Particle physics research

Defense research, charmed quark — the week in infographics

Who spends on defense research?

Russia’s invasion of Ukraine in February sparked European interest in pouring more money into defense research and development (R&D). Three countries represent the bulk of European defense R&D. France is currently spending the most (5.6 billion euros; $5.6 billion), followed by Germany, according to the European Defense Agency in Brussels. The United Kingdom, which is no longer part of the European Union, is the other major donor to the region. For decades, the three countries had cut spending as they increasingly relied on the NATO (North Atlantic Treaty Organization) umbrella for protection, as well as on partnerships with the United States and the improbability of war in Europe. European defense spending is still largely eclipsed by that of the United States.

Source: AAAS/EDA/ONS

The intrinsic charm of the proton

Physics textbooks describe the proton as a subatomic particle that contains three quarks, bound together by elementary particles called gluons. But quantum theory predicts that the proton can also contain quark-antiquark pairs, including some quarks – called charmed quarks – that are more massive than the proton itself. These are considered “intrinsic”, which means that they are part of the proton on long time scales and are not produced by interactions with an external particle. However, attempts to confirm intrinsic charm in experiments have so far failed. In an article by Naturethe NNPDF collaboration reports an analysis of the collision data that serves as proof – if not a discovery – of the proton’s intrinsic charm.

The collaboration used machine learning techniques to analyze experimental data sets and found an intrinsic charm present in the proton with a statistical significance of 2.5 times the standard deviation (σ). The baseline analysis excluded measurements made by the European Muon Collaboration (EMC) in the early 1980s – data generally considered too imprecise to be conclusive – and those announced in July 2021 by the LHCb collaboration at the Large Collider in hadrons from CERN, European Laboratory for Particle Physics near Geneva, Switzerland. Including these data in the analysis increased the statistical significance to 3σwhich is considered proof of an effect in particle physics.

Figure 1

Plate tectonics control ocean oxygen

This graph shows how the position of the continents may have influenced ocean circulation and oxygen levels. Authors of an article in Nature simulated the state of the global ocean at 28 time points spanning the last 540 million years – longer than any previous effort – given the continental configuration at each time point. The results show that surface oxygen concentrations depend mainly on temperature, with cold waters being more oxygenated than warm waters.

a, At the start of the Paleozoic era, 540 to 460 million years ago, ocean circulation was slow, resulting in very low levels of oxygen (anoxia) in the deep ocean. The bottom panel shows simulated data for deep ocean oxygen over the same period. Low oxygen regions also form when organic particles, sinking from biomass to the surface, are broken down by microorganisms. b, In contrast, the circulation in more recent periods could be vigorous, oxygenating the deep ocean. Higher rates of biomass production at the surface may have produced larger regions of low oxygen content during certain periods. This News & Views article explains more.

Figure 1