Portal:Physics/Selected article/June 2011

This is a representation of a proton. It is composed of two up quarks and one down quark.

• A quark is an elementary particle and a fundamental constituent of matter. Quarks combine to form composite particles called hadrons, the most stable of which are protons and neutrons, the components of atomic nuclei. For this reason, much of what is known about quarks has been drawn from observations of the hadrons themselves. There are six types of quarks, known as flavors: up, down, charm, strange, top, and bottom.

• Murray Gell-Mann born September 15, 1929) is an American physicist and polymath who received the 1969 Nobel Prize in physics for his work on the theory of elementary particles. He is a Distinguished Fellow and co-founder of the Santa Fe Institute and the Presidential Professor of Physics and Medicine at the University of Southern California. He formulated the quark model of hadronic resonances, among other significant contributions.

• George Zweig (born on May 30, 1937 in Moscow, Russia) was originally trained as a particle physicist under Richard Feynman. Zweig proposed the existence of quarks while a graduate student in Physics at the California Institute of Technology in 1964 (independently of Murray Gell-Mann). Zweig dubbed them "aces" after the four playing cards, because he speculated there were four of them. Like Gell-Mann, he realized that several important properties of particles such as protons and neutrons could be explained by treating them as triplets of other constituent particles (which he called aces).