Abstract:
The asymmetries between charm and anticharm mesons observed
in fixed-target photoproduction experiments are an order of
magnitude larger than the asymmetries predicted by
conventional perturbative QCD. We show that these charm
meson asymmetries can be explained by a heavy-quark
recombination mechanism for heavy meson production. In this
process, a charm quark combines with a light antiquark from
the hard-scattering process and they subsequently hadronize
into a state including the charm meson. This recombination
mechanism can be calculated within perturbative QCD up to
some nonperturbative constants. After using symmetries of
QCD to reduce the number of free parameters to two, we
obtain a good fit to all the data on the asymmetries for
charmed mesons from the E687 and E691 experiments.