The bottom (or beauty) quark
The bottom (or beauty) quark is a third-generation quark with a charge of −⅓ times the electron charge. It has a large mass (around 4.2 GeV/c2 — more that four times the mass of a proton!). The bottom quark is notable because it is a product in almost all decays of the top quark and is a frequent decay product for the Higgs boson.
History of the discovery
The bottom quark was predicted in 1973 by physicists Makoto Kobayashi and Toshihide Maskawa as part of their explanation for CP violation. The name “bottom” was introduced in 1975 by Haim Harari. The bottom quark was discovered in 1977 by the Fermilab E288 experiment team led by Leon M. Lederman, when collisions produced bottomonia (mesons with a bottom quark and its antiquark). Kobayashi and Maskawa won the 2008 Nobel Prize in Physics for their explanation of CP violation. Upon its discovery, there were efforts to name the bottom quark “beauty”, but “bottom” became the predominant name.