I want to align the propagators that go from the circle to the vertices p_3 and p_4
Here is my MWE:
\documentclass[amsmath,amssymb,aps,12pt,eqsecnum]{revtex4}
\usepackage[a4paper]{geometry}
\linespread{1}
\usepackage{slashed}
\usepackage{simplewick}
\usepackage{feynmp-auto}
\usepackage[pdftex]{graphicx}
\usepackage{textcomp}
\usepackage{gensymb}
\begin{document}
\begin{fmffile}{counterterms3}
\begin{fmfgraph*}(100,100)
\fmfbottom{i0,i1,i2,i3}
\fmftop{o1,o2}
\fmf{plain}{i1,v2}
\fmf{plain}{i2,v1}
\fmf{plain,left}{v2,v3}
\fmf{plain,right}{v1,v3}
\fmf{plain}{v3,o1}
\fmf{plain}{v3,o2}
\fmfv{label=$p_1$}{i1}
\fmfv{label=$p_2$}{i2}
\fmfv{label=$p_3$}{o1}
\fmfv{label=$p_4$}{o2}
\fmffreeze
\fmf{phantom}{v1,v2}
\fmf{plain,left}{v1,v2}
\fmf{plain,left}{v2,v1}
\fmf{dot}{v3}
\end{fmfgraph*}
\end{fmffile}
\end{document}
As you can see, the propagators from the circle go horizontal at the vertex with the dot, rather than going in the same direction as the propagators which lead to p_3 and p_4