The prompt $J/\psi$ production in Association with a $c\bar{c}$ Pair within the Framework of Non-relativistic QCD via photon-photon collision at the International Linear Collider

Abstract

We present a systematical study on the prompt $J/\psi$ production in association with a $c\bar{c}$ pair via the process, $\gamma \gamma \to H(c\bar{c})+c+\bar{c}$, within the framework of non-relativistic QCD at the future high-energy $e^{+}{e}^{-}$ collider - International Linear Collider (ILC), including both direct and feed-down contributions. For direct $J/\psi$ production, the states with color-octet channels, especially the ${}^3{P}_J^{[8]}$ and ${}^1{S}_0^{[8]}$ ones, provide dominant contribution to the production cross-section, which are about fifty-two times over that of the color-singlet one. This is clearly shown by the transverse momentum ($p_t$) and rapidity distributions. The feed-down contribution from ${\psi }^{\prime }$ and ${\chi }_{cJ}$ ($J=0,1,2$) is sizable, which is about $20\%$ to the total prompt cross-section. Besides the yields, we also calculate the $J/\psi$ polarization parameter $\lambda$. In small $p_t$ region, the polarization of the prompt $J/\psi$ is longitudinal due to large contributions through the ${}^3{P}_J^{[8]}$ channel, and becomes transverse in high $p_t$ region due to ${}^3{S}_1^{[8]}$ channel. Thus the $J/\psi$ production via photon-photon collisions at the ILC shall provide a useful platform for testing the color-octet mechanism.

Comments: 8 pages, 8 figures. References updated and discussions improved. To be published in Phys.Rev.D