Counting quarks ine+e−annihilation

Abstract

A comparison of asymptotically-free-quark-model predictions and $e^{+}{e}^{-}$ annihilation data can be made by using a dispersion relation to continue the data into the spacelike region. We make this comparison for several models, including when appropriate the effect of heavy-quark masses. We conclude that the "old" theory with no charm is excluded, the standard model with charm is acceptable if heavy leptons are produced, and sixquark models are viable if no heavy leptons are produced.