole degree of freedom is not trivial, and its study is worth further consideration.

Adapting a technique recently developed in atomic electron systems to nuclear physics, the authors employ a deep-learning method to analyze a Skyrme energy density functional (Skyrme-EDF) with the goal to construct an orbital-free functional that depends only on the particle density distribution. In a first step they compute the energy and particle densities of a nucleus using the Skyrme Kohn-Sham + Bardeen-Cooper-Schrieffer method. With those sets of data and a deep-learning approach they then train an orbital-free functional. When applied to the ${}^{24}$Mg nucleus, the newly constructed functional successfully reproduces the binding energy of the original Skyrme-EDF, with an accuracy of about 40 keV. The significant computational advantage compared to traditional EDF approaches promises useful alternatives for future applications such as for calculating more complex nuclear shapes in heavy and superheavy nuclei.

View an interview with PRX Life Lead Editor Margaret Gardel and Managing Editor Serena Bradde from the 2023 APS March Meeting for more information on the journal.

New results from the GlueX experiment provide improved cross sections for the photoproduction from the proton of $J/\psi$ mesons via the $\gamma +p\to J/\psi +p$ reaction. Such mesons have charm/anti-charm heavy-quark content. Measurements of this reaction near the kinematic threshold can help constrain aspects of the density distribution of gluons in the proton and how they contribute to the proton mass, under the assumption that $J/\psi$ production proceeds primarily through the exchange of gluons with the proton. However, these new measurements suggest contributions in addition to gluon exchange, pointing to the need for further theoretical work and more precise experimental measurements.

Researchers revisit a neglected decay mode with implications for fundamental physics and for dating some of the oldest rocks on Earth and in the Solar System.

Viewpoint on:
M. Stukel et al. (KDK Collaboration)
Phys. Rev. Lett. 131, 052503 (2023)

L. Hariasz et al. (KDK Collaboration)
Phys. Rev. C 108, 014327 (2023)

Potassium-40 (${}^{40}$K) is a long-lived, naturally occurring radioisotope whose decay properties impact geochronology as well as rare-event searches. The KDK Collaboration reports first experimental evidence for the existence of the very rare electron-capture branch from ${}^{40}$K to the ground state of ${}^{40}$Ar, suppressed by two orders of magnitude as compared to the decay to the excited state of ${}^{40}$Ar. This measurement quantifies a previously ill-known background in rare-event searches, resolves a longstanding uncertainty in potassium-based geological age estimates, and benchmarks the theoretical modeling of highly forbidden weak decays including a neutrinoless double-$\beta$ decay.

To mark the 241st American Astronomical Society meeting, Physical Review Letters, Physical Review C, and Physical Review D highlighted several significant papers in astrophysics to illustrate the type of research these journals seek to publish.

APS has appointed Professor Joseph Kapusta, School of Physics and Astronomy, University of Minnesota as the Lead Editor of Physical Review C. Professor Kapusta takes the helm following the journal’s previous Lead Editor Benjamin F. Gibson.

A look back at Physical Review C’s first half century, and a salute to the talented authors and diligent referees who have made the journal a success.

Researchers look back at key contributions to the field of nuclear physics.

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