EPJ H Highlight - The Quark Model: A Personal Perspective

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Published on 15 November 2023

The properties of hadrons - both protons and neutrons, and heavier short-lived particles - are explained by the quark model. This was introduced by André Petermann (whose 1963 paper, in French, went unnoticed for 50 years); Murray Gell-Mann (whose insistence that they are purely mathematical entities discouraged take-up of the idea); and George Zweig.

The idea that protons and neutrons were composed of even smaller particles, with non-integral electric charges, was proposed in 1963/64 by Andre Petermann, George Zweig and Murray Gell-Mann, who dubbed them ‘quarks’. It was not until the mid-1970s, however, that the quark model became widely accepted. Chris Llewellyn Smith, now an emeritus professor at the University of Oxford and formerly the Director-General of CERN who put together the proposal to build the Large Hadron Collider, has published a ‘personal perspective’ on the development of the quark model and of the theory of the force that holds them together (quantum chromodynamics or QCD) in EPJ H: Historical Perspectives on Contemporary Physics. He had a ringside seat as a student in theoretical particle physics at Oxford from 1964-7, as a post-doctoral Fellow at CERN and at the Stanford Linear Accelerator Center where experiments that confirmed the reality of quarks were performed.

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EPJ E Topical review - Lift at low Reynolds number

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Published on 14 November 2023

In hydrodynamics, a lift phenomenon arises when a force acts on an object perpendicularly to its initial motion. In everyday life, we are familiar with this effect allowing for instance planes to take off or soccer balls to follow bent trajectories. For such big and fast objects, inertia combines with symmetry breaking (wing shape profile or ball rotation) to give rise to lift. However, lift forces are also at play at low Reynolds numbers, i.e. for small objects or slow flows where fluid viscosity dominates over inertia.

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EPJ D Topical Issue: Physics of Ionized Gases and Spectroscopy of Isolated Complex Systems: Fundamentals and Applications

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Published on 06 November 2023

Guest Editors: Bratislav Obradović, Jovan Cvetić, Dragana Ilić, Vladimir Srećković and Sylwia Ptasinska

This EPJ D Topical Issue presents selected papers covering a wide range of topics from fundamental studies to applications of ionized gases: Atomic Collision Processes - Electron and Photon Interactions with Atomic Particles, Heavy Particle Collisions, Swarms and Transport Phenomena; Particle and Laser Beam Interactions with Solids - Atomic Collisions in Solids, Sputtering and Deposition, Laser and Plasma Interaction with Surfaces; Low Temperature Plasmas - Plasma Spectroscopy and other Diagnostic Methods, Gas Discharges, Plasma Applications and Devices; General Plasmas - Fusion Plasmas, Astrophysical Plasmas and Collective Phenomena.

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