Dear PF, I would like to thank you for existence of Physics forums since it appears very helpful. Dear PF, I was reading one paper and trying to derive Feynman rules for some vertices, but I could not get the same result as given in paper, as a guideline I use ‘t Hooft’s diagrammar and the same is given in appendices of Cheng and Lee – Gauge Theory of elementary particle physics. I attach extract from one Arxiv paper, extract from diagrammar and what I was trying to write. Could you please have a look and advise me what I do wrong? Thank you in advance.