Quarkonium formation in statistical and kinetic models

I review the present status of two related models addressing scenarios in which the formation of heavy quarkonium states in high energy heavy ion collisions proceed via “off-diagonal” combinations of a quark and an antiquark. The physical process involved belongs to a general class of quark “recombination”, although technically the recombining quarks here were never previously bound in a quarkonium state. Features of these processes relevant as a signature of color deconfinement are discussed.