#quark model

                            How the quark flavors got their names

The quark flavors were given their names for various different reasons.

The up and down quarks are named after the up and down components of isospin, which they carry. Strange quarks were given their name because they were discovered to be components of the strange particles discovered in cosmic rays years before the quark model was proposed; these particles were deemed "strange" because they had unusually long lifetimes.  Sheldon Glashow, who coproposed charm quark with James Bjorken, is quoted as saying, "We called our construct the 'charmed quark', for we were fascinated and pleased by the symmetry it brought to the subnuclear world." The names "bottom" and "top", coined by Haim Harari, were chosen because they are "logical partners for up and down quarks". In the past, bottom and top quarks were sometimes referred to as "beauty" and "truth" respectively, but these names have somewhat fallen out of use. While "truth" never did catch on, accelerator complexes devoted to massive production of bottom quarks are sometimes called "beauty factories".

                                         Quark Flavors and Colors

Quarks are described as coming in six different flavors, but each quark has an anti-quark, so there are also six different anti-flavors. The six quark flavors are named up, down, strange, charm, bottom and top; the six anti-flavors, anti-up, anti-down, anti-strange, anti-charm, anti-bottom and anti-top.

Protons are viewed as being constructed of two up-quarks and one down-quark. Up-quarks have an electric charge of +2e/3 and down-quarks have an electric charge of -e/3. Adding these charges up, we get a net charge of +1e for a proton. Neutrons are viewed as being constructed of two down-quarks and one up-quark, in which the electric charges add up to 0 (zero).

Each of the six flavors of quarks can have three different colors: red, blue and yellow. There are, of course, also anti-colors: anti-red, anti-blue and anti-yellow. The quark forces (strong force) bind quarks together only in colorless combinations of three quarks (baryons), quark-antiquark pairs (mesons) and possibly larger combinations such as the pentaquark that could also meet the colorless requirement.