At some point an unknown reaction called baryogenesis violated the conservation of baryon number, leading to a very small excess of quarks and leptons over antiquarks and anti-leptons — of the order of 1 part in 30 million. (sciencedaily.com)
With the missing baryon problem seemingly alleviated, the current model of galaxy formation is holding up well to the increased scrutiny possible with Gaia.» (sciencedaily.com)
Our understanding of the structure of matter was revolutionized in 1964 when American physicist, Murray Gell - Mann, proposed that a category of particles known as baryons, which includes protons and neutrons, are composed of three fractionally charged objects called quarks, and that another category, mesons, are formed of quark - antiquark pairs. (sciencedaily.com)