; Wang, Jian-Xiong] Chinese Acad Sci, Inst High Energy Phys, Beijing 100049, Peoples R China
; [He, Zhi-Guo
; Wang, Jian-Xiong] CAS, Theoret Phys Ctr Sci Facil, Beijing 100049, Peoples R China
; [He, Zhi-Guo] Univ Barcelona, Dept Estructura & Constituents Mat, E-08028 Barcelona, Catalonia, Spain
; [He, Zhi-Guo] Univ Barcelona, Inst Ciencies Cosmos, E-08028 Barcelona, Catalonia, Spain
In this work, we have calculated the tree level color-singlet contribution to the inclusive J / psi production in Gamma decay of the alpha(5)(s) order QCD process Gamma -> J / psi + c (c) over barg and alpha(2)alpha(2)(s) order QED processes Gamma -> gamma* -> J / psi + (c) over bar and Gamma -> J / psi + gg. It is found that the contribution of the QED processes is comparable with that of the QCD process and the numerical results of the QCD process alone are about an order of magnitude smaller than the previous theoretical predictions. Our prediction in total is 4.2 x 10(-5) which is about an order of magnitude smaller than the recent CLEO measurement on the branching fraction B(Gamma -> J / psi + X). It indicates that the J / psi production mechanism in Gamma decay is not well understood and further theoretical work and experimental analysis are still necessary.