I try to draw this Feynman diagram with feynmf
in LaTeX
:
Here is my code:
\begin{fmffile}{edm_neutrino}
\begin{fmfchar*}(50,40)
\fmfkeep{vlm1}
\fmfleft{o}\fmflabel{$\nu_\tau$}{o}
\fmfright{i}\fmflabel{$\nu_\tau$}{i}
\fmftop{g}\fmflabel{$\gamma_\mu$}{g}
\fmf{plain, tension=1.5}{i,v1} \fmflabel{$Y_{ib}$}{v1}
\fmf{phantom, label=$\tau_j$, tension=0.8, left=1.0,tag=1}{v2,v1}
\fmf{dashes_arrow, label=$W^+$, left=-1.0, tension=0.4}{v2,v1}
\fmf{plain, tension=2.5}{v2,o}
\fmfposition
\fmfipath{p[]}
\fmfiset{p1}{vpath1(__v2,__v1)}
\fmfi{fermion}{subpath (0,2length(p1)/3) of p1}
\fmfi{fermion}{subpath (2length(p1)/3,length(p1)) of p1}
\fmfi{photon}{point length(p1)/3 of p1 -- point 2length(p1)/3 of p1}
%should go to g
\end{fmfchar*}
\end{fmffile}
But I don't know how to connect the point on the W^-
line to the external point g
. Is there any possibility to write something like that?
\fmfi{photon}{point 2length(p1)/3 of p1 -- point g}
This line is not correct, I know. But how to fix?
Thank you very much for reading! matthias