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

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

$$\begin{array}{cc\vert ccc} & & \multicolumn{3}{\vert c}{{\r... ...16\\ & 2 & & 14& 17\\ & 3 & 12& 15& 18\\ \end{array}\, .$$ (2)