Relative yield of D mesons in hadronic collisions
Kartvelishvili V.G. , Likhoded A.K.
The smallness of the с-quark sea in ordinary hadrons leads to the need for considering two-gluon charm production. For the case of D mesons this corresponds to the production of small invariant masses of the DD pair and dominance of the first two partial waves of the cc quarks. The smallness of the interaction that leads to hyperfine D-D* splitting causes the D* to have a larger production cross section than D, i.e., &(D* D*)><r(DD).