High Energy Physics and Computational Science

  A new theoretical analysis connects the results of high-energy particle experiments at the Large Hadron Collider with three-proton correlations inside nuclei. How triplets of protons and neutrons behave is an important ingredient in theories of dense nuclear matter. Directly observing that behavior is beyond the reach of terrestrial labs. However, Alejandro Kievsky of Italy’s National Institute of Nuclear Physics and his collaborators have now demonstrated that it can be inferred from particle collisions recorded by the ALICE experiment at CERN’s Large Hadron Collider in Switzerland [ 1 ]. Last year, the ALICE experiment reported the results of smashing together beams of protons at an energy of 13 TeV. The kaons, protons, and deuterons that reached ALICE’s detectors carried with them correlations that arose when the particles sprang to life from a volume a few femtometers across. To determine what happens in that tiny volume, Kievsky and his collaborators analyzed the case of t...

  Using observations made with an array of thousands of particle detectors, researchers have uncovered an important clue about cosmic rays that originate from outside of our Galaxy. The cosmic rays pummeling Earth’s atmosphere are atoms stripped of their electrons and accelerated to high energies. Where and how cosmic rays are accelerated remains uncertain. However, their energy spectrum is clear. The spectrum follows a descending power law that extends from 10 9  eV all the way to 10 20  eV. One of its most important features is a kink or “knee” at around 4 × 10 15  eV (4 PeV), where the slope steepens. Now researchers from the Large High Altitude Air Shower Observatory (LHAASO) in southwest China have produced the most precise characterization of the knee so far [ 1 ]. The LHAASO findings shed new light on the knee’s origin, which has perplexed astronomers and physicists for nearly 70 years. The LHAASO observations were made using the Square Kilometer Array (KM2A)...