This Feynman diagram accompanied the announcement on the public LHCb site. How would you describe the origins of the up and down quark anti-quark pairs that that contribute to the decay of the ##\Xi_{cc}^{++}##?
Just testing my current knowledge- would the particle ##X## be a ##\Sigma^+## ? And would this be the corresponding Feynman diagram?
Also, rather than a gluon, could the mediation particle be a photon or ##Z^0##?
A meson can be produced by a high energy photon scattering off a nucleon in an interaction such as
$$\gamma + p \rightarrow p + \pi^0$$
As long as the photon is sufficiently energetic, mesons heavier than the pion can be produced, as well as multiple mesons such as ##\pi^{+} + \pi^{-}##...