1 *CMZ : 17/07/98 15.44.31 by Federico Carminati
3 C*********************************************************************
5 SUBROUTINE LUJOIN(NJOIN,IJOIN)
7 C...Purpose: to connect a sequence of partons with colour flow indices,
8 C...as required for subsequent shower evolution (or other operations).
10 COMMON /LUJETS/ N,K(200000,5),P(200000,5),V(200000,5)
13 COMMON /LUDAT1/ MSTU(200),PARU(200),MSTJ(200),PARJ(200)
16 COMMON /LUDAT2/ KCHG(500,3),PMAS(500,4),PARF(2000),VCKM(4,4)
21 C...Check that partons are of right types to be connected.
22 IF(NJOIN.LT.2) GOTO 120
26 IF(I.LE.0.OR.I.GT.N) GOTO 120
27 IF(K(I,1).LT.1.OR.K(I,1).GT.3) GOTO 120
30 KQ=KCHG(KC,2)*ISIGN(1,K(I,2))
32 IF(IJN.NE.1.AND.IJN.NE.NJOIN.AND.KQ.NE.2) GOTO 120
33 IF(KQ.NE.2) KQSUM=KQSUM+KQ
34 100 IF(IJN.EQ.1) KQS=KQ
35 IF(KQSUM.NE.0) GOTO 120
37 C...Connect the partons sequentially (closing for gluon loop).
39 IF(KQS.EQ.2) KCS=INT(4.5+RLU(0))
43 IF(IJN.NE.1) IP=IJOIN(IJN-1)
44 IF(IJN.EQ.1) IP=IJOIN(NJOIN)
45 IF(IJN.NE.NJOIN) IN=IJOIN(IJN+1)
46 IF(IJN.EQ.NJOIN) IN=IJOIN(1)
49 IF(IJN.EQ.1.AND.KQS.NE.2) K(I,9-KCS)=0
50 110 IF(IJN.EQ.NJOIN.AND.KQS.NE.2) K(I,KCS)=0
52 C...Error exit: no action taken.
55 &'(LUJOIN:) given entries can not be joined by one string')