up previous
Up: QCDINS homepage Previous: Package description

SUBROUTINE QIPSTO - Store 4-momentum array into PHEP of HW, set pointers




In this routine the momenta QIPHEP(*,I) and particle identities of all outgoing partons are stored into the PHEP common block of HERWIG. In addition, an array of IHEP pointers, QIPLIS(JLP,ILP), is constructed.


Table 1: Variables set in QIPSTO.
Name Description
PHEP(*,10+I) Momentum of the I'th outgoing parton from instanton subprocess,
  with $1\leq {\rm I}\leq 2n_f-1+n_g$
IDHEP(10+I) IDPDG of I'th outgoing parton from instanton subprocess
IDHW(10+I) HERWIG identity of I'th outgoing parton
QIPLIS(JLP,ILP) Array of IHEP pointers


Let us illustrate the procedure on the example given in the description of the subroutine QIPLST: Suppose we have $n_f=3,n_g=3$, and that $q^\prime$ is a quark with with particle data group identity 3. Then the parton type array QIPTYP(JLP,ILP) might be of the form

\begin{displaymath}
\begin{array}{cc\vert cccccc}
& & \multicolumn{6}{\vert c}{...
...NLIS(ILP)} & & 3 & 4 & 3 & 0 & \ldots & 0 \\
\end{array}\, .
\end{displaymath} (1)

The bold-face gluon entry $\bf 21$ and the bold-face antiquark entry $\bf -3$ are to indicate that these partons are marked as incoming. The momentum assignments are then as in Table 2.

Table 2: Example of internal momentum assignments.
QIPHEP(*,1) Momentum of quark 1
QIPHEP(*,2) Momentum of antiquark -2
QIPHEP(*,3) Momentum of quark 2
QIPHEP(*,4) Momentum of gluon
QIPHEP(*,5) Momentum of gluon
QIPHEP(*,6) Momentum of quark 3
QIPHEP(*,7) Momentum of gluon
QIPHEP(*,8) Momentum of antiquark -1


These momenta are stored into the PHEP common block as shown in Table 3.

Table 3: Example of momentum assignments in PHEP common block.
PHEP(*,11) Momentum of quark 1
PHEP(*,12) Momentum of antiquark -2
PHEP(*,13) Momentum of quark 2
PHEP(*,14) Momentum of gluon
PHEP(*,15) Momentum of gluon
PHEP(*,16) Momentum of quark 3
PHEP(*,17) Momentum of gluon
PHEP(*,18) Momentum of antiquark -1


The array of IHEP pointers, QIPLIS(JLP,ILP), has then the form
\begin{displaymath}
\begin{array}{cc\vert ccc}
& & \multicolumn{3}{\vert c}{{\r...
...16\\
& 2 & & 14& 17\\
& 3 & 12& 15& 18\\
\end{array}\, .
\end{displaymath} (2)


up previous
Up: QCDINS homepage Previous: Package description

A. Ringwald and F. Schrempp

1999-08-21