<IMG SRC="navi.gif" WIDTH=160 HEIGHT=440 usemap="#navi" BORDER=0> What is the World Made of?     The Naming of Quarks

The naming of quarks...

...began when, in 1964, Murray Gell-Mann and George Zweig suggested that hundreds of the particles known at the time could be explained as combinations of just three fundamental particles. Gell-Mann chose the name "quarks," pronounced "kworks," for these three particles, a nonsense word used by James Joyce in the novel Finnegan's Wake:

"Three quarks for Muster Mark!"

In order to make their calculations work, the quarks had to be assigned fractional electrical charges of 2/3 and -1/3. Such charges had never been observed before. Quarks are never observed by themselves, and so initially these quarks were regarded as mathematical fiction. Experiments have since convinced physicists that not only do quarks exist, but there are six of them, not three.

How did quarks get their silly names?

There are six flavors of quarks. "Flavors" just means different kinds. The two lightest are called up and down .

The third quark is called strange . It was named after the "strangely" long lifetime of the K particle, the first composite particle found to contain this quark.

The fourth quark type, the charm quark , was named on a whim. It was discovered in 1974 almost simultaneously at both the Stanford Linear Accelerator Center (SLAC) and at Brookhaven National Laboratory.

The fifth and sixth quarks were sometimes called truth and beauty in the past, but even physicists thought that was too cute.

The bottom quark was first discovered at Fermi National Lab (Fermilab) in 1977, in a composite particle called Upsilon ().
The top quark was discovered last, also at Fermilab, in 1995. It is the most massive quark. It had been predicted for a long time but had never been observed successfully until then.