Editing Charm quark (section)

=== Later and current research ===
In 2002, the SELEX Collaboration at [[Fermilab]] published the first observation of the doubly charmed baryon [[Ξcc++|{{subatomic particle|Double charmed xi+}} ("double charmed xi+")]].{{sfn|Mattson et al.|2002}} It is a three-quark particle containing two charm quarks. The team found doubly charmed baryons with an up quark are more massive and have a higher rate of production than those with a down quark.{{sfn|Yap|2002}}

In 2007, the [[BaBar experiment|BaBar]] and [[Belle experiment|Belle]] collaborations each reported evidence for the mixing of two neutral charmed mesons, [[D meson|{{subatomic particle|D0}} and {{subatomic particle|antiD0}}]].{{sfn|Aubert et al.|2007}}{{sfn|Starič et al.|2007}}{{sfn|Gersabeck|2014|p=2}} The evidence confirmed the mixing rate is small, as is predicted by the [[standard model]].{{sfn|Aubert et al.|2007|p=4}} Neither studies found evidence for [[CP violation]] between the decays of the two charmed particles.{{sfn|Aubert et al.|2007}}{{sfn|Starič et al.|2007}}

In 2022, the [[NNPDF]] Collaboration found evidence for the existence of intrinsic charm quarks in the proton.{{sfn|The NNPDF Collaboration|2022}}{{sfn|Thompson|Howe|2022}} In the same year, physicists also conducted a direct search for [[Higgs boson]] decays into charm quarks using the [[ATLAS detector]] of the [[Large Hadron Collider]].{{sfn|Aad et al.|2022}} They have determined that the Higgs–charm coupling is weaker than the Higgs–bottom coupling.{{sfn|ATLAS experiment|2022}} On 7 July 2022, the [[LHCb experiment]] announced they had found evidence of direct CP violation in the decay of the D<sup>0</sup> meson into [[pion]]s.{{sfn|LHCb experiment|2022|loc = "This is the first evidence of direct CP violation in an individual charm–hadron decay (D<sup>0</sup> → π<sup>–</sup> π<sup>+</sup>), with a significance of 3.8''σ''"}}