HIJING/hipyset1_35/pyscat_hijing.F

   1 * $Id$
   2
   3 C*********************************************************************
   4
   5       SUBROUTINE PYSCAT_HIJING
   6
   7 C...Finds outgoing flavours and event type; sets up the kinematics
   8 C...and colour flow of the hard scattering.
   9 #include "lujets_hijing.inc"
  10 #include "ludat1_hijing.inc"
  11 #include "ludat2_hijing.inc"
  12 #include "ludat3_hijing.inc"
  13 #include "pysubs_hijing.inc"
  14 #include "pypars_hijing.inc"
  15 #include "pyint1_hijing.inc"
  16 #include "pyint2_hijing.inc"
  17 #include "pyint3_hijing.inc"
  18 #include "pyint4_hijing.inc"
  19 #include "pyint5_hijing.inc"
  20       DIMENSION WDTP(0:40),WDTE(0:40,0:5),PMQ(2),Z(2),CTHE(2),PHI(2)
  21
  22 C...Choice of subprocess, number of documentation lines.
  23       ISUB=MINT(1)
  24       IDOC=6+ISET(ISUB)
  25       IF(ISUB.EQ.95) IDOC=8
  26       MINT(3)=IDOC-6
  27       IF(IDOC.GE.9) IDOC=IDOC+2
  28       MINT(4)=IDOC
  29       IPU1=MINT(84)+1
  30       IPU2=MINT(84)+2
  31       IPU3=MINT(84)+3
  32       IPU4=MINT(84)+4
  33       IPU5=MINT(84)+5
  34       IPU6=MINT(84)+6
  35
  36 C...Reset K, P and V vectors. Store incoming particles.
  37       DO 100 JT=1,MSTP(126)+10
  38       I=MINT(83)+JT
  39       DO 100 J=1,5
  40       K(I,J)=0
  41       P(I,J)=0.
  42   100 V(I,J)=0.
  43       DO 110 JT=1,2
  44       I=MINT(83)+JT
  45       K(I,1)=21
  46       K(I,2)=MINT(10+JT)
  47       P(I,1)=0.
  48       P(I,2)=0.
  49       P(I,5)=VINT(2+JT)
  50       P(I,3)=VINT(5)*(-1)**(JT+1)
  51   110 P(I,4)=SQRT(P(I,3)**2+P(I,5)**2)
  52       MINT(6)=2
  53       KFRES=0
  54
  55 C...Store incoming partons in their CM-frame.
  56       SH=VINT(44)
  57       SHR=SQRT(SH)
  58       SHP=VINT(26)*VINT(2)
  59       SHPR=SQRT(SHP)
  60       SHUSER=SHR
  61       IF(ISET(ISUB).GE.3) SHUSER=SHPR
  62       DO 120 JT=1,2
  63       I=MINT(84)+JT
  64       K(I,1)=14
  65       K(I,2)=MINT(14+JT)
  66       K(I,3)=MINT(83)+2+JT
  67   120 P(I,5)=ULMASS_HIJING(K(I,2))
  68       IF(P(IPU1,5)+P(IPU2,5).GE.SHUSER) THEN
  69         P(IPU1,5)=0.
  70         P(IPU2,5)=0.
  71       ENDIF
  72       P(IPU1,4)=0.5*(SHUSER+(P(IPU1,5)**2-P(IPU2,5)**2)/SHUSER)
  73       P(IPU1,3)=SQRT(MAX(0.,P(IPU1,4)**2-P(IPU1,5)**2))
  74       P(IPU2,4)=SHUSER-P(IPU1,4)
  75       P(IPU2,3)=-P(IPU1,3)
  76
  77 C...Copy incoming partons to documentation lines.
  78       DO 130 JT=1,2
  79       I1=MINT(83)+4+JT
  80       I2=MINT(84)+JT
  81       K(I1,1)=21
  82       K(I1,2)=K(I2,2)
  83       K(I1,3)=I1-2
  84       DO 130 J=1,5
  85   130 P(I1,J)=P(I2,J)
  86
  87 C...Choose new quark flavour for relevant annihilation graphs.
  88       IF(ISUB.EQ.12.OR.ISUB.EQ.53) THEN
  89         CALL PYWIDT_HIJING(21,SHR,WDTP,WDTE)
  90         RKFL=(WDTE(0,1)+WDTE(0,2)+WDTE(0,4))*RLU_HIJING(0)
  91         DO 140 I=1,2*MSTP(1)
  92         KFLQ=I
  93         RKFL=RKFL-(WDTE(I,1)+WDTE(I,2)+WDTE(I,4))
  94         IF(RKFL.LE.0.) GOTO 150
  95   140   CONTINUE
  96   150   CONTINUE
  97       ENDIF
  98
  99 C...Final state flavours and colour flow: default values.
 100       JS=1
 101       MINT(21)=MINT(15)
 102       MINT(22)=MINT(16)
 103       MINT(23)=0
 104       MINT(24)=0
 105       KCC=20
 106       KCS=ISIGN(1,MINT(15))
 107
 108       IF(ISUB.LE.10) THEN
 109       IF(ISUB.EQ.1) THEN
 110 C...f + fb -> gamma*/Z0.
 111         KFRES=23
 112
 113       ELSEIF(ISUB.EQ.2) THEN
 114 C...f + fb' -> W+/- .
 115         KCH1=KCHG(IABS(MINT(15)),1)*ISIGN(1,MINT(15))
 116         KCH2=KCHG(IABS(MINT(16)),1)*ISIGN(1,MINT(16))
 117         KFRES=ISIGN(24,KCH1+KCH2)
 118
 119       ELSEIF(ISUB.EQ.3) THEN
 120 C...f + fb -> H0.
 121         KFRES=25
 122
 123       ELSEIF(ISUB.EQ.4) THEN
 124 C...gamma + W+/- -> W+/-.
 125
 126       ELSEIF(ISUB.EQ.5) THEN
 127 C...Z0 + Z0 -> H0.
 128         XH=SH/SHP
 129         MINT(21)=MINT(15)
 130         MINT(22)=MINT(16)
 131         PMQ(1)=ULMASS_HIJING(MINT(21))
 132         PMQ(2)=ULMASS_HIJING(MINT(22))
 133   240   JT=INT(1.5+RLU_HIJING(0))
 134         ZMIN=2.*PMQ(JT)/SHPR
 135         ZMAX=1.-PMQ(3-JT)/SHPR-(SH-PMQ(JT)**2)/(SHPR*(SHPR-PMQ(3-JT)))
 136         ZMAX=MIN(1.-XH,ZMAX)
 137         Z(JT)=ZMIN+(ZMAX-ZMIN)*RLU_HIJING(0)
 138         IF(-1.+(1.+XH)/(1.-Z(JT))-XH/(1.-Z(JT))**2.LT.
 139      &  (1.-XH)**2/(4.*XH)*RLU_HIJING(0)) GOTO 240
 140         SQC1=1.-4.*PMQ(JT)**2/(Z(JT)**2*SHP)
 141         IF(SQC1.LT.1.E-8) GOTO 240
 142         C1=SQRT(SQC1)
 143         C2=1.+2.*(PMAS(23,1)**2-PMQ(JT)**2)/(Z(JT)*SHP)
 144         CTHE(JT)=(C2-(C2**2-C1**2)/(C2+(2.*RLU_HIJING(0)-1.)*C1))/C1
 145         CTHE(JT)=MIN(1.,MAX(-1.,CTHE(JT)))
 146         Z(3-JT)=1.-XH/(1.-Z(JT))
 147         SQC1=1.-4.*PMQ(3-JT)**2/(Z(3-JT)**2*SHP)
 148         IF(SQC1.LT.1.E-8) GOTO 240
 149         C1=SQRT(SQC1)
 150         C2=1.+2.*(PMAS(23,1)**2-PMQ(3-JT)**2)/(Z(3-JT)*SHP)
 151         CTHE(3-JT)=(C2-(C2**2-C1**2)/(C2+(2.*RLU_HIJING(0)-1.)*C1))/C1
 152         CTHE(3-JT)=MIN(1.,MAX(-1.,CTHE(3-JT)))
 153         PHIR=PARU(2)*RLU_HIJING(0)
 154         CPHI=COS(PHIR)
 155         ANG=CTHE(1)*CTHE(2)-SQRT(1.-CTHE(1)**2)*SQRT(1.-CTHE(2)**2)*CPHI
 156         Z1=2.-Z(JT)
 157         Z2=ANG*SQRT(Z(JT)**2-4.*PMQ(JT)**2/SHP)
 158         Z3=1.-Z(JT)-XH+(PMQ(1)**2+PMQ(2)**2)/SHP
 159         Z(3-JT)=2./(Z1**2-Z2**2)*(Z1*Z3+Z2*SQRT(Z3**2-(Z1**2-Z2**2)*
 160      &  PMQ(3-JT)**2/SHP))
 161         ZMIN=2.*PMQ(3-JT)/SHPR
 162         ZMAX=1.-PMQ(JT)/SHPR-(SH-PMQ(3-JT)**2)/(SHPR*(SHPR-PMQ(JT)))
 163         ZMAX=MIN(1.-XH,ZMAX)
 164         IF(Z(3-JT).LT.ZMIN.OR.Z(3-JT).GT.ZMAX) GOTO 240
 165         KCC=22
 166         KFRES=25
 167
 168       ELSEIF(ISUB.EQ.6) THEN
 169 C...Z0 + W+/- -> W+/-.
 170
 171       ELSEIF(ISUB.EQ.7) THEN
 172 C...W+ + W- -> Z0.
 173
 174       ELSEIF(ISUB.EQ.8) THEN
 175 C...W+ + W- -> H0.
 176         XH=SH/SHP
 177   250   DO 280 JT=1,2
 178         I=MINT(14+JT)
 179         IA=IABS(I)
 180         IF(IA.LE.10) THEN
 181           RVCKM=VINT(180+I)*RLU_HIJING(0)
 182           DO 270 J=1,MSTP(1)
 183           IB=2*J-1+MOD(IA,2)
 184           IPM=(5-ISIGN(1,I))/2
 185           IDC=J+MDCY(IA,2)+2
 186           IF(MDME(IDC,1).NE.1.AND.MDME(IDC,1).NE.IPM) GOTO 270
 187           MINT(20+JT)=ISIGN(IB,I)
 188           RVCKM=RVCKM-VCKM((IA+1)/2,(IB+1)/2)
 189           IF(RVCKM.LE.0.) GOTO 280
 190   270     CONTINUE
 191         ELSE
 192           IB=2*((IA+1)/2)-1+MOD(IA,2)
 193           MINT(20+JT)=ISIGN(IB,I)
 194         ENDIF
 195   280   PMQ(JT)=ULMASS_HIJING(MINT(20+JT))
 196         JT=INT(1.5+RLU_HIJING(0))
 197         ZMIN=2.*PMQ(JT)/SHPR
 198         ZMAX=1.-PMQ(3-JT)/SHPR-(SH-PMQ(JT)**2)/(SHPR*(SHPR-PMQ(3-JT)))
 199         ZMAX=MIN(1.-XH,ZMAX)
 200         Z(JT)=ZMIN+(ZMAX-ZMIN)*RLU_HIJING(0)
 201         IF(-1.+(1.+XH)/(1.-Z(JT))-XH/(1.-Z(JT))**2.LT.
 202      &  (1.-XH)**2/(4.*XH)*RLU_HIJING(0)) GOTO 250
 203         SQC1=1.-4.*PMQ(JT)**2/(Z(JT)**2*SHP)
 204         IF(SQC1.LT.1.E-8) GOTO 250
 205         C1=SQRT(SQC1)
 206         C2=1.+2.*(PMAS(24,1)**2-PMQ(JT)**2)/(Z(JT)*SHP)
 207         CTHE(JT)=(C2-(C2**2-C1**2)/(C2+(2.*RLU_HIJING(0)-1.)*C1))/C1
 208         CTHE(JT)=MIN(1.,MAX(-1.,CTHE(JT)))
 209         Z(3-JT)=1.-XH/(1.-Z(JT))
 210         SQC1=1.-4.*PMQ(3-JT)**2/(Z(3-JT)**2*SHP)
 211         IF(SQC1.LT.1.E-8) GOTO 250
 212         C1=SQRT(SQC1)
 213         C2=1.+2.*(PMAS(24,1)**2-PMQ(3-JT)**2)/(Z(3-JT)*SHP)
 214         CTHE(3-JT)=(C2-(C2**2-C1**2)/(C2+(2.*RLU_HIJING(0)-1.)*C1))/C1
 215         CTHE(3-JT)=MIN(1.,MAX(-1.,CTHE(3-JT)))
 216         PHIR=PARU(2)*RLU_HIJING(0)
 217         CPHI=COS(PHIR)
 218         ANG=CTHE(1)*CTHE(2)-SQRT(1.-CTHE(1)**2)*SQRT(1.-CTHE(2)**2)*CPHI
 219         Z1=2.-Z(JT)
 220         Z2=ANG*SQRT(Z(JT)**2-4.*PMQ(JT)**2/SHP)
 221         Z3=1.-Z(JT)-XH+(PMQ(1)**2+PMQ(2)**2)/SHP
 222         Z(3-JT)=2./(Z1**2-Z2**2)*(Z1*Z3+Z2*SQRT(Z3**2-(Z1**2-Z2**2)*
 223      &  PMQ(3-JT)**2/SHP))
 224         ZMIN=2.*PMQ(3-JT)/SHPR
 225         ZMAX=1.-PMQ(JT)/SHPR-(SH-PMQ(3-JT)**2)/(SHPR*(SHPR-PMQ(JT)))
 226         ZMAX=MIN(1.-XH,ZMAX)
 227         IF(Z(3-JT).LT.ZMIN.OR.Z(3-JT).GT.ZMAX) GOTO 250
 228         KCC=22
 229         KFRES=25
 230       ENDIF
 231
 232       ELSEIF(ISUB.LE.20) THEN
 233       IF(ISUB.EQ.11) THEN
 234 C...f + f' -> f + f'; th = (p(f)-p(f))**2.
 235         KCC=MINT(2)
 236         IF(MINT(15)*MINT(16).LT.0) KCC=KCC+2
 237
 238       ELSEIF(ISUB.EQ.12) THEN
 239 C...f + fb -> f' + fb'; th = (p(f)-p(f'))**2.
 240         MINT(21)=ISIGN(KFLQ,MINT(15))
 241         MINT(22)=-MINT(21)
 242         KCC=4
 243
 244       ELSEIF(ISUB.EQ.13) THEN
 245 C...f + fb -> g + g; th arbitrary.
 246         MINT(21)=21
 247         MINT(22)=21
 248         KCC=MINT(2)+4
 249
 250       ELSEIF(ISUB.EQ.14) THEN
 251 C...f + fb -> g + gam; th arbitrary.
 252         IF(RLU_HIJING(0).GT.0.5) JS=2
 253         MINT(20+JS)=21
 254         MINT(23-JS)=22
 255         KCC=17+JS
 256
 257       ELSEIF(ISUB.EQ.15) THEN
 258 C...f + fb -> g + Z0; th arbitrary.
 259         IF(RLU_HIJING(0).GT.0.5) JS=2
 260         MINT(20+JS)=21
 261         MINT(23-JS)=23
 262         KCC=17+JS
 263
 264       ELSEIF(ISUB.EQ.16) THEN
 265 C...f + fb' -> g + W+/-; th = (p(f)-p(W-))**2 or (p(fb')-p(W+))**2.
 266         KCH1=KCHG(IABS(MINT(15)),1)*ISIGN(1,MINT(15))
 267         KCH2=KCHG(IABS(MINT(16)),1)*ISIGN(1,MINT(16))
 268         IF(MINT(15)*(KCH1+KCH2).LT.0) JS=2
 269         MINT(20+JS)=21
 270         MINT(23-JS)=ISIGN(24,KCH1+KCH2)
 271         KCC=17+JS
 272
 273       ELSEIF(ISUB.EQ.17) THEN
 274 C...f + fb -> g + H0; th arbitrary.
 275         IF(RLU_HIJING(0).GT.0.5) JS=2
 276         MINT(20+JS)=21
 277         MINT(23-JS)=25
 278         KCC=17+JS
 279
 280       ELSEIF(ISUB.EQ.18) THEN
 281 C...f + fb -> gamma + gamma; th arbitrary.
 282         MINT(21)=22
 283         MINT(22)=22
 284
 285       ELSEIF(ISUB.EQ.19) THEN
 286 C...f + fb -> gamma + Z0; th arbitrary.
 287         IF(RLU_HIJING(0).GT.0.5) JS=2
 288         MINT(20+JS)=22
 289         MINT(23-JS)=23
 290
 291       ELSEIF(ISUB.EQ.20) THEN
 292 C...f + fb' -> gamma + W+/-; th = (p(f)-p(W-))**2 or (p(fb')-p(W+))**2.
 293         KCH1=KCHG(IABS(MINT(15)),1)*ISIGN(1,MINT(15))
 294         KCH2=KCHG(IABS(MINT(16)),1)*ISIGN(1,MINT(16))
 295         IF(MINT(15)*(KCH1+KCH2).LT.0) JS=2
 296         MINT(20+JS)=22
 297         MINT(23-JS)=ISIGN(24,KCH1+KCH2)
 298       ENDIF
 299
 300       ELSEIF(ISUB.LE.30) THEN
 301       IF(ISUB.EQ.21) THEN
 302 C...f + fb -> gamma + H0; th arbitrary.
 303         IF(RLU_HIJING(0).GT.0.5) JS=2
 304         MINT(20+JS)=22
 305         MINT(23-JS)=25
 306
 307       ELSEIF(ISUB.EQ.22) THEN
 308 C...f + fb -> Z0 + Z0; th arbitrary.
 309         MINT(21)=23
 310         MINT(22)=23
 311
 312       ELSEIF(ISUB.EQ.23) THEN
 313 C...f + fb' -> Z0 + W+/-; th = (p(f)-p(W-))**2 or (p(fb')-p(W+))**2.
 314         KCH1=KCHG(IABS(MINT(15)),1)*ISIGN(1,MINT(15))
 315         KCH2=KCHG(IABS(MINT(16)),1)*ISIGN(1,MINT(16))
 316         IF(MINT(15)*(KCH1+KCH2).LT.0) JS=2
 317         MINT(20+JS)=23
 318         MINT(23-JS)=ISIGN(24,KCH1+KCH2)
 319
 320       ELSEIF(ISUB.EQ.24) THEN
 321 C...f + fb -> Z0 + H0; th arbitrary.
 322         IF(RLU_HIJING(0).GT.0.5) JS=2
 323         MINT(20+JS)=23
 324         MINT(23-JS)=25
 325
 326       ELSEIF(ISUB.EQ.25) THEN
 327 C...f + fb -> W+ + W-; th = (p(f)-p(W-))**2.
 328         MINT(21)=-ISIGN(24,MINT(15))
 329         MINT(22)=-MINT(21)
 330
 331       ELSEIF(ISUB.EQ.26) THEN
 332 C...f + fb' -> W+/- + H0; th = (p(f)-p(W-))**2 or (p(fb')-p(W+))**2.
 333         KCH1=KCHG(IABS(MINT(15)),1)*ISIGN(1,MINT(15))
 334         KCH2=KCHG(IABS(MINT(16)),1)*ISIGN(1,MINT(16))
 335         IF(MINT(15)*(KCH1+KCH2).GT.0) JS=2
 336         MINT(20+JS)=ISIGN(24,KCH1+KCH2)
 337         MINT(23-JS)=25
 338
 339       ELSEIF(ISUB.EQ.27) THEN
 340 C...f + fb -> H0 + H0.
 341
 342       ELSEIF(ISUB.EQ.28) THEN
 343 C...f + g -> f + g; th = (p(f)-p(f))**2.
 344         KCC=MINT(2)+6
 345         IF(MINT(15).EQ.21) KCC=KCC+2
 346         IF(MINT(15).NE.21) KCS=ISIGN(1,MINT(15))
 347         IF(MINT(16).NE.21) KCS=ISIGN(1,MINT(16))
 348
 349       ELSEIF(ISUB.EQ.29) THEN
 350 C...f + g -> f + gamma; th = (p(f)-p(f))**2.
 351         IF(MINT(15).EQ.21) JS=2
 352         MINT(23-JS)=22
 353         KCC=15+JS
 354         KCS=ISIGN(1,MINT(14+JS))
 355
 356       ELSEIF(ISUB.EQ.30) THEN
 357 C...f + g -> f + Z0; th = (p(f)-p(f))**2.
 358         IF(MINT(15).EQ.21) JS=2
 359         MINT(23-JS)=23
 360         KCC=15+JS
 361         KCS=ISIGN(1,MINT(14+JS))
 362       ENDIF
 363
 364       ELSEIF(ISUB.LE.40) THEN
 365       IF(ISUB.EQ.31) THEN
 366 C...f + g -> f' + W+/-; th = (p(f)-p(f'))**2; choose flavour f'.
 367         IF(MINT(15).EQ.21) JS=2
 368         I=MINT(14+JS)
 369         IA=IABS(I)
 370         MINT(23-JS)=ISIGN(24,KCHG(IA,1)*I)
 371         RVCKM=VINT(180+I)*RLU_HIJING(0)
 372         DO 220 J=1,MSTP(1)
 373         IB=2*J-1+MOD(IA,2)
 374         IPM=(5-ISIGN(1,I))/2
 375         IDC=J+MDCY(IA,2)+2
 376         IF(MDME(IDC,1).NE.1.AND.MDME(IDC,1).NE.IPM) GOTO 220
 377         MINT(20+JS)=ISIGN(IB,I)
 378         RVCKM=RVCKM-VCKM((IA+1)/2,(IB+1)/2)
 379         IF(RVCKM.LE.0.) GOTO 230
 380   220   CONTINUE
 381   230   KCC=15+JS
 382         KCS=ISIGN(1,MINT(14+JS))
 383
 384       ELSEIF(ISUB.EQ.32) THEN
 385 C...f + g -> f + H0; th = (p(f)-p(f))**2.
 386         IF(MINT(15).EQ.21) JS=2
 387         MINT(23-JS)=25
 388         KCC=15+JS
 389         KCS=ISIGN(1,MINT(14+JS))
 390
 391       ELSEIF(ISUB.EQ.33) THEN
 392 C...f + gamma -> f + g.
 393
 394       ELSEIF(ISUB.EQ.34) THEN
 395 C...f + gamma -> f + gamma.
 396
 397       ELSEIF(ISUB.EQ.35) THEN
 398 C...f + gamma -> f + Z0.
 399
 400       ELSEIF(ISUB.EQ.36) THEN
 401 C...f + gamma -> f' + W+/-.
 402
 403       ELSEIF(ISUB.EQ.37) THEN
 404 C...f + gamma -> f + H0.
 405
 406       ELSEIF(ISUB.EQ.38) THEN
 407 C...f + Z0 -> f + g.
 408
 409       ELSEIF(ISUB.EQ.39) THEN
 410 C...f + Z0 -> f + gamma.
 411
 412       ELSEIF(ISUB.EQ.40) THEN
 413 C...f + Z0 -> f + Z0.
 414       ENDIF
 415
 416       ELSEIF(ISUB.LE.50) THEN
 417       IF(ISUB.EQ.41) THEN
 418 C...f + Z0 -> f' + W+/-.
 419
 420       ELSEIF(ISUB.EQ.42) THEN
 421 C...f + Z0 -> f + H0.
 422
 423       ELSEIF(ISUB.EQ.43) THEN
 424 C...f + W+/- -> f' + g.
 425
 426       ELSEIF(ISUB.EQ.44) THEN
 427 C...f + W+/- -> f' + gamma.
 428
 429       ELSEIF(ISUB.EQ.45) THEN
 430 C...f + W+/- -> f' + Z0.
 431
 432       ELSEIF(ISUB.EQ.46) THEN
 433 C...f + W+/- -> f' + W+/-.
 434
 435       ELSEIF(ISUB.EQ.47) THEN
 436 C...f + W+/- -> f' + H0.
 437
 438       ELSEIF(ISUB.EQ.48) THEN
 439 C...f + H0 -> f + g.
 440
 441       ELSEIF(ISUB.EQ.49) THEN
 442 C...f + H0 -> f + gamma.
 443
 444       ELSEIF(ISUB.EQ.50) THEN
 445 C...f + H0 -> f + Z0.
 446       ENDIF
 447
 448       ELSEIF(ISUB.LE.60) THEN
 449       IF(ISUB.EQ.51) THEN
 450 C...f + H0 -> f' + W+/-.
 451
 452       ELSEIF(ISUB.EQ.52) THEN
 453 C...f + H0 -> f + H0.
 454
 455       ELSEIF(ISUB.EQ.53) THEN
 456 C...g + g -> f + fb; th arbitrary.
 457         KCS=(-1)**INT(1.5+RLU_HIJING(0))
 458         MINT(21)=ISIGN(KFLQ,KCS)
 459         MINT(22)=-MINT(21)
 460         KCC=MINT(2)+10
 461
 462       ELSEIF(ISUB.EQ.54) THEN
 463 C...g + gamma -> f + fb.
 464
 465       ELSEIF(ISUB.EQ.55) THEN
 466 C...g + Z0 -> f + fb.
 467
 468       ELSEIF(ISUB.EQ.56) THEN
 469 C...g + W+/- -> f + fb'.
 470
 471       ELSEIF(ISUB.EQ.57) THEN
 472 C...g + H0 -> f + fb.
 473
 474       ELSEIF(ISUB.EQ.58) THEN
 475 C...gamma + gamma -> f + fb.
 476
 477       ELSEIF(ISUB.EQ.59) THEN
 478 C...gamma + Z0 -> f + fb.
 479
 480       ELSEIF(ISUB.EQ.60) THEN
 481 C...gamma + W+/- -> f + fb'.
 482       ENDIF
 483
 484       ELSEIF(ISUB.LE.70) THEN
 485       IF(ISUB.EQ.61) THEN
 486 C...gamma + H0 -> f + fb.
 487
 488       ELSEIF(ISUB.EQ.62) THEN
 489 C...Z0 + Z0 -> f + fb.
 490
 491       ELSEIF(ISUB.EQ.63) THEN
 492 C...Z0 + W+/- -> f + fb'.
 493
 494       ELSEIF(ISUB.EQ.64) THEN
 495 C...Z0 + H0 -> f + fb.
 496
 497       ELSEIF(ISUB.EQ.65) THEN
 498 C...W+ + W- -> f + fb.
 499
 500       ELSEIF(ISUB.EQ.66) THEN
 501 C...W+/- + H0 -> f + fb'.
 502
 503       ELSEIF(ISUB.EQ.67) THEN
 504 C...H0 + H0 -> f + fb.
 505
 506       ELSEIF(ISUB.EQ.68) THEN
 507 C...g + g -> g + g; th arbitrary.
 508         KCC=MINT(2)+12
 509         KCS=(-1)**INT(1.5+RLU_HIJING(0))
 510
 511       ELSEIF(ISUB.EQ.69) THEN
 512 C...gamma + gamma -> W+ + W-.
 513
 514       ELSEIF(ISUB.EQ.70) THEN
 515 C...gamma + W+/- -> gamma + W+/-
 516       ENDIF
 517
 518       ELSEIF(ISUB.LE.80) THEN
 519       IF(ISUB.EQ.71.OR.ISUB.EQ.72) THEN
 520 C...Z0 + Z0 -> Z0 + Z0; Z0 + Z0 -> W+ + W-.
 521         XH=SH/SHP
 522         MINT(21)=MINT(15)
 523         MINT(22)=MINT(16)
 524         PMQ(1)=ULMASS_HIJING(MINT(21))
 525         PMQ(2)=ULMASS_HIJING(MINT(22))
 526   290   JT=INT(1.5+RLU_HIJING(0))
 527         ZMIN=2.*PMQ(JT)/SHPR
 528         ZMAX=1.-PMQ(3-JT)/SHPR-(SH-PMQ(JT)**2)/(SHPR*(SHPR-PMQ(3-JT)))
 529         ZMAX=MIN(1.-XH,ZMAX)
 530         Z(JT)=ZMIN+(ZMAX-ZMIN)*RLU_HIJING(0)
 531         IF(-1.+(1.+XH)/(1.-Z(JT))-XH/(1.-Z(JT))**2.LT.
 532      &  (1.-XH)**2/(4.*XH)*RLU_HIJING(0)) GOTO 290
 533         SQC1=1.-4.*PMQ(JT)**2/(Z(JT)**2*SHP)
 534         IF(SQC1.LT.1.E-8) GOTO 290
 535         C1=SQRT(SQC1)
 536         C2=1.+2.*(PMAS(23,1)**2-PMQ(JT)**2)/(Z(JT)*SHP)
 537         CTHE(JT)=(C2-(C2**2-C1**2)/(C2+(2.*RLU_HIJING(0)-1.)*C1))/C1
 538         CTHE(JT)=MIN(1.,MAX(-1.,CTHE(JT)))
 539         Z(3-JT)=1.-XH/(1.-Z(JT))
 540         SQC1=1.-4.*PMQ(3-JT)**2/(Z(3-JT)**2*SHP)
 541         IF(SQC1.LT.1.E-8) GOTO 290
 542         C1=SQRT(SQC1)
 543         C2=1.+2.*(PMAS(23,1)**2-PMQ(3-JT)**2)/(Z(3-JT)*SHP)
 544         CTHE(3-JT)=(C2-(C2**2-C1**2)/(C2+(2.*RLU_HIJING(0)-1.)*C1))/C1
 545         CTHE(3-JT)=MIN(1.,MAX(-1.,CTHE(3-JT)))
 546         PHIR=PARU(2)*RLU_HIJING(0)
 547         CPHI=COS(PHIR)
 548         ANG=CTHE(1)*CTHE(2)-SQRT(1.-CTHE(1)**2)*SQRT(1.-CTHE(2)**2)*CPHI
 549         Z1=2.-Z(JT)
 550         Z2=ANG*SQRT(Z(JT)**2-4.*PMQ(JT)**2/SHP)
 551         Z3=1.-Z(JT)-XH+(PMQ(1)**2+PMQ(2)**2)/SHP
 552         Z(3-JT)=2./(Z1**2-Z2**2)*(Z1*Z3+Z2*SQRT(Z3**2-(Z1**2-Z2**2)*
 553      &  PMQ(3-JT)**2/SHP))
 554         ZMIN=2.*PMQ(3-JT)/SHPR
 555         ZMAX=1.-PMQ(JT)/SHPR-(SH-PMQ(3-JT)**2)/(SHPR*(SHPR-PMQ(JT)))
 556         ZMAX=MIN(1.-XH,ZMAX)
 557         IF(Z(3-JT).LT.ZMIN.OR.Z(3-JT).GT.ZMAX) GOTO 290
 558         KCC=22
 559
 560       ELSEIF(ISUB.EQ.73) THEN
 561 C...Z0 + W+/- -> Z0 + W+/-.
 562         XH=SH/SHP
 563   300   JT=INT(1.5+RLU_HIJING(0))
 564         I=MINT(14+JT)
 565         IA=IABS(I)
 566         IF(IA.LE.10) THEN
 567           RVCKM=VINT(180+I)*RLU_HIJING(0)
 568           DO 320 J=1,MSTP(1)
 569           IB=2*J-1+MOD(IA,2)
 570           IPM=(5-ISIGN(1,I))/2
 571           IDC=J+MDCY(IA,2)+2
 572           IF(MDME(IDC,1).NE.1.AND.MDME(IDC,1).NE.IPM) GOTO 320
 573           MINT(20+JT)=ISIGN(IB,I)
 574           RVCKM=RVCKM-VCKM((IA+1)/2,(IB+1)/2)
 575           IF(RVCKM.LE.0.) GOTO 330
 576   320     CONTINUE
 577         ELSE
 578           IB=2*((IA+1)/2)-1+MOD(IA,2)
 579           MINT(20+JT)=ISIGN(IB,I)
 580         ENDIF
 581   330   PMQ(JT)=ULMASS_HIJING(MINT(20+JT))
 582         MINT(23-JT)=MINT(17-JT)
 583         PMQ(3-JT)=ULMASS_HIJING(MINT(23-JT))
 584         JT=INT(1.5+RLU_HIJING(0))
 585         ZMIN=2.*PMQ(JT)/SHPR
 586         ZMAX=1.-PMQ(3-JT)/SHPR-(SH-PMQ(JT)**2)/(SHPR*(SHPR-PMQ(3-JT)))
 587         ZMAX=MIN(1.-XH,ZMAX)
 588         Z(JT)=ZMIN+(ZMAX-ZMIN)*RLU_HIJING(0)
 589         IF(-1.+(1.+XH)/(1.-Z(JT))-XH/(1.-Z(JT))**2.LT.
 590      &  (1.-XH)**2/(4.*XH)*RLU_HIJING(0)) GOTO 300
 591         SQC1=1.-4.*PMQ(JT)**2/(Z(JT)**2*SHP)
 592         IF(SQC1.LT.1.E-8) GOTO 300
 593         C1=SQRT(SQC1)
 594         C2=1.+2.*(PMAS(23,1)**2-PMQ(JT)**2)/(Z(JT)*SHP)
 595         CTHE(JT)=(C2-(C2**2-C1**2)/(C2+(2.*RLU_HIJING(0)-1.)*C1))/C1
 596         CTHE(JT)=MIN(1.,MAX(-1.,CTHE(JT)))
 597         Z(3-JT)=1.-XH/(1.-Z(JT))
 598         SQC1=1.-4.*PMQ(3-JT)**2/(Z(3-JT)**2*SHP)
 599         IF(SQC1.LT.1.E-8) GOTO 300
 600         C1=SQRT(SQC1)
 601         C2=1.+2.*(PMAS(23,1)**2-PMQ(3-JT)**2)/(Z(3-JT)*SHP)
 602         CTHE(3-JT)=(C2-(C2**2-C1**2)/(C2+(2.*RLU_HIJING(0)-1.)*C1))/C1
 603         CTHE(3-JT)=MIN(1.,MAX(-1.,CTHE(3-JT)))
 604         PHIR=PARU(2)*RLU_HIJING(0)
 605         CPHI=COS(PHIR)
 606         ANG=CTHE(1)*CTHE(2)-SQRT(1.-CTHE(1)**2)*SQRT(1.-CTHE(2)**2)*CPHI
 607         Z1=2.-Z(JT)
 608         Z2=ANG*SQRT(Z(JT)**2-4.*PMQ(JT)**2/SHP)
 609         Z3=1.-Z(JT)-XH+(PMQ(1)**2+PMQ(2)**2)/SHP
 610         Z(3-JT)=2./(Z1**2-Z2**2)*(Z1*Z3+Z2*SQRT(Z3**2-(Z1**2-Z2**2)*
 611      &  PMQ(3-JT)**2/SHP))
 612         ZMIN=2.*PMQ(3-JT)/SHPR
 613         ZMAX=1.-PMQ(JT)/SHPR-(SH-PMQ(3-JT)**2)/(SHPR*(SHPR-PMQ(JT)))
 614         ZMAX=MIN(1.-XH,ZMAX)
 615         IF(Z(3-JT).LT.ZMIN.OR.Z(3-JT).GT.ZMAX) GOTO 300
 616         KCC=22
 617
 618       ELSEIF(ISUB.EQ.74) THEN
 619 C...Z0 + H0 -> Z0 + H0.
 620
 621       ELSEIF(ISUB.EQ.75) THEN
 622 C...W+ + W- -> gamma + gamma.
 623
 624       ELSEIF(ISUB.EQ.76.OR.ISUB.EQ.77) THEN
 625 C...W+ + W- -> Z0 + Z0; W+ + W- -> W+ + W-.
 626         XH=SH/SHP
 627   340   DO 370 JT=1,2
 628         I=MINT(14+JT)
 629         IA=IABS(I)
 630         IF(IA.LE.10) THEN
 631           RVCKM=VINT(180+I)*RLU_HIJING(0)
 632           DO 360 J=1,MSTP(1)
 633           IB=2*J-1+MOD(IA,2)
 634           IPM=(5-ISIGN(1,I))/2
 635           IDC=J+MDCY(IA,2)+2
 636           IF(MDME(IDC,1).NE.1.AND.MDME(IDC,1).NE.IPM) GOTO 360
 637           MINT(20+JT)=ISIGN(IB,I)
 638           RVCKM=RVCKM-VCKM((IA+1)/2,(IB+1)/2)
 639           IF(RVCKM.LE.0.) GOTO 370
 640   360     CONTINUE
 641         ELSE
 642           IB=2*((IA+1)/2)-1+MOD(IA,2)
 643           MINT(20+JT)=ISIGN(IB,I)
 644         ENDIF
 645   370   PMQ(JT)=ULMASS_HIJING(MINT(20+JT))
 646         JT=INT(1.5+RLU_HIJING(0))
 647         ZMIN=2.*PMQ(JT)/SHPR
 648         ZMAX=1.-PMQ(3-JT)/SHPR-(SH-PMQ(JT)**2)/(SHPR*(SHPR-PMQ(3-JT)))
 649         ZMAX=MIN(1.-XH,ZMAX)
 650         Z(JT)=ZMIN+(ZMAX-ZMIN)*RLU_HIJING(0)
 651         IF(-1.+(1.+XH)/(1.-Z(JT))-XH/(1.-Z(JT))**2.LT.
 652      &  (1.-XH)**2/(4.*XH)*RLU_HIJING(0)) GOTO 340
 653         SQC1=1.-4.*PMQ(JT)**2/(Z(JT)**2*SHP)
 654         IF(SQC1.LT.1.E-8) GOTO 340
 655         C1=SQRT(SQC1)
 656         C2=1.+2.*(PMAS(24,1)**2-PMQ(JT)**2)/(Z(JT)*SHP)
 657         CTHE(JT)=(C2-(C2**2-C1**2)/(C2+(2.*RLU_HIJING(0)-1.)*C1))/C1
 658         CTHE(JT)=MIN(1.,MAX(-1.,CTHE(JT)))
 659         Z(3-JT)=1.-XH/(1.-Z(JT))
 660         SQC1=1.-4.*PMQ(3-JT)**2/(Z(3-JT)**2*SHP)
 661         IF(SQC1.LT.1.E-8) GOTO 340
 662         C1=SQRT(SQC1)
 663         C2=1.+2.*(PMAS(24,1)**2-PMQ(3-JT)**2)/(Z(3-JT)*SHP)
 664         CTHE(3-JT)=(C2-(C2**2-C1**2)/(C2+(2.*RLU_HIJING(0)-1.)*C1))/C1
 665         CTHE(3-JT)=MIN(1.,MAX(-1.,CTHE(3-JT)))
 666         PHIR=PARU(2)*RLU_HIJING(0)
 667         CPHI=COS(PHIR)
 668         ANG=CTHE(1)*CTHE(2)-SQRT(1.-CTHE(1)**2)*SQRT(1.-CTHE(2)**2)*CPHI
 669         Z1=2.-Z(JT)
 670         Z2=ANG*SQRT(Z(JT)**2-4.*PMQ(JT)**2/SHP)
 671         Z3=1.-Z(JT)-XH+(PMQ(1)**2+PMQ(2)**2)/SHP
 672         Z(3-JT)=2./(Z1**2-Z2**2)*(Z1*Z3+Z2*SQRT(Z3**2-(Z1**2-Z2**2)*
 673      &  PMQ(3-JT)**2/SHP))
 674         ZMIN=2.*PMQ(3-JT)/SHPR
 675         ZMAX=1.-PMQ(JT)/SHPR-(SH-PMQ(3-JT)**2)/(SHPR*(SHPR-PMQ(JT)))
 676         ZMAX=MIN(1.-XH,ZMAX)
 677         IF(Z(3-JT).LT.ZMIN.OR.Z(3-JT).GT.ZMAX) GOTO 340
 678         KCC=22
 679
 680       ELSEIF(ISUB.EQ.78) THEN
 681 C...W+/- + H0 -> W+/- + H0.
 682
 683       ELSEIF(ISUB.EQ.79) THEN
 684 C...H0 + H0 -> H0 + H0.
 685       ENDIF
 686
 687       ELSEIF(ISUB.LE.90) THEN
 688       IF(ISUB.EQ.81) THEN
 689 C...q + qb -> Q' + Qb'; th = (p(q)-p(q'))**2.
 690         MINT(21)=ISIGN(MINT(46),MINT(15))
 691         MINT(22)=-MINT(21)
 692         KCC=4
 693
 694       ELSEIF(ISUB.EQ.82) THEN
 695 C...g + g -> Q + Qb; th arbitrary.
 696         KCS=(-1)**INT(1.5+RLU_HIJING(0))
 697         MINT(21)=ISIGN(MINT(46),KCS)
 698         MINT(22)=-MINT(21)
 699         KCC=MINT(2)+10
 700       ENDIF
 701
 702       ELSEIF(ISUB.LE.100) THEN
 703       IF(ISUB.EQ.95) THEN
 704 C...Low-pT ( = energyless g + g -> g + g).
 705         KCC=MINT(2)+12
 706         KCS=(-1)**INT(1.5+RLU_HIJING(0))
 707
 708       ELSEIF(ISUB.EQ.96) THEN
 709 C...Multiple interactions (should be reassigned to QCD process).
 710       ENDIF
 711
 712       ELSEIF(ISUB.LE.110) THEN
 713       IF(ISUB.EQ.101) THEN
 714 C...g + g -> gamma*/Z0.
 715         KCC=21
 716         KFRES=22
 717
 718       ELSEIF(ISUB.EQ.102) THEN
 719 C...g + g -> H0.
 720         KCC=21
 721         KFRES=25
 722       ENDIF
 723
 724       ELSEIF(ISUB.LE.120) THEN
 725       IF(ISUB.EQ.111) THEN
 726 C...f + fb -> g + H0; th arbitrary.
 727         IF(RLU_HIJING(0).GT.0.5) JS=2
 728         MINT(20+JS)=21
 729         MINT(23-JS)=25
 730         KCC=17+JS
 731
 732       ELSEIF(ISUB.EQ.112) THEN
 733 C...f + g -> f + H0; th = (p(f) - p(f))**2.
 734         IF(MINT(15).EQ.21) JS=2
 735         MINT(23-JS)=25
 736         KCC=15+JS
 737         KCS=ISIGN(1,MINT(14+JS))
 738
 739       ELSEIF(ISUB.EQ.113) THEN
 740 C...g + g -> g + H0; th arbitrary.
 741         IF(RLU_HIJING(0).GT.0.5) JS=2
 742         MINT(23-JS)=25
 743         KCC=22+JS
 744         KCS=(-1)**INT(1.5+RLU_HIJING(0))
 745
 746       ELSEIF(ISUB.EQ.114) THEN
 747 C...g + g -> gamma + gamma; th arbitrary.
 748         IF(RLU_HIJING(0).GT.0.5) JS=2
 749         MINT(21)=22
 750         MINT(22)=22
 751         KCC=21
 752
 753       ELSEIF(ISUB.EQ.115) THEN
 754 C...g + g -> gamma + Z0.
 755
 756       ELSEIF(ISUB.EQ.116) THEN
 757 C...g + g -> Z0 + Z0.
 758
 759       ELSEIF(ISUB.EQ.117) THEN
 760 C...g + g -> W+ + W-.
 761       ENDIF
 762
 763       ELSEIF(ISUB.LE.140) THEN
 764       IF(ISUB.EQ.121) THEN
 765 C...g + g -> f + fb + H0.
 766       ENDIF
 767
 768       ELSEIF(ISUB.LE.160) THEN
 769       IF(ISUB.EQ.141) THEN
 770 C...f + fb -> gamma*/Z0/Z'0.
 771         KFRES=32
 772
 773       ELSEIF(ISUB.EQ.142) THEN
 774 C...f + fb' -> H+/-.
 775         KCH1=KCHG(IABS(MINT(15)),1)*ISIGN(1,MINT(15))
 776         KCH2=KCHG(IABS(MINT(16)),1)*ISIGN(1,MINT(16))
 777         KFRES=ISIGN(37,KCH1+KCH2)
 778
 779       ELSEIF(ISUB.EQ.143) THEN
 780 C...f + fb' -> R.
 781         KFRES=ISIGN(40,MINT(15)+MINT(16))
 782       ENDIF
 783
 784       ELSE
 785       IF(ISUB.EQ.161) THEN
 786 C...g + f -> H+/- + f'; th = (p(f)-p(f))**2.
 787         IF(MINT(16).EQ.21) JS=2
 788         IA=IABS(MINT(17-JS))
 789         MINT(20+JS)=ISIGN(37,KCHG(IA,1)*MINT(17-JS))
 790         JA=IA+MOD(IA,2)-MOD(IA+1,2)
 791         MINT(23-JS)=ISIGN(JA,MINT(17-JS))
 792         KCC=18-JS
 793         IF(MINT(15).NE.21) KCS=ISIGN(1,MINT(15))
 794         IF(MINT(16).NE.21) KCS=ISIGN(1,MINT(16))
 795       ENDIF
 796       ENDIF
 797
 798       IF(IDOC.EQ.7) THEN
 799 C...Resonance not decaying: store colour connection indices.
 800         I=MINT(83)+7
 801         K(IPU3,1)=1
 802         K(IPU3,2)=KFRES
 803         K(IPU3,3)=I
 804         P(IPU3,4)=SHUSER
 805         P(IPU3,5)=SHUSER
 806         K(IPU1,4)=IPU2
 807         K(IPU1,5)=IPU2
 808         K(IPU2,4)=IPU1
 809         K(IPU2,5)=IPU1
 810         K(I,1)=21
 811         K(I,2)=KFRES
 812         P(I,4)=SHUSER
 813         P(I,5)=SHUSER
 814         N=IPU3
 815         MINT(21)=KFRES
 816         MINT(22)=0
 817
 818       ELSEIF(IDOC.EQ.8) THEN
 819 C...2 -> 2 processes: store outgoing partons in their CM-frame.
 820         DO 390 JT=1,2
 821         I=MINT(84)+2+JT
 822         K(I,1)=1
 823         IF(IABS(MINT(20+JT)).LE.10.OR.MINT(20+JT).EQ.21) K(I,1)=3
 824         K(I,2)=MINT(20+JT)
 825         K(I,3)=MINT(83)+IDOC+JT-2
 826         IF(IABS(K(I,2)).LE.10.OR.K(I,2).EQ.21) THEN
 827           P(I,5)=ULMASS_HIJING(K(I,2))
 828         ELSE
 829           P(I,5)=SQRT(VINT(63+MOD(JS+JT,2)))
 830         ENDIF
 831   390   CONTINUE
 832         IF(P(IPU3,5)+P(IPU4,5).GE.SHR) THEN
 833           KFA1=IABS(MINT(21))
 834           KFA2=IABS(MINT(22))
 835           IF((KFA1.GT.3.AND.KFA1.NE.21).OR.(KFA2.GT.3.AND.KFA2.NE.21))
 836      &    THEN
 837             MINT(51)=1
 838             RETURN
 839           ENDIF
 840           P(IPU3,5)=0.
 841           P(IPU4,5)=0.
 842         ENDIF
 843         P(IPU3,4)=0.5*(SHR+(P(IPU3,5)**2-P(IPU4,5)**2)/SHR)
 844         P(IPU3,3)=SQRT(MAX(0.,P(IPU3,4)**2-P(IPU3,5)**2))
 845         P(IPU4,4)=SHR-P(IPU3,4)
 846         P(IPU4,3)=-P(IPU3,3)
 847         N=IPU4
 848         MINT(7)=MINT(83)+7
 849         MINT(8)=MINT(83)+8
 850
 851 C...Rotate outgoing partons using cos(theta)=(th-uh)/lam(sh,sqm3,sqm4).
 852         CALL LUDBRB_HIJING(IPU3,IPU4,ACOS(VINT(23)),VINT(24),0D0,0D0,0D0
 853      $       )
 854
 855       ELSEIF(IDOC.EQ.9) THEN
 856 C'''2 -> 3 processes:
 857
 858       ELSEIF(IDOC.EQ.11) THEN
 859 C...Z0 + Z0 -> H0, W+ + W- -> H0: store Higgs and outgoing partons.
 860         PHI(1)=PARU(2)*RLU_HIJING(0)
 861         PHI(2)=PHI(1)-PHIR
 862         DO 400 JT=1,2
 863         I=MINT(84)+2+JT
 864         K(I,1)=1
 865         IF(IABS(MINT(20+JT)).LE.10.OR.MINT(20+JT).EQ.21) K(I,1)=3
 866         K(I,2)=MINT(20+JT)
 867         K(I,3)=MINT(83)+IDOC+JT-2
 868         P(I,5)=ULMASS_HIJING(K(I,2))
 869         IF(0.5*SHPR*Z(JT).LE.P(I,5)) P(I,5)=0.
 870         PABS=SQRT(MAX(0.,(0.5*SHPR*Z(JT))**2-P(I,5)**2))
 871         PTABS=PABS*SQRT(MAX(0.,1.-CTHE(JT)**2))
 872         P(I,1)=PTABS*COS(PHI(JT))
 873         P(I,2)=PTABS*SIN(PHI(JT))
 874         P(I,3)=PABS*CTHE(JT)*(-1)**(JT+1)
 875         P(I,4)=0.5*SHPR*Z(JT)
 876         IZW=MINT(83)+6+JT
 877         K(IZW,1)=21
 878         K(IZW,2)=23
 879         IF(ISUB.EQ.8) K(IZW,2)=ISIGN(24,LUCHGE_HIJING(MINT(14+JT)))
 880         K(IZW,3)=IZW-2
 881         P(IZW,1)=-P(I,1)
 882         P(IZW,2)=-P(I,2)
 883         P(IZW,3)=(0.5*SHPR-PABS*CTHE(JT))*(-1)**(JT+1)
 884         P(IZW,4)=0.5*SHPR*(1.-Z(JT))
 885   400   P(IZW,5)=-SQRT(MAX(0.,P(IZW,3)**2+PTABS**2-P(IZW,4)**2))
 886         I=MINT(83)+9
 887         K(IPU5,1)=1
 888         K(IPU5,2)=KFRES
 889         K(IPU5,3)=I
 890         P(IPU5,5)=SHR
 891         P(IPU5,1)=-P(IPU3,1)-P(IPU4,1)
 892         P(IPU5,2)=-P(IPU3,2)-P(IPU4,2)
 893         P(IPU5,3)=-P(IPU3,3)-P(IPU4,3)
 894         P(IPU5,4)=SHPR-P(IPU3,4)-P(IPU4,4)
 895         K(I,1)=21
 896         K(I,2)=KFRES
 897         DO 410 J=1,5
 898   410   P(I,J)=P(IPU5,J)
 899         N=IPU5
 900         MINT(23)=KFRES
 901
 902       ELSEIF(IDOC.EQ.12) THEN
 903 C...Z0 and W+/- scattering: store bosons and outgoing partons.
 904         PHI(1)=PARU(2)*RLU_HIJING(0)
 905         PHI(2)=PHI(1)-PHIR
 906         DO 420 JT=1,2
 907         I=MINT(84)+2+JT
 908         K(I,1)=1
 909         IF(IABS(MINT(20+JT)).LE.10.OR.MINT(20+JT).EQ.21) K(I,1)=3
 910         K(I,2)=MINT(20+JT)
 911         K(I,3)=MINT(83)+IDOC+JT-2
 912         P(I,5)=ULMASS_HIJING(K(I,2))
 913         IF(0.5*SHPR*Z(JT).LE.P(I,5)) P(I,5)=0.
 914         PABS=SQRT(MAX(0.,(0.5*SHPR*Z(JT))**2-P(I,5)**2))
 915         PTABS=PABS*SQRT(MAX(0.,1.-CTHE(JT)**2))
 916         P(I,1)=PTABS*COS(PHI(JT))
 917         P(I,2)=PTABS*SIN(PHI(JT))
 918         P(I,3)=PABS*CTHE(JT)*(-1)**(JT+1)
 919         P(I,4)=0.5*SHPR*Z(JT)
 920         IZW=MINT(83)+6+JT
 921         K(IZW,1)=21
 922         IF(MINT(14+JT).EQ.MINT(20+JT)) THEN
 923           K(IZW,2)=23
 924         ELSE
 925            K(IZW,2)=ISIGN(24,LUCHGE_HIJING(MINT(14+JT))
 926      $          -LUCHGE_HIJING(MINT(20+JT)))
 927         ENDIF
 928         K(IZW,3)=IZW-2
 929         P(IZW,1)=-P(I,1)
 930         P(IZW,2)=-P(I,2)
 931         P(IZW,3)=(0.5*SHPR-PABS*CTHE(JT))*(-1)**(JT+1)
 932         P(IZW,4)=0.5*SHPR*(1.-Z(JT))
 933         P(IZW,5)=-SQRT(MAX(0.,P(IZW,3)**2+PTABS**2-P(IZW,4)**2))
 934         IPU=MINT(84)+4+JT
 935         K(IPU,1)=3
 936         K(IPU,2)=KFPR(ISUB,JT)
 937         K(IPU,3)=MINT(83)+8+JT
 938         IF(IABS(K(IPU,2)).LE.10.OR.K(IPU,2).EQ.21) THEN
 939           P(IPU,5)=ULMASS_HIJING(K(IPU,2))
 940         ELSE
 941           P(IPU,5)=SQRT(VINT(63+MOD(JS+JT,2)))
 942         ENDIF
 943         MINT(22+JT)=K(IZW,2)
 944   420   CONTINUE
 945         IF(ISUB.EQ.72) K(MINT(84)+4+INT(1.5+RLU_HIJING(0)),2)=-24
 946 C...Find rotation and boost for hard scattering subsystem.
 947         I1=MINT(83)+7
 948         I2=MINT(83)+8
 949         BEXCM=(P(I1,1)+P(I2,1))/(P(I1,4)+P(I2,4))
 950         BEYCM=(P(I1,2)+P(I2,2))/(P(I1,4)+P(I2,4))
 951         BEZCM=(P(I1,3)+P(I2,3))/(P(I1,4)+P(I2,4))
 952         GAMCM=(P(I1,4)+P(I2,4))/SHR
 953         BEPCM=BEXCM*P(I1,1)+BEYCM*P(I1,2)+BEZCM*P(I1,3)
 954         PX=P(I1,1)+GAMCM*(GAMCM/(1.+GAMCM)*BEPCM-P(I1,4))*BEXCM
 955         PY=P(I1,2)+GAMCM*(GAMCM/(1.+GAMCM)*BEPCM-P(I1,4))*BEYCM
 956         PZ=P(I1,3)+GAMCM*(GAMCM/(1.+GAMCM)*BEPCM-P(I1,4))*BEZCM
 957         THECM=ULANGL_HIJING(PZ,SQRT(PX**2+PY**2))
 958         PHICM=ULANGL_HIJING(PX,PY)
 959 C...Store hard scattering subsystem. Rotate and boost it.
 960         SQLAM=(SH-P(IPU5,5)**2-P(IPU6,5)**2)**2-4.*P(IPU5,5)**2*
 961      &  P(IPU6,5)**2
 962         PABS=SQRT(MAX(0.,SQLAM/(4.*SH)))
 963         CTHWZ=VINT(23)
 964         STHWZ=SQRT(MAX(0.,1.-CTHWZ**2))
 965         PHIWZ=VINT(24)-PHICM
 966         P(IPU5,1)=PABS*STHWZ*COS(PHIWZ)
 967         P(IPU5,2)=PABS*STHWZ*SIN(PHIWZ)
 968         P(IPU5,3)=PABS*CTHWZ
 969         P(IPU5,4)=SQRT(PABS**2+P(IPU5,5)**2)
 970         P(IPU6,1)=-P(IPU5,1)
 971         P(IPU6,2)=-P(IPU5,2)
 972         P(IPU6,3)=-P(IPU5,3)
 973         P(IPU6,4)=SQRT(PABS**2+P(IPU6,5)**2)
 974         CALL LUDBRB_HIJING(IPU5,IPU6,THECM,PHICM,DBLE(BEXCM),DBLE(BEYCM)
 975      $       ,DBLE(BEZCM))
 976         DO 430 JT=1,2
 977         I1=MINT(83)+8+JT
 978         I2=MINT(84)+4+JT
 979         K(I1,1)=21
 980         K(I1,2)=K(I2,2)
 981         DO 430 J=1,5
 982   430   P(I1,J)=P(I2,J)
 983         N=IPU6
 984         MINT(7)=MINT(83)+9
 985         MINT(8)=MINT(83)+10
 986       ENDIF
 987
 988       IF(IDOC.GE.8) THEN
 989 C...Store colour connection indices.
 990         DO 440 J=1,2
 991         JC=J
 992         IF(KCS.EQ.-1) JC=3-J
 993         IF(ICOL(KCC,1,JC).NE.0.AND.K(IPU1,1).EQ.14) K(IPU1,J+3)=
 994      &  K(IPU1,J+3)+MINT(84)+ICOL(KCC,1,JC)
 995         IF(ICOL(KCC,2,JC).NE.0.AND.K(IPU2,1).EQ.14) K(IPU2,J+3)=
 996      &  K(IPU2,J+3)+MINT(84)+ICOL(KCC,2,JC)
 997         IF(ICOL(KCC,3,JC).NE.0.AND.K(IPU3,1).EQ.3) K(IPU3,J+3)=
 998      &  MSTU(5)*(MINT(84)+ICOL(KCC,3,JC))
 999   440   IF(ICOL(KCC,4,JC).NE.0.AND.K(IPU4,1).EQ.3) K(IPU4,J+3)=
1000      &  MSTU(5)*(MINT(84)+ICOL(KCC,4,JC))
1001
1002 C...Copy outgoing partons to documentation lines.
1003         DO 450 I=1,2
1004         I1=MINT(83)+IDOC-2+I
1005         I2=MINT(84)+2+I
1006         K(I1,1)=21
1007         K(I1,2)=K(I2,2)
1008         IF(IDOC.LE.9) K(I1,3)=0
1009         IF(IDOC.GE.11) K(I1,3)=MINT(83)+2+I
1010         DO 450 J=1,5
1011   450   P(I1,J)=P(I2,J)
1012       ENDIF
1013       MINT(52)=N
1014
1015 C...Low-pT events: remove gluons used for string drawing purposes.
1016       IF(ISUB.EQ.95) THEN
1017         K(IPU3,1)=K(IPU3,1)+10
1018         K(IPU4,1)=K(IPU4,1)+10
1019         DO 460 J=41,66
1020   460   VINT(J)=0.
1021         DO 470 I=MINT(83)+5,MINT(83)+8
1022         DO 470 J=1,5
1023   470   P(I,J)=0.
1024       ENDIF
1025
1026       RETURN
1027       END