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Category: particle physics – Page 14

First physics results from the sPHENIX particle detector

The sPHENIX particle detector, the newest experiment at the Relativistic Heavy Ion Collider (RHIC) at the U.S. Department of Energy’s (DOE) Brookhaven National Laboratory, has released its first physics results: precision measurements of the number and energy density of thousands of particles streaming from collisions of near-light-speed gold ions.

As described in two papers recently accepted for publication in Physical Review C and the Journal of High Energy Physics, these measurements lay the foundation for the ’s detailed exploration of the quark–gluon plasma (QGP), a unique state of matter that existed just microseconds after the Big Bang some 14 billion years ago. Both studies are available on the arXiv preprint server.

The new measurements reveal that the more head-on the nuclear smashups are, the more charged particles they produce and the more total energy those firework-like sprays of particles carry. That matches nicely with results from other detectors that have tracked QGP-generating collisions at RHIC since 2000, confirming that the new detector is performing as promised.

A new way to wobble: Scientists uncover mechanism that causes formation of planets

Instead of a tempest in a teapot, imagine the cosmos in a canister. Scientists have performed experiments using nested, spinning cylinders to confirm that an uneven wobble in a ring of electrically conductive fluid like liquid metal or plasma causes particles on the inside of the ring to drift inward. Since revolving rings of plasma also occur around stars and black holes, these new findings imply that the wobbles can cause matter in those rings to fall toward the central mass and form planets.

The scientists found that the wobble could grow in a new, unexpected way. Researchers already knew that wobbles could grow from the interaction between plasma and magnetic fields in a gravitational field. But these new results show that wobbles can more easily arise in a region between two jets of fluid with different velocities, an area known as a free shear layer.

“This finding shows that the wobble might occur more often throughout the universe than we expected, potentially being responsible for the formation of more solar systems than once thought,” said Yin Wang, a staff research physicist at the U.S. Department of Energy’s (DOE) Princeton Plasma Physics Laboratory (PPPL) and lead author of the paper reporting the results in Physical Review Letters. “It’s an important insight into the formation of planets throughout the cosmos.”

How a triatomic molecule works off excess energy

A resonance effect can significantly affect how a three-atom molecule cools down when excited, RIKEN physicists have found. The study, published in Physical Review A, highlights the complexity of the relaxation dynamics of even simple molecules.

Small, energetic molecules in a vacuum—such as those in the upper atmosphere or —can either break apart or cool down by releasing their energy through emitting light.

“The energy-dissipation mechanism of molecules via is crucial to understanding the stability of hot, excited molecules,” says Toshiyuki Azuma of the RIKEN Atomic, Molecular & Optical Physics Laboratory. “It’s essential in in dilute environments such as Earth’s .”

Tunneling magnetoresistance in altermagnetic RuO₂-based magnetic tunnel junctions

A research team affiliated with UNIST announced the successful development of a novel semiconductor device that uses a new class of materials, known as altermagnetism. This breakthrough is expected to significantly advance the development of ultra-fast, energy-efficient AI semiconductor chips.

Jointly led by Professor Jung-Woo Yoo from the Department of Materials Science and Engineering and Professor Changhee Sohn from the Department of Physics at UNIST, the team succeeded in fabricating (MTJs) using altermagnetic ruthenium oxide (RuO2). They also measured a practical level of tunneling magnetoresistance (TMR) in these devices, demonstrating their potential for spintronic applications.

The research was led by Seunghyun Noh from the Department of Materials Science and Engineering and Kyuhyun Kim from the Department of Physics at UNIST. The findings were published in Physical Review Letters on June 20, 2025.

Breaking: Major Antimatter Discovery May Help Solve Mystery of Existence

We’re now a step closer to understanding how the Universe avoided an antimatter apocalypse. CERN scientists have discovered tantalizing clues of a fundamental difference in the way physics handles matter and antimatter.

Experiments at the Large Hadron Collider (LHC) have verified an asymmetry between matter and antimatter forms of a particle called a baryon.

Known as a charge-parity (CP) violation, the effect has only previously been detected in another class of particles, called mesons. But experimental evidence in baryons, which make up the bulk of the Universe’s matter, is something physicists have been long hunting for.

Scientists successfully develop half metal material that conducts single-spin electrons

Researchers at Forschungszentrum Jülich have successfully created the world’s first experimentally verified two-dimensional half metal—a material that conducts electricity using electrons of just one spin type: either “spin-up” or “spin-down.” Their findings, now published as an Editors’ Suggestion in Physical Review Letters, mark a milestone in the quest for materials enabling energy-efficient spintronic that go beyond conventional electronics.

Half metals are key to spintronics: Unlike traditional conductors, half metals allow only one spin orientation to pass through. This makes them ideal candidates for spintronics, a next-generation information technology that leverages both the charge and the spin of electrons for data storage and processing. In conventional electronics, on the other hand, only the charge is used.

However, all known half metals operate only at and lose their special properties at the surface—limiting their use. This was until now, when the team at Forschungszentrum Jülich engineered a 2D half metal in the form of an ultrathin alloy of iron and palladium, just two atoms thick, on a palladium crystal. Using a state-of-the-art imaging technique called spin-resolved momentum microscopy, they showed that the alloy allows only one spin type to conduct, confirming the long-sought 2D half-metallicity.

Where did all the antimatter go? This mismatch in how subatomic particles behave could hold a clue

The first-known observations of matter–antimatter asymmetry in a decaying composite subatomic particle that belongs to the baryon class are reported from the LHCb experiment located at the Large Hadron Collider at CERN. This effect, known as charge–parity (CP) violation, has been theoretically predicted, but hitherto escaped observation in baryons. The experimental verification of this asymmetry violation in baryons, published in Nature this week, is important as baryons make up most of the matter in the observable universe.

Cosmological models suggest that matter and antimatter were created in equal amounts at the Big Bang, but in the present-day universe matter seems to dominate antimatter. This imbalance is thought to be driven by differences in the behavior of matter and antimatter: a violation of symmetry known as CP violation.

This effect has been predicted by the Standard Model of physics and observed experimentally in subatomic particles called mesons more than 60 years ago, but never previously observed in baryons. As opposed to mesons, which are formed by two quarks, baryons are formed by three quarks—particles that make up most of matter such as neutrons and protons are baryons.

Researchers Solve Long-Standing Magnetic Problem With Atom-Thin Semiconductor

Scientists found a way to control magnetism in ultra-thin materials using CrPS₄, opening the door to more compact and energy-efficient technologies. A recent scientific breakthrough has unveiled a promising new technique for manipulating magnetism in ultra-thin materials, potentially paving the w

Scientists Discover a New “Magic Number” That Could Rewrite the Rules of Nuclear Physics

Physicists have discovered that silicon-22 reveals a new proton magic number offering critical insights into nuclear structure and the forces shaping the universe’s rarest atoms. In nuclear physics, “magic numbers” refer to certain quantities of protons or neutrons that make an atomic nucleus sig

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