Towards a solution of the charmonium production controversy: k_t-factorization versus color octet mechanism

Abstract

The cross section of χ_{cJ} hadroproduction is calculated in the k_t-factorization approach. We find a significant contribution of the χ_{c1} state due to non-applicability of the Landau-Yang theorem because of off-shell gluons. The results are in agreement with data and, in contrast to the collinear factorization, show a dominance of the color singlet part and a strong suppression of the color octet contribution. Our results could therefore lead to a solution of the longstanding controversy between the color singlet model and the color octet mechanism.

Figures (5)

• Figure 1: The basic diagram
• Figure 2: The effective vertex
• Figure 3: The transverse momentum differential cross section in comparison to the data and a NLO QCD calculation
• Figure 4: The individual contributions from $\chi_{c1}$ and $\chi_{c2}$
• Figure 5: The color octet contribution