; Li, Rong
; Wang, Jian-Xiong] Chinese Acad Sci, Inst High Energy Phys, Beijing 100049, Peoples R China
; [Chang, Chao-Hsi] Chinese Acad Sci, Inst Theoret Phys, Beijing 100080, Peoples R China
; [Chang, Chao-Hsi
; Li, Rong
; Wang, Jian-Xiong] Chinese Acad Sci, Theoret Phys Ctr Sci Facil, Beijing 100049, Peoples R China
We investigate the J/psi polarization in photoproduction at the Hadron Electron Ring Accelerator (HERA) up to the next-to-leading order of QCD. The results show that the transverse momentum p(t) and energy fraction z distributions of J/psi production do not agree with the observed ones very well. The theoretical uncertainties for the z distributions of the J/psi polarization parameters with respect to various choices of the renormalization and factorization scales are too large to give a definite predication. The uncertainties for the p(t) distributions of these parameters are small when p(t) > 3 GeV and the obtained p(t) distributions cannot describe the experimental data even in this region.