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Category: particle physics – Page 73

Particle physicists have been looking for so-called “sterile neutrinos” for a few decades now. They are a hypothesized particle that would have a tiny mass like the three known neutrinos but would not interact by the weak force or any other Standard Model force, only through gravitational interactions.

Its existence—or their existence—would solve some anomalies seen in , help answer questions beyond the Standard Model of particle physics, and, if massive enough, could explain cold dark matter or warm dark matter.

But have not been seen in any particle experiments, despite many attempts. Now an experiment by the IceCube Collaboration has used 10.7 years of data from their detector near the Amundsen-Scott South Pole Station to lower the probability that at least one sterile neutrino does not exist. Their paper appears in Physical Review Letters.

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When water freezes slowly, the location where water turns into ice—known as the freezing front—forms a straight line. Researchers from the University of Twente showed how droplets that interact with such a freezing front cause surprising deformations of this front. These new insights were published in Physical Review Letters and show potential for applications in cryopreservation and food engineering techniques.

When water freezes, it is often thought of as a predictable, solid block forming layer by layer. But what happens if the progressing freezing front encounters or ? Researchers from the University of Twente have explored this question, discovering that droplets can cause surprising deformations in the way ice forms.

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Researchers have developed a new quantum theory that for the first time defines the precise shape of a photon, showing its interaction with atoms and its environment.

This breakthrough allows for the visualization of photons and could revolutionize nanophotonic technologies, enhancing secure communication, pathogen detection, and molecular control in chemical reactions.

A groundbreaking quantum theory has allowed researchers to define the exact shape of a single photon for the first time.

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String theory aims to explain all fundamental forces and particles in the universe—essentially, how the world operates on the smallest scales. Though it has not yet been experimentally verified, work in string theory has already led to significant advancements in mathematics and theoretical physics.

Dr. Ksenia Fedosova, a researcher at the Mathematics Münster Cluster of Excellence at the University of Münster has, along with two co-authors, added a new piece to this puzzle: They have proven a conjecture related to so-called 4-graviton scattering, which physicists have proposed for certain equations. The results have been published in the Proceedings of the National Academy of Sciences.

Gravitons are hypothetical particles responsible for gravity. “The 4-graviton scattering can be thought of as two gravitons moving freely through space until they interact in a ‘black box’ and then emerge as two gravitons,” explains Fedosova, providing the physical background for her work. “The goal is to determine the probability of what happens in this black box.”

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Researchers at UC Berkeley proposed that axions, hypothetical particles, could be detected shortly after a supernova’s gamma rays. They suggest that the Fermi Gamma-ray Space Telescope has a 1 in 10 chance of observing this phenomenon. Axions would be produced during the early moments of a star’s collapse and would then transform into high-energy gamma rays in the star’s magnetic field.

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ABSTRACT. We present a detailed study of the large-scale shock front in Stephan’s Quintet, a by-product of past and ongoing interactions. Using integral-field spectroscopy from the new William Herschel Telescope Enhanced Area Velocity Explorer (WEAVE), recent 144 MHz observations from the LOFAR Two-metre Sky Survey, and archival data from the Very Large Array and JWST, we obtain new measurements of key shock properties and determine its impact on the system. Harnessing the WEAVE large integral field unit’s field of view (90 |$\times$| 78 arcsec|$^{2}$|⁠), spectral resolution (⁠|$R\sim 2500$|⁠), and continuous wavelength coverage across the optical band, we perform robust emission-line modelling and dynamically locate the shock within the multiphase intergalactic medium with higher precision than previously possible. The shocking of the cold gas phase is hypersonic, and comparisons with shock models show that it can readily account for the observed emission-line ratios. In contrast, we demonstrate that the shock is relatively weak in the hot plasma visible in X-rays (with Mach number of |$\mathcal {M}\sim 2\!-\!4$|⁠), making it inefficient at producing the relativistic particles needed to explain the observed synchrotron emission. Instead, we propose that it has led to an adiabatic compression of the medium, which has increased the radio luminosity 10-fold. Comparison of the Balmer line-derived extinction map with the molecular gas and hot dust observed with JWST suggests that pre-existing dust may have survived the collision, allowing the condensation of H|$_2$| – a key channel for dissipating the shock energy.

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Strong interactions between subatomic particles like electrons occur when they are at a specific energy level known as the van Hove singularity. These interactions give rise to unusual properties in quantum materials, such as superconductivity at high temperatures, potentially ushering in exciting technologies of tomorrow.

Research suggests that allow electrons to flow only on their surface to be promising . However, the quantum properties of these materials remain relatively unexplored.

A study co-led by Nanyang Asst Prof Chang Guoqing of NTU’s School of Physical and Mathematical Sciences identified two types of van Hove singularities in the topological materials rhodium monosilicide (RhSi) and cobalt monosilicide (CoSi).

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Protons and neutrons–known collectively as nucleons–are both the building blocks of matter, but one of these particles has received a bit more attention in certain types of nuclear physics experiments.

Until now. New results published in Physical Review Letters describe a first-time glimpse of the internal structure of the neutron thanks to the development of a special, 10-years-in-the-making detector installed in Experimental Hall B at the U.S. Department of Energy’s Thomas Jefferson National Accelerator Facility.

“We detected the neutron for the first time in this type of reaction, and it’s quite an important result for the study of nucleons,” said Silvia Niccolai, a research director at the French National Centre for Scientific Research (CNRS).

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