Color screening and the suppression of the charmonium state yield in nuclear reactions

We discuss the negative Feynman-[Formula Presented] regime of the new data for the production of the [Formula Presented] meson in [Formula Presented] collisions at [Formula Presented] at CERN-SPS (of the NA50 Collaboration). We extract from the CERN data [Formula Presented] mb under the assumption that the [Formula Presented] is produced as a result of the space-time evolution of a pointlike [Formula Presented] pair which expands with time to the full size of the charmonium state. In the analysis we assume the existence of a relationship between the distribution of color in a hadron and the cross section of its interaction with a nucleon. However, our result is rather sensitive to the pattern of the expansion of the wave packet and significantly larger values of [Formula Presented] are not ruled out by the data. We show that recent CERN data confirm the suggestion of Gerland [Phys. Rev. Lett. 81, 762 1998)that color fluctuations of the strengths in charmonium-nucleon interaction are the major source of suppression of the [Formula Presented] yield as observed at CERN in both [Formula Presented] and [Formula Presented] collisions.