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Category: particle physics – Page 5

Nuclear mass measurement reveals new proton magic number

In nuclear physics, “magic numbers” identify specific numbers of protons or neutrons that lead to especially stable nuclei. Recognizing these numbers helps scientists better understand the structure of nuclei.

The for stable, long-lived isotopes have long been known, but the magic numbers for exotic, short-lived isotopes are less well understood. By studying these rare cases, researchers can gain deeper insight into the nuclear “building code” under extreme conditions. This, in turn, improves our understanding of how elements formed in the universe and sheds light on the behavior of the nuclear force.

As part of this effort, researchers from the Institute of Modern Physics (IMP) of the Chinese Academy of Sciences have precisely measured for the first time the mass of an extremely short-lived and neutron-deficient nucleus, silicon-22, revealing that the number 14 in silicon-22 is a new magic number.

New particle acceleration strategy uses cold atoms to unlock cosmic mysteries

Scientists have used ultracold atoms to successfully demonstrate a novel method of particle acceleration that could unlock a new understanding of how cosmic rays behave, a new study reveals.

More than 70 years after its formulation, researchers have observed the Fermi acceleration mechanism in a laboratory by colliding against engineered movable potential barriers—delivering a significant milestone in high-energy astrophysics and beyond.

Fermi acceleration is the mechanism responsible for the generation of cosmic rays, as postulated by physicist Enrico Fermi in 1949. The process itself also features some universal properties that have spawned a wide range of mathematical models, such as the Fermi-Ulam model. Until now, however, it has been difficult to create a reliable Fermi accelerator on Earth.

Elusive romance of top-quark pairs observed at Large Hadron Collider

An unforeseen feature in proton-proton collisions previously observed by the CMS experiment at CERN’s Large Hadron Collider (LHC) has now been confirmed by its sister experiment ATLAS.

The result, reported yesterday at the European Physical Society’s High-Energy Physics conference in Marseille, suggests that —the heaviest and shortest-lived of all the elementary particles—can momentarily pair up with their antimatter counterparts to produce a “quasi-bound-state” called toponium. Further input based on complex theoretical calculations of the strong nuclear force—called (QCD)—will enable physicists to understand the true nature of this elusive dance.

High-energy collisions between protons at the LHC routinely produce top quark–antiquark pairs. Measuring the probability, or cross section, of this process is both an important test of the Standard Model of particle physics and a powerful way to search for the existence of new particles that are not described by the theory.

Pretrained jet foundation model successfully utilized for tau reconstruction

Simulating data in particle physics is expensive and not perfectly accurate. To get around this, researchers are now exploring the use of foundation models—large AI models trained in a general, task-agnostic way on large amounts of data.

Just like how language models can be pretrained on the full dataset of internet text before being fine-tuned for specific tasks, these models can learn from large datasets of particle jets, even without labels.

After the pretraining, they can be fine-tuned to solve specific problems using much less data than traditional approaches.

Elusive romance of top-quark pairs observed at the LHC

An unforeseen feature in proton-proton collisions previously observed by the CMS experiment at CERN’s Large Hadron Collider (LHC) has now been confirmed by its sister experiment ATLAS. The result, reported yesterday at the European Physical Society’s High-Energy Physics conference in Marseille, suggests that top quarks – the heaviest and shortest-lived of all the elementary particles – can momentarily pair up with their antimatter counterparts to produce a “quasi-bound-state” called toponium. Further input based on complex theoretical calculations of the strong nuclear force — called quantum chromodynamics (QCD) — will enable physicists to understand the true nature of this elusive dance.

High-energy collisions between protons at the LHC routinely produce top quark–antiquark pairs. Measuring the probability, or cross section, of this process is both an important test of the Standard Model of particle physics and a powerful way to search for the existence of new particles that are not described by the theory.

Last year, CMS researchers were analysing a large sample of top quark–antiquark production data collected from 2016 to 2018 to search for new types of Higgs bosons when they observed something unusual. The team saw a surplus of top quark–antiquark pairs, which is often considered as a smoking gun for the presence of new particles. Intriguingly, the excess appeared at the very minimum energy required to produce such a pair of top quarks. This led the team to consider an alternative hypothesis of something that had long been considered too difficult to detect at the LHC: a short-lived union of a top quark and a top antiquark.

An approach to realize heralded photon storage in a Rydberg superatom

Quantum technologies, systems that operate leveraging quantum mechanical effects, have the potential to outperform classical technologies in some specific tasks. Over the past decades, some researchers have also been trying to realize quantum networks, systems comprised of multiple connected quantum devices.

So far, have been the most widely used particles for carrying across different devices in quantum networks. The main reasons for this are that photons can travel at remarkable speeds, while weakly interacting with their surrounding environment, which helps to preserve the quantum states they are carrying.

To successfully employ photons in quantum networks, however, physicists and engineers need to be able to confirm that they are stored successfully without destroying them.

Hydrogen atom transfer method selectively transforms carboxylic acids using an inexpensive photocatalyst

Carboxylic acids are ubiquitous in bioactive organic molecules and readily available chemical building blocks. Carboxylic acids can be converted into carboxy radicals that can initiate versatile carbon–carbon and carbon–heteroatom bond formations, which are highly desirable for developing materials and pharmaceuticals. Currently, however, there are few applicable methods that use inexpensive catalysts.

To this end, researchers from WPI-ICReDD and University of Shizuoka have developed a facile hydrogen atom transfer (HAT) method that selectively transforms into carboxy radicals using xanthone, an inexpensive commercial organic ketone photocatalyst. This research was published in the Journal of the American Chemical Society.

HAT converts substrates into radical species by removing a hydrogen atom and ketones are highly accessible, inexpensive, and known for HAT photocatalysis. However, selective HAT for carboxylic acids is challenging because the O–H bond is stronger than adjacent C–H bonds. Nonetheless, using the artificial force–induced reaction (AFIR) method, a developed at ICReDD, the authors identified xanthone as a promising ketone photocatalyst for selective O–H bond HAT.

Detecting Ice Structures from Space

Depending on the temperature and pressure, ice adopts one of 20 different crystalline phases. Researchers can typically tell one ice phase from the other using x rays or neutron beams, but such techniques are impractical for studying ice on distant celestial bodies. Thomas Loerting from the University of Innsbruck in Austria and his colleagues have now shown that infrared spectroscopy can discriminate between two types of high-pressure ice [1]. The results suggest that astronomical observatories in the infrared could probe ice-covered planets or moons, revealing information about their geological evolution and potential habitability.

The ice in your freezer is hexagonal ice, but at lower temperatures, higher pressures, or both, other forms can exist. Ice phases are distinguished by the ordering of oxygen atoms and hydrogen atoms. For example, ice V has oxygens arranged in ring structures, while its hydrogens have random (disordered) positions. This phase, which is stable at pressures of 500 megapascals and temperatures of 253 K, is thought to form in the interior of Jupiter’s moon Ganymede, Saturn’s moon Enceladus, and other icy moons.

In the lab, Loerting’s colleague, Christina Tonauer, created ice V, along with a related, hydrogen-ordered version called ice XIII. The team performed near-infrared spectroscopy on both samples and identified several distinguishing features, including a structure-dependent “shoulder” around 1.6 µm, a wavelength associated with stretching modes. According to the team’s calculations, the features are strong enough that astronomical instruments, such as those on the JWST observatory and the Jupiter-visiting JUICE mission, could potentially observe them on a body like Ganymede. “The detection of high-pressure ice phases at or near the surface could point to internal processes such as tectonic activity, cryovolcanism, or convective transport from deeper layers,” Loerting says.

Stars That Shouldn’t Shine Are Pointing Straight to Dark Matter’s Identity

Deep in the center of our galaxy, scientists believe a strange type of star may be quietly glowing—not from fusion like our Sun, but from the invisible fuel of dark matter.

These “dark dwarfs” could act like cosmic detectors, collecting heavy, elusive particles that heat them from the inside. If we find them—and especially if we spot one missing its lithium—it could finally point us toward what dark matter really is.

Dark dwarfs & dark matter basics

“We Might Be Seeing a New Force”: Physicists Detect Possible Fifth Law of Nature Hidden Deep Inside Atomic Structures

IN A NUTSHELL 🔬 Physicists from Germany, Switzerland, and Australia have identified potential evidence of a mysterious fifth force within atoms. 📏 The discovery challenges the Standard Model of physics, which traditionally categorizes forces into four main types. 🧩 Researchers propose the existence of a hypothetical Yukawa particle that could mediate this new force within