Quasi-two-body decays in the perturbative QCD approach Ai-Jun Ma, Wen-Fei Wang, Ya Li and Zhen-Jun Xiao Eur. Phys. J. C, 79 6 (2019) 539 Published online: 24 June 2019 DOI: 10.1140/epjc/s10052-019-7055-2