Lifeboat Foundation

You can think of our atmosphere as a big chemistry set, a global churn of gaseous molecules and particles that constantly bounce off and change each other in complicated ways. While the particles are very small, often less than 1% of the thickness of human hair, they have outsized impacts. For example, particles are the seeds of cloud droplets, and the abundance of the particles changes the reflectivity and the amount of clouds, rainfall and climate.

However, a paper just published in Physical Review D by physicists from the University of Warsaw and the University of Oxford has shown that many of these prejudices were unfounded. Tachyons are not only not ruled out by the theory, but allow us to understand its causal structure better.

Motion at speeds beyond the speed of light is one of the most controversial issues in physics. Hypothetical particles that could move at superluminal speeds, called tachyons (from the Greek tachýs—fast, quick), are the “enfant terrible” of modern physics. Until recently, they were widely regarded as creations that do not fit into the special theory of relativity.

At least three reasons for the non-existence of tachyons within quantum theory were known so far. The first: the ground state of the tachyon field was supposed to be unstable, which would mean that such superluminal particles would form “avalanches.” The second: a change in the inertial observer was supposed to lead to a change in the number of particles observed in his reference system, yet the existence of, say, seven particles cannot depend on who is looking at them. The third reason: the energy of the superluminal particles could take on negative values.

We evaluate the top-bottom interference contribution to the fully inclusive Higgs production cross section at next-to-next-to-leading order in QCD. Although bottom-quark-mass effects are power suppressed, the accuracy of state-of-the-art theory predictions makes an exact determination of this effect indispensable. The total effect of the interference at 13 TeV is −1.99_-0.15^+0.30 pb, while the pure mathcalO(alpha_s^4)$ correction is 0.43 pb. With this result, we address one of the leading theory uncertainties of the cross section.

Exclusive: Tests show billions of people globally are drinking water contaminated by plastic particles, with 83% of samples found to be polluted.

Like the flutter of a butterfly’s wings, sometimes small and minute changes can lead to big and unexpected results and changes in our lives. Recently, a team of researchers at Pohang University of Science and Technology (POSTECH) made a very small change to develop a material called “spin-orbit torque (SOT),” which is a hot topic in next-generation DRAM memory.

This research team, led by Professor Daesu Lee and Yongjoo Jo, a PhD candidate, from the Department of Physics and Professor Si-Young Choi from the Department of Materials Science and Engineering at POSTECH, achieved highly efficient field-free (i.e. SOT magnetization switching that does not require the assistance of a magnetic field) SOT magnetization switching through atom-level control of composite oxides.

Their findings were recently published in Nano Letters (“Field-Free Spin–Orbit Torque Magnetization Switching in a Single-Phase Ferromagnetic and Spin Hall Oxide”).

Brazilian physicist César Lattes, considered a national hero for his discoveries, paved the way for trailblazing research projects in particle astrophysics across Latin America and beyond.

Gaussian ray tracing: fast tracing of particle scenes.

Nicolas Moenne-Loccoz, Ashkan Mirzaei, Or Perel, Riccardo de Lutio, Janick Martinez Esturo, Gavriel State, Sanja Fidler, Nicholas Sharp, Zan Gojcic NVDIA 2024 https://arxiv.org/abs/2407.07090 https://radiancefields.com/3d-gaussian-ray–…

Today, things are taking an exciting step forward with the introduction of 3D Gaussian Ray Tracing (3DGRT).

Electrons inherently carry both spin and orbital angular momentum (i.e., properties that help to understand the rotating motions and behavior of particles). While some physicists and engineers have been trying to leverage the spin angular momentum of electrons to develop new technologies known as spintronics, these particles’ orbital momentum has so far been rarely considered.

Currently, generating an orbital current (i.e., a flow of orbital angular momentum) remains far more challenging than generating a spin current. Nonetheless, approaches to successfully leverage the orbital angular momentum of electrons could open the possibility for the development of a new class of devices called orbitronics.

Researchers at Keio University and Johannes Gutenberg University report the successful generation of an orbital current from magnetization dynamics, a phenomenon called orbital pumping. Their paper, published in Nature Electronics, outlines a promising approach that could allow engineers to develop new technologies leveraging the orbital angular momentum of electrons.

In the decade since their discovery at Drexel University, the family of two-dimensional materials called MXenes has shown a great deal of promise for applications ranging from water desalination and energy storage to electromagnetic shielding and telecommunications, among others. While researchers have long speculated about the genesis of their versatility, a recent study led by Drexel and the University of California, Los Angeles, has provided the first clear look at the surface chemical structure foundational to MXenes’ capabilities.

Using advanced imaging techniques, known as scanning tunneling microscopy (STM) and scanning tunneling spectroscopy (STS), the team, which also includes researchers from California State University Northridge, and Lawrence Berkeley National Laboratory, mapped the electrochemical surface topography of the titanium carbide MXene — the most-studied and widely used member of the family.

Their findings, published in the 5th anniversary issue of the Cell Press journal Matter (“Atomic-scale investigations of Ti 3 C 2 Tx MXene surfaces”), will help to explain the range of properties exhibited by members of the MXene family and allow researchers to tailor new materials for specific applications.