Fragmentation of charmed quark to double-charmed hadrons

We consider the production of hadrons containing two charmed quarks in pp and ee collisions, and we perform a numerical comparison of the fragmentation approach with the full calculation at 𝒪(αs⁴). We conclude that the non-fragmentation contributions remain important up to transverse momenta as large as about 40 GeV, thus making questionable the applicability of the fragmentation approximation at smaller transverse momenta.