The LHCb collaboration has just presented at the Rencontres de
Moriond EW and in a
special CERN Seminar the first observation of CP violation in charm particle decays. Quarks can be split into two sectors: those with the same electrical charge as the up quark (up-type quarks, charge +2/3), and those with the same charge as the down quark (down-type quarks, charge -1/3). Differences in the properties of matter and antimatter, arising from the so-called phenomenon of CP violation, had been observed in the past using the decays of K and B mesons, i.e. of particles that contain strange or beauty quarks, which are both down-type quarks. By contrast, despite decades of experimental searches, CP violation in the decays of charmed particles, i.e. containing the charm quark, which is an up-type quark, escaped detection so far. The result announced today constitutes the first observation of CP violation in decays of a charmed particle.
