Fragmentation production of J/psi and psi' at the Tevatron

Abstract

We present a calculation of the charm and gluon fragmentation contributions to inclusive $J/\psi$ and $\psi'$ production at large transverse momentum at the Tevatron. For $\psi$ production, we include both fragmentation directly into $\psi$ and fragmentation into $\chi_c$ followed by the radiative decay $\chi_c \to \psi + \gamma$. We find that fragmentation overwhelms the leading-order mechanisms for prompt $\psi$ production at large $p_T$, and that the dominant contributions come from fragmentation into $\chi_c$. Our results are consistent with recent data on $\psi$ production from the CDF and D0 experiments. In the case of prompt $\psi'$ production, the dominant mechanism at large $p_T$ is charm fragmentation into $\psi'$. We find serious disagreement between our theoretical predictions and recent $\psi'$ data from the Tevatron.