[2] The D mesons were discovered in 1976 by the Mark I detector at the Stanford Linear Accelerator Center.
Such transitions involve a change of the internal charm quantum number, and can take place only via the weak interaction.
In 2019, an analysis by the LHCb experiment reported the first observation of CP violation in the decays of the neutral D0 meson, with a significance of over five standard deviations.
[13] The results of a subsequent data analysis by the same collaboration was presented in 2022, which announced that they found evidence of direct CP violation in the decay of the D0 meson into pions.
[14] In 2021 it was confirmed with a significance of more than seven standard deviations, that the neutral D0 meson spontaneously transforms into its own antiparticle and back.