Contents of Linking Vertices

Linking Vertices

When the number of loops is specified in a command, every line radiating from the center has that number of loops. A gluonlink following the will pertain solely to the last line drawn. In order to permit linkages to other or multiple vertex lines the vertexlink and vertexlinks commands are used. Unlike gluonlink, vertexlink(s) preceds the statement. The format is \vertexlinkn, where n is the line number of the vertex to be linked. For a vertex drawn in a \S direction, line one is the first drawn, the S line drawn to the centre (or if you prefer the N line coming out of the middle of the vertex). The others are counted clockwise around the midpoint (\vertexmidx,\vertexmidy). \vertexlinks is an abbreviation of

\vertexlink1\vertexlink2\vertexlink3
\vertexlink1\vertexlink2\vertexlink3\vertexlink4

for a three and four line vertex respectively. For instance, when the line

\vertexlink2\vertexlink3\flipvertex\drawvertex\gluon[\NE 4](0,0)[3]

is encountered a four-gluon vertex (four lines each with 3 loops) is drawn in the flipped configuration. The tip of the southwestern arm is at (0,0) and the northwestern and northeastern arms have links attached (ending at vertextwox,y and vertexthreex,y respectively). The only time that a \N, \S, \E or \W gluon vertex requires a link is for vertexone when a three-gluon vertex is drawn. Vertices are generally linked to gluon lines but may also be linked together directly as in the following example.

$\begin{picture}(8000,12000) \vertexlink3 \drawvertex\gluon[\SE 4](0,14500)[3] \f... ...[2] \flipvertex\drawvertex\gluon[\E 4](\vertextwox,\vertextwoy)[4] \end{picture}$

which was produced by the three statements

\begin{picture}(8000,12000)
\vertexlink3 \drawvertex\gluon[\SE 4](0,11500)[3]
\flipvertex\drawvertex\gluon[\SE 3](\vertexthreex,\vertexthreey)[2]
\flipvertex\drawvertex\gluon[\E 4](\vertextwox,\vertextwoy)[4]
\end{picture}

Note that the E four-gluon vertex requires no special links (since it is drawn using CURLY style gluons). In parting note that links may be drawn both with THINLINES and THICKLINES and will not appear when used within phantom mode (section 4.1.2).