Study of color-octet matrix elements through production in annihilation Yi-Jie Li, Guang-Zhi Xu, Pan-Pan Zhang, Yu-Jie Zhang and Kui-Yong Liu Eur. Phys. J. C, 77 9 (2017) 597 Published online: 09 September 2017 DOI: 10.1140/epjc/s10052-017-5120-2