3D Phase Space Measurements in Plasmas

We present a detailed dynamical analysis of the Quaoar–Weywot system based on nearly 20 yr of high-precision astrometric data, including new Hubble Space Telescope observations and stellar occultations. Our study reveals that Weywot’s orbit deviates significantly from a purely Keplerian model, requiring the inclusion of Quaoar’s nonspherical gravitational field and center-of-body–center-of-light (COB-COL) offsets in our orbit models. We place a robust upper limit on Weywot’s orbital eccentricity (e < 0.02), substantially lower than previous estimates, which has important implications for the strength of mean-motion resonances acting on Quaoar’s ring system. Under the assumption that Quaoar’s rings lie in its equatorial plane, we detect Quaoar’s dynamical oblateness, J₂, at ∼2σ confidence. The low J₂ value found under that assumption implies that Quaoar is differentiated, with a total bulk density of 1751 ± 13 (stat.) kg m⁻³. Additionally, we detect significant COB-COL offsets likely arising from latitudinal albedo variations across Quaoar’s surface. These offsets are necessary to achieve a statistically robust orbit fit and highlight the importance of accounting for surface heterogeneity when modeling the orbits of dwarf planet moons. These findings improve our understanding of Quaoar’s interior and surface while providing key insights into the stability and confinement mechanisms of its rings.

Recent advances in Bragg coherent diffraction imaging (BCDI) experimental techniques permit routine measurement of multiple Bragg peaks from a single crystalline grain. The resulting images contain the full lattice distortion vector field which can be differentiated to provide lattice strain and rotation. With the advent of fourth-generation synchrotron light sources, such multi-peak datasets are produced at high rates, facilitating the need for rapid phase retrieval of the multiple peaks and subsequent image analysis. Here we describe and demonstrate a new implementation of a coupled phase retrieval technique for multi-peak BCDI which simultaneously treats each Bragg peak of the dataset and produces a three-dimensional image of the crystal's morphology and lattice distortion field. In addition, this method uses the redundant information contained in the various Bragg diffraction patterns to detect and suppress spurious signal appearing on the detector in a subset of the measurements. Compared with manual data editing, adaptive coupling produces a more consistent phase profile in reciprocal space and sharper surfaces in direct space, with no significant difference in computational cost. These improvements reduce the need for manual preprocessing and enable robust high-throughput analysis of multi-peak BCDI data, supporting near-real-time strain microscopy at modern synchrotron facilities.

Metallic delafossite oxides are of exceptional interest due to their ultraclean metallic transport. In the case of PdCrO₂, this arises in a triangular-lattice antiferromagnet, creating a unique opportunity to study frustrated magnetism in a very clean metal. Here, we combine a chemical vapor transport crystal growth approach with magnetic, thermodynamic, magnetotransport, and neutron scattering measurements to elucidate the striking anomalous Hall effect (AHE) in antiferromagnetic PdCrO₂. The unconventional AHE (with anomalous Hall conductivity ~10⁵ Ω⁻¹cm⁻¹) and a large positive magnetoresistance effect (>1,000%) are shown to exhibit complex temperature dependencies, persisting to almost seven times the Néel temperature (~250 K). These effects are directly compared to elastic neutron scattering, inelastic neutron scattering, and neutron magnetic pair distribution function data, establishing unambiguous links between anomalous magnetotransport properties and directly probed short-range spin fluctuations. The latter occur over a notably broad temperature range due to geometrical magnetic frustration. Connecting to recent experimental and theoretical developments, these findings are discussed in terms of a temperature-dependent interplay between chiral spin order and chiral spin fluctuations, significantly elucidating the high-temperature anomalous magnetotransport in such compounds.

Interfacing is a consistent weak point in the manufacturing of microscale gas chromatography columns. Current techniques for interfacing with microfluidic systems often degrade under high temperatures and thermal cycling and suffer from dead volumes. To address these challenges, we fabricated all-metal interfaces that connect 3D-printed microchannels (500 µm diameter) to industry-standard stainless-steel (SS) capillaries. Our fabrication process uses SS binder-jet printing and bronze infiltration to fuse the capillary to the printed part and reduce dead volumes at the interface while utilizing pressure control to prevent the infiltrant from filling the channel or capillary. These interfaces withstood pressures greater than 100 PSI and showed no leakage after thermal cycling to 350 °C. Cross-sections of the interfaces show smooth connections between the channel and capillary with minimal dead volume.

The hierarchy between the mass parameter of the Higgs boson and larger mass scales becomes ever more puzzling as experiments explore higher energies. Neutral naturalness is the umbrella term for symmetry-based explanations for these hierarchies whose quark symmetry partners are not charged under the SU(3)

 color gauge group of the Standard Model. Though the first manifestations of this idea predate the physics runs of the Large Hadron Collider, since the Higgs discovery this paradigm has grown and developed to include a wide variety of concrete realizations with connections to intriguing collider signals. Determining the phenomenology of such models often requires the characterization—typically relying on lattice calculations—of a new confining gauge symmetry. This presents additional motivation to further develop our understanding of nonperturbative field theory as well as to pursue specific lattice studies. The wide range of suggested hidden sectors also produces a variety of dark matter candidates, intersections with astrophysics and cosmology, and ties to neutrinos and flavor. In this review, we orient the reader within both this growing collection of specific models and the physical phenomena they produce. We also survey the often less familiar dynamics of hidden-sector glueballs and quirks. In addition to providing a guide to past efforts, we reveal interesting directions for further study.

Searching for life elsewhere in the universe is one of the most highly prioritized pursuits in astronomy today. However, the ability to observe evidence of Earth-like life through biosignatures is limited by the number of planets in the solar neighborhood with conditions similar to Earth. The occurrence rate of Earth-like planets in the habitable zones of Sun-like stars, η⊕, is therefore crucial for addressing the apparent lack of consensus on its value in the literature. Here we present a review of the current understanding of η⊕. We first provide definitions for parameters that contribute to η⊕. Then, we discuss the previous and current estimated parameter values and the context of the limitations on the analyses that produced these estimates. We compile an extensive list of the factors that go into any calculation of η⊕, and how detection techniques and surveys differ in their sensitivity and ability to accurately constrain η⊕. Understanding and refining the value of η⊕ is crucial for upcoming missions and telescopes, such as the planned Habitable Worlds Observatory and the Large Interferometer for Exoplanets, which aim to search for biosignatures on exoplanets in the solar neighborhood.