More quarks

In this chapter we have chosen just a few cameos from the history of particle physics to illustrate how physicists have learned to understand the structure of Nature's laws as applied to the world of fundamental particles. Cecil Powell's orchard initially provided a feast of new particles, each one with its own properties and characteristics. As these were studied, it became possible to reconstruct the patterns of symmetry and to follow chains of reasoning, leading to the prediction of as-yet-undiscovered species. The charmed quark was just one example.

From charm to beauty

The charmed quark was an important piece in the jigsaw puzzle of the world of the very small. Its place was in the section for hadrons, particles which respond to the strong nuclear force. The fit was perfect, but the jigsaw was not yet complete. There were two more vacant places. In 1977, Leon Lederman (1922-) and his team at Fermilab discovered a resonant state called Y, with a mass about three times larger than that of J/y. This state behaved in the same sort of anomalous way as J/y; its lifetime was much too long. The most likely explanation was that Y was a combination of a new quark, rather picturesquely called the 'beauty' (or b) quark, and its antiquark. Y has 'hidden beauty' in the same sort of way that J/y has 'hidden charm'.

The one remaining vacant place was not filled for some time. The particle designated to fill the space was given a name before it was seen. Eventually, in 1995, the existence of the t (or 'truth') quark was confirmed by two huge experimental groups working independently at Fermilab.

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