D meson

A D meson is a charmed meson, which is to say, any meson containing one charmed quark. There are three types of D meson: D+ (consisting of a charmed quark plus a down antiquark), D0 (a charmed quark plus an up antiquark), and D+s (a charmed quark plus a strange antiquark). D mesons were first observed at the Stanford Linear Accelerator Center in 1976 by G. Goldhaber and collaborators.