3 C*********************************************************************
5 SUBROUTINE LU2ENT_HIJING(IP,KF1,KF2,PECM)
7 C...Purpose: to store two partons/particles in their CM frame,
8 C...with the first along the +z axis.
9 #include "lujets_hijing.inc"
10 #include "ludat1_hijing.inc"
11 #include "ludat2_hijing.inc"
15 IF(MSTU(12).GE.1) CALL LULIST_HIJING(0)
17 IF(IPA.GT.MSTU(4)-1) CALL LUERRM_HIJING(21,
18 &'(LU2ENT_HIJING:) writing outside LUJETS_HIJING memory')
19 KC1=LUCOMP_HIJING(KF1)
20 KC2=LUCOMP_HIJING(KF2)
21 IF(KC1.EQ.0.OR.KC2.EQ.0) CALL LUERRM_HIJING(12,
22 &'(LU2ENT_HIJING:) unknown flavour code')
24 C...Find masses. Reset K, P and V vectors.
26 IF(MSTU(10).EQ.1) PM1=P(IPA,5)
27 IF(MSTU(10).GE.2) PM1=ULMASS_HIJING(KF1)
29 IF(MSTU(10).EQ.1) PM2=P(IPA+1,5)
30 IF(MSTU(10).GE.2) PM2=ULMASS_HIJING(KF2)
38 KQ1=KCHG(KC1,2)*ISIGN(1,KF1)
39 KQ2=KCHG(KC2,2)*ISIGN(1,KF2)
40 IF(KQ1+KQ2.NE.0.AND.KQ1+KQ2.NE.4) CALL LUERRM_HIJING(2,
41 &'(LU2ENT_HIJING:) unphysical flavour combination')
45 C...Store partons/particles in K vectors for normal case.
48 IF(KQ1.NE.0.AND.KQ2.NE.0) K(IPA,1)=2
51 C...Store partons in K vectors for parton shower evolution.
53 IF(KQ1.EQ.0.OR.KQ2.EQ.0) CALL LUERRM_HIJING(2,
54 & '(LU2ENT_HIJING:) requested flavours can not develop'//
58 K(IPA,4)=MSTU(5)*(IPA+1)
60 K(IPA+1,4)=MSTU(5)*IPA
64 C...Check kinematics and store partons/particles in P vectors.
65 IF(PECM.LE.PM1+PM2) CALL LUERRM_HIJING(13,
66 &'(LU2ENT_HIJING:) energy smaller than sum of masses')
67 PA=SQRT(MAX(0.,(PECM**2-PM1**2-PM2**2)**2-(2.*PM1*PM2)**2))/
70 P(IPA,4)=SQRT(PM1**2+PA**2)
73 P(IPA+1,4)=SQRT(PM2**2+PA**2)
76 C...Set N. Optionally fragment/decay.
78 IF(IP.EQ.0) CALL LUEXEC_HIJING