HIJING/hipyset1_35/pysigh_hijing.F

   1 * $Id$
   2
   3 C***********************************************************************
   4
   5       SUBROUTINE PYSIGH_HIJING(NCHN,SIGS)
   6
   7 C...Differential matrix elements for all included subprocesses.
   8 C...Note that what is coded is (disregarding the COMFAC factor)
   9 C...1) for 2 -> 1 processes: s-hat/pi*d(sigma-hat), where,
  10 C...when d(sigma-hat) is given in the zero-width limit, the delta
  11 C...function in tau is replaced by a Breit-Wigner:
  12 C...1/pi*(s*m_res*Gamma_res)/((s*tau-m_res^2)^2+(m_res*Gamma_res)^2);
  13 C...2) for 2 -> 2 processes: (s-hat)**2/pi*d(sigma-hat)/d(t-hat);
  14 C...i.e., dimensionless quantities. COMFAC contains the factor
  15 C...pi/s and the conversion factor from GeV^-2 to mb.
  16 #include "ludat1_hijing.inc"
  17 #include "ludat2_hijing.inc"
  18 #include "ludat3_hijing.inc"
  19 #include "pysubs_hijing.inc"
  20 #include "pypars_hijing.inc"
  21 #include "pyint1_hijing.inc"
  22 #include "pyint2_hijing.inc"
  23 #include "pyint3_hijing.inc"
  24 #include "pyint4_hijing.inc"
  25 #include "pyint5_hijing.inc"
  26       DIMENSION X(2),XPQ(-6:6),KFAC(2,-40:40),WDTP(0:40),WDTE(0:40,0:5)
  27
  28 C...Reset number of channels and cross-section.
  29       NCHN=0
  30       SIGS=0.
  31
  32 C...Read kinematical variables and limits.
  33       ISUB=MINT(1)
  34       TAUMIN=VINT(11)
  35       YSTMIN=VINT(12)
  36       CTNMIN=VINT(13)
  37       CTPMIN=VINT(14)
  38       XT2MIN=VINT(15)
  39       TAUPMN=VINT(16)
  40       TAU=VINT(21)
  41       YST=VINT(22)
  42       CTH=VINT(23)
  43       XT2=VINT(25)
  44       TAUP=VINT(26)
  45       TAUMAX=VINT(31)
  46       YSTMAX=VINT(32)
  47       CTNMAX=VINT(33)
  48       CTPMAX=VINT(34)
  49       XT2MAX=VINT(35)
  50       TAUPMX=VINT(36)
  51
  52 C...Derive kinematical quantities.
  53       IF(ISET(ISUB).LE.2.OR.ISET(ISUB).EQ.5) THEN
  54         X(1)=SQRT(TAU)*EXP(YST)
  55         X(2)=SQRT(TAU)*EXP(-YST)
  56       ELSE
  57         X(1)=SQRT(TAUP)*EXP(YST)
  58         X(2)=SQRT(TAUP)*EXP(-YST)
  59       ENDIF
  60       IF(MINT(43).EQ.4.AND.ISET(ISUB).GE.1.AND.
  61      &(X(1).GT.0.999.OR.X(2).GT.0.999)) RETURN
  62       SH=TAU*VINT(2)
  63       SQM3=VINT(63)
  64       SQM4=VINT(64)
  65       RM3=SQM3/SH
  66       RM4=SQM4/SH
  67       BE34=SQRT((1.-RM3-RM4)**2-4.*RM3*RM4)
  68       RPTS=4.*VINT(71)**2/SH
  69       BE34L=SQRT(MAX(0.,(1.-RM3-RM4)**2-4.*RM3*RM4-RPTS))
  70       RM34=2.*RM3*RM4
  71       RSQM=1.+RM34
  72       RTHM=(4.*RM3*RM4+RPTS)/(1.-RM3-RM4+BE34L)
  73       TH=-0.5*SH*MAX(RTHM,1.-RM3-RM4-BE34*CTH)
  74       UH=-0.5*SH*MAX(RTHM,1.-RM3-RM4+BE34*CTH)
  75       SQPTH=0.25*SH*BE34**2*(1.-CTH**2)
  76       SH2=SH**2
  77       TH2=TH**2
  78       UH2=UH**2
  79
  80 C...Choice of Q2 scale.
  81       IF(ISET(ISUB).EQ.1.OR.ISET(ISUB).EQ.3) THEN
  82         Q2=SH
  83       ELSEIF(MOD(ISET(ISUB),2).EQ.0.OR.ISET(ISUB).EQ.5) THEN
  84         IF(MSTP(32).EQ.1) THEN
  85           Q2=2.*SH*TH*UH/(SH**2+TH**2+UH**2)
  86         ELSEIF(MSTP(32).EQ.2) THEN
  87           Q2=SQPTH+0.5*(SQM3+SQM4)
  88         ELSEIF(MSTP(32).EQ.3) THEN
  89           Q2=MIN(-TH,-UH)
  90         ELSEIF(MSTP(32).EQ.4) THEN
  91           Q2=SH
  92         ENDIF
  93         IF(ISET(ISUB).EQ.5.AND.MSTP(82).GE.2) Q2=Q2+PARP(82)**2
  94       ENDIF
  95
  96 C...Store derived kinematical quantities.
  97       VINT(41)=X(1)
  98       VINT(42)=X(2)
  99       VINT(44)=SH
 100       VINT(43)=SQRT(SH)
 101       VINT(45)=TH
 102       VINT(46)=UH
 103       VINT(48)=SQPTH
 104       VINT(47)=SQRT(SQPTH)
 105       VINT(50)=TAUP*VINT(2)
 106       VINT(49)=SQRT(MAX(0.,VINT(50)))
 107       VINT(52)=Q2
 108       VINT(51)=SQRT(Q2)
 109
 110 C...Calculate parton structure functions.
 111       IF(ISET(ISUB).LE.0) GOTO 145
 112       IF(MINT(43).GE.2) THEN
 113         Q2SF=Q2
 114         IF(ISET(ISUB).EQ.3.OR.ISET(ISUB).EQ.4) THEN
 115           Q2SF=PMAS(23,1)**2
 116           IF(ISUB.EQ.8.OR.ISUB.EQ.76.OR.ISUB.EQ.77) Q2SF=PMAS(24,1)**2
 117         ENDIF
 118         DO 100 I=3-MINT(41),MINT(42)
 119         XSF=X(I)
 120         IF(ISET(ISUB).EQ.5) XSF=X(I)/VINT(142+I)
 121         CALL PYSTFU_HIJING(MINT(10+I),XSF,Q2SF,XPQ,I)
 122         DO 100 KFL=-6,6
 123   100   XSFX(I,KFL)=XPQ(KFL)
 124       ENDIF
 125
 126 C...Calculate alpha_strong and K-factor.
 127       IF(MSTP(33).NE.3) AS=ULALPS_HIJING(Q2)
 128       FACK=1.
 129       FACA=1.
 130       IF(MSTP(33).EQ.1) THEN
 131         FACK=PARP(31)
 132       ELSEIF(MSTP(33).EQ.2) THEN
 133         FACK=PARP(31)
 134         FACA=PARP(32)/PARP(31)
 135       ELSEIF(MSTP(33).EQ.3) THEN
 136         Q2AS=PARP(33)*Q2
 137         IF(ISET(ISUB).EQ.5.AND.MSTP(82).GE.2) Q2AS=Q2AS+
 138      &  PARU(112)*PARP(82)
 139         AS=ULALPS_HIJING(Q2AS)
 140       ENDIF
 141       RADC=1.+AS/PARU(1)
 142
 143 C...Set flags for allowed reacting partons/leptons.
 144       DO 130 I=1,2
 145       DO 110 J=-40,40
 146   110 KFAC(I,J)=0
 147       IF(MINT(40+I).EQ.1) THEN
 148         KFAC(I,MINT(10+I))=1
 149       ELSE
 150         DO 120 J=-40,40
 151         KFAC(I,J)=KFIN(I,J)
 152         IF(ABS(J).GT.MSTP(54).AND.J.NE.21) KFAC(I,J)=0
 153         IF(ABS(J).LE.6) THEN
 154           IF(XSFX(I,J).LT.1.E-10) KFAC(I,J)=0
 155         ELSEIF(J.EQ.21) THEN
 156           IF(XSFX(I,0).LT.1.E-10) KFAC(I,21)=0
 157         ENDIF
 158   120   CONTINUE
 159       ENDIF
 160   130 CONTINUE
 161
 162 C...Lower and upper limit for flavour loops.
 163       MIN1=0
 164       MAX1=0
 165       MIN2=0
 166       MAX2=0
 167       DO 140 J=-20,20
 168       IF(KFAC(1,-J).EQ.1) MIN1=-J
 169       IF(KFAC(1,J).EQ.1) MAX1=J
 170       IF(KFAC(2,-J).EQ.1) MIN2=-J
 171       IF(KFAC(2,J).EQ.1) MAX2=J
 172   140 CONTINUE
 173       MINA=MIN(MIN1,MIN2)
 174       MAXA=MAX(MAX1,MAX2)
 175
 176 C...Common conversion factors (including Jacobian) for subprocesses.
 177       SQMZ=PMAS(23,1)**2
 178       GMMZ=PMAS(23,1)*PMAS(23,2)
 179       SQMW=PMAS(24,1)**2
 180       GMMW=PMAS(24,1)*PMAS(24,2)
 181       SQMH=PMAS(25,1)**2
 182       GMMH=PMAS(25,1)*PMAS(25,2)
 183       SQMZP=PMAS(32,1)**2
 184       GMMZP=PMAS(32,1)*PMAS(32,2)
 185       SQMHC=PMAS(37,1)**2
 186       GMMHC=PMAS(37,1)*PMAS(37,2)
 187       SQMR=PMAS(40,1)**2
 188       GMMR=PMAS(40,1)*PMAS(40,2)
 189       AEM=PARU(101)
 190       XW=PARU(102)
 191
 192 C...Phase space integral in tau and y*.
 193       COMFAC=PARU(1)*PARU(5)/VINT(2)
 194       IF(MINT(43).EQ.4) COMFAC=COMFAC*FACK
 195       IF((MINT(43).GE.2.OR.ISET(ISUB).EQ.3.OR.ISET(ISUB).EQ.4).AND.
 196      &ISET(ISUB).NE.5) THEN
 197         ATAU0=LOG(TAUMAX/TAUMIN)
 198         ATAU1=(TAUMAX-TAUMIN)/(TAUMAX*TAUMIN)
 199         H1=COEF(ISUB,1)+(ATAU0/ATAU1)*COEF(ISUB,2)/TAU
 200         IF(MINT(72).GE.1) THEN
 201           TAUR1=VINT(73)
 202           GAMR1=VINT(74)
 203           ATAU2=LOG(TAUMAX/TAUMIN*(TAUMIN+TAUR1)/(TAUMAX+TAUR1))/TAUR1
 204           ATAU3=(ATAN((TAUMAX-TAUR1)/GAMR1)-ATAN((TAUMIN-TAUR1)/GAMR1))/
 205      &    GAMR1
 206           H1=H1+(ATAU0/ATAU2)*COEF(ISUB,3)/(TAU+TAUR1)+
 207      &    (ATAU0/ATAU3)*COEF(ISUB,4)*TAU/((TAU-TAUR1)**2+GAMR1**2)
 208         ENDIF
 209         IF(MINT(72).EQ.2) THEN
 210           TAUR2=VINT(75)
 211           GAMR2=VINT(76)
 212           ATAU4=LOG(TAUMAX/TAUMIN*(TAUMIN+TAUR2)/(TAUMAX+TAUR2))/TAUR2
 213           ATAU5=(ATAN((TAUMAX-TAUR2)/GAMR2)-ATAN((TAUMIN-TAUR2)/GAMR2))/
 214      &    GAMR2
 215           H1=H1+(ATAU0/ATAU4)*COEF(ISUB,5)/(TAU+TAUR2)+
 216      &    (ATAU0/ATAU5)*COEF(ISUB,6)*TAU/((TAU-TAUR2)**2+GAMR2**2)
 217         ENDIF
 218         COMFAC=COMFAC*ATAU0/(TAU*H1)
 219       ENDIF
 220       IF(MINT(43).EQ.4.AND.ISET(ISUB).NE.5) THEN
 221         AYST0=YSTMAX-YSTMIN
 222         AYST1=0.5*(YSTMAX-YSTMIN)**2
 223         AYST2=AYST1
 224         AYST3=2.*(ATAN(EXP(YSTMAX))-ATAN(EXP(YSTMIN)))
 225         H2=(AYST0/AYST1)*COEF(ISUB,7)*(YST-YSTMIN)+(AYST0/AYST2)*
 226      &  COEF(ISUB,8)*(YSTMAX-YST)+(AYST0/AYST3)*COEF(ISUB,9)/COSH(YST)
 227         COMFAC=COMFAC*AYST0/H2
 228       ENDIF
 229
 230 C...2 -> 1 processes: reduction in angular part of phase space integral
 231 C...for case of decaying resonance.
 232       ACTH0=CTNMAX-CTNMIN+CTPMAX-CTPMIN
 233       IF((ISET(ISUB).EQ.1.OR.ISET(ISUB).EQ.3).AND.
 234      &MDCY(KFPR(ISUB,1),1).EQ.1) THEN
 235         IF(KFPR(ISUB,1).EQ.25.OR.KFPR(ISUB,1).EQ.37) THEN
 236           COMFAC=COMFAC*0.5*ACTH0
 237         ELSE
 238           COMFAC=COMFAC*0.125*(3.*ACTH0+CTNMAX**3-CTNMIN**3+
 239      &    CTPMAX**3-CTPMIN**3)
 240         ENDIF
 241
 242 C...2 -> 2 processes: angular part of phase space integral.
 243       ELSEIF(ISET(ISUB).EQ.2.OR.ISET(ISUB).EQ.4) THEN
 244         ACTH1=LOG((MAX(RM34,RSQM-CTNMIN)*MAX(RM34,RSQM-CTPMIN))/
 245      &  (MAX(RM34,RSQM-CTNMAX)*MAX(RM34,RSQM-CTPMAX)))
 246         ACTH2=LOG((MAX(RM34,RSQM+CTNMAX)*MAX(RM34,RSQM+CTPMAX))/
 247      &  (MAX(RM34,RSQM+CTNMIN)*MAX(RM34,RSQM+CTPMIN)))
 248         ACTH3=1./MAX(RM34,RSQM-CTNMAX)-1./MAX(RM34,RSQM-CTNMIN)+
 249      &  1./MAX(RM34,RSQM-CTPMAX)-1./MAX(RM34,RSQM-CTPMIN)
 250         ACTH4=1./MAX(RM34,RSQM+CTNMIN)-1./MAX(RM34,RSQM+CTNMAX)+
 251      &  1./MAX(RM34,RSQM+CTPMIN)-1./MAX(RM34,RSQM+CTPMAX)
 252         H3=COEF(ISUB,10)+
 253      &  (ACTH0/ACTH1)*COEF(ISUB,11)/MAX(RM34,RSQM-CTH)+
 254      &  (ACTH0/ACTH2)*COEF(ISUB,12)/MAX(RM34,RSQM+CTH)+
 255      &  (ACTH0/ACTH3)*COEF(ISUB,13)/MAX(RM34,RSQM-CTH)**2+
 256      &  (ACTH0/ACTH4)*COEF(ISUB,14)/MAX(RM34,RSQM+CTH)**2
 257         COMFAC=COMFAC*ACTH0*0.5*BE34/H3
 258       ENDIF
 259
 260 C...2 -> 3, 4 processes: phace space integral in tau'.
 261       IF(MINT(43).GE.2.AND.(ISET(ISUB).EQ.3.OR.ISET(ISUB).EQ.4)) THEN
 262         ATAUP0=LOG(TAUPMX/TAUPMN)
 263         ATAUP1=((1.-TAU/TAUPMX)**4-(1.-TAU/TAUPMN)**4)/(4.*TAU)
 264         H4=COEF(ISUB,15)+
 265      &  ATAUP0/ATAUP1*COEF(ISUB,16)/TAUP*(1.-TAU/TAUP)**3
 266         IF(1.-TAU/TAUP.GT.1.E-4) THEN
 267           FZW=(1.+TAU/TAUP)*LOG(TAUP/TAU)-2.*(1.-TAU/TAUP)
 268         ELSE
 269           FZW=1./6.*(1.-TAU/TAUP)**3*TAU/TAUP
 270         ENDIF
 271         COMFAC=COMFAC*ATAUP0*FZW/H4
 272       ENDIF
 273
 274 C...Phase space integral for low-pT and multiple interactions.
 275       IF(ISET(ISUB).EQ.5) THEN
 276         COMFAC=PARU(1)*PARU(5)*FACK*0.5*VINT(2)/SH2
 277         ATAU0=LOG(2.*(1.+SQRT(1.-XT2))/XT2-1.)
 278         ATAU1=2.*ATAN(1./XT2-1.)/SQRT(XT2)
 279         H1=COEF(ISUB,1)+(ATAU0/ATAU1)*COEF(ISUB,2)/SQRT(TAU)
 280         COMFAC=COMFAC*ATAU0/H1
 281         AYST0=YSTMAX-YSTMIN
 282         AYST1=0.5*(YSTMAX-YSTMIN)**2
 283         AYST3=2.*(ATAN(EXP(YSTMAX))-ATAN(EXP(YSTMIN)))
 284         H2=(AYST0/AYST1)*COEF(ISUB,7)*(YST-YSTMIN)+(AYST0/AYST1)*
 285      &  COEF(ISUB,8)*(YSTMAX-YST)+(AYST0/AYST3)*COEF(ISUB,9)/COSH(YST)
 286         COMFAC=COMFAC*AYST0/H2
 287         IF(MSTP(82).LE.1) COMFAC=COMFAC*XT2**2*(1./VINT(149)-1.)
 288 C...For MSTP(82)>=2 an additional factor (xT2/(xT2+VINT(149))**2 is
 289 C...introduced to make cross-section finite for xT2 -> 0.
 290         IF(MSTP(82).GE.2) COMFAC=COMFAC*XT2**2/(VINT(149)*
 291      &  (1.+VINT(149)))
 292       ENDIF
 293
 294 C...A: 2 -> 1, tree diagrams.
 295
 296   145 IF(ISUB.LE.10) THEN
 297       IF(ISUB.EQ.1) THEN
 298 C...f + fb -> gamma*/Z0.
 299         MINT(61)=2
 300         CALL PYWIDT_HIJING(23,SQRT(SH),WDTP,WDTE)
 301         FACZ=COMFAC*AEM**2*4./3.
 302         DO 150 I=MINA,MAXA
 303         IF(I.EQ.0.OR.KFAC(1,I)*KFAC(2,-I).EQ.0) GOTO 150
 304         EI=KCHG(IABS(I),1)/3.
 305         AI=SIGN(1.,EI)
 306         VI=AI-4.*EI*XW
 307         FACF=1.
 308         IF(IABS(I).LE.10) FACF=FACA/3.
 309         NCHN=NCHN+1
 310         ISIG(NCHN,1)=I
 311         ISIG(NCHN,2)=-I
 312         ISIG(NCHN,3)=1
 313         SIGH(NCHN)=FACF*FACZ*(EI**2*VINT(111)+EI*VI/(8.*XW*(1.-XW))*
 314      &  SH*(SH-SQMZ)/((SH-SQMZ)**2+GMMZ**2)*VINT(112)+(VI**2+AI**2)/
 315      &  (16.*XW*(1.-XW))**2*SH2/((SH-SQMZ)**2+GMMZ**2)*VINT(114))
 316   150   CONTINUE
 317
 318       ELSEIF(ISUB.EQ.2) THEN
 319 C...f + fb' -> W+/-.
 320         CALL PYWIDT_HIJING(24,SQRT(SH),WDTP,WDTE)
 321         FACW=COMFAC*(AEM/XW)**2*1./24*SH2/((SH-SQMW)**2+GMMW**2)
 322         DO 170 I=MIN1,MAX1
 323         IF(I.EQ.0.OR.KFAC(1,I).EQ.0) GOTO 170
 324         IA=IABS(I)
 325         DO 160 J=MIN2,MAX2
 326         IF(J.EQ.0.OR.KFAC(2,J).EQ.0) GOTO 160
 327         JA=IABS(J)
 328         IF(I*J.GT.0.OR.MOD(IA+JA,2).EQ.0) GOTO 160
 329         IF((IA.LE.10.AND.JA.GT.10).OR.(IA.GT.10.AND.JA.LE.10)) GOTO 160
 330         KCHW=(KCHG(IA,1)*ISIGN(1,I)+KCHG(JA,1)*ISIGN(1,J))/3
 331         FACF=1.
 332         IF(IA.LE.10) FACF=VCKM((IA+1)/2,(JA+1)/2)*FACA/3.
 333         NCHN=NCHN+1
 334         ISIG(NCHN,1)=I
 335         ISIG(NCHN,2)=J
 336         ISIG(NCHN,3)=1
 337         SIGH(NCHN)=FACF*FACW*(WDTE(0,1)+WDTE(0,(5-KCHW)/2)+WDTE(0,4))
 338   160   CONTINUE
 339   170   CONTINUE
 340
 341       ELSEIF(ISUB.EQ.3) THEN
 342 C...f + fb -> H0.
 343         CALL PYWIDT_HIJING(25,SQRT(SH),WDTP,WDTE)
 344         FACH=COMFAC*(AEM/XW)**2*1./48.*(SH/SQMW)**2*
 345      &  SH2/((SH-SQMH)**2+GMMH**2)*(WDTE(0,1)+WDTE(0,2)+WDTE(0,4))
 346         DO 180 I=MINA,MAXA
 347         IF(I.EQ.0.OR.KFAC(1,I)*KFAC(2,-I).EQ.0) GOTO 180
 348         RMQ=PMAS(IABS(I),1)**2/SH
 349         NCHN=NCHN+1
 350         ISIG(NCHN,1)=I
 351         ISIG(NCHN,2)=-I
 352         ISIG(NCHN,3)=1
 353         SIGH(NCHN)=FACH*RMQ*SQRT(MAX(0.,1.-4.*RMQ))
 354   180   CONTINUE
 355
 356       ELSEIF(ISUB.EQ.4) THEN
 357 C...gamma + W+/- -> W+/-.
 358
 359       ELSEIF(ISUB.EQ.5) THEN
 360 C...Z0 + Z0 -> H0.
 361         CALL PYWIDT_HIJING(25,SQRT(SH),WDTP,WDTE)
 362         FACH=COMFAC*1./(128.*PARU(1)**2*16.*(1.-XW)**3)*(AEM/XW)**4*
 363      &  (SH/SQMW)**2*SH2/((SH-SQMH)**2+GMMH**2)*
 364      &  (WDTE(0,1)+WDTE(0,2)+WDTE(0,4))
 365         DO 200 I=MIN1,MAX1
 366         IF(I.EQ.0.OR.KFAC(1,I).EQ.0) GOTO 200
 367         DO 190 J=MIN2,MAX2
 368         IF(J.EQ.0.OR.KFAC(2,J).EQ.0) GOTO 190
 369         EI=KCHG(IABS(I),1)/3.
 370         AI=SIGN(1.,EI)
 371         VI=AI-4.*EI*XW
 372         EJ=KCHG(IABS(J),1)/3.
 373         AJ=SIGN(1.,EJ)
 374         VJ=AJ-4.*EJ*XW
 375         NCHN=NCHN+1
 376         ISIG(NCHN,1)=I
 377         ISIG(NCHN,2)=J
 378         ISIG(NCHN,3)=1
 379         SIGH(NCHN)=FACH*(VI**2+AI**2)*(VJ**2+AJ**2)
 380   190   CONTINUE
 381   200   CONTINUE
 382
 383       ELSEIF(ISUB.EQ.6) THEN
 384 C...Z0 + W+/- -> W+/-.
 385
 386       ELSEIF(ISUB.EQ.7) THEN
 387 C...W+ + W- -> Z0.
 388
 389       ELSEIF(ISUB.EQ.8) THEN
 390 C...W+ + W- -> H0.
 391         CALL PYWIDT_HIJING(25,SQRT(SH),WDTP,WDTE)
 392         FACH=COMFAC*1./(128*PARU(1)**2)*(AEM/XW)**4*(SH/SQMW)**2*
 393      &  SH2/((SH-SQMH)**2+GMMH**2)*(WDTE(0,1)+WDTE(0,2)+WDTE(0,4))
 394         DO 220 I=MIN1,MAX1
 395         IF(I.EQ.0.OR.KFAC(1,I).EQ.0) GOTO 220
 396         EI=SIGN(1.,FLOAT(I))*KCHG(IABS(I),1)
 397         DO 210 J=MIN2,MAX2
 398         IF(J.EQ.0.OR.KFAC(2,J).EQ.0) GOTO 210
 399         EJ=SIGN(1.,FLOAT(J))*KCHG(IABS(J),1)
 400         IF(EI*EJ.GT.0.) GOTO 210
 401         NCHN=NCHN+1
 402         ISIG(NCHN,1)=I
 403         ISIG(NCHN,2)=J
 404         ISIG(NCHN,3)=1
 405         SIGH(NCHN)=FACH*VINT(180+I)*VINT(180+J)
 406   210   CONTINUE
 407   220   CONTINUE
 408       ENDIF
 409
 410 C...B: 2 -> 2, tree diagrams.
 411
 412       ELSEIF(ISUB.LE.20) THEN
 413       IF(ISUB.EQ.11) THEN
 414 C...f + f' -> f + f'.
 415         FACQQ1=COMFAC*AS**2*4./9.*(SH2+UH2)/TH2
 416         FACQQB=COMFAC*AS**2*4./9.*((SH2+UH2)/TH2*FACA-
 417      &  MSTP(34)*2./3.*UH2/(SH*TH))
 418         FACQQ2=COMFAC*AS**2*4./9.*((SH2+TH2)/UH2-
 419      &  MSTP(34)*2./3.*SH2/(TH*UH))
 420         DO 240 I=MIN1,MAX1
 421         IF(I.EQ.0.OR.KFAC(1,I).EQ.0) GOTO 240
 422         DO 230 J=MIN2,MAX2
 423         IF(J.EQ.0.OR.KFAC(2,J).EQ.0) GOTO 230
 424         NCHN=NCHN+1
 425         ISIG(NCHN,1)=I
 426         ISIG(NCHN,2)=J
 427         ISIG(NCHN,3)=1
 428         SIGH(NCHN)=FACQQ1
 429         IF(I.EQ.-J) SIGH(NCHN)=FACQQB
 430         IF(I.EQ.J) THEN
 431           SIGH(NCHN)=0.5*SIGH(NCHN)
 432           NCHN=NCHN+1
 433           ISIG(NCHN,1)=I
 434           ISIG(NCHN,2)=J
 435           ISIG(NCHN,3)=2
 436           SIGH(NCHN)=0.5*FACQQ2
 437         ENDIF
 438   230   CONTINUE
 439   240   CONTINUE
 440
 441       ELSEIF(ISUB.EQ.12) THEN
 442 C...f + fb -> f' + fb' (q + qb -> q' + qb' only).
 443         CALL PYWIDT_HIJING(21,SQRT(SH),WDTP,WDTE)
 444         FACQQB=COMFAC*AS**2*4./9.*(TH2+UH2)/SH2*(WDTE(0,1)+WDTE(0,2)+
 445      &  WDTE(0,3)+WDTE(0,4))
 446         DO 250 I=MINA,MAXA
 447         IF(I.EQ.0.OR.KFAC(1,I)*KFAC(2,-I).EQ.0) GOTO 250
 448         NCHN=NCHN+1
 449         ISIG(NCHN,1)=I
 450         ISIG(NCHN,2)=-I
 451         ISIG(NCHN,3)=1
 452         SIGH(NCHN)=FACQQB
 453   250   CONTINUE
 454
 455       ELSEIF(ISUB.EQ.13) THEN
 456 C...f + fb -> g + g (q + qb -> g + g only).
 457         FACGG1=COMFAC*AS**2*32./27.*(UH/TH-(2.+MSTP(34)*1./4.)*UH2/SH2)
 458         FACGG2=COMFAC*AS**2*32./27.*(TH/UH-(2.+MSTP(34)*1./4.)*TH2/SH2)
 459         DO 260 I=MINA,MAXA
 460         IF(I.EQ.0.OR.KFAC(1,I)*KFAC(2,-I).EQ.0) GOTO 260
 461         NCHN=NCHN+1
 462         ISIG(NCHN,1)=I
 463         ISIG(NCHN,2)=-I
 464         ISIG(NCHN,3)=1
 465         SIGH(NCHN)=0.5*FACGG1
 466         NCHN=NCHN+1
 467         ISIG(NCHN,1)=I
 468         ISIG(NCHN,2)=-I
 469         ISIG(NCHN,3)=2
 470         SIGH(NCHN)=0.5*FACGG2
 471   260   CONTINUE
 472
 473       ELSEIF(ISUB.EQ.14) THEN
 474 C...f + fb -> g + gamma (q + qb -> g + gamma only).
 475         FACGG=COMFAC*AS*AEM*8./9.*(TH2+UH2)/(TH*UH)
 476         DO 270 I=MINA,MAXA
 477         IF(I.EQ.0.OR.KFAC(1,I)*KFAC(2,-I).EQ.0) GOTO 270
 478         EI=KCHG(IABS(I),1)/3.
 479         NCHN=NCHN+1
 480         ISIG(NCHN,1)=I
 481         ISIG(NCHN,2)=-I
 482         ISIG(NCHN,3)=1
 483         SIGH(NCHN)=FACGG*EI**2
 484   270   CONTINUE
 485
 486       ELSEIF(ISUB.EQ.15) THEN
 487 C...f + fb -> g + Z0 (q + qb -> g + Z0 only).
 488         FACZG=COMFAC*AS*AEM/(XW*(1.-XW))*1./18.*
 489      &  (TH2+UH2+2.*SQM4*SH)/(TH*UH)
 490         FACZG=FACZG*WIDS(23,2)
 491         DO 280 I=MINA,MAXA
 492         IF(I.EQ.0.OR.KFAC(1,I)*KFAC(2,-I).EQ.0) GOTO 280
 493         EI=KCHG(IABS(I),1)/3.
 494         AI=SIGN(1.,EI)
 495         VI=AI-4.*EI*XW
 496         NCHN=NCHN+1
 497         ISIG(NCHN,1)=I
 498         ISIG(NCHN,2)=-I
 499         ISIG(NCHN,3)=1
 500         SIGH(NCHN)=FACZG*(VI**2+AI**2)
 501   280   CONTINUE
 502
 503       ELSEIF(ISUB.EQ.16) THEN
 504 C...f + fb' -> g + W+/- (q + qb' -> g + W+/- only).
 505         FACWG=COMFAC*AS*AEM/XW*2./9.*(TH2+UH2+2.*SQM4*SH)/(TH*UH)
 506         DO 300 I=MIN1,MAX1
 507         IF(I.EQ.0.OR.KFAC(1,I).EQ.0) GOTO 300
 508         IA=IABS(I)
 509         DO 290 J=MIN2,MAX2
 510         IF(J.EQ.0.OR.KFAC(2,J).EQ.0) GOTO 290
 511         JA=IABS(J)
 512         IF(I*J.GT.0.OR.MOD(IA+JA,2).EQ.0) GOTO 290
 513         KCHW=(KCHG(IA,1)*ISIGN(1,I)+KCHG(JA,1)*ISIGN(1,J))/3
 514         FCKM=1.
 515         IF(MINT(43).EQ.4) FCKM=VCKM((IA+1)/2,(JA+1)/2)
 516         NCHN=NCHN+1
 517         ISIG(NCHN,1)=I
 518         ISIG(NCHN,2)=J
 519         ISIG(NCHN,3)=1
 520         SIGH(NCHN)=FACWG*FCKM*WIDS(24,(5-KCHW)/2)
 521   290   CONTINUE
 522   300   CONTINUE
 523
 524       ELSEIF(ISUB.EQ.17) THEN
 525 C...f + fb -> g + H0 (q + qb -> g + H0 only).
 526
 527       ELSEIF(ISUB.EQ.18) THEN
 528 C...f + fb -> gamma + gamma.
 529         FACGG=COMFAC*FACA*AEM**2*1./3.*(TH2+UH2)/(TH*UH)
 530         DO 310 I=MINA,MAXA
 531         IF(I.EQ.0.OR.KFAC(1,I)*KFAC(2,-I).EQ.0) GOTO 310
 532         EI=KCHG(IABS(I),1)/3.
 533         NCHN=NCHN+1
 534         ISIG(NCHN,1)=I
 535         ISIG(NCHN,2)=-I
 536         ISIG(NCHN,3)=1
 537         SIGH(NCHN)=FACGG*EI**4
 538   310   CONTINUE
 539
 540       ELSEIF(ISUB.EQ.19) THEN
 541 C...f + fb -> gamma + Z0.
 542         FACGZ=COMFAC*FACA*AEM**2/(XW*(1.-XW))*1./24.*
 543      &  (TH2+UH2+2.*SQM4*SH)/(TH*UH)
 544         FACGZ=FACGZ*WIDS(23,2)
 545         DO 320 I=MINA,MAXA
 546         IF(I.EQ.0.OR.KFAC(1,I)*KFAC(2,-I).EQ.0) GOTO 320
 547         EI=KCHG(IABS(I),1)/3.
 548         AI=SIGN(1.,EI)
 549         VI=AI-4.*EI*XW
 550         NCHN=NCHN+1
 551         ISIG(NCHN,1)=I
 552         ISIG(NCHN,2)=-I
 553         ISIG(NCHN,3)=1
 554         SIGH(NCHN)=FACGZ*EI**2*(VI**2+AI**2)
 555   320   CONTINUE
 556
 557       ELSEIF(ISUB.EQ.20) THEN
 558 C...f + fb' -> gamma + W+/-.
 559         FACGW=COMFAC*FACA*AEM**2/XW*1./6.*
 560      &  ((2.*UH-TH)/(3.*(SH-SQM4)))**2*(TH2+UH2+2.*SQM4*SH)/(TH*UH)
 561         DO 340 I=MIN1,MAX1
 562         IF(I.EQ.0.OR.KFAC(1,I).EQ.0) GOTO 340
 563         IA=IABS(I)
 564         DO 330 J=MIN2,MAX2
 565         IF(J.EQ.0.OR.KFAC(2,J).EQ.0) GOTO 330
 566         JA=IABS(J)
 567         IF(I*J.GT.0.OR.MOD(IA+JA,2).EQ.0) GOTO 330
 568         KCHW=(KCHG(IA,1)*ISIGN(1,I)+KCHG(JA,1)*ISIGN(1,J))/3
 569         FCKM=1.
 570         IF(MINT(43).EQ.4) FCKM=VCKM((IA+1)/2,(JA+1)/2)
 571         NCHN=NCHN+1
 572         ISIG(NCHN,1)=I
 573         ISIG(NCHN,2)=J
 574         ISIG(NCHN,3)=1
 575         SIGH(NCHN)=FACGW*FCKM*WIDS(24,(5-KCHW)/2)
 576   330   CONTINUE
 577   340   CONTINUE
 578       ENDIF
 579
 580       ELSEIF(ISUB.LE.30) THEN
 581       IF(ISUB.EQ.21) THEN
 582 C...f + fb -> gamma + H0.
 583
 584       ELSEIF(ISUB.EQ.22) THEN
 585 C...f + fb -> Z0 + Z0.
 586         FACZZ=COMFAC*FACA*(AEM/(XW*(1.-XW)))**2*1./768.*
 587      &  (UH/TH+TH/UH+2.*(SQM3+SQM4)*SH/(TH*UH)-
 588      &  SQM3*SQM4*(1./TH2+1./UH2))
 589         FACZZ=FACZZ*WIDS(23,1)
 590         DO 350 I=MINA,MAXA
 591         IF(I.EQ.0.OR.KFAC(1,I)*KFAC(2,-I).EQ.0) GOTO 350
 592         EI=KCHG(IABS(I),1)/3.
 593         AI=SIGN(1.,EI)
 594         VI=AI-4.*EI*XW
 595         NCHN=NCHN+1
 596         ISIG(NCHN,1)=I
 597         ISIG(NCHN,2)=-I
 598         ISIG(NCHN,3)=1
 599         SIGH(NCHN)=FACZZ*(VI**4+6.*VI**2*AI**2+AI**4)
 600   350   CONTINUE
 601
 602       ELSEIF(ISUB.EQ.23) THEN
 603 C...f + fb' -> Z0 + W+/-.
 604         FACZW=COMFAC*FACA*(AEM/XW)**2*1./6.
 605         FACZW=FACZW*WIDS(23,2)
 606         THUH=MAX(TH*UH-SQM3*SQM4,SH*CKIN(3)**2)
 607         DO 370 I=MIN1,MAX1
 608         IF(I.EQ.0.OR.KFAC(1,I).EQ.0) GOTO 370
 609         IA=IABS(I)
 610         DO 360 J=MIN2,MAX2
 611         IF(J.EQ.0.OR.KFAC(2,J).EQ.0) GOTO 360
 612         JA=IABS(J)
 613         IF(I*J.GT.0.OR.MOD(IA+JA,2).EQ.0) GOTO 360
 614         KCHW=(KCHG(IA,1)*ISIGN(1,I)+KCHG(JA,1)*ISIGN(1,J))/3
 615         EI=KCHG(IA,1)/3.
 616         AI=SIGN(1.,EI)
 617         VI=AI-4.*EI*XW
 618         EJ=KCHG(JA,1)/3.
 619         AJ=SIGN(1.,EJ)
 620         VJ=AJ-4.*EJ*XW
 621         IF(VI+AI.GT.0) THEN
 622           VISAV=VI
 623           AISAV=AI
 624           VI=VJ
 625           AI=AJ
 626           VJ=VISAV
 627           AJ=AISAV
 628         ENDIF
 629         FCKM=1.
 630         IF(MINT(43).EQ.4) FCKM=VCKM((IA+1)/2,(JA+1)/2)
 631         NCHN=NCHN+1
 632         ISIG(NCHN,1)=I
 633         ISIG(NCHN,2)=J
 634         ISIG(NCHN,3)=1
 635         SIGH(NCHN)=FACZW*FCKM*(1./(SH-SQMW)**2*
 636      &  ((9.-8.*XW)/4.*THUH+(8.*XW-6.)/4.*SH*(SQM3+SQM4))+
 637      &  (THUH-SH*(SQM3+SQM4))/(2.*(SH-SQMW))*((VJ+AJ)/TH-(VI+AI)/UH)+
 638      &  THUH/(16.*(1.-XW))*((VJ+AJ)**2/TH2+(VI+AI)**2/UH2)+
 639      &  SH*(SQM3+SQM4)/(8.*(1.-XW))*(VI+AI)*(VJ+AJ)/(TH*UH))*
 640      &  WIDS(24,(5-KCHW)/2)
 641   360   CONTINUE
 642   370   CONTINUE
 643
 644       ELSEIF(ISUB.EQ.24) THEN
 645 C...f + fb -> Z0 + H0.
 646         THUH=MAX(TH*UH-SQM3*SQM4,SH*CKIN(3)**2)
 647         FACHZ=COMFAC*FACA*(AEM/(XW*(1.-XW)))**2*1./96.*
 648      &  (THUH+2.*SH*SQMZ)/(SH-SQMZ)**2
 649         FACHZ=FACHZ*WIDS(23,2)*WIDS(25,2)
 650         DO 380 I=MINA,MAXA
 651         IF(I.EQ.0.OR.KFAC(1,I)*KFAC(2,-I).EQ.0) GOTO 380
 652         EI=KCHG(IABS(I),1)/3.
 653         AI=SIGN(1.,EI)
 654         VI=AI-4.*EI*XW
 655         NCHN=NCHN+1
 656         ISIG(NCHN,1)=I
 657         ISIG(NCHN,2)=-I
 658         ISIG(NCHN,3)=1
 659         SIGH(NCHN)=FACHZ*(VI**2+AI**2)
 660   380   CONTINUE
 661
 662       ELSEIF(ISUB.EQ.25) THEN
 663 C...f + fb -> W+ + W-.
 664         FACWW=COMFAC*FACA*(AEM/XW)**2*1./12.
 665         FACWW=FACWW*WIDS(24,1)
 666         THUH=MAX(TH*UH-SQM3*SQM4,SH*CKIN(3)**2)
 667         DO 390 I=MINA,MAXA
 668         IF(I.EQ.0.OR.KFAC(1,I)*KFAC(2,-I).EQ.0) GOTO 390
 669         EI=KCHG(IABS(I),1)/3.
 670         AI=SIGN(1.,EI)
 671         VI=AI-4.*EI*XW
 672         DSIGWW=THUH/SH2*(3.-(SH-3.*(SQM3+SQM4))/(SH-SQMZ)*
 673      &  (VI+AI)/(2.*AI*(1.-XW))+(SH/(SH-SQMZ))**2*
 674      &  (1.-2.*(SQM3+SQM4)/SH+12.*SQM3*SQM4/SH2)*(VI**2+AI**2)/
 675      &  (8.*(1.-XW)**2))-2.*SQMZ/(SH-SQMZ)*(VI+AI)/AI+
 676      &  SQMZ*SH/(SH-SQMZ)**2*(1.-2.*(SQM3+SQM4)/SH)*(VI**2+AI**2)/
 677      &  (2.*(1.-XW))
 678         IF(KCHG(IABS(I),1).LT.0) THEN
 679           DSIGWW=DSIGWW+2.*(1.+SQMZ/(SH-SQMZ)*(VI+AI)/(2.*AI))*
 680      &    (THUH/(SH*TH)-(SQM3+SQM4)/TH)+THUH/TH2
 681         ELSE
 682           DSIGWW=DSIGWW+2.*(1.+SQMZ/(SH-SQMZ)*(VI+AI)/(2.*AI))*
 683      &    (THUH/(SH*UH)-(SQM3+SQM4)/UH)+THUH/UH2
 684         ENDIF
 685         NCHN=NCHN+1
 686         ISIG(NCHN,1)=I
 687         ISIG(NCHN,2)=-I
 688         ISIG(NCHN,3)=1
 689         SIGH(NCHN)=FACWW*DSIGWW
 690   390   CONTINUE
 691
 692       ELSEIF(ISUB.EQ.26) THEN
 693 C...f + fb' -> W+/- + H0.
 694         THUH=MAX(TH*UH-SQM3*SQM4,SH*CKIN(3)**2)
 695         FACHW=COMFAC*FACA*(AEM/XW)**2*1./24.*(THUH+2.*SH*SQMW)/
 696      &  (SH-SQMW)**2
 697         FACHW=FACHW*WIDS(25,2)
 698         DO 410 I=MIN1,MAX1
 699         IF(I.EQ.0.OR.KFAC(1,I).EQ.0) GOTO 410
 700         IA=IABS(I)
 701         DO 400 J=MIN2,MAX2
 702         IF(J.EQ.0.OR.KFAC(1,J).EQ.0) GOTO 400
 703         JA=IABS(J)
 704         IF(I*J.GT.0.OR.MOD(IA+JA,2).EQ.0) GOTO 400
 705         KCHW=(KCHG(IA,1)*ISIGN(1,I)+KCHG(JA,1)*ISIGN(1,J))/3
 706         FCKM=1.
 707         IF(MINT(43).EQ.4) FCKM=VCKM((IA+1)/2,(JA+1)/2)
 708         NCHN=NCHN+1
 709         ISIG(NCHN,1)=I
 710         ISIG(NCHN,2)=J
 711         ISIG(NCHN,3)=1
 712         SIGH(NCHN)=FACHW*FCKM*WIDS(24,(5-KCHW)/2)
 713   400   CONTINUE
 714   410   CONTINUE
 715
 716       ELSEIF(ISUB.EQ.27) THEN
 717 C...f + fb -> H0 + H0.
 718
 719       ELSEIF(ISUB.EQ.28) THEN
 720 C...f + g -> f + g (q + g -> q + g only).
 721         FACQG1=COMFAC*AS**2*4./9.*((2.+MSTP(34)*1./4.)*UH2/TH2-UH/SH)*
 722      &  FACA
 723         FACQG2=COMFAC*AS**2*4./9.*((2.+MSTP(34)*1./4.)*SH2/TH2-SH/UH)
 724         DO 430 I=MINA,MAXA
 725         IF(I.EQ.0) GOTO 430
 726         DO 420 ISDE=1,2
 727         IF(ISDE.EQ.1.AND.KFAC(1,I)*KFAC(2,21).EQ.0) GOTO 420
 728         IF(ISDE.EQ.2.AND.KFAC(1,21)*KFAC(2,I).EQ.0) GOTO 420
 729         NCHN=NCHN+1
 730         ISIG(NCHN,ISDE)=I
 731         ISIG(NCHN,3-ISDE)=21
 732         ISIG(NCHN,3)=1
 733         SIGH(NCHN)=FACQG1
 734         NCHN=NCHN+1
 735         ISIG(NCHN,ISDE)=I
 736         ISIG(NCHN,3-ISDE)=21
 737         ISIG(NCHN,3)=2
 738         SIGH(NCHN)=FACQG2
 739   420   CONTINUE
 740   430   CONTINUE
 741
 742       ELSEIF(ISUB.EQ.29) THEN
 743 C...f + g -> f + gamma (q + g -> q + gamma only).
 744         FGQ=COMFAC*FACA*AS*AEM*1./3.*(SH2+UH2)/(-SH*UH)
 745         DO 450 I=MINA,MAXA
 746         IF(I.EQ.0) GOTO 450
 747         EI=KCHG(IABS(I),1)/3.
 748         FACGQ=FGQ*EI**2
 749         DO 440 ISDE=1,2
 750         IF(ISDE.EQ.1.AND.KFAC(1,I)*KFAC(2,21).EQ.0) GOTO 440
 751         IF(ISDE.EQ.2.AND.KFAC(1,21)*KFAC(2,I).EQ.0) GOTO 440
 752         NCHN=NCHN+1
 753         ISIG(NCHN,ISDE)=I
 754         ISIG(NCHN,3-ISDE)=21
 755         ISIG(NCHN,3)=1
 756         SIGH(NCHN)=FACGQ
 757   440   CONTINUE
 758   450   CONTINUE
 759
 760       ELSEIF(ISUB.EQ.30) THEN
 761 C...f + g -> f + Z0 (q + g -> q + Z0 only).
 762         FZQ=COMFAC*FACA*AS*AEM/(XW*(1.-XW))*1./48.*
 763      &  (SH2+UH2+2.*SQM4*TH)/(-SH*UH)
 764         FZQ=FZQ*WIDS(23,2)
 765         DO 470 I=MINA,MAXA
 766         IF(I.EQ.0) GOTO 470
 767         EI=KCHG(IABS(I),1)/3.
 768         AI=SIGN(1.,EI)
 769         VI=AI-4.*EI*XW
 770         FACZQ=FZQ*(VI**2+AI**2)
 771         DO 460 ISDE=1,2
 772         IF(ISDE.EQ.1.AND.KFAC(1,I)*KFAC(2,21).EQ.0) GOTO 460
 773         IF(ISDE.EQ.2.AND.KFAC(1,21)*KFAC(2,I).EQ.0) GOTO 460
 774         NCHN=NCHN+1
 775         ISIG(NCHN,ISDE)=I
 776         ISIG(NCHN,3-ISDE)=21
 777         ISIG(NCHN,3)=1
 778         SIGH(NCHN)=FACZQ
 779   460   CONTINUE
 780   470   CONTINUE
 781       ENDIF
 782
 783       ELSEIF(ISUB.LE.40) THEN
 784       IF(ISUB.EQ.31) THEN
 785 C...f + g -> f' + W+/- (q + g -> q' + W+/- only).
 786         FACWQ=COMFAC*FACA*AS*AEM/XW*1./12.*
 787      &  (SH2+UH2+2.*SQM4*TH)/(-SH*UH)
 788         DO 490 I=MINA,MAXA
 789         IF(I.EQ.0) GOTO 490
 790         IA=IABS(I)
 791         KCHW=ISIGN(1,KCHG(IA,1)*ISIGN(1,I))
 792         DO 480 ISDE=1,2
 793         IF(ISDE.EQ.1.AND.KFAC(1,I)*KFAC(2,21).EQ.0) GOTO 480
 794         IF(ISDE.EQ.2.AND.KFAC(1,21)*KFAC(2,I).EQ.0) GOTO 480
 795         NCHN=NCHN+1
 796         ISIG(NCHN,ISDE)=I
 797         ISIG(NCHN,3-ISDE)=21
 798         ISIG(NCHN,3)=1
 799         SIGH(NCHN)=FACWQ*VINT(180+I)*WIDS(24,(5-KCHW)/2)
 800   480   CONTINUE
 801   490   CONTINUE
 802
 803       ELSEIF(ISUB.EQ.32) THEN
 804 C...f + g -> f + H0 (q + g -> q + H0 only).
 805
 806       ELSEIF(ISUB.EQ.33) THEN
 807 C...f + gamma -> f + g (q + gamma -> q + g only).
 808
 809       ELSEIF(ISUB.EQ.34) THEN
 810 C...f + gamma -> f + gamma.
 811
 812       ELSEIF(ISUB.EQ.35) THEN
 813 C...f + gamma -> f + Z0.
 814
 815       ELSEIF(ISUB.EQ.36) THEN
 816 C...f + gamma -> f' + W+/-.
 817
 818       ELSEIF(ISUB.EQ.37) THEN
 819 C...f + gamma -> f + H0.
 820
 821       ELSEIF(ISUB.EQ.38) THEN
 822 C...f + Z0 -> f + g (q + Z0 -> q + g only).
 823
 824       ELSEIF(ISUB.EQ.39) THEN
 825 C...f + Z0 -> f + gamma.
 826
 827       ELSEIF(ISUB.EQ.40) THEN
 828 C...f + Z0 -> f + Z0.
 829       ENDIF
 830
 831       ELSEIF(ISUB.LE.50) THEN
 832       IF(ISUB.EQ.41) THEN
 833 C...f + Z0 -> f' + W+/-.
 834
 835       ELSEIF(ISUB.EQ.42) THEN
 836 C...f + Z0 -> f + H0.
 837
 838       ELSEIF(ISUB.EQ.43) THEN
 839 C...f + W+/- -> f' + g (q + W+/- -> q' + g only).
 840
 841       ELSEIF(ISUB.EQ.44) THEN
 842 C...f + W+/- -> f' + gamma.
 843
 844       ELSEIF(ISUB.EQ.45) THEN
 845 C...f + W+/- -> f' + Z0.
 846
 847       ELSEIF(ISUB.EQ.46) THEN
 848 C...f + W+/- -> f' + W+/-.
 849
 850       ELSEIF(ISUB.EQ.47) THEN
 851 C...f + W+/- -> f' + H0.
 852
 853       ELSEIF(ISUB.EQ.48) THEN
 854 C...f + H0 -> f + g (q + H0 -> q + g only).
 855
 856       ELSEIF(ISUB.EQ.49) THEN
 857 C...f + H0 -> f + gamma.
 858
 859       ELSEIF(ISUB.EQ.50) THEN
 860 C...f + H0 -> f + Z0.
 861       ENDIF
 862
 863       ELSEIF(ISUB.LE.60) THEN
 864       IF(ISUB.EQ.51) THEN
 865 C...f + H0 -> f' + W+/-.
 866
 867       ELSEIF(ISUB.EQ.52) THEN
 868 C...f + H0 -> f + H0.
 869
 870       ELSEIF(ISUB.EQ.53) THEN
 871 C...g + g -> f + fb (g + g -> q + qb only).
 872         CALL PYWIDT_HIJING(21,SQRT(SH),WDTP,WDTE)
 873         FACQQ1=COMFAC*AS**2*1./6.*(UH/TH-(2.+MSTP(34)*1./4.)*UH2/SH2)*
 874      &  (WDTE(0,1)+WDTE(0,2)+WDTE(0,3)+WDTE(0,4))*FACA
 875         FACQQ2=COMFAC*AS**2*1./6.*(TH/UH-(2.+MSTP(34)*1./4.)*TH2/SH2)*
 876      &  (WDTE(0,1)+WDTE(0,2)+WDTE(0,3)+WDTE(0,4))*FACA
 877         IF(KFAC(1,21)*KFAC(2,21).EQ.0) GOTO 500
 878         NCHN=NCHN+1
 879         ISIG(NCHN,1)=21
 880         ISIG(NCHN,2)=21
 881         ISIG(NCHN,3)=1
 882         SIGH(NCHN)=FACQQ1
 883         NCHN=NCHN+1
 884         ISIG(NCHN,1)=21
 885         ISIG(NCHN,2)=21
 886         ISIG(NCHN,3)=2
 887         SIGH(NCHN)=FACQQ2
 888   500   CONTINUE
 889
 890       ELSEIF(ISUB.EQ.54) THEN
 891 C...g + gamma -> f + fb (g + gamma -> q + qb only).
 892
 893       ELSEIF(ISUB.EQ.55) THEN
 894 C...g + gamma -> f + fb (g + gamma -> q + qb only).
 895
 896       ELSEIF(ISUB.EQ.56) THEN
 897 C...g + gamma -> f + fb (g + gamma -> q + qb only).
 898
 899       ELSEIF(ISUB.EQ.57) THEN
 900 C...g + gamma -> f + fb (g + gamma -> q + qb only).
 901
 902       ELSEIF(ISUB.EQ.58) THEN
 903 C...gamma + gamma -> f + fb.
 904
 905       ELSEIF(ISUB.EQ.59) THEN
 906 C...gamma + Z0 -> f + fb.
 907
 908       ELSEIF(ISUB.EQ.60) THEN
 909 C...gamma + W+/- -> f + fb'.
 910       ENDIF
 911
 912       ELSEIF(ISUB.LE.70) THEN
 913       IF(ISUB.EQ.61) THEN
 914 C...gamma + H0 -> f + fb.
 915
 916       ELSEIF(ISUB.EQ.62) THEN
 917 C...Z0 + Z0 -> f + fb.
 918
 919       ELSEIF(ISUB.EQ.63) THEN
 920 C...Z0 + W+/- -> f + fb'.
 921
 922       ELSEIF(ISUB.EQ.64) THEN
 923 C...Z0 + H0 -> f + fb.
 924
 925       ELSEIF(ISUB.EQ.65) THEN
 926 C...W+ + W- -> f + fb.
 927
 928       ELSEIF(ISUB.EQ.66) THEN
 929 C...W+/- + H0 -> f + fb'.
 930
 931       ELSEIF(ISUB.EQ.67) THEN
 932 C...H0 + H0 -> f + fb.
 933
 934       ELSEIF(ISUB.EQ.68) THEN
 935 C...g + g -> g + g.
 936         FACGG1=COMFAC*AS**2*9./4.*(SH2/TH2+2.*SH/TH+3.+2.*TH/SH+
 937      &  TH2/SH2)*FACA
 938         FACGG2=COMFAC*AS**2*9./4.*(UH2/SH2+2.*UH/SH+3.+2.*SH/UH+
 939      &  SH2/UH2)*FACA
 940         FACGG3=COMFAC*AS**2*9./4.*(TH2/UH2+2.*TH/UH+3+2.*UH/TH+UH2/TH2)
 941         IF(KFAC(1,21)*KFAC(2,21).EQ.0) GOTO 510
 942         NCHN=NCHN+1
 943         ISIG(NCHN,1)=21
 944         ISIG(NCHN,2)=21
 945         ISIG(NCHN,3)=1
 946         SIGH(NCHN)=0.5*FACGG1
 947         NCHN=NCHN+1
 948         ISIG(NCHN,1)=21
 949         ISIG(NCHN,2)=21
 950         ISIG(NCHN,3)=2
 951         SIGH(NCHN)=0.5*FACGG2
 952         NCHN=NCHN+1
 953         ISIG(NCHN,1)=21
 954         ISIG(NCHN,2)=21
 955         ISIG(NCHN,3)=3
 956         SIGH(NCHN)=0.5*FACGG3
 957   510   CONTINUE
 958
 959       ELSEIF(ISUB.EQ.69) THEN
 960 C...gamma + gamma -> W+ + W-.
 961
 962       ELSEIF(ISUB.EQ.70) THEN
 963 C...gamma + W+/- -> gamma + W+/-.
 964       ENDIF
 965
 966       ELSEIF(ISUB.LE.80) THEN
 967       IF(ISUB.EQ.71) THEN
 968 C...Z0 + Z0 -> Z0 + Z0.
 969         BE2=1.-4.*SQMZ/SH
 970         TH=-0.5*SH*BE2*(1.-CTH)
 971         UH=-0.5*SH*BE2*(1.+CTH)
 972         SHANG=1./(1.-XW)*SQMW/SQMZ*(1.+BE2)**2
 973         ASHRE=(SH-SQMH)/((SH-SQMH)**2+GMMH**2)*SHANG
 974         ASHIM=-GMMH/((SH-SQMH)**2+GMMH**2)*SHANG
 975         THANG=1./(1.-XW)*SQMW/SQMZ*(BE2-CTH)**2
 976         ATHRE=(TH-SQMH)/((TH-SQMH)**2+GMMH**2)*THANG
 977         ATHIM=-GMMH/((TH-SQMH)**2+GMMH**2)*THANG
 978         UHANG=1./(1.-XW)*SQMW/SQMZ*(BE2+CTH)**2
 979         AUHRE=(UH-SQMH)/((UH-SQMH)**2+GMMH**2)*UHANG
 980         AUHIM=-GMMH/((UH-SQMH)**2+GMMH**2)*UHANG
 981         FACH=0.5*COMFAC*1./(4096.*PARU(1)**2*16.*(1.-XW)**2)*
 982      &  (AEM/XW)**4*(SH/SQMW)**2*((ASHRE+ATHRE+AUHRE)**2+
 983      &  (ASHIM+ATHIM+AUHIM)**2)*SQMZ/SQMW
 984         DO 530 I=MIN1,MAX1
 985         IF(I.EQ.0.OR.KFAC(1,I).EQ.0) GOTO 530
 986         EI=KCHG(IABS(I),1)/3.
 987         AI=SIGN(1.,EI)
 988         VI=AI-4.*EI*XW
 989         AVI=AI**2+VI**2
 990         DO 520 J=MIN2,MAX2
 991         IF(J.EQ.0.OR.KFAC(2,J).EQ.0) GOTO 520
 992         EJ=KCHG(IABS(J),1)/3.
 993         AJ=SIGN(1.,EJ)
 994         VJ=AJ-4.*EJ*XW
 995         AVJ=AJ**2+VJ**2
 996         NCHN=NCHN+1
 997         ISIG(NCHN,1)=I
 998         ISIG(NCHN,2)=J
 999         ISIG(NCHN,3)=1
1000         SIGH(NCHN)=FACH*AVI*AVJ
1001   520   CONTINUE
1002   530   CONTINUE
1003
1004       ELSEIF(ISUB.EQ.72) THEN
1005 C...Z0 + Z0 -> W+ + W-.
1006         BE2=SQRT((1.-4.*SQMW/SH)*(1.-4.*SQMZ/SH))
1007         CTH2=CTH**2
1008         TH=-0.5*SH*(1.-2.*(SQMW+SQMZ)/SH-BE2*CTH)
1009         UH=-0.5*SH*(1.-2.*(SQMW+SQMZ)/SH+BE2*CTH)
1010         SHANG=4.*SQRT(SQMW/(SQMZ*(1.-XW)))*(1.-2.*SQMW/SH)*
1011      &  (1.-2.*SQMZ/SH)
1012         ASHRE=(SH-SQMH)/((SH-SQMH)**2+GMMH**2)*SHANG
1013         ASHIM=-GMMH/((SH-SQMH)**2+GMMH**2)*SHANG
1014         ATWRE=(1.-XW)/SQMZ*SH/(TH-SQMW)*((CTH-BE2)**2*(3./2.+BE2/2.*CTH-
1015      &  (SQMW+SQMZ)/SH+(SQMW-SQMZ)**2/(SH*SQMW))+4.*((SQMW+SQMZ)/SH*
1016      &  (1.-3.*CTH2)+8.*SQMW*SQMZ/SH2*(2.*CTH2-1.)+
1017      &  4.*(SQMW**2+SQMZ**2)/SH2*CTH2+2.*(SQMW+SQMZ)/SH*BE2*CTH))
1018         ATWIM=0.
1019         AUWRE=(1.-XW)/SQMZ*SH/(UH-SQMW)*((CTH+BE2)**2*(3./2.-BE2/2.*CTH-
1020      &  (SQMW+SQMZ)/SH+(SQMW-SQMZ)**2/(SH*SQMW))+4.*((SQMW+SQMZ)/SH*
1021      &  (1.-3.*CTH2)+8.*SQMW*SQMZ/SH2*(2.*CTH2-1.)+
1022      &  4.*(SQMW**2+SQMZ**2)/SH2*CTH2-2.*(SQMW+SQMZ)/SH*BE2*CTH))
1023         AUWIM=0.
1024         A4RE=2.*(1.-XW)/SQMZ*(3.-CTH2-4.*(SQMW+SQMZ)/SH)
1025         A4IM=0.
1026         FACH=COMFAC*1./(4096.*PARU(1)**2*16.*(1.-XW)**2)*(AEM/XW)**4*
1027      &  (SH/SQMW)**2*((ASHRE+ATWRE+AUWRE+A4RE)**2+
1028      &  (ASHIM+ATWIM+AUWIM+A4IM)**2)*SQMZ/SQMW
1029         DO 550 I=MIN1,MAX1
1030         IF(I.EQ.0.OR.KFAC(1,I).EQ.0) GOTO 550
1031         EI=KCHG(IABS(I),1)/3.
1032         AI=SIGN(1.,EI)
1033         VI=AI-4.*EI*XW
1034         AVI=AI**2+VI**2
1035         DO 540 J=MIN2,MAX2
1036         IF(J.EQ.0.OR.KFAC(2,J).EQ.0) GOTO 540
1037         EJ=KCHG(IABS(J),1)/3.
1038         AJ=SIGN(1.,EJ)
1039         VJ=AJ-4.*EJ*XW
1040         AVJ=AJ**2+VJ**2
1041         NCHN=NCHN+1
1042         ISIG(NCHN,1)=I
1043         ISIG(NCHN,2)=J
1044         ISIG(NCHN,3)=1
1045         SIGH(NCHN)=FACH*AVI*AVJ
1046   540   CONTINUE
1047   550   CONTINUE
1048
1049       ELSEIF(ISUB.EQ.73) THEN
1050 C...Z0 + W+/- -> Z0 + W+/-.
1051         BE2=1.-2.*(SQMZ+SQMW)/SH+((SQMZ-SQMW)/SH)**2
1052         EP1=1.+(SQMZ-SQMW)/SH
1053         EP2=1.-(SQMZ-SQMW)/SH
1054         TH=-0.5*SH*BE2*(1.-CTH)
1055         UH=(SQMZ-SQMW)**2/SH-0.5*SH*BE2*(1.+CTH)
1056         THANG=SQRT(SQMW/(SQMZ*(1.-XW)))*(BE2-EP1*CTH)*(BE2-EP2*CTH)
1057         ATHRE=(TH-SQMH)/((TH-SQMH)**2+GMMH**2)*THANG
1058         ATHIM=-GMMH/((TH-SQMH)**2+GMMH**2)*THANG
1059         ASWRE=(1.-XW)/SQMZ*SH/(SH-SQMW)*(-BE2*(EP1+EP2)**4*CTH+
1060      &  1./4.*(BE2+EP1*EP2)**2*((EP1-EP2)**2-4.*BE2*CTH)+
1061      &  2.*BE2*(BE2+EP1*EP2)*(EP1+EP2)**2*CTH-
1062      &  1./16.*SH/SQMW*(EP1**2-EP2**2)**2*(BE2+EP1*EP2)**2)
1063         ASWIM=0.
1064         AUWRE=(1.-XW)/SQMZ*SH/(UH-SQMW)*(-BE2*(EP2+EP1*CTH)*
1065      &  (EP1+EP2*CTH)*(BE2+EP1*EP2)+BE2*(EP2+EP1*CTH)*
1066      &  (BE2+EP1*EP2*CTH)*(2.*EP2-EP2*CTH+EP1)-BE2*(EP2+EP1*CTH)**2*
1067      &  (BE2-EP2**2*CTH)-1./8.*(BE2+EP1*EP2*CTH)**2*((EP1+EP2)**2+
1068      &  2.*BE2*(1.-CTH))+1./32.*SH/SQMW*(BE2+EP1*EP2*CTH)**2*
1069      &  (EP1**2-EP2**2)**2-BE2*(EP1+EP2*CTH)*(EP2+EP1*CTH)*
1070      &  (BE2+EP1*EP2)+BE2*(EP1+EP2*CTH)*(BE2+EP1*EP2*CTH)*
1071      &  (2.*EP1-EP1*CTH+EP2)-BE2*(EP1+EP2*CTH)**2*(BE2-EP1**2*CTH)-
1072      &  1./8.*(BE2+EP1*EP2*CTH)**2*((EP1+EP2)**2+2.*BE2*(1.-CTH))+
1073      &  1./32.*SH/SQMW*(BE2+EP1*EP2*CTH)**2*(EP1**2-EP2**2)**2)
1074         AUWIM=0.
1075         A4RE=(1.-XW)/SQMZ*(EP1**2*EP2**2*(CTH**2-1.)-
1076      &  2.*BE2*(EP1**2+EP2**2+EP1*EP2)*CTH-2.*BE2*EP1*EP2)
1077         A4IM=0.
1078         FACH=COMFAC*1./(4096.*PARU(1)**2*4.*(1.-XW))*(AEM/XW)**4*
1079      &  (SH/SQMW)**2*((ATHRE+ASWRE+AUWRE+A4RE)**2+
1080      &  (ATHIM+ASWIM+AUWIM+A4IM)**2)*SQRT(SQMZ/SQMW)
1081         DO 570 I=MIN1,MAX1
1082         IF(I.EQ.0.OR.KFAC(1,I).EQ.0) GOTO 570
1083         EI=KCHG(IABS(I),1)/3.
1084         AI=SIGN(1.,EI)
1085         VI=AI-4.*EI*XW
1086         AVI=AI**2+VI**2
1087         DO 560 J=MIN2,MAX2
1088         IF(J.EQ.0.OR.KFAC(2,J).EQ.0) GOTO 560
1089         EJ=KCHG(IABS(J),1)/3.
1090         AJ=SIGN(1.,EJ)
1091         VJ=AI-4.*EJ*XW
1092         AVJ=AJ**2+VJ**2
1093         NCHN=NCHN+1
1094         ISIG(NCHN,1)=I
1095         ISIG(NCHN,2)=J
1096         ISIG(NCHN,3)=1
1097         SIGH(NCHN)=FACH*(AVI*VINT(180+J)+VINT(180+I)*AVJ)
1098   560   CONTINUE
1099   570   CONTINUE
1100
1101       ELSEIF(ISUB.EQ.75) THEN
1102 C...W+ + W- -> gamma + gamma.
1103
1104       ELSEIF(ISUB.EQ.76) THEN
1105 C...W+ + W- -> Z0 + Z0.
1106         BE2=SQRT((1.-4.*SQMW/SH)*(1.-4.*SQMZ/SH))
1107         CTH2=CTH**2
1108         TH=-0.5*SH*(1.-2.*(SQMW+SQMZ)/SH-BE2*CTH)
1109         UH=-0.5*SH*(1.-2.*(SQMW+SQMZ)/SH+BE2*CTH)
1110         SHANG=4.*SQRT(SQMW/(SQMZ*(1.-XW)))*(1.-2.*SQMW/SH)*
1111      &  (1.-2.*SQMZ/SH)
1112         ASHRE=(SH-SQMH)/((SH-SQMH)**2+GMMH**2)*SHANG
1113         ASHIM=-GMMH/((SH-SQMH)**2+GMMH**2)*SHANG
1114         ATWRE=(1.-XW)/SQMZ*SH/(TH-SQMW)*((CTH-BE2)**2*(3./2.+BE2/2.*CTH-
1115      &  (SQMW+SQMZ)/SH+(SQMW-SQMZ)**2/(SH*SQMW))+4.*((SQMW+SQMZ)/SH*
1116      &  (1.-3.*CTH2)+8.*SQMW*SQMZ/SH2*(2.*CTH2-1.)+
1117      &  4.*(SQMW**2+SQMZ**2)/SH2*CTH2+2.*(SQMW+SQMZ)/SH*BE2*CTH))
1118         ATWIM=0.
1119         AUWRE=(1.-XW)/SQMZ*SH/(UH-SQMW)*((CTH+BE2)**2*(3./2.-BE2/2.*CTH-
1120      &  (SQMW+SQMZ)/SH+(SQMW-SQMZ)**2/(SH*SQMW))+4.*((SQMW+SQMZ)/SH*
1121      &  (1.-3.*CTH2)+8.*SQMW*SQMZ/SH2*(2.*CTH2-1.)+
1122      &  4.*(SQMW**2+SQMZ**2)/SH2*CTH2-2.*(SQMW+SQMZ)/SH*BE2*CTH))
1123         AUWIM=0.
1124         A4RE=2.*(1.-XW)/SQMZ*(3.-CTH2-4.*(SQMW+SQMZ)/SH)
1125         A4IM=0.
1126         FACH=0.5*COMFAC*1./(4096.*PARU(1)**2)*(AEM/XW)**4*(SH/SQMW)**2*
1127      &  ((ASHRE+ATWRE+AUWRE+A4RE)**2+(ASHIM+ATWIM+AUWIM+A4IM)**2)
1128         DO 590 I=MIN1,MAX1
1129         IF(I.EQ.0.OR.KFAC(1,I).EQ.0) GOTO 590
1130         EI=SIGN(1.,FLOAT(I))*KCHG(IABS(I),1)
1131         DO 580 J=MIN2,MAX2
1132         IF(J.EQ.0.OR.KFAC(2,J).EQ.0) GOTO 580
1133         EJ=SIGN(1.,FLOAT(J))*KCHG(IABS(J),1)
1134         IF(EI*EJ.GT.0.) GOTO 580
1135         NCHN=NCHN+1
1136         ISIG(NCHN,1)=I
1137         ISIG(NCHN,2)=J
1138         ISIG(NCHN,3)=1
1139         SIGH(NCHN)=FACH*VINT(180+I)*VINT(180+J)
1140   580   CONTINUE
1141   590   CONTINUE
1142
1143       ELSEIF(ISUB.EQ.77) THEN
1144 C...W+/- + W+/- -> W+/- + W+/-.
1145         BE2=1.-4.*SQMW/SH
1146         BE4=BE2**2
1147         CTH2=CTH**2
1148         CTH3=CTH**3
1149         TH=-0.5*SH*BE2*(1.-CTH)
1150         UH=-0.5*SH*BE2*(1.+CTH)
1151         SHANG=(1.+BE2)**2
1152         ASHRE=(SH-SQMH)/((SH-SQMH)**2+GMMH**2)*SHANG
1153         ASHIM=-GMMH/((SH-SQMH)**2+GMMH**2)*SHANG
1154         THANG=(BE2-CTH)**2
1155         ATHRE=(TH-SQMH)/((TH-SQMH)**2+GMMH**2)*THANG
1156         ATHIM=-GMMH/((TH-SQMH)**2+GMMH**2)*THANG
1157         SGZANG=1./SQMW*BE2*(3.-BE2)**2*CTH
1158         ASGRE=XW*SGZANG
1159         ASGIM=0.
1160         ASZRE=(1.-XW)*SH/(SH-SQMZ)*SGZANG
1161         ASZIM=0.
1162         TGZANG=1./SQMW*(BE2*(4.-2.*BE2+BE4)+BE2*(4.-10.*BE2+BE4)*CTH+
1163      &  (2.-11.*BE2+10.*BE4)*CTH2+BE2*CTH3)
1164         ATGRE=0.5*XW*SH/TH*TGZANG
1165         ATGIM=0.
1166         ATZRE=0.5*(1.-XW)*SH/(TH-SQMZ)*TGZANG
1167         ATZIM=0.
1168         A4RE=1./SQMW*(1.+2.*BE2-6.*BE2*CTH-CTH2)
1169         A4IM=0.
1170         FACH=COMFAC*1./(4096.*PARU(1)**2)*(AEM/XW)**4*(SH/SQMW)**2*
1171      &  ((ASHRE+ATHRE+ASGRE+ASZRE+ATGRE+ATZRE+A4RE)**2+
1172      &  (ASHIM+ATHIM+ASGIM+ASZIM+ATGIM+ATZIM+A4IM)**2)
1173         DO 610 I=MIN1,MAX1
1174         IF(I.EQ.0.OR.KFAC(1,I).EQ.0) GOTO 610
1175         EI=SIGN(1.,FLOAT(I))*KCHG(IABS(I),1)
1176         DO 600 J=MIN2,MAX2
1177         IF(J.EQ.0.OR.KFAC(2,J).EQ.0) GOTO 600
1178         EJ=SIGN(1.,FLOAT(J))*KCHG(IABS(J),1)
1179         IF(EI*EJ.GT.0.) GOTO 600
1180         NCHN=NCHN+1
1181         ISIG(NCHN,1)=I
1182         ISIG(NCHN,2)=J
1183         ISIG(NCHN,3)=1
1184         SIGH(NCHN)=FACH*VINT(180+I)*VINT(180+J)
1185   600   CONTINUE
1186   610   CONTINUE
1187
1188       ELSEIF(ISUB.EQ.78) THEN
1189 C...W+/- + H0 -> W+/- + H0.
1190
1191       ELSEIF(ISUB.EQ.79) THEN
1192 C...H0 + H0 -> H0 + H0.
1193
1194       ENDIF
1195
1196 C...C: 2 -> 2, tree diagrams with masses.
1197
1198       ELSEIF(ISUB.LE.90) THEN
1199       IF(ISUB.EQ.81) THEN
1200 C...q + qb -> Q + QB.
1201         FACQQB=COMFAC*AS**2*4./9.*(((TH-SQM3)**2+
1202      &  (UH-SQM3)**2)/SH2+2.*SQM3/SH)
1203         IF(MSTP(35).GE.1) THEN
1204           IF(MSTP(35).EQ.1) THEN
1205             ALSSG=PARP(35)
1206           ELSE
1207             MST115=MSTU(115)
1208             MSTU(115)=MSTP(36)
1209             Q2BN=SQRT(SQM3*((SQRT(SH)-2.*SQRT(SQM3))**2+PARP(36)**2))
1210             ALSSG=ULALPS_HIJING(Q2BN)
1211             MSTU(115)=MST115
1212           ENDIF
1213           XREPU=PARU(1)*ALSSG/(6.*SQRT(MAX(1E-20,1.-4.*SQM3/SH)))
1214           FREPU=XREPU/(EXP(MIN(100.,XREPU))-1.)
1215           PARI(81)=FREPU
1216           FACQQB=FACQQB*FREPU
1217         ENDIF
1218         DO 620 I=MINA,MAXA
1219         IF(I.EQ.0.OR.KFAC(1,I)*KFAC(2,-I).EQ.0) GOTO 620
1220         NCHN=NCHN+1
1221         ISIG(NCHN,1)=I
1222         ISIG(NCHN,2)=-I
1223         ISIG(NCHN,3)=1
1224         SIGH(NCHN)=FACQQB
1225   620   CONTINUE
1226
1227       ELSEIF(ISUB.EQ.82) THEN
1228 C...g + g -> Q + QB.
1229         FACQQ1=COMFAC*FACA*AS**2*1./6.*((UH-SQM3)/(TH-SQM3)-
1230      &  2.*(UH-SQM3)**2/SH2+4.*SQM3/SH*(TH*UH-SQM3**2)/(TH-SQM3)**2)
1231         FACQQ2=COMFAC*FACA*AS**2*1./6.*((TH-SQM3)/(UH-SQM3)-
1232      &  2.*(TH-SQM3)**2/SH2+4.*SQM3/SH*(TH*UH-SQM3**2)/(UH-SQM3)**2)
1233         IF(MSTP(35).GE.1) THEN
1234           IF(MSTP(35).EQ.1) THEN
1235             ALSSG=PARP(35)
1236           ELSE
1237             MST115=MSTU(115)
1238             MSTU(115)=MSTP(36)
1239             Q2BN=SQRT(SQM3*((SQRT(SH)-2.*SQRT(SQM3))**2+PARP(36)**2))
1240             ALSSG=ULALPS_HIJING(Q2BN)
1241             MSTU(115)=MST115
1242           ENDIF
1243           XATTR=4.*PARU(1)*ALSSG/(3.*SQRT(MAX(1E-20,1.-4.*SQM3/SH)))
1244           FATTR=XATTR/(1.-EXP(-MIN(100.,XATTR)))
1245           XREPU=PARU(1)*ALSSG/(6.*SQRT(MAX(1E-20,1.-4.*SQM3/SH)))
1246           FREPU=XREPU/(EXP(MIN(100.,XREPU))-1.)
1247           FATRE=(2.*FATTR+5.*FREPU)/7.
1248           PARI(81)=FATRE
1249           FACQQ1=FACQQ1*FATRE
1250           FACQQ2=FACQQ2*FATRE
1251         ENDIF
1252         IF(KFAC(1,21)*KFAC(2,21).EQ.0) GOTO 630
1253         NCHN=NCHN+1
1254         ISIG(NCHN,1)=21
1255         ISIG(NCHN,2)=21
1256         ISIG(NCHN,3)=1
1257         SIGH(NCHN)=FACQQ1
1258         NCHN=NCHN+1
1259         ISIG(NCHN,1)=21
1260         ISIG(NCHN,2)=21
1261         ISIG(NCHN,3)=2
1262         SIGH(NCHN)=FACQQ2
1263   630   CONTINUE
1264
1265       ENDIF
1266
1267 C...D: Mimimum bias processes.
1268
1269       ELSEIF(ISUB.LE.100) THEN
1270       IF(ISUB.EQ.91) THEN
1271 C...Elastic scattering.
1272         SIGS=XSEC(ISUB,1)
1273
1274       ELSEIF(ISUB.EQ.92) THEN
1275 C...Single diffractive scattering.
1276         SIGS=XSEC(ISUB,1)
1277
1278       ELSEIF(ISUB.EQ.93) THEN
1279 C...Double diffractive scattering.
1280         SIGS=XSEC(ISUB,1)
1281
1282       ELSEIF(ISUB.EQ.94) THEN
1283 C...Central diffractive scattering.
1284         SIGS=XSEC(ISUB,1)
1285
1286       ELSEIF(ISUB.EQ.95) THEN
1287 C...Low-pT scattering.
1288         SIGS=XSEC(ISUB,1)
1289
1290       ELSEIF(ISUB.EQ.96) THEN
1291 C...Multiple interactions: sum of QCD processes.
1292         CALL PYWIDT_HIJING(21,SQRT(SH),WDTP,WDTE)
1293
1294 C...q + q' -> q + q'.
1295         FACQQ1=COMFAC*AS**2*4./9.*(SH2+UH2)/TH2
1296         FACQQB=COMFAC*AS**2*4./9.*((SH2+UH2)/TH2*FACA-
1297      &  MSTP(34)*2./3.*UH2/(SH*TH))
1298         FACQQ2=COMFAC*AS**2*4./9.*((SH2+TH2)/UH2-
1299      &  MSTP(34)*2./3.*SH2/(TH*UH))
1300         DO 650 I=-3,3
1301         IF(I.EQ.0) GOTO 650
1302         DO 640 J=-3,3
1303         IF(J.EQ.0) GOTO 640
1304         NCHN=NCHN+1
1305         ISIG(NCHN,1)=I
1306         ISIG(NCHN,2)=J
1307         ISIG(NCHN,3)=111
1308         SIGH(NCHN)=FACQQ1
1309         IF(I.EQ.-J) SIGH(NCHN)=FACQQB
1310         IF(I.EQ.J) THEN
1311           SIGH(NCHN)=0.5*SIGH(NCHN)
1312           NCHN=NCHN+1
1313           ISIG(NCHN,1)=I
1314           ISIG(NCHN,2)=J
1315           ISIG(NCHN,3)=112
1316           SIGH(NCHN)=0.5*FACQQ2
1317         ENDIF
1318   640   CONTINUE
1319   650   CONTINUE
1320
1321 C...q + qb -> q' + qb' or g + g.
1322         FACQQB=COMFAC*AS**2*4./9.*(TH2+UH2)/SH2*(WDTE(0,1)+WDTE(0,2)+
1323      &  WDTE(0,3)+WDTE(0,4))
1324         FACGG1=COMFAC*AS**2*32./27.*(UH/TH-(2.+MSTP(34)*1./4.)*UH2/SH2)
1325         FACGG2=COMFAC*AS**2*32./27.*(TH/UH-(2.+MSTP(34)*1./4.)*TH2/SH2)
1326         DO 660 I=-3,3
1327         IF(I.EQ.0) GOTO 660
1328         NCHN=NCHN+1
1329         ISIG(NCHN,1)=I
1330         ISIG(NCHN,2)=-I
1331         ISIG(NCHN,3)=121
1332         SIGH(NCHN)=FACQQB
1333         NCHN=NCHN+1
1334         ISIG(NCHN,1)=I
1335         ISIG(NCHN,2)=-I
1336         ISIG(NCHN,3)=131
1337         SIGH(NCHN)=0.5*FACGG1
1338         NCHN=NCHN+1
1339         ISIG(NCHN,1)=I
1340         ISIG(NCHN,2)=-I
1341         ISIG(NCHN,3)=132
1342         SIGH(NCHN)=0.5*FACGG2
1343   660   CONTINUE
1344
1345 C...q + g -> q + g.
1346         FACQG1=COMFAC*AS**2*4./9.*((2.+MSTP(34)*1./4.)*UH2/TH2-UH/SH)*
1347      &  FACA
1348         FACQG2=COMFAC*AS**2*4./9.*((2.+MSTP(34)*1./4.)*SH2/TH2-SH/UH)
1349         DO 680 I=-3,3
1350         IF(I.EQ.0) GOTO 680
1351         DO 670 ISDE=1,2
1352         NCHN=NCHN+1
1353         ISIG(NCHN,ISDE)=I
1354         ISIG(NCHN,3-ISDE)=21
1355         ISIG(NCHN,3)=281
1356         SIGH(NCHN)=FACQG1
1357         NCHN=NCHN+1
1358         ISIG(NCHN,ISDE)=I
1359         ISIG(NCHN,3-ISDE)=21
1360         ISIG(NCHN,3)=282
1361         SIGH(NCHN)=FACQG2
1362   670   CONTINUE
1363   680   CONTINUE
1364
1365 C...g + g -> q + qb or g + g.
1366         FACQQ1=COMFAC*AS**2*1./6.*(UH/TH-(2.+MSTP(34)*1./4.)*UH2/SH2)*
1367      &  (WDTE(0,1)+WDTE(0,2)+WDTE(0,3)+WDTE(0,4))*FACA
1368         FACQQ2=COMFAC*AS**2*1./6.*(TH/UH-(2.+MSTP(34)*1./4.)*TH2/SH2)*
1369      &  (WDTE(0,1)+WDTE(0,2)+WDTE(0,3)+WDTE(0,4))*FACA
1370         FACGG1=COMFAC*AS**2*9./4.*(SH2/TH2+2.*SH/TH+3.+2.*TH/SH+
1371      &  TH2/SH2)*FACA
1372         FACGG2=COMFAC*AS**2*9./4.*(UH2/SH2+2.*UH/SH+3.+2.*SH/UH+
1373      &  SH2/UH2)*FACA
1374         FACGG3=COMFAC*AS**2*9./4.*(TH2/UH2+2.*TH/UH+3+2.*UH/TH+UH2/TH2)
1375         NCHN=NCHN+1
1376         ISIG(NCHN,1)=21
1377         ISIG(NCHN,2)=21
1378         ISIG(NCHN,3)=531
1379         SIGH(NCHN)=FACQQ1
1380         NCHN=NCHN+1
1381         ISIG(NCHN,1)=21
1382         ISIG(NCHN,2)=21
1383         ISIG(NCHN,3)=532
1384         SIGH(NCHN)=FACQQ2
1385         NCHN=NCHN+1
1386         ISIG(NCHN,1)=21
1387         ISIG(NCHN,2)=21
1388         ISIG(NCHN,3)=681
1389         SIGH(NCHN)=0.5*FACGG1
1390         NCHN=NCHN+1
1391         ISIG(NCHN,1)=21
1392         ISIG(NCHN,2)=21
1393         ISIG(NCHN,3)=682
1394         SIGH(NCHN)=0.5*FACGG2
1395         NCHN=NCHN+1
1396         ISIG(NCHN,1)=21
1397         ISIG(NCHN,2)=21
1398         ISIG(NCHN,3)=683
1399         SIGH(NCHN)=0.5*FACGG3
1400       ENDIF
1401
1402 C...E: 2 -> 1, loop diagrams.
1403
1404       ELSEIF(ISUB.LE.110) THEN
1405       IF(ISUB.EQ.101) THEN
1406 C...g + g -> gamma*/Z0.
1407
1408       ELSEIF(ISUB.EQ.102) THEN
1409 C...g + g -> H0.
1410         CALL PYWIDT_HIJING(25,SQRT(SH),WDTP,WDTE)
1411         ETARE=0.
1412         ETAIM=0.
1413         DO 690 I=1,2*MSTP(1)
1414         EPS=4.*PMAS(I,1)**2/SH
1415         IF(EPS.LE.1.) THEN
1416           IF(EPS.GT.1.E-4) THEN
1417             ROOT=SQRT(1.-EPS)
1418             RLN=LOG((1.+ROOT)/(1.-ROOT))
1419           ELSE
1420             RLN=LOG(4./EPS-2.)
1421           ENDIF
1422           PHIRE=0.25*(RLN**2-PARU(1)**2)
1423           PHIIM=0.5*PARU(1)*RLN
1424         ELSE
1425           PHIRE=-(ASIN(1./SQRT(EPS)))**2
1426           PHIIM=0.
1427         ENDIF
1428         ETARE=ETARE+0.5*EPS*(1.+(EPS-1.)*PHIRE)
1429         ETAIM=ETAIM+0.5*EPS*(EPS-1.)*PHIIM
1430   690   CONTINUE
1431         ETA2=ETARE**2+ETAIM**2
1432         FACH=COMFAC*FACA*(AS/PARU(1)*AEM/XW)**2*1./512.*
1433      &  (SH/SQMW)**2*ETA2*SH2/((SH-SQMH)**2+GMMH**2)*
1434      &  (WDTE(0,1)+WDTE(0,2)+WDTE(0,4))
1435         IF(KFAC(1,21)*KFAC(2,21).EQ.0) GOTO 700
1436         NCHN=NCHN+1
1437         ISIG(NCHN,1)=21
1438         ISIG(NCHN,2)=21
1439         ISIG(NCHN,3)=1
1440         SIGH(NCHN)=FACH
1441   700   CONTINUE
1442
1443       ENDIF
1444
1445 C...F: 2 -> 2, box diagrams.
1446
1447       ELSEIF(ISUB.LE.120) THEN
1448       IF(ISUB.EQ.111) THEN
1449 C...f + fb -> g + H0 (q + qb -> g + H0 only).
1450         A5STUR=0.
1451         A5STUI=0.
1452         DO 710 I=1,2*MSTP(1)
1453         SQMQ=PMAS(I,1)**2
1454         EPSS=4.*SQMQ/SH
1455         EPSH=4.*SQMQ/SQMH
1456         A5STUR=A5STUR+SQMQ/SQMH*(4.+4.*SH/(TH+UH)*(PYW1AU_HIJING(EPSS,1)
1457      $       -PYW1AU_HIJING(EPSH,1))+(1.-4.*SQMQ/(TH+UH))
1458      $       *(PYW2AU_HIJING(EPSS,1)-PYW2AU_HIJING(EPSH,1)))
1459         A5STUI=A5STUI+SQMQ/SQMH*(4.*SH/(TH+UH)*(PYW1AU_HIJING(EPSS,2)-
1460      &       PYW1AU_HIJING(EPSH,2))+(1.-4.*SQMQ/(TH+UH))
1461      $       *(PYW2AU_HIJING(EPSS,2)-PYW2AU_HIJING(EPSH,2)))
1462   710   CONTINUE
1463         FACGH=COMFAC*FACA/(144.*PARU(1)**2)*AEM/XW*AS**3*SQMH/SQMW*
1464      &  SQMH/SH*(UH**2+TH**2)/(UH+TH)**2*(A5STUR**2+A5STUI**2)
1465         FACGH=FACGH*WIDS(25,2)
1466         DO 720 I=MINA,MAXA
1467         IF(I.EQ.0.OR.KFAC(1,I)*KFAC(2,-I).EQ.0) GOTO 720
1468         NCHN=NCHN+1
1469         ISIG(NCHN,1)=I
1470         ISIG(NCHN,2)=-I
1471         ISIG(NCHN,3)=1
1472         SIGH(NCHN)=FACGH
1473   720   CONTINUE
1474
1475       ELSEIF(ISUB.EQ.112) THEN
1476 C...f + g -> f + H0 (q + g -> q + H0 only).
1477         A5TSUR=0.
1478         A5TSUI=0.
1479         DO 730 I=1,2*MSTP(1)
1480         SQMQ=PMAS(I,1)**2
1481         EPST=4.*SQMQ/TH
1482         EPSH=4.*SQMQ/SQMH
1483         A5TSUR=A5TSUR+SQMQ/SQMH*(4.+4.*TH/(SH+UH)*(PYW1AU_HIJING(EPST,1)
1484      $       -PYW1AU_HIJING(EPSH,1))+(1.-4.*SQMQ/(SH+UH))
1485      $       *(PYW2AU_HIJING(EPST,1)-PYW2AU_HIJING(EPSH,1)))
1486         A5TSUI=A5TSUI+SQMQ/SQMH*(4.*TH/(SH+UH)*(PYW1AU_HIJING(EPST,2)-
1487      &       PYW1AU_HIJING(EPSH,2))+(1.-4.*SQMQ/(SH+UH))
1488      $       *(PYW2AU_HIJING(EPST,2)-PYW2AU_HIJING(EPSH,2)))
1489   730   CONTINUE
1490         FACQH=COMFAC*FACA/(384.*PARU(1)**2)*AEM/XW*AS**3*SQMH/SQMW*
1491      &  SQMH/(-TH)*(UH**2+SH**2)/(UH+SH)**2*(A5TSUR**2+A5TSUI**2)
1492         FACQH=FACQH*WIDS(25,2)
1493         DO 750 I=MINA,MAXA
1494         IF(I.EQ.0) GOTO 750
1495         DO 740 ISDE=1,2
1496         IF(ISDE.EQ.1.AND.KFAC(1,I)*KFAC(2,21).EQ.0) GOTO 740
1497         IF(ISDE.EQ.2.AND.KFAC(1,21)*KFAC(2,I).EQ.0) GOTO 740
1498         NCHN=NCHN+1
1499         ISIG(NCHN,ISDE)=I
1500         ISIG(NCHN,3-ISDE)=21
1501         ISIG(NCHN,3)=1
1502         SIGH(NCHN)=FACQH
1503   740   CONTINUE
1504   750   CONTINUE
1505
1506       ELSEIF(ISUB.EQ.113) THEN
1507 C...g + g -> g + H0.
1508         A2STUR=0.
1509         A2STUI=0.
1510         A2USTR=0.
1511         A2USTI=0.
1512         A2TUSR=0.
1513         A2TUSI=0.
1514         A4STUR=0.
1515         A4STUI=0.
1516         DO 760 I=6,2*MSTP(1)
1517 C'''Only t-quarks yet included
1518         SQMQ=PMAS(I,1)**2
1519         EPSS=4.*SQMQ/SH
1520         EPST=4.*SQMQ/TH
1521         EPSU=4.*SQMQ/UH
1522         EPSH=4.*SQMQ/SQMH
1523         IF(EPSH.LT.1.E-6) GOTO 760
1524         BESTU=0.5*(1.+SQRT(1.+EPSS*TH/UH))
1525         BEUST=0.5*(1.+SQRT(1.+EPSU*SH/TH))
1526         BETUS=0.5*(1.+SQRT(1.+EPST*UH/SH))
1527         BEUTS=BESTU
1528         BETSU=BEUST
1529         BESUT=BETUS
1530         W3STUR=PYI3AU_HIJING(BESTU,EPSH,1)-PYI3AU_HIJING(BESTU,EPSS,1)-
1531      &  PYI3AU_HIJING(BESTU,EPSU,1)
1532         W3STUI=PYI3AU_HIJING(BESTU,EPSH,2)-PYI3AU_HIJING(BESTU,EPSS,2)-
1533      &  PYI3AU_HIJING(BESTU,EPSU,2)
1534         W3SUTR=PYI3AU_HIJING(BESUT,EPSH,1)-PYI3AU_HIJING(BESUT,EPSS,1)-
1535      &  PYI3AU_HIJING(BESUT,EPST,1)
1536         W3SUTI=PYI3AU_HIJING(BESUT,EPSH,2)-PYI3AU_HIJING(BESUT,EPSS,2)-
1537      &  PYI3AU_HIJING(BESUT,EPST,2)
1538         W3TSUR=PYI3AU_HIJING(BETSU,EPSH,1)-PYI3AU_HIJING(BETSU,EPST,1)-
1539      &  PYI3AU_HIJING(BETSU,EPSU,1)
1540         W3TSUI=PYI3AU_HIJING(BETSU,EPSH,2)-PYI3AU_HIJING(BETSU,EPST,2)-
1541      &  PYI3AU_HIJING(BETSU,EPSU,2)
1542         W3TUSR=PYI3AU_HIJING(BETUS,EPSH,1)-PYI3AU_HIJING(BETUS,EPST,1)-
1543      &  PYI3AU_HIJING(BETUS,EPSS,1)
1544         W3TUSI=PYI3AU_HIJING(BETUS,EPSH,2)-PYI3AU_HIJING(BETUS,EPST,2)-
1545      &  PYI3AU_HIJING(BETUS,EPSS,2)
1546         W3USTR=PYI3AU_HIJING(BEUST,EPSH,1)-PYI3AU_HIJING(BEUST,EPSU,1)-
1547      &  PYI3AU_HIJING(BEUST,EPST,1)
1548         W3USTI=PYI3AU_HIJING(BEUST,EPSH,2)-PYI3AU_HIJING(BEUST,EPSU,2)-
1549      &  PYI3AU_HIJING(BEUST,EPST,2)
1550         W3UTSR=PYI3AU_HIJING(BEUTS,EPSH,1)-PYI3AU_HIJING(BEUTS,EPSU,1)-
1551      &  PYI3AU_HIJING(BEUTS,EPSS,1)
1552         W3UTSI=PYI3AU_HIJING(BEUTS,EPSH,2)-PYI3AU_HIJING(BEUTS,EPSU,2)-
1553      &  PYI3AU_HIJING(BEUTS,EPSS,2)
1554         B2STUR=SQMQ/SQMH**2*(SH*(UH-SH)/(SH+UH)+2.*TH*UH*(UH+2.*SH)/
1555      &       (SH+UH)**2*(PYW1AU_HIJING(EPST,1)-PYW1AU_HIJING(EPSH,1))
1556      $       +(SQMQ-SH/4.)*(0.5*PYW2AU_HIJING(EPSS,1)+0.5
1557      $       *PYW2AU_HIJING(EPSH,1)-PYW2AU_HIJING(EPST,1)+W3STUR)+SH**2
1558      $       *(2.*SQMQ/(SH+UH)**2-0.5/(SH+UH))*(PYW2AU_HIJING(EPST,1)
1559      $       -PYW2AU_HIJING(EPSH,1))+0.5*TH*UH/SH*(PYW2AU_HIJING(EPSH,1)
1560      $       -2.*PYW2AU_HIJING(EPST,1))+0.125*(SH-12.*SQMQ-4.*TH*UH/SH)
1561      $       *W3TSUR)
1562         B2STUI=SQMQ/SQMH**2*(2.*TH*UH*(UH+2.*SH)/(SH+UH)**2*
1563      &  (PYW1AU_HIJING(EPST,2)-PYW1AU_HIJING(EPSH,2))+(SQMQ-SH/4.)*
1564      &       (0.5*PYW2AU_HIJING(EPSS,2)+0.5*PYW2AU_HIJING(EPSH,2)
1565      $       -PYW2AU_HIJING(EPST,2)+W3STUI)+SH**2*(2.*SQMQ/(SH+UH)**2-0
1566      $       .5/(SH+UH))*(PYW2AU_HIJING(EPST,2)-PYW2AU_HIJING(EPSH,2))+0
1567      $       .5*TH*UH/SH*(PYW2AU_HIJING(EPSH,2)-2.*PYW2AU_HIJING(EPST,2)
1568      $       )+0.125*(SH-12.*SQMQ-4.*TH*UH/SH)*W3TSUI)
1569         B2SUTR=SQMQ/SQMH**2*(SH*(TH-SH)/(SH+TH)+2.*UH*TH*(TH+2.*SH)/
1570      &       (SH+TH)**2*(PYW1AU_HIJING(EPSU,1)-PYW1AU_HIJING(EPSH,1))
1571      $       +(SQMQ-SH/4.)*(0.5*PYW2AU_HIJING(EPSS,1)+0.5
1572      $       *PYW2AU_HIJING(EPSH,1)-PYW2AU_HIJING(EPSU,1)+W3SUTR)+SH**2
1573      $       *(2.*SQMQ/(SH+TH)**2-0.5/(SH+TH))*(PYW2AU_HIJING(EPSU,1)
1574      $       -PYW2AU_HIJING(EPSH,1))+0.5*UH*TH/SH*(PYW2AU_HIJING(EPSH,1)
1575      $       -2.*PYW2AU_HIJING(EPSU,1))+0.125*(SH-12.*SQMQ-4.*UH*TH/SH)
1576      $       *W3USTR)
1577         B2SUTI=SQMQ/SQMH**2*(2.*UH*TH*(TH+2.*SH)/(SH+TH)**2*
1578      &  (PYW1AU_HIJING(EPSU,2)-PYW1AU_HIJING(EPSH,2))+(SQMQ-SH/4.)*
1579      &       (0.5*PYW2AU_HIJING(EPSS,2)+0.5*PYW2AU_HIJING(EPSH,2)
1580      $       -PYW2AU_HIJING(EPSU,2)+W3SUTI)+SH**2*(2.*SQMQ/(SH+TH)**2-0
1581      $       .5/(SH+TH))*(PYW2AU_HIJING(EPSU,2)-PYW2AU_HIJING(EPSH,2))+0
1582      $       .5*UH*TH/SH*(PYW2AU_HIJING(EPSH,2)-2.*PYW2AU_HIJING(EPSU,2)
1583      $       )+0.125*(SH-12.*SQMQ-4.*UH*TH/SH)*W3USTI)
1584         B2TSUR=SQMQ/SQMH**2*(TH*(UH-TH)/(TH+UH)+2.*SH*UH*(UH+2.*TH)/
1585      &       (TH+UH)**2*(PYW1AU_HIJING(EPSS,1)-PYW1AU_HIJING(EPSH,1))
1586      $       +(SQMQ-TH/4.)*(0.5*PYW2AU_HIJING(EPST,1)+0.5
1587      $       *PYW2AU_HIJING(EPSH,1)-PYW2AU_HIJING(EPSS,1)+W3TSUR)+TH**2
1588      $       *(2.*SQMQ/(TH+UH)**2-0.5/(TH+UH))*(PYW2AU_HIJING(EPSS,1)
1589      $       -PYW2AU_HIJING(EPSH,1))+0.5*SH*UH/TH*(PYW2AU_HIJING(EPSH,1)
1590      $       -2.*PYW2AU_HIJING(EPSS,1))+0.125*(TH-12.*SQMQ-4.*SH*UH/TH)
1591      $       *W3STUR)
1592         B2TSUI=SQMQ/SQMH**2*(2.*SH*UH*(UH+2.*TH)/(TH+UH)**2*
1593      &  (PYW1AU_HIJING(EPSS,2)-PYW1AU_HIJING(EPSH,2))+(SQMQ-TH/4.)*
1594      &       (0.5*PYW2AU_HIJING(EPST,2)+0.5*PYW2AU_HIJING(EPSH,2)
1595      $       -PYW2AU_HIJING(EPSS,2)+W3TSUI)+TH**2*(2.*SQMQ/(TH+UH)**2-0
1596      $       .5/(TH+UH))*(PYW2AU_HIJING(EPSS,2)-PYW2AU_HIJING(EPSH,2))+0
1597      $       .5*SH*UH/TH*(PYW2AU_HIJING(EPSH,2)-2.*PYW2AU_HIJING(EPSS,2)
1598      $       )+0.125*(TH-12.*SQMQ-4.*SH*UH/TH)*W3STUI)
1599         B2TUSR=SQMQ/SQMH**2*(TH*(SH-TH)/(TH+SH)+2.*UH*SH*(SH+2.*TH)/
1600      &       (TH+SH)**2*(PYW1AU_HIJING(EPSU,1)-PYW1AU_HIJING(EPSH,1))
1601      $       +(SQMQ-TH/4.)*(0.5*PYW2AU_HIJING(EPST,1)+0.5
1602      $       *PYW2AU_HIJING(EPSH,1)-PYW2AU_HIJING(EPSU,1)+W3TUSR)+TH**2
1603      $       *(2.*SQMQ/(TH+SH)**2-0.5/(TH+SH))*(PYW2AU_HIJING(EPSU,1)
1604      $       -PYW2AU_HIJING(EPSH,1))+0.5*UH*SH/TH*(PYW2AU_HIJING(EPSH,1)
1605      $       -2.*PYW2AU_HIJING(EPSU,1))+0.125*(TH-12.*SQMQ-4.*UH*SH/TH)
1606      $       *W3UTSR)
1607         B2TUSI=SQMQ/SQMH**2*(2.*UH*SH*(SH+2.*TH)/(TH+SH)**2*
1608      &  (PYW1AU_HIJING(EPSU,2)-PYW1AU_HIJING(EPSH,2))+(SQMQ-TH/4.)*
1609      &       (0.5*PYW2AU_HIJING(EPST,2)+0.5*PYW2AU_HIJING(EPSH,2)
1610      $       -PYW2AU_HIJING(EPSU,2)+W3TUSI)+TH**2*(2.*SQMQ/(TH+SH)**2-0
1611      $       .5/(TH+SH))*(PYW2AU_HIJING(EPSU,2)-PYW2AU_HIJING(EPSH,2))+0
1612      $       .5*UH*SH/TH*(PYW2AU_HIJING(EPSH,2)-2.*PYW2AU_HIJING(EPSU,2)
1613      $       )+0.125*(TH-12.*SQMQ-4.*UH*SH/TH)*W3UTSI)
1614         B2USTR=SQMQ/SQMH**2*(UH*(TH-UH)/(UH+TH)+2.*SH*TH*(TH+2.*UH)/
1615      &       (UH+TH)**2*(PYW1AU_HIJING(EPSS,1)-PYW1AU_HIJING(EPSH,1))
1616      $       +(SQMQ-UH/4.)*(0.5*PYW2AU_HIJING(EPSU,1)+0.5
1617      $       *PYW2AU_HIJING(EPSH,1)-PYW2AU_HIJING(EPSS,1)+W3USTR)+UH**2
1618      $       *(2.*SQMQ/(UH+TH)**2-0.5/(UH+TH))*(PYW2AU_HIJING(EPSS,1)
1619      $       -PYW2AU_HIJING(EPSH,1))+0.5*SH*TH/UH*(PYW2AU_HIJING(EPSH,1)
1620      $       -2.*PYW2AU_HIJING(EPSS,1))+0.125*(UH-12.*SQMQ-4.*SH*TH/UH)
1621      $       *W3SUTR)
1622         B2USTI=SQMQ/SQMH**2*(2.*SH*TH*(TH+2.*UH)/(UH+TH)**2*
1623      &  (PYW1AU_HIJING(EPSS,2)-PYW1AU_HIJING(EPSH,2))+(SQMQ-UH/4.)*
1624      &       (0.5*PYW2AU_HIJING(EPSU,2)+0.5*PYW2AU_HIJING(EPSH,2)
1625      $       -PYW2AU_HIJING(EPSS,2)+W3USTI)+UH**2*(2.*SQMQ/(UH+TH)**2-0
1626      $       .5/(UH+TH))*(PYW2AU_HIJING(EPSS,2)-PYW2AU_HIJING(EPSH,2))+0
1627      $       .5*SH*TH/UH*(PYW2AU_HIJING(EPSH,2)-2.*PYW2AU_HIJING(EPSS,2)
1628      $       )+0.125*(UH-12.*SQMQ-4.*SH*TH/UH)*W3SUTI)
1629         B2UTSR=SQMQ/SQMH**2*(UH*(SH-UH)/(UH+SH)+2.*TH*SH*(SH+2.*UH)/
1630      &       (UH+SH)**2*(PYW1AU_HIJING(EPST,1)-PYW1AU_HIJING(EPSH,1))
1631      $       +(SQMQ-UH/4.)*(0.5*PYW2AU_HIJING(EPSU,1)+0.5
1632      $       *PYW2AU_HIJING(EPSH,1)-PYW2AU_HIJING(EPST,1)+W3UTSR)+UH**2
1633      $       *(2.*SQMQ/(UH+SH)**2-0.5/(UH+SH))*(PYW2AU_HIJING(EPST,1)
1634      $       -PYW2AU_HIJING(EPSH,1))+0.5*TH*SH/UH*(PYW2AU_HIJING(EPSH,1)
1635      $       -2.*PYW2AU_HIJING(EPST,1))+0.125*(UH-12.*SQMQ-4.*TH*SH/UH)
1636      $       *W3TUSR)
1637         B2UTSI=SQMQ/SQMH**2*(2.*TH*SH*(SH+2.*UH)/(UH+SH)**2*
1638      &  (PYW1AU_HIJING(EPST,2)-PYW1AU_HIJING(EPSH,2))+(SQMQ-UH/4.)*
1639      &       (0.5*PYW2AU_HIJING(EPSU,2)+0.5*PYW2AU_HIJING(EPSH,2)
1640      $       -PYW2AU_HIJING(EPST,2)+W3UTSI)+UH**2*(2.*SQMQ/(UH+SH)**2-0
1641      $       .5/(UH+SH))*(PYW2AU_HIJING(EPST,2)-PYW2AU_HIJING(EPSH,2))+0
1642      $       .5*TH*SH/UH*(PYW2AU_HIJING(EPSH,2)-2.*PYW2AU_HIJING(EPST,2)
1643      $       )+0.125*(UH-12.*SQMQ-4.*TH*SH/UH)*W3TUSI)
1644         B4STUR=SQMQ/SQMH*(-2./3.+(SQMQ/SQMH-1./4.)*(PYW2AU_HIJING(EPSS,1
1645      $       )-PYW2AU_HIJING(EPSH,1)+W3STUR))
1646         B4STUI=SQMQ/SQMH*(SQMQ/SQMH-1./4.)*(PYW2AU_HIJING(EPSS,2)-
1647      &  PYW2AU_HIJING(EPSH,2)+W3STUI)
1648         B4TUSR=SQMQ/SQMH*(-2./3.+(SQMQ/SQMH-1./4.)*(PYW2AU_HIJING(EPST,1
1649      $       )-PYW2AU_HIJING(EPSH,1)+W3TUSR))
1650         B4TUSI=SQMQ/SQMH*(SQMQ/SQMH-1./4.)*(PYW2AU_HIJING(EPST,2)-
1651      &  PYW2AU_HIJING(EPSH,2)+W3TUSI)
1652         B4USTR=SQMQ/SQMH*(-2./3.+(SQMQ/SQMH-1./4.)*(PYW2AU_HIJING(EPSU,1
1653      $       )-PYW2AU_HIJING(EPSH,1)+W3USTR))
1654         B4USTI=SQMQ/SQMH*(SQMQ/SQMH-1./4.)*(PYW2AU_HIJING(EPSU,2)-
1655      &  PYW2AU_HIJING(EPSH,2)+W3USTI)
1656         A2STUR=A2STUR+B2STUR+B2SUTR
1657         A2STUI=A2STUI+B2STUI+B2SUTI
1658         A2USTR=A2USTR+B2USTR+B2UTSR
1659         A2USTI=A2USTI+B2USTI+B2UTSI
1660         A2TUSR=A2TUSR+B2TUSR+B2TSUR
1661         A2TUSI=A2TUSI+B2TUSI+B2TSUI
1662         A4STUR=A4STUR+B4STUR+B4USTR+B4TUSR
1663         A4STUI=A4STUI+B4STUI+B4USTI+B4TUSI
1664   760   CONTINUE
1665         FACGH=COMFAC*FACA*3./(128.*PARU(1)**2)*AEM/XW*AS**3*
1666      &  SQMH/SQMW*SQMH**3/(SH*TH*UH)*(A2STUR**2+A2STUI**2+A2USTR**2+
1667      &  A2USTI**2+A2TUSR**2+A2TUSI**2+A4STUR**2+A4STUI**2)
1668         FACGH=FACGH*WIDS(25,2)
1669         IF(KFAC(1,21)*KFAC(2,21).EQ.0) GOTO 770
1670         NCHN=NCHN+1
1671         ISIG(NCHN,1)=21
1672         ISIG(NCHN,2)=21
1673         ISIG(NCHN,3)=1
1674         SIGH(NCHN)=FACGH
1675   770   CONTINUE
1676
1677       ELSEIF(ISUB.EQ.114) THEN
1678 C...g + g -> gamma + gamma.
1679         ASRE=0.
1680         ASIM=0.
1681         DO 780 I=1,2*MSTP(1)
1682         EI=KCHG(IABS(I),1)/3.
1683         SQMQ=PMAS(I,1)**2
1684         EPSS=4.*SQMQ/SH
1685         EPST=4.*SQMQ/TH
1686         EPSU=4.*SQMQ/UH
1687         IF(EPSS+ABS(EPST)+ABS(EPSU).LT.3.E-6) THEN
1688           A0STUR=1.+(TH-UH)/SH*LOG(TH/UH)+0.5*(TH2+UH2)/SH2*
1689      &    (LOG(TH/UH)**2+PARU(1)**2)
1690           A0STUI=0.
1691           A0TSUR=1.+(SH-UH)/TH*LOG(-SH/UH)+0.5*(SH2+UH2)/TH2*
1692      &    LOG(-SH/UH)**2
1693           A0TSUI=-PARU(1)*((SH-UH)/TH+(SH2+UH2)/TH2*LOG(-SH/UH))
1694           A0UTSR=1.+(TH-SH)/UH*LOG(-TH/SH)+0.5*(TH2+SH2)/UH2*
1695      &    LOG(-TH/SH)**2
1696           A0UTSI=PARU(1)*((TH-SH)/UH+(TH2+SH2)/UH2*LOG(-TH/SH))
1697           A1STUR=-1.
1698           A1STUI=0.
1699           A2STUR=-1.
1700           A2STUI=0.
1701         ELSE
1702           BESTU=0.5*(1.+SQRT(1.+EPSS*TH/UH))
1703           BEUST=0.5*(1.+SQRT(1.+EPSU*SH/TH))
1704           BETUS=0.5*(1.+SQRT(1.+EPST*UH/SH))
1705           BEUTS=BESTU
1706           BETSU=BEUST
1707           BESUT=BETUS
1708           A0STUR=1.+(1.+2.*TH/SH)*PYW1AU_HIJING(EPST,1)+(1.+2.*UH/SH)*
1709      &         PYW1AU_HIJING(EPSU,1)+0.5*((TH2+UH2)/SH2-EPSS)
1710      $         *(PYW2AU_HIJING(EPST,1)+PYW2AU_HIJING(EPSU,1))-0.25*EPST
1711      $         *(1.-0.5*EPSS)*(PYI3AU_HIJING(BESUT,EPSS,1)
1712      $         +PYI3AU_HIJING(BESUT,EPST,1))-0.25*EPSU*(1.-0.5*EPSS)
1713      $         *(PYI3AU_HIJING(BESTU,EPSS,1)+PYI3AU_HIJING(BESTU,EPSU,1)
1714      $         )+0.25*(-2.*(TH2+UH2)/SH2+4.*EPSS+EPST+EPSU+0.5*EPST*EPSU
1715      $         )*(PYI3AU_HIJING(BETSU,EPST,1)+PYI3AU_HIJING(BETSU,EPSU,1
1716      $         ))
1717           A0STUI=(1.+2.*TH/SH)*PYW1AU_HIJING(EPST,2)+(1.+2.*UH/SH)*
1718      &         PYW1AU_HIJING(EPSU,2)+0.5*((TH2+UH2)/SH2-EPSS)
1719      $         *(PYW2AU_HIJING(EPST,2)+PYW2AU_HIJING(EPSU,2))-0.25*EPST
1720      $         *(1.-0.5*EPSS)*(PYI3AU_HIJING(BESUT,EPSS,2)
1721      $         +PYI3AU_HIJING(BESUT,EPST,2))-0.25*EPSU*(1.-0.5*EPSS)
1722      $         *(PYI3AU_HIJING(BESTU,EPSS,2)+PYI3AU_HIJING(BESTU,EPSU,2)
1723      $         )+0.25*(-2.*(TH2+UH2)/SH2+4.*EPSS+EPST+EPSU+0.5*EPST*EPSU
1724      $         )*(PYI3AU_HIJING(BETSU,EPST,2)+PYI3AU_HIJING(BETSU,EPSU,2
1725      $         ))
1726           A0TSUR=1.+(1.+2.*SH/TH)*PYW1AU_HIJING(EPSS,1)+(1.+2.*UH/TH)*
1727      &         PYW1AU_HIJING(EPSU,1)+0.5*((SH2+UH2)/TH2-EPST)
1728      $         *(PYW2AU_HIJING(EPSS,1)+PYW2AU_HIJING(EPSU,1))-0.25*EPSS
1729      $         *(1.-0.5*EPST)*(PYI3AU_HIJING(BETUS,EPST,1)
1730      $         +PYI3AU_HIJING(BETUS,EPSS,1))-0.25*EPSU*(1.-0.5*EPST)
1731      $         *(PYI3AU_HIJING(BETSU,EPST,1)+PYI3AU_HIJING(BETSU,EPSU,1)
1732      $         )+0.25*(-2.*(SH2+UH2)/TH2+4.*EPST+EPSS+EPSU+0.5*EPSS*EPSU
1733      $         )*(PYI3AU_HIJING(BESTU,EPSS,1)+PYI3AU_HIJING(BESTU,EPSU,1
1734      $         ))
1735           A0TSUI=(1.+2.*SH/TH)*PYW1AU_HIJING(EPSS,2)+(1.+2.*UH/TH)*
1736      &         PYW1AU_HIJING(EPSU,2)+0.5*((SH2+UH2)/TH2-EPST)
1737      $         *(PYW2AU_HIJING(EPSS,2)+PYW2AU_HIJING(EPSU,2))-0.25*EPSS
1738      $         *(1.-0.5*EPST)*(PYI3AU_HIJING(BETUS,EPST,2)
1739      $         +PYI3AU_HIJING(BETUS,EPSS,2))-0.25*EPSU*(1.-0.5*EPST)
1740      $         *(PYI3AU_HIJING(BETSU,EPST,2)+PYI3AU_HIJING(BETSU,EPSU,2)
1741      $         )+0.25*(-2.*(SH2+UH2)/TH2+4.*EPST+EPSS+EPSU+0.5*EPSS*EPSU
1742      $         )*(PYI3AU_HIJING(BESTU,EPSS,2)+PYI3AU_HIJING(BESTU,EPSU,2
1743      $         ))
1744           A0UTSR=1.+(1.+2.*TH/UH)*PYW1AU_HIJING(EPST,1)+(1.+2.*SH/UH)*
1745      &         PYW1AU_HIJING(EPSS,1)+0.5*((TH2+SH2)/UH2-EPSU)
1746      $         *(PYW2AU_HIJING(EPST,1)+PYW2AU_HIJING(EPSS,1))-0.25*EPST
1747      $         *(1.-0.5*EPSU)*(PYI3AU_HIJING(BEUST,EPSU,1)
1748      $         +PYI3AU_HIJING(BEUST,EPST,1))-0.25*EPSS*(1.-0.5*EPSU)
1749      $         *(PYI3AU_HIJING(BEUTS,EPSU,1)+PYI3AU_HIJING(BEUTS,EPSS,1)
1750      $         )+0.25*(-2.*(TH2+SH2)/UH2+4.*EPSU+EPST+EPSS+0.5*EPST*EPSS
1751      $         )*(PYI3AU_HIJING(BETUS,EPST,1)+PYI3AU_HIJING(BETUS,EPSS,1
1752      $         ))
1753           A0UTSI=(1.+2.*TH/UH)*PYW1AU_HIJING(EPST,2)+(1.+2.*SH/UH)*
1754      &         PYW1AU_HIJING(EPSS,2)+0.5*((TH2+SH2)/UH2-EPSU)
1755      $         *(PYW2AU_HIJING(EPST,2)+PYW2AU_HIJING(EPSS,2))-0.25*EPST
1756      $         *(1.-0.5*EPSU)*(PYI3AU_HIJING(BEUST,EPSU,2)
1757      $         +PYI3AU_HIJING(BEUST,EPST,2))-0.25*EPSS*(1.-0.5*EPSU)
1758      $         *(PYI3AU_HIJING(BEUTS,EPSU,2)+PYI3AU_HIJING(BEUTS,EPSS,2)
1759      $         )+0.25*(-2.*(TH2+SH2)/UH2+4.*EPSU+EPST+EPSS+0.5*EPST*EPSS
1760      $         )*(PYI3AU_HIJING(BETUS,EPST,2)+PYI3AU_HIJING(BETUS,EPSS,2
1761      $         ))
1762           A1STUR=-1.-0.25*(EPSS+EPST+EPSU)*(PYW2AU_HIJING(EPSS,1)+
1763      &         PYW2AU_HIJING(EPST,1)+PYW2AU_HIJING(EPSU,1))+0.25*(EPSU+0
1764      $         .5*EPSS*EPST)*(PYI3AU_HIJING(BESUT,EPSS,1)
1765      $         +PYI3AU_HIJING(BESUT,EPST,1))+0.25*(EPST+0.5*EPSS*EPSU)
1766      $         *(PYI3AU_HIJING(BESTU,EPSS,1)+PYI3AU_HIJING(BESTU,EPSU,1)
1767      $         )+0.25*(EPSS+0.5*EPST*EPSU)*(PYI3AU_HIJING(BETSU,EPST,1)
1768      $         +PYI3AU_HIJING(BETSU,EPSU,1))
1769           A1STUI=-0.25*(EPSS+EPST+EPSU)*(PYW2AU_HIJING(EPSS,2)
1770      $         +PYW2AU_HIJING(EPST,2)+PYW2AU_HIJING(EPSU,2))+0.25*(EPSU
1771      $         +0.5*EPSS*EPST)*(PYI3AU_HIJING(BESUT,EPSS,2)
1772      $         +PYI3AU_HIJING(BESUT,EPST,2))+0.25*(EPST+0.5*EPSS*EPSU)
1773      $         *(PYI3AU_HIJING(BESTU,EPSS,2)+PYI3AU_HIJING(BESTU,EPSU,2)
1774      $         )+0.25*(EPSS+0.5*EPST*EPSU)*(PYI3AU_HIJING(BETSU,EPST,2)
1775      $         +PYI3AU_HIJING(BETSU,EPSU,2))
1776           A2STUR=-1.+0.125*EPSS*EPST*(PYI3AU_HIJING(BESUT,EPSS,1)+
1777      &         PYI3AU_HIJING(BESUT,EPST,1))+0.125*EPSS*EPSU
1778      $         *(PYI3AU_HIJING(BESTU,EPSS,1)+PYI3AU_HIJING(BESTU,EPSU,1)
1779      $         )+0.125*EPST*EPSU*(PYI3AU_HIJING(BETSU,EPST,1)
1780      $         +PYI3AU_HIJING(BETSU,EPSU,1))
1781           A2STUI=0.125*EPSS*EPST*(PYI3AU_HIJING(BESUT,EPSS,2)+
1782      &         PYI3AU_HIJING(BESUT,EPST,2))+0.125*EPSS*EPSU
1783      $         *(PYI3AU_HIJING(BESTU,EPSS,2)+PYI3AU_HIJING(BESTU,EPSU,2)
1784      $         )+0.125*EPST*EPSU*(PYI3AU_HIJING(BETSU,EPST,2)
1785      $         +PYI3AU_HIJING(BETSU,EPSU,2))
1786         ENDIF
1787         ASRE=ASRE+EI**2*(A0STUR+A0TSUR+A0UTSR+4.*A1STUR+A2STUR)
1788         ASIM=ASIM+EI**2*(A0STUI+A0TSUI+A0UTSI+4.*A1STUI+A2STUI)
1789   780   CONTINUE
1790         FACGG=COMFAC*FACA/(8.*PARU(1)**2)*AS**2*AEM**2*(ASRE**2+ASIM**2)
1791         IF(KFAC(1,21)*KFAC(2,21).EQ.0) GOTO 790
1792         NCHN=NCHN+1
1793         ISIG(NCHN,1)=21
1794         ISIG(NCHN,2)=21
1795         ISIG(NCHN,3)=1
1796         SIGH(NCHN)=FACGG
1797   790   CONTINUE
1798
1799       ELSEIF(ISUB.EQ.115) THEN
1800 C...g + g -> gamma + Z0.
1801
1802       ELSEIF(ISUB.EQ.116) THEN
1803 C...g + g -> Z0 + Z0.
1804
1805       ELSEIF(ISUB.EQ.117) THEN
1806 C...g + g -> W+ + W-.
1807
1808       ENDIF
1809
1810 C...G: 2 -> 3, tree diagrams.
1811
1812       ELSEIF(ISUB.LE.140) THEN
1813       IF(ISUB.EQ.121) THEN
1814 C...g + g -> f + fb + H0.
1815
1816       ENDIF
1817
1818 C...H: 2 -> 1, tree diagrams, non-standard model processes.
1819
1820       ELSEIF(ISUB.LE.160) THEN
1821       IF(ISUB.EQ.141) THEN
1822 C...f + fb -> gamma*/Z0/Z'0.
1823         MINT(61)=2
1824         CALL PYWIDT_HIJING(32,SQRT(SH),WDTP,WDTE)
1825         FACZP=COMFAC*AEM**2*4./9.
1826         DO 800 I=MINA,MAXA
1827         IF(I.EQ.0.OR.KFAC(1,I)*KFAC(2,-I).EQ.0) GOTO 800
1828         EI=KCHG(IABS(I),1)/3.
1829         AI=SIGN(1.,EI)
1830         VI=AI-4.*EI*XW
1831         API=SIGN(1.,EI)
1832         VPI=API-4.*EI*XW
1833         NCHN=NCHN+1
1834         ISIG(NCHN,1)=I
1835         ISIG(NCHN,2)=-I
1836         ISIG(NCHN,3)=1
1837         SIGH(NCHN)=FACZP*(EI**2*VINT(111)+EI*VI/(8.*XW*(1.-XW))*
1838      &  SH*(SH-SQMZ)/((SH-SQMZ)**2+GMMZ**2)*VINT(112)+EI*VPI/(8.*XW*
1839      &  (1.-XW))*SH*(SH-SQMZP)/((SH-SQMZP)**2+GMMZP**2)*VINT(113)+
1840      &  (VI**2+AI**2)/(16.*XW*(1.-XW))**2*SH2/((SH-SQMZ)**2+GMMZ**2)*
1841      &  VINT(114)+2.*(VI*VPI+AI*API)/(16.*XW*(1.-XW))**2*SH2*
1842      &  ((SH-SQMZ)*(SH-SQMZP)+GMMZ*GMMZP)/(((SH-SQMZ)**2+GMMZ**2)*
1843      &  ((SH-SQMZP)**2+GMMZP**2))*VINT(115)+(VPI**2+API**2)/
1844      &  (16.*XW*(1.-XW))**2*SH2/((SH-SQMZP)**2+GMMZP**2)*VINT(116))
1845   800   CONTINUE
1846
1847       ELSEIF(ISUB.EQ.142) THEN
1848 C...f + fb' -> H+/-.
1849         CALL PYWIDT_HIJING(37,SQRT(SH),WDTP,WDTE)
1850         FHC=COMFAC*(AEM/XW)**2*1./48.*(SH/SQMW)**2*SH2/
1851      &  ((SH-SQMHC)**2+GMMHC**2)
1852 C'''No construction yet for leptons
1853         DO 840 I=1,MSTP(54)/2
1854         IL=2*I-1
1855         IU=2*I
1856         RMQL=PMAS(IL,1)**2/SH
1857         RMQU=PMAS(IU,1)**2/SH
1858         FACHC=FHC*((RMQL*PARU(121)+RMQU/PARU(121))*(1.-RMQL-RMQU)-
1859      &  4.*RMQL*RMQU)/SQRT(MAX(0.,(1.-RMQL-RMQU)**2-4.*RMQL*RMQU))
1860         IF(KFAC(1,IL)*KFAC(2,-IU).EQ.0) GOTO 810
1861         KCHHC=(KCHG(IL,1)-KCHG(IU,1))/3
1862         NCHN=NCHN+1
1863         ISIG(NCHN,1)=IL
1864         ISIG(NCHN,2)=-IU
1865         ISIG(NCHN,3)=1
1866         SIGH(NCHN)=FACHC*(WDTE(0,1)+WDTE(0,(5-KCHHC)/2)+WDTE(0,4))
1867   810   IF(KFAC(1,-IL)*KFAC(2,IU).EQ.0) GOTO 820
1868         KCHHC=(-KCHG(IL,1)+KCHG(IU,1))/3
1869         NCHN=NCHN+1
1870         ISIG(NCHN,1)=-IL
1871         ISIG(NCHN,2)=IU
1872         ISIG(NCHN,3)=1
1873         SIGH(NCHN)=FACHC*(WDTE(0,1)+WDTE(0,(5-KCHHC)/2)+WDTE(0,4))
1874   820   IF(KFAC(1,IU)*KFAC(2,-IL).EQ.0) GOTO 830
1875         KCHHC=(KCHG(IU,1)-KCHG(IL,1))/3
1876         NCHN=NCHN+1
1877         ISIG(NCHN,1)=IU
1878         ISIG(NCHN,2)=-IL
1879         ISIG(NCHN,3)=1
1880         SIGH(NCHN)=FACHC*(WDTE(0,1)+WDTE(0,(5-KCHHC)/2)+WDTE(0,4))
1881   830   IF(KFAC(1,-IU)*KFAC(2,IL).EQ.0) GOTO 840
1882         KCHHC=(-KCHG(IU,1)+KCHG(IL,1))/3
1883         NCHN=NCHN+1
1884         ISIG(NCHN,1)=-IU
1885         ISIG(NCHN,2)=IL
1886         ISIG(NCHN,3)=1
1887         SIGH(NCHN)=FACHC*(WDTE(0,1)+WDTE(0,(5-KCHHC)/2)+WDTE(0,4))
1888   840   CONTINUE
1889
1890       ELSEIF(ISUB.EQ.143) THEN
1891 C...f + fb -> R.
1892         CALL PYWIDT_HIJING(40,SQRT(SH),WDTP,WDTE)
1893         FACR=COMFAC*(AEM/XW)**2*1./9.*SH2/((SH-SQMR)**2+GMMR**2)
1894         DO 860 I=MIN1,MAX1
1895         IF(I.EQ.0.OR.KFAC(1,I).EQ.0) GOTO 860
1896         IA=IABS(I)
1897         DO 850 J=MIN2,MAX2
1898         IF(J.EQ.0.OR.KFAC(2,J).EQ.0) GOTO 850
1899         JA=IABS(J)
1900         IF(I*J.GT.0.OR.IABS(IA-JA).NE.2) GOTO 850
1901         NCHN=NCHN+1
1902         ISIG(NCHN,1)=I
1903         ISIG(NCHN,2)=J
1904         ISIG(NCHN,3)=1
1905         SIGH(NCHN)=FACR*(WDTE(0,1)+WDTE(0,(10-(I+J))/4)+WDTE(0,4))
1906   850   CONTINUE
1907   860   CONTINUE
1908
1909       ENDIF
1910
1911 C...I: 2 -> 2, tree diagrams, non-standard model processes.
1912
1913       ELSE
1914       IF(ISUB.EQ.161) THEN
1915 C...f + g -> f' + H+/- (q + g -> q' + H+/- only).
1916         FHCQ=COMFAC*FACA*AS*AEM/XW*1./24
1917         DO 900 I=1,MSTP(54)
1918         IU=I+MOD(I,2)
1919         SQMQ=PMAS(IU,1)**2
1920         FACHCQ=FHCQ/PARU(121)*SQMQ/SQMW*(SH/(SQMQ-UH)+
1921      &  2.*SQMQ*(SQMHC-UH)/(SQMQ-UH)**2+(SQMQ-UH)/SH+
1922      &  2.*SQMQ/(SQMQ-UH)+2.*(SQMHC-UH)/(SQMQ-UH)*(SQMHC-SQMQ-SH)/SH)
1923         IF(KFAC(1,-I)*KFAC(2,21).EQ.0) GOTO 870
1924         KCHHC=ISIGN(1,-KCHG(I,1))
1925         NCHN=NCHN+1
1926         ISIG(NCHN,1)=-I
1927         ISIG(NCHN,2)=21
1928         ISIG(NCHN,3)=1
1929         SIGH(NCHN)=FACHCQ*(WDTE(0,1)+WDTE(0,(5-KCHHC)/2)+WDTE(0,4))
1930   870   IF(KFAC(1,I)*KFAC(2,21).EQ.0) GOTO 880
1931         KCHHC=ISIGN(1,KCHG(I,1))
1932         NCHN=NCHN+1
1933         ISIG(NCHN,1)=I
1934         ISIG(NCHN,2)=21
1935         ISIG(NCHN,3)=1
1936         SIGH(NCHN)=FACHCQ*(WDTE(0,1)+WDTE(0,(5-KCHHC)/2)+WDTE(0,4))
1937   880   IF(KFAC(1,21)*KFAC(2,-I).EQ.0) GOTO 890
1938         KCHHC=ISIGN(1,-KCHG(I,1))
1939         NCHN=NCHN+1
1940         ISIG(NCHN,1)=21
1941         ISIG(NCHN,2)=-I
1942         ISIG(NCHN,3)=1
1943         SIGH(NCHN)=FACHCQ*(WDTE(0,1)+WDTE(0,(5-KCHHC)/2)+WDTE(0,4))
1944   890   IF(KFAC(1,21)*KFAC(2,I).EQ.0) GOTO 900
1945         KCHHC=ISIGN(1,KCHG(I,1))
1946         NCHN=NCHN+1
1947         ISIG(NCHN,1)=21
1948         ISIG(NCHN,2)=I
1949         ISIG(NCHN,3)=1
1950         SIGH(NCHN)=FACHCQ*(WDTE(0,1)+WDTE(0,(5-KCHHC)/2)+WDTE(0,4))
1951   900   CONTINUE
1952
1953       ENDIF
1954       ENDIF
1955
1956 C...Multiply with structure functions.
1957       IF(ISUB.LE.90.OR.ISUB.GE.96) THEN
1958         DO 910 ICHN=1,NCHN
1959         IF(MINT(41).EQ.2) THEN
1960           KFL1=ISIG(ICHN,1)
1961           IF(KFL1.EQ.21) KFL1=0
1962           SIGH(ICHN)=SIGH(ICHN)*XSFX(1,KFL1)
1963         ENDIF
1964         IF(MINT(42).EQ.2) THEN
1965           KFL2=ISIG(ICHN,2)
1966           IF(KFL2.EQ.21) KFL2=0
1967           SIGH(ICHN)=SIGH(ICHN)*XSFX(2,KFL2)
1968         ENDIF
1969   910   SIGS=SIGS+SIGH(ICHN)
1970       ENDIF
1971
1972       RETURN
1973       END