2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/190542$J/ψ$ production cross section considering the contributions of both color-singlet and color-octet $c\bar c$ channels is calculated. The result is used to study the suppression of $J/ψ$ in nuclear collisions. With absorption cross sections for $(c \bar c)_8$ $σ_{abs}^8\simeq 11mb $ and $(c \bar c)_1$ $σ_{abs}^1\simeq 0mb $ the p-A and A-B data except for Pb-Pb can be explained. Possible explanations of additional suppression in Pb-Pb are discussed.12 pages, 2 figures, RevtexHigh Energy Physics - Phenomenologytext