The production rate of prompt ψ′'s at large transverse momentum at the Fermilab Tevatron is larger than theoretical expectations by about a factor of 30. As a solution to this puzzle, we suggest that the dominant ψ′ production mechanism is the fragmentation of a gluon into a cc̄ pair in a pointlike color-octet S-wave state, which subsequently evolves nonperturbatively into a ψ′ plus light hadrons. This contribution to the fragmentation function is enhanced by a short-distance factor of 1/αs2, which may compensate for its suppression by v4, where v is the relative momentum of the charm quark in the ψ′.
ASJC Scopus subject areas
- Physics and Astronomy(all)