Can any one help me with this. I want to draw an arrow and a loop with rounded nodes as in the image?
I am waiting for your expertise.
[Tex/LaTex] How to draw arrow and loop with rounded heads instead of arrow shapes
diagramsnodes
Related Solutions
Here's a little example: two "outer" nodes, each one containing a graph (formed with "inner" nodes) and some edges and arrows connecting outer nodes to outer nodes, and inner nodes from one graph to inner nodes of the other; the remember picture option lets you access inner and outer nodes at any time:
\documentclass{article}
\usepackage{tikz}
\usetikzlibrary{positioning,calc}
\begin{document}
\begin{tikzpicture}[remember picture,
inner/.style={circle,draw=blue!50,fill=blue!20,thick,inner sep=3pt},
outer/.style={draw=green,fill=green!20,thick,inner sep=10pt}
]
\node[outer,draw=green] (A) {
\begin{tikzpicture}
\node [inner,draw=blue] (ai) {A1};
\node [inner,draw=blue,below=of ai] (aii) {A2};
\node [inner,draw=blue,right=of aii] (aiii) {A3};
\draw[red,thick] (ai) -- (aii) -- (aiii) -- (ai);
\end{tikzpicture}
};
\node[outer,draw=green,right=of A] (B) {
\begin{tikzpicture}
\node [inner,draw=blue] (bi) {B1};
\node [inner,draw=blue,below=of bi] (bii) {B2};
\node [inner,draw=blue,right=of bii] (biii) {B3};
\node [inner,draw=blue,right=of bi] (biv) {B4};
\draw[red,thick] (bi) -- (bii) -- (biii) -- (biv) -- (bi) -- (biii);
\end{tikzpicture}
};
\draw[thick,orange,->] (ai) -- (bii);
\draw[orange,->] (aiii) -- (bi);
\draw[orange,->] (A.90) -- ($(A.90)+(0,1)$) -| (B);
\end{tikzpicture}
\end{document}
If you don't mind switching to plain Metapost syntax, and making your graphic into an external file, you can import the feynmp definitions and use them in a regular MP diagram. This provides a simple way to do diagrams with layouts that the standard bits of feynmf don't support.
Here's my first attempt at what you describe above.
which was produced with this MP input:
prologues := 3;
outputtemplate := "%j%c.eps";
input feynmp
beginfig(1);
z1 = -z2 = 20 up;
z3 = (-60,40);
z4 = z3 reflectedabout(up,down);
z5 = z3 reflectedabout(left,right);
z6 = z4 reflectedabout(left,right);
draw fermion z3 -- z1;
draw fermion z5 -- z2;
draw fermion z1 -- z4;
draw fermion z2 -- z6;
draw photon z1 -- z2;
label.lft(btex $\gamma$ etex, .5[z1,z2]);
label.ulft(btex $\mu^-$ etex, z3);
label.urt (btex $\mu^-$ etex, z4);
label.llft(btex $e^-$ etex, z5);
label.lrt (btex $e^-$ etex, z6);
fill fullcircle scaled 4 shifted z1;
fill fullcircle scaled 4 shifted z2;
path a[];
a1 = subpath (0.3,0.6) of (z5--z2) shifted 8 up;
drawarrow a1; label.top(btex $p_i$ etex, point .5 of a1);
a2 = subpath (0.4,0.7) of (z2--z6) shifted 8 up;
drawarrow a2; label.top(btex $p_i$ etex, point .5 of a2);
endfig;
end.
However if you would prefer to stick more closely to your original input, then you can use an fmfcmd to add a new line style to add the momentum arrows. Like this:
\begin{fmfgraph*}(120,55)
\fmfleftn{i}{2}
\fmfrightn{o}{2}
\fmf{fermion}{i1,v1,o1}
\fmf{fermion}{i2,v2,o2}
\fmf{photon,label=$\gamma$}{v1,v2}
\fmfdotn{v}{2}
\fmflabel{$e^-$}{i1}
\fmflabel{$e^-$}{o1}
\fmflabel{$\mu^-$}{i2}
\fmflabel{$\mu^-$}{o2}
% additions here
\fmffreeze
\fmfcmd{style_def marrow expr p = drawarrow subpath (1/4, 3/4) of p shifted 6 up
withpen pencircle scaled 0.4; label.top(btex $p_i$ etex, point 0.5 of p
shifted 6 up); enddef;}
\fmf{marrow}{i1,v1,o1}
\end{fmfgraph*}
which produces this:
Note that the fmffreeze stops the extra connections messing up the layout. And I freely admit that the labels are a bit of a hack.
To produce this output, by the way, I found it convenient to put the fmfgraph into a LaTeX file like this:
\documentclass{article}
\usepackage{feynmp-auto}
\begin{document}
\begin{fmffile}{first}
\begin{fmfgraph*}(120,55)
... graph commands here ...
\end{fmfgraph*}
\end{fmffile}
\end{document}
Note that I had to change the size of the OP to something that came out readable on my system.
Best Answer
I used TikZ; for your specific question about the arrow tips, I used the arrows library (see Section 23 Arrow Tip Library of the pgf manual). The following code can be used as a starting point: