Triple-Reggeon Feynman diagram occurring in the calculation of the amplitude for single diffraction, corresponding tothe dissociation of hadron b in the interaction with hadron a. (See Ref.1). Each of the Reggeon legscan be a Pomeron or a secondary Reggeon (e.g. $f$-trajectories), resulting in eight different combinations of Pomerons andReggeons. In the text, we use the notation $(R_1R_2)R_3$ for the configuration shown in this figure. | ![](https://alice-publications.web.cern.ch/sites/default/files/papers/2834/Fig03-21380.png ) |