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Unexplored interactions between electrons and atomic nuclei shed light on dark matter

Dark matter particles could be mediators of the interaction between electrons and atomic nuclei, as shown by a study conducted by junior group leader, Dr. Konstantin Gaul, Dr. Lei Cong, and Professor Dr. Dmitry Budker, of Johannes Gutenberg University Mainz (JGU), Helmholtz Institute Mainz (HIM) and the PRISMA++ Cluster of Excellence. Their work, published last week in Physical Review Letters, presents new constraints on previously unexplored candidates for dark matter and, more generally, some hypothetical particles that are not included in the Standard Model of particle physics ℠.

Using results from precision measurements on barium monofluoride (BaF) molecules, the team constrained these interactions mediated by Z’ bosons for the first time. Z’ bosons are hypothetical mediators of the weak interaction and possible dark matter particles in several SM extensions. “These results address a significant blind spot in physics: a regime of forces between electrons and nuclei that had remained unexplored by both laboratory experiments and cosmological data,” explained Gaul.

Our universe is made up of about 4% of visible, or ordinary, matter. This includes planets, stars, and life on Earth. The remaining 96% of the universe is invisible and consists of dark matter and dark energy, with dark matter making up about 23%. Astrophysical observations confirm its presence throughout the cosmos, where it, for example, plays an important part in the structure of galaxies. However, we don’t know what particles make up dark matter. Many theories and ongoing experiments are looking for an answer to this open question.

Researchers find coherent ferrons—polarization waves with potential across quantum and telecom applications

In new research published in Nature Materials, a team of researchers led by Columbia University chemist Xiaoyang Zhu, in collaboration with fellow Columbians Xavier Roy, Milan Delor, Dmitri Basov, and James McIver, has observed coherent ferrons for the first time.

Ferrons are electronic quasiparticles, predicted since the 1960s, that carry polarization. The oscillating polarization wave that the team, led by Columbia postdocs Jeongheon Choe and Taketo Handa, observed represents a new type of information carrier that could prove much faster than conventional electronics.

In ferroelectric materials, the dipole moments of unit cells line up, becoming polarized. Collective excitation of these dipoles creates the ferron quasiparticle, which has an inherent dipole moment. This means one side of each tiny particle is slightly more negatively charged than the other. Ferrons are similar to another quasiparticle that’s been of interest to Zhu and colleagues in recent years: magnons.

Chip-scale photonic approach achieves ultralow-noise microwave and millimeter-wave signal generation

Researchers led by Dr. Changmin Ahn and Prof. Jungwon Kim at KAIST, in collaboration with Prof. Hansuek Lee, have demonstrated a chip-scale photonic approach for generating ultralow-noise and highly stable microwave and millimeter-wave signals based on optical frequency combs (microcombs), offering a potential pathway toward compact, high-performance frequency sources for next-generation technologies.

High-frequency signals in the tens to hundreds of gigahertz range are essential for emerging applications such as 6G communications, radar, and precision sensing. However, achieving both low noise and high stability at these frequencies remains a fundamental challenge for conventional electronic signal sources.

In the first study, published in Laser & Photonics Reviews, the researchers addressed the long-standing challenge of transferring the stability of an optical reference to a microcomb. Direct stabilization is difficult due to the lack of carrier-envelope offset detection in high-repetition-rate microcombs. To overcome this, they used a mode-locked laser as a transfer oscillator and synchronized it to the microcomb using electro-optic sampling.

Lab-grown diamond device could change how radiation doses are measured

A team led by researchers from Tokyo Metropolitan University, in collaboration with Tohoku University and Orbray Co., Ltd., using heteroepitaxial diamond materials developed by Orbray, have shown that lab-grown diamonds might realize a radiation dosimeter compatible with both medical diagnosis and radiation therapy.

The work is published in the journal Medical Physics.

They demonstrated that a diamond-based dosimeter could accurately measure doses in the same energy range as diagnostic X-rays, with far better sensitivity per volume than conventional detectors. Using the same device for dosimetry during both diagnosis and therapies could enable improved consistency.

Scientists Solve 100-Year-Old Schrödinger Mystery About Color Perception

New research into how humans perceive color differences is helping resolve questions tied to a theory first proposed nearly 100 years ago by physicist Erwin Schrödinger. A team led by Los Alamos National Laboratory scientist Roxana Bujack used geometry to mathematically describe how people experience hue, saturation and lightness. Their findings, presented at a visualization science conference, strengthen and formalize Schrödinger’s model by showing these color qualities are fundamental properties of the color system itself.

“What we conclude is that these color qualities don’t emerge from additional external constructs such as cultural or learned experiences but reflect the intrinsic properties of the color metric itself,” Bujack said. “This metric geometrically encodes the perceived color distance — that is, how different two colors appear to an observer.”

By formally defining these perceptual characteristics, the researchers believe they have supplied a crucial missing piece in Schrödinger’s long-standing vision of a complete model capable of defining hue, saturation, and lightness entirely through geometric relationships between colors.

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