  Double open-charm production is one of the most promising channels to
disentangle single from double parton scattering (DPS) and study different
properties of DPS. Several studies of the DPS contributions have been made. A
missing ingredient so far has been the study of polarization effects, arising
from spin correlations between the two partons inside an unpolarized proton. We
investigate the impact polarization has on the double open-charm cross section.
We show that the longitudinally polarized gluons can give significant
contributions to the cross section, but for most of the considered kinematic
region only have a moderate effect on the shape. We compare our findings to the
LHCb data in the D0D0 final state, identify observables where polarization does
have an impact on the distribution of the final state particles, and suggest
measurements which could lead to first experimental indications of, or limits
on, polarization in DPS.
