HIJING/hijing1_36/hijsft.F

   1 * $Id$
   2 C
   3 C
   4 C*******************************************************************
   5 C                                                                  *
   6 C               Subroutine HIJSFT                                  *
   7 C                                                                  *
   8 C  Scatter two excited strings, JP from proj and JT from target    *
   9 C*******************************************************************
  10         SUBROUTINE HIJSFT(JP,JT,JOUT,IERROR)
  11 #include "hijcrdn.inc"
  12 #include "hiparnt.inc"
  13 #include "hijdat.inc"
  14 #include "hijjet1.inc"
  15 #include "hijjet2.inc"
  16 #include "histrng.inc"
  17 #include "dpmcom1.inc"
  18 #include "dpmcom2.inc"
  19         SAVE
  20 C*******************************************************************
  21 C       JOUT-> the number
  22 C       of hard scatterings preceding this soft collision.
  23 C       IHNT2(13)-> 1=
  24 C       double diffrac 2=single diffrac, 3=non-single diffrac.
  25 C*******************************************************************
  26         IERROR=0
  27         JJP=JP
  28         JJT=JT
  29         NDPM=0
  30         IOPMAIN=0
  31         IF(JP.GT.IHNT2(1) .OR. JT.GT.IHNT2(3)) RETURN
  32
  33         EPP=PP(JP,4)+PP(JP,3)
  34         EPM=PP(JP,4)-PP(JP,3)
  35         ETP=PT(JT,4)+PT(JT,3)
  36         ETM=PT(JT,4)-PT(JT,3)
  37
  38         WP=EPP+ETP
  39         WM=EPM+ETM
  40         SW=WP*WM
  41 C               ********total W+,W- and center-of-mass energy
  42
  43         IF(WP.LT.0.0 .OR. WM.LT.0.0) GO TO 1000
  44
  45         IF(JOUT.EQ.0) THEN
  46                 IF(EPP.LT.0.0) GO TO 1000
  47                 IF(EPM.LT.0.0) GO TO 1000
  48                 IF(ETP.LT.0.0) GO TO 1000
  49                 IF(ETM.LT.0.0) GO TO 1000
  50                 IF(EPP/(EPM+0.01).LE.ETP/(ETM+0.01)) RETURN
  51         ENDIF
  52 C               ********For strings which does not follow a jet-prod,
  53 C                       scatter only if Ycm(JP)>Ycm(JT). When jets
  54 C                       are produced just before this collision
  55 C                       this requirement has already be enforced
  56 C                       (see SUBROUTINE HIJHRD)
  57         IHNT2(11)=JP
  58         IHNT2(12)=JT
  59 C
  60 C
  61 C
  62         MISS=0
  63         PKC1=0.0
  64         PKC2=0.0
  65         PKC11=0.0
  66         PKC12=0.0
  67         PKC21=0.0
  68         PKC22=0.0
  69         DPKC11=0.0
  70         DPKC12=0.0
  71         DPKC21=0.0
  72         DPKC22=0.0
  73         IF(NFP(JP,10).EQ.1.OR.NFT(JT,10).EQ.1) THEN
  74            IF(NFP(JP,10).EQ.1) THEN
  75               PHI1=ULANGL_HIJING(PP(JP,10),PP(JP,11))
  76               PPJET=SQRT(PP(JP,10)**2+PP(JP,11)**2)
  77               PKC1=PPJET
  78               PKC11=PP(JP,10)
  79               PKC12=PP(JP,11)
  80            ENDIF
  81            IF(NFT(JT,10).EQ.1) THEN
  82               PHI2=ULANGL_HIJING(PT(JT,10),PT(JT,11))
  83               PTJET=SQRT(PT(JT,10)**2+PT(JT,11)**2)
  84               PKC2=PTJET
  85               PKC21=PT(JT,10)
  86               PKC22=PT(JT,11)
  87            ENDIF
  88            IF(IHPR2(4).GT.0.AND.IHNT2(1).GT.1.AND.IHNT2(3).GT.1) THEN
  89               IF(NFP(JP,10).EQ.0) THEN
  90                  PHI=-PHI2
  91               ELSE IF(NFT(JT,10).EQ.0) THEN
  92                  PHI=PHI1
  93               ELSE
  94                  PHI=(PHI1+PHI2-HIPR1(40))/2.0
  95               ENDIF
  96               BX=HINT1(19)*COS(HINT1(20))
  97               BY=HINT1(19)*SIN(HINT1(20))
  98               XP0=YP(1,JP)
  99               YP0=YP(2,JP)
 100               XT0=YT(1,JT)+BX
 101               YT0=YT(2,JT)+BY
 102               R1=MAX(1.2*IHNT2(1)**0.3333333,
 103      &               SQRT(XP0**2+YP0**2))
 104               R2=MAX(1.2*IHNT2(3)**0.3333333,
 105      &               SQRT((XT0-BX)**2+(YT0-BY)**2))
 106               IF(ABS(COS(PHI)).LT.1.0E-5) THEN
 107                  DD1=R1
 108                  DD2=R1
 109                  DD3=ABS(BY+SQRT(R2**2-(XP0-BX)**2)-YP0)
 110                  DD4=ABS(BY-SQRT(R2**2-(XP0-BX)**2)-YP0)
 111                  GO TO 5
 112               ENDIF
 113               BB=2.0*SIN(PHI)*(COS(PHI)*YP0-SIN(PHI)*XP0)
 114               CC=(YP0**2-R1**2)*COS(PHI)**2+XP0*SIN(PHI)*(
 115      &                          XP0*SIN(PHI)-2.0*YP0*COS(PHI))
 116               DD=BB**2-4.0*CC
 117               IF(DD.LT.0.0) GO TO 10
 118               XX1=(-BB+SQRT(DD))/2.0
 119               XX2=(-BB-SQRT(DD))/2.0
 120               DD1=ABS((XX1-XP0)/COS(PHI))
 121               DD2=ABS((XX2-XP0)/COS(PHI))
 122 C
 123               BB=2.0*SIN(PHI)*(COS(PHI)*(YT0-BY)-SIN(PHI)*XT0)-2.0*BX
 124               CC=(BX**2+(YT0-BY)**2-R2**2)*COS(PHI)**2+XT0*SIN(PHI)
 125      &           *(XT0*SIN(PHI)-2.0*COS(PHI)*(YT0-BY))
 126      &           -2.0*BX*SIN(PHI)*(COS(PHI)*(YT0-BY)-SIN(PHI)*XT0)
 127               DD=BB**2-4.0*CC
 128               IF(DD.LT.0.0) GO TO 10
 129               XX1=(-BB+SQRT(DD))/2.0
 130               XX2=(-BB-SQRT(DD))/2.0
 131               DD3=ABS((XX1-XT0)/COS(PHI))
 132               DD4=ABS((XX2-XT0)/COS(PHI))
 133 C
 134  5            DD1=MIN(DD1,DD3)
 135               DD2=MIN(DD2,DD4)
 136               IF(DD1.LT.HIPR1(13)) DD1=0.0
 137               IF(DD2.LT.HIPR1(13)) DD2=0.0
 138               IF(NFP(JP,10).EQ.1.AND.PPJET.GT.HIPR1(11)) THEN
 139                  DP1=DD1*HIPR1(14)/2.0
 140                  DP1=MIN(DP1,PPJET-HIPR1(11))
 141                  PKC1=PPJET-DP1
 142                  DPX1=COS(PHI1)*DP1
 143                  DPY1=SIN(PHI1)*DP1
 144                  PKC11=PP(JP,10)-DPX1
 145                  PKC12=PP(JP,11)-DPY1
 146                  IF(DP1.GT.0.0) THEN
 147                     CTHEP=PP(JP,12)/SQRT(PP(JP,12)**2+PPJET**2)
 148                     DPZ1=DP1*CTHEP/SQRT(1.0-CTHEP**2)
 149                     DPE1=SQRT(DPX1**2+DPY1**2+DPZ1**2)
 150                     EPPPRM=PP(JP,4)+PP(JP,3)-DPE1-DPZ1
 151                     EPMPRM=PP(JP,4)-PP(JP,3)-DPE1+DPZ1
 152                     IF(EPPPRM.LE.0.0.OR.EPMPRM.LE.0.0) GO TO 15
 153                     EPP=EPPPRM
 154                     EPM=EPMPRM
 155                     PP(JP,10)=PKC11
 156                     PP(JP,11)=PKC12
 157                     NPJ(JP)=NPJ(JP)+1
 158                     KFPJ(JP,NPJ(JP))=21
 159                     PJPX(JP,NPJ(JP))=DPX1
 160                     PJPY(JP,NPJ(JP))=DPY1
 161                     PJPZ(JP,NPJ(JP))=DPZ1
 162                     PJPE(JP,NPJ(JP))=DPE1
 163                     PJPM(JP,NPJ(JP))=0.0
 164                     PP(JP,3)=PP(JP,3)-DPZ1
 165                     PP(JP,4)=PP(JP,4)-DPE1
 166                  ENDIF
 167               ENDIF
 168  15           IF(NFT(JT,10).EQ.1.AND.PTJET.GT.HIPR1(11)) THEN
 169                  DP2=DD2*HIPR1(14)/2.0
 170                  DP2=MIN(DP2,PTJET-HIPR1(11))
 171                  PKC2=PTJET-DP2
 172                  DPX2=COS(PHI2)*DP2
 173                  DPY2=SIN(PHI2)*DP2
 174                  PKC21=PT(JT,10)-DPX2
 175                  PKC22=PT(JT,11)-DPY2
 176                  IF(DP2.GT.0.0) THEN
 177                     CTHET=PT(JT,12)/SQRT(PT(JT,12)**2+PTJET**2)
 178                     DPZ2=DP2*CTHET/SQRT(1.0-CTHET**2)
 179                     DPE2=SQRT(DPX2**2+DPY2**2+DPZ2**2)
 180                     ETPPRM=PT(JT,4)+PT(JT,3)-DPE2-DPZ2
 181                     ETMPRM=PT(JT,4)-PT(JT,3)-DPE2+DPZ2
 182                     IF(ETPPRM.LE.0.0.OR.ETMPRM.LE.0.0) GO TO 16
 183                     ETP=ETPPRM
 184                     ETM=ETMPRM
 185                     PT(JT,10)=PKC21
 186                     PT(JT,11)=PKC22
 187                     NTJ(JT)=NTJ(JT)+1
 188                     KFTJ(JT,NTJ(JT))=21
 189                     PJTX(JT,NTJ(JT))=DPX2
 190                     PJTY(JT,NTJ(JT))=DPY2
 191                     PJTZ(JT,NTJ(JT))=DPZ2
 192                     PJTE(JT,NTJ(JT))=DPE2
 193                     PJTM(JT,NTJ(JT))=0.0
 194                     PT(JT,3)=PT(JT,3)-DPZ2
 195                     PT(JT,4)=PT(JT,4)-DPE2
 196                  ENDIF
 197               ENDIF
 198  16           DPKC11=-(PP(JP,10)-PKC11)/2.0
 199               DPKC12=-(PP(JP,11)-PKC12)/2.0
 200               DPKC21=-(PT(JT,10)-PKC21)/2.0
 201               DPKC22=-(PT(JT,11)-PKC22)/2.0
 202               WP=EPP+ETP
 203               WM=EPM+ETM
 204               SW=WP*WM
 205            ENDIF
 206         ENDIF
 207 C               ********If jet is quenched the pt from valence quark
 208 C                       hard scattering has to reduced by d*kapa
 209 C
 210 C
 211 10      PTP02=PP(JP,1)**2+PP(JP,2)**2
 212         PTT02=PT(JT,1)**2+PT(JT,2)**2
 213 C
 214         AMQ=MAX(PP(JP,14)+PP(JP,15),PT(JT,14)+PT(JT,15))
 215         AMX=HIPR1(1)+AMQ
 216 C               ********consider mass cut-off for strings which
 217 C                       must also include quark's mass
 218         AMP0=AMX
 219         DPM0=AMX
 220         NFDP=0
 221         IF(NFP(JP,5).LE.2.AND.NFP(JP,3).NE.0) THEN
 222                 AMP0=ULMASS_HIJING(NFP(JP,3))
 223                 NFDP=NFP(JP,3)+2*NFP(JP,3)/ABS(NFP(JP,3))
 224                 DPM0=ULMASS_HIJING(NFDP)
 225                 IF(DPM0.LE.0.0) THEN
 226                         NFDP=NFDP-2*NFDP/ABS(NFDP)
 227                         DPM0=ULMASS_HIJING(NFDP)
 228                 ENDIF
 229         ENDIF
 230         AMT0=AMX
 231         DTM0=AMX
 232         NFDT=0
 233         IF(NFT(JT,5).LE.2.AND.NFT(JT,3).NE.0) THEN
 234                 AMT0=ULMASS_HIJING(NFT(JT,3))
 235                 NFDT=NFT(JT,3)+2*NFT(JT,3)/ABS(NFT(JT,3))
 236                 DTM0=ULMASS_HIJING(NFDT)
 237                 IF(DTM0.LE.0.0) THEN
 238                         NFDT=NFDT-2*NFDT/ABS(NFDT)
 239                         DTM0=ULMASS_HIJING(NFDT)
 240                 ENDIF
 241         ENDIF
 242 C
 243         AMPN=SQRT(AMP0**2+PTP02)
 244         AMTN=SQRT(AMT0**2+PTT02)
 245         SNN=(AMPN+AMTN)**2+0.001
 246 C
 247         IF(SW.LT.SNN+0.001) GO TO 4000
 248 C               ********Scatter only if SW>SNN
 249 C*****give some PT kick to the two exited strings******************
 250 20      SWPTN=4.0*(MAX(AMP0,AMT0)**2+MAX(PTP02,PTT02))
 251         SWPTD=4.0*(MAX(DPM0,DTM0)**2+MAX(PTP02,PTT02))
 252         SWPTX=4.0*(AMX**2+MAX(PTP02,PTT02))
 253         IF(SW.LE.SWPTN) THEN
 254                 PKCMX=0.0
 255         ELSE IF(SW.GT.SWPTN .AND. SW.LE.SWPTD
 256      &          .AND.NPJ(JP).EQ.0.AND.NTJ(JT).EQ.0) THEN
 257            PKCMX=SQRT(SW/4.0-MAX(AMP0,AMT0)**2)
 258      &           -SQRT(MAX(PTP02,PTT02))
 259         ELSE IF(SW.GT.SWPTD .AND. SW.LE.SWPTX
 260      &          .AND.NPJ(JP).EQ.0.AND.NTJ(JT).EQ.0) THEN
 261            PKCMX=SQRT(SW/4.0-MAX(DPM0,DTM0)**2)
 262      &           -SQRT(MAX(PTP02,PTT02))
 263         ELSE IF(SW.GT.SWPTX) THEN
 264            PKCMX=SQRT(SW/4.0-AMX**2)-SQRT(MAX(PTP02,PTT02))
 265         ENDIF
 266 C               ********maximun PT kick
 267 C*********************************************************
 268 C
 269         IF(NFP(JP,10).EQ.1.OR.NFT(JT,10).EQ.1) THEN
 270                 IF(PKC1.GT.PKCMX) THEN
 271                         PKC1=PKCMX
 272                         PKC11=PKC1*COS(PHI1)
 273                         PKC12=PKC1*SIN(PHI1)
 274                         DPKC11=-(PP(JP,10)-PKC11)/2.0
 275                         DPKC12=-(PP(JP,11)-PKC12)/2.0
 276                 ENDIF
 277                 IF(PKC2.GT.PKCMX) THEN
 278                         PKC2=PKCMX
 279                         PKC21=PKC2*COS(PHI2)
 280                         PKC22=PKC2*SIN(PHI2)
 281                         DPKC21=-(PT(JT,10)-PKC21)/2.0
 282                         DPKC22=-(PT(JT,11)-PKC22)/2.0
 283                 ENDIF
 284                 DPKC1=DPKC11+DPKC21
 285                 DPKC2=DPKC12+DPKC22
 286                 NFP(JP,10)=-NFP(JP,10)
 287                 NFT(JT,10)=-NFT(JT,10)
 288                 GO TO 40
 289         ENDIF
 290 C               ********If the valence quarks had a hard-collision
 291 C                       the pt kick is the pt from hard-collision.
 292         I_SNG=0
 293         IF(IHPR2(13).NE.0 .AND. RLU_HIJING(0).LE.HIDAT(4)) I_SNG=1
 294         IF((NFP(JP,5).EQ.3 .OR.NFT(JT,5).EQ.3).OR.
 295      &          (NPJ(JP).NE.0.OR.NFP(JP,10).NE.0).OR.
 296      &          (NTJ(JT).NE.0.OR.NFT(JT,10).NE.0)) I_SNG=0
 297 C
 298 C               ********decite whether to have single-diffractive
 299         IF(IHPR2(5).EQ.0) THEN
 300                 PKC=HIPR1(2)*SQRT(-ALOG(1.0-RLU_HIJING(0)
 301      &                  *(1.0-EXP(-PKCMX**2/HIPR1(2)**2))))
 302                 GO TO 30
 303         ENDIF
 304         PKC=HIRND2(3,0.0,PKCMX**2)
 305         PKC=SQRT(PKC)
 306         IF(PKC.GT.HIPR1(20))
 307      &     PKC=HIPR1(2)*SQRT(-ALOG(EXP(-HIPR1(20)**2/HIPR1(2)**2)
 308      &         -RLU_HIJING(0)*(EXP(-HIPR1(20)**2/HIPR1(2)**2)-
 309      &         EXP(-PKCMX**2/HIPR1(2)**2))))
 310 C
 311         IF(I_SNG.EQ.1) PKC=0.65*SQRT(
 312      &          -ALOG(1.0-RLU_HIJING(0)*(1.0-EXP(-PKCMX**2/0.65**2))))
 313 C                       ********select PT kick
 314 30      PHI0=2.0*HIPR1(40)*RLU_HIJING(0)
 315         PKC11=PKC*SIN(PHI0)
 316         PKC12=PKC*COS(PHI0)
 317         PKC21=-PKC11
 318         PKC22=-PKC12
 319         DPKC1=0.0
 320         DPKC2=0.0
 321 40      PP11=PP(JP,1)+PKC11-DPKC1
 322         PP12=PP(JP,2)+PKC12-DPKC2
 323         PT11=PT(JT,1)+PKC21-DPKC1
 324         PT12=PT(JT,2)+PKC22-DPKC2
 325         PTP2=PP11**2+PP12**2
 326         PTT2=PT11**2+PT12**2
 327 C
 328         AMPN=SQRT(AMP0**2+PTP2)
 329         AMTN=SQRT(AMT0**2+PTT2)
 330         SNN=(AMPN+AMTN)**2+0.001
 331 C***************************************
 332         WP=EPP+ETP
 333         WM=EPM+ETM
 334         SW=WP*WM
 335 C****************************************
 336         IF(SW.LT.SNN) THEN
 337            MISS=MISS+1
 338            IF(MISS.LE.100) then
 339               PKC=0.0
 340               GO TO 30
 341            ENDIF
 342            IF(IHPR2(10).NE.0)
 343      &       WRITE(6,*) 'Error occured in Pt kick section of HIJSFT'
 344            GO TO 4000
 345         ENDIF
 346 C******************************************************************
 347         AMPD=SQRT(DPM0**2+PTP2)
 348         AMTD=SQRT(DTM0**2+PTT2)
 349
 350         AMPX=SQRT(AMX**2+PTP2)
 351         AMTX=SQRT(AMX**2+PTT2)
 352
 353         DPN=AMPN**2/SW
 354         DTN=AMTN**2/SW
 355         DPD=AMPD**2/SW
 356         DTD=AMTD**2/SW
 357         DPX=AMPX**2/SW
 358         DTX=AMTX**2/SW
 359 C
 360         SPNTD=(AMPN+AMTD)**2
 361         SPNTX=(AMPN+AMTX)**2
 362 C                       ********CM energy if proj=N,targ=N*
 363         SPDTN=(AMPD+AMTN)**2
 364         SPXTN=(AMPX+AMTN)**2
 365 C                       ********CM energy if proj=N*,targ=N
 366         SPDTX=(AMPD+AMTX)**2
 367         SPXTD=(AMPX+AMTD)**2
 368         SDD=(AMPD+AMTD)**2
 369         SXX=(AMPX+AMTX)**2
 370
 371 C
 372 C
 373 C               ********CM energy if proj=delta, targ=delta
 374 C****************There are many different cases**********
 375 c       IF(IHPR2(15).EQ.1) GO TO 500
 376 C
 377 C               ********to have DPM type soft interactions
 378 C
 379  45     CONTINUE
 380         IF(SW.GT.SXX+0.001) THEN
 381            IF(I_SNG.EQ.0) THEN
 382               D1=DPX
 383               D2=DTX
 384               NFP3=0
 385               NFT3=0
 386               GO TO 400
 387            ELSE
 388 c**** 5/30/1998 this is identical to the above statement. Added to
 389 c**** avoid questional branching to block.
 390               IF((NFP(JP,5).EQ.3 .AND.NFT(JT,5).EQ.3).OR.
 391      &           (NPJ(JP).NE.0.OR.NFP(JP,10).NE.0).OR.
 392      &           (NTJ(JT).NE.0.OR.NFT(JT,10).NE.0)) THEN
 393                  D1=DPX
 394                  D2=DTX
 395                  NFP3=0
 396                  NFT3=0
 397                  GO TO 400
 398               ENDIF
 399 C               ********do not allow excited strings to have
 400 C                       single-diffr
 401               IF(RLU_HIJING(0).GT.0.5.OR.(NFT(JT,5).GT.2.OR.
 402      &                NTJ(JT).NE.0.OR.NFT(JT,10).NE.0)) THEN
 403                  D1=DPN
 404                  D2=DTX
 405                  NFP3=NFP(JP,3)
 406                  NFT3=0
 407                  GO TO 220
 408               ELSE
 409                  D1=DPX
 410                  D2=DTN
 411                  NFP3=0
 412                  NFT3=NFT(JT,3)
 413                  GO TO 240
 414               ENDIF
 415 C               ********have single diffractive collision
 416            ENDIF
 417         ELSE IF(SW.GT.MAX(SPDTX,SPXTD)+0.001 .AND.
 418      &                          SW.LE.SXX+0.001) THEN
 419            IF(((NPJ(JP).EQ.0.AND.NTJ(JT).EQ.0.AND.
 420      &         RLU_HIJING(0).GT.0.5).OR.(NPJ(JP).EQ.0
 421      &         .AND.NTJ(JT).NE.0)).AND.NFP(JP,5).LE.2) THEN
 422               D1=DPD
 423               D2=DTX
 424               NFP3=NFDP
 425               NFT3=0
 426               GO TO 220
 427            ELSE IF(NTJ(JT).EQ.0.AND.NFT(JT,5).LE.2) THEN
 428               D1=DPX
 429               D2=DTD
 430               NFP3=0
 431               NFT3=NFDT
 432               GO TO 240
 433            ENDIF
 434            GO TO 4000
 435         ELSE IF(SW.GT.MIN(SPDTX,SPXTD)+0.001.AND.
 436      &                  SW.LE.MAX(SPDTX,SPXTD)+0.001) THEN
 437            IF(SPDTX.LE.SPXTD.AND.NPJ(JP).EQ.0
 438      &                       .AND.NFP(JP,5).LE.2) THEN
 439               D1=DPD
 440               D2=DTX
 441               NFP3=NFDP
 442               NFT3=0
 443               GO TO 220
 444            ELSE IF(SPDTX.GT.SPXTD.AND.NTJ(JT).EQ.0
 445      &                       .AND.NFT(JT,5).LE.2) THEN
 446               D1=DPX
 447               D2=DTD
 448               NFP3=0
 449               NFT3=NFDT
 450               GO TO 240
 451            ENDIF
 452 c*** 5/30/1998 added to avoid questional branching to another block
 453 c*** this is identical to the statement following the next ELSE IF
 454            IF(((NPJ(JP).EQ.0.AND.NTJ(JT).EQ.0
 455      &       .AND.RLU_HIJING(0).GT.0.5).OR.(NPJ(JP).EQ.0
 456      &        .AND.NTJ(JT).NE.0)).AND.NFP(JP,5).LE.2) THEN
 457               D1=DPN
 458               D2=DTX
 459               NFP3=NFP(JP,3)
 460               NFT3=0
 461               GO TO 220
 462            ELSE IF(NTJ(JT).EQ.0.AND.NFT(JT,5).LE.2) THEN
 463               D1=DPX
 464               D2=DTN
 465               NFP3=0
 466               NFT3=NFT(JT,3)
 467               GO TO 240
 468            ENDIF
 469            GO TO 4000
 470         ELSE IF(SW.GT.MAX(SPNTX,SPXTN)+0.001 .AND.
 471      &                  SW.LE.MIN(SPDTX,SPXTD)+0.001) THEN
 472            IF(((NPJ(JP).EQ.0.AND.NTJ(JT).EQ.0
 473      &       .AND.RLU_HIJING(0).GT.0.5).OR.(NPJ(JP).EQ.0
 474      &        .AND.NTJ(JT).NE.0)).AND.NFP(JP,5).LE.2) THEN
 475               D1=DPN
 476               D2=DTX
 477               NFP3=NFP(JP,3)
 478               NFT3=0
 479               GO TO 220
 480            ELSE IF(NTJ(JT).EQ.0.AND.NFT(JT,5).LE.2) THEN
 481               D1=DPX
 482               D2=DTN
 483               NFP3=0
 484               NFT3=NFT(JT,3)
 485               GO TO 240
 486            ENDIF
 487            GO TO 4000
 488         ELSE IF(SW.GT.MIN(SPNTX,SPXTN)+0.001 .AND.
 489      &                  SW.LE.MAX(SPNTX,SPXTN)+0.001) THEN
 490            IF(SPNTX.LE.SPXTN.AND.NPJ(JP).EQ.0
 491      &                           .AND.NFP(JP,5).LE.2) THEN
 492               D1=DPN
 493               D2=DTX
 494               NFP3=NFP(JP,3)
 495               NFT3=0
 496               GO TO 220
 497            ELSEIF(SPNTX.GT.SPXTN.AND.NTJ(JT).EQ.0
 498      &                           .AND.NFT(JT,5).LE.2) THEN
 499               D1=DPX
 500               D2=DTN
 501               NFP3=0
 502               NFT3=NFT(JT,3)
 503               GO TO 240
 504            ENDIF
 505            GO TO 4000
 506         ELSE IF(SW.LE.MIN(SPNTX,SPXTN)+0.001 .AND.
 507      &                  (NPJ(JP).NE.0 .OR.NTJ(JT).NE.0)) THEN
 508            GO TO 4000
 509         ELSE IF(SW.LE.MIN(SPNTX,SPXTN)+0.001 .AND.
 510      &          NFP(JP,5).GT.2.AND.NFT(JT,5).GT.2) THEN
 511            GO TO 4000
 512         ELSE IF(SW.GT.SDD+0.001.AND.SW.LE.
 513      &                     MIN(SPNTX,SPXTN)+0.001) THEN
 514            D1=DPD
 515            D2=DTD
 516            NFP3=NFDP
 517            NFT3=NFDT
 518            GO TO 100
 519         ELSE IF(SW.GT.MAX(SPNTD,SPDTN)+0.001
 520      &                      .AND. SW.LE.SDD+0.001) THEN
 521            IF(RLU_HIJING(0).GT.0.5) THEN
 522               D1=DPD
 523               D2=DTN
 524               NFP3=NFDP
 525               NFT3=NFT(JT,3)
 526               GO TO 100
 527            ELSE
 528               D1=DPN
 529               D2=DTD
 530               NFP3=NFP(JP,3)
 531               NFT3=NFDT
 532               GO TO 100
 533            ENDIF
 534         ELSE IF(SW.GT.MIN(SPNTD,SPDTN)+0.001
 535      &          .AND. SW.LE.MAX(SPNTD,SPDTN)+0.001) THEN
 536            IF(SPNTD.GT.SPDTN) THEN
 537               D1=DPD
 538               D2=DTN
 539               NFP3=NFDP
 540               NFT3=NFT(JT,3)
 541               GO TO 100
 542            ELSE
 543               D1=DPN
 544               D2=DTD
 545               NFP3=NFP(JP,3)
 546               NFT3=NFDT
 547               GO TO 100
 548            ENDIF
 549         ELSE IF(SW.LE.MIN(SPNTD,SPDTN)+0.001) THEN
 550            D1=DPN
 551            D2=DTN
 552            NFP3=NFP(JP,3)
 553            NFT3=NFT(JT,3)
 554            GO TO 100
 555         ENDIF
 556         WRITE(6,*) ' Error in HIJSFT: There is no path to here'
 557         RETURN
 558 C
 559 C***************  elastic scattering ***************
 560 C       this is like elastic, both proj and targ mass
 561 C       must be fixed
 562 C***************************************************
 563 100     NFP5=MAX(2,NFP(JP,5))
 564         NFT5=MAX(2,NFT(JT,5))
 565         BB1=1.0+D1-D2
 566         BB2=1.0+D2-D1
 567         IF(BB1**2.LT.4.0*D1 .OR. BB2**2.LT.4.0*D2) THEN
 568                 MISS=MISS+1
 569                 IF(MISS.GT.100.OR.PKC.EQ.0.0) GO TO 3000
 570                 PKC=PKC*0.5
 571                 GO TO 30
 572         ENDIF
 573         IF(RLU_HIJING(0).LT.0.5) THEN
 574                 X1=(BB1-SQRT(BB1**2-4.0*D1))/2.0
 575                 X2=(BB2-SQRT(BB2**2-4.0*D2))/2.0
 576         ELSE
 577                 X1=(BB1+SQRT(BB1**2-4.0*D1))/2.0
 578                 X2=(BB2+SQRT(BB2**2-4.0*D2))/2.0
 579         ENDIF
 580         IHNT2(13)=2
 581         GO TO 600
 582 C
 583 C********** Single diffractive ***********************
 584 C either proj or targ's mass is fixed
 585 C*****************************************************
 586 220     NFP5=MAX(2,NFP(JP,5))
 587         NFT5=3
 588         IF(NFP3.EQ.0) NFP5=3
 589         BB2=1.0+D2-D1
 590         IF(BB2**2.LT.4.0*D2) THEN
 591                 MISS=MISS+1
 592                 IF(MISS.GT.100.OR.PKC.EQ.0.0) GO TO 3000
 593                 PKC=PKC*0.5
 594                 GO TO 30
 595         ENDIF
 596         XMIN=(BB2-SQRT(BB2**2-4.0*D2))/2.0
 597         XMAX=(BB2+SQRT(BB2**2-4.0*D2))/2.0
 598         MISS4=0
 599 222     X2=HIRND2(6,XMIN,XMAX)
 600         X1=D1/(1.0-X2)
 601         IF(X2*(1.0-X1).LT.(D2+1.E-4/SW)) THEN
 602                 MISS4=MISS4+1
 603                 IF(MISS4.LE.1000) GO TO 222
 604                 GO TO 5000
 605         ENDIF
 606         IHNT2(13)=2
 607         GO TO 600
 608 C                       ********Fix proj mass*********
 609 240     NFP5=3
 610         NFT5=MAX(2,NFT(JT,5))
 611         IF(NFT3.EQ.0) NFT5=3
 612         BB1=1.0+D1-D2
 613         IF(BB1**2.LT.4.0*D1) THEN
 614                 MISS=MISS+1
 615                 IF(MISS.GT.100.OR.PKC.EQ.0.0) GO TO 3000
 616                 PKC=PKC*0.5
 617                 GO TO 30
 618         ENDIF
 619         XMIN=(BB1-SQRT(BB1**2-4.0*D1))/2.0
 620         XMAX=(BB1+SQRT(BB1**2-4.0*D1))/2.0
 621         MISS4=0
 622 242     X1=HIRND2(6,XMIN,XMAX)
 623         X2=D2/(1.0-X1)
 624         IF(X1*(1.0-X2).LT.(D1+1.E-4/SW)) THEN
 625                 MISS4=MISS4+1
 626                 IF(MISS4.LE.1000) GO TO 242
 627                 GO TO 5000
 628         ENDIF
 629         IHNT2(13)=2
 630         GO TO 600
 631 C                       ********Fix targ mass*********
 632 C
 633 C*************non-single diffractive**********************
 634 C       both proj and targ may not be fixed in mass
 635 C*********************************************************
 636 C
 637 400     NFP5=3
 638         NFT5=3
 639         BB1=1.0+D1-D2
 640         BB2=1.0+D2-D1
 641         IF(BB1**2.LT.4.0*D1 .OR. BB2**2.LT.4.0*D2) THEN
 642                 MISS=MISS+1
 643                 IF(MISS.GT.100.OR.PKC.EQ.0.0) GO TO 3000
 644                 PKC=PKC*0.5
 645                 GO TO 30
 646         ENDIF
 647         XMIN1=(BB1-SQRT(BB1**2-4.0*D1))/2.0
 648         XMAX1=(BB1+SQRT(BB1**2-4.0*D1))/2.0
 649         XMIN2=(BB2-SQRT(BB2**2-4.0*D2))/2.0
 650         XMAX2=(BB2+SQRT(BB2**2-4.0*D2))/2.0
 651         MISS4=0
 652 410     X1=HIRND2(4,XMIN1,XMAX1)
 653         X2=HIRND2(4,XMIN2,XMAX2)
 654         IF(NFP(JP,5).EQ.3.OR.NFT(JT,5).EQ.3) THEN
 655                 X1=HIRND2(6,XMIN1,XMAX1)
 656                 X2=HIRND2(6,XMIN2,XMAX2)
 657         ENDIF
 658 C                       ********
 659         IF(ABS(NFP(JP,1)*NFP(JP,2)).GT.1000000.OR.
 660      &                  ABS(NFP(JP,1)*NFP(JP,2)).LT.100) THEN
 661                 X1=HIRND2(5,XMIN1,XMAX1)
 662         ENDIF
 663         IF(ABS(NFT(JT,1)*NFT(JT,2)).GT.1000000.OR.
 664      &                  ABS(NFT(JT,1)*NFT(JT,2)).LT.100) THEN
 665                 X2=HIRND2(5,XMIN2,XMAX2)
 666         ENDIF
 667 c       IF(IOPMAIN.EQ.3) X1=HIRND2(6,XMIN1,XMAX1)
 668 c       IF(IOPMAIN.EQ.2) X2=HIRND2(6,XMIN2,XMAX2)
 669 C       ********For q-qbar or (qq)-(qq)bar system use symetric
 670 C               distribution, for q-(qq) or qbar-(qq)bar use
 671 C               unsymetrical distribution
 672 C
 673         IF(ABS(NFP(JP,1)*NFP(JP,2)).GT.1000000) X1=1.0-X1
 674         XXP=X1*(1.0-X2)
 675         XXT=X2*(1.0-X1)
 676         IF(XXP.LT.(D1+1.E-4/SW) .OR. XXT.LT.(D2+1.E-4/SW)) THEN
 677                 MISS4=MISS4+1
 678                 IF(MISS4.LE.1000) GO TO 410
 679                 GO TO 5000
 680         ENDIF
 681         IHNT2(13)=3
 682 C***************************************************
 683 C***************************************************
 684 600     CONTINUE
 685         IF(X1*(1.0-X2).LT.(AMPN**2-1.E-4)/SW.OR.
 686      &                  X2*(1.0-X1).LT.(AMTN**2-1.E-4)/SW) THEN
 687                 MISS=MISS+1
 688                 IF(MISS.GT.100.OR.PKC.EQ.0.0) GO TO 2000
 689                 PKC=0.0
 690                 GO TO 30
 691         ENDIF
 692 C
 693         EPP=(1.0-X2)*WP
 694         EPM=X1*WM
 695         ETP=X2*WP
 696         ETM=(1.0-X1)*WM
 697         PP(JP,3)=(EPP-EPM)/2.0
 698         PP(JP,4)=(EPP+EPM)/2.0
 699         IF(EPP*EPM-PTP2.LT.0.0) GO TO 6000
 700         PP(JP,5)=SQRT(EPP*EPM-PTP2)
 701         NFP(JP,3)=NFP3
 702         NFP(JP,5)=NFP5
 703
 704         PT(JT,3)=(ETP-ETM)/2.0
 705         PT(JT,4)=(ETP+ETM)/2.0
 706         IF(ETP*ETM-PTT2.LT.0.0) GO TO 6000
 707         PT(JT,5)=SQRT(ETP*ETM-PTT2)
 708         NFT(JT,3)=NFT3
 709         NFT(JT,5)=NFT5
 710 C*****recoil PT from hard-inter is shared by two end-partons
 711 C       so that pt=p1+p2
 712         PP(JP,1)=PP11-PKC11
 713         PP(JP,2)=PP12-PKC12
 714
 715         KICKDIP=1
 716         KICKDIT=1
 717         IF(ABS(NFP(JP,1)*NFP(JP,2)).GT.1000000.OR.
 718      &                  ABS(NFP(JP,1)*NFP(JP,2)).LT.100) THEN
 719                 KICKDIP=0
 720         ENDIF
 721         IF(ABS(NFT(JT,1)*NFT(JT,2)).GT.1000000.OR.
 722      &                  ABS(NFT(JT,1)*NFT(JT,2)).LT.100) THEN
 723                 KICKDIT=0
 724         ENDIF
 725         IF((KICKDIP.EQ.0.AND.RLU_HIJING(0).LT.0.5)
 726      &     .OR.(KICKDIP.NE.0.AND.RLU_HIJING(0)
 727      &     .LT.0.5/(1.0+(PKC11**2+PKC12**2)/HIPR1(22)**2))) THEN
 728            PP(JP,6)=(PP(JP,1)-PP(JP,6)-PP(JP,8)-DPKC1)/2.0+PP(JP,6)
 729            PP(JP,7)=(PP(JP,2)-PP(JP,7)-PP(JP,9)-DPKC2)/2.0+PP(JP,7)
 730            PP(JP,8)=(PP(JP,1)-PP(JP,6)-PP(JP,8)-DPKC1)/2.0
 731      &              +PP(JP,8)+PKC11
 732            PP(JP,9)=(PP(JP,2)-PP(JP,7)-PP(JP,9)-DPKC2)/2.0
 733      &              +PP(JP,9)+PKC12
 734         ELSE
 735            PP(JP,8)=(PP(JP,1)-PP(JP,6)-PP(JP,8)-DPKC1)/2.0+PP(JP,8)
 736            PP(JP,9)=(PP(JP,2)-PP(JP,7)-PP(JP,9)-DPKC2)/2.0+PP(JP,9)
 737            PP(JP,6)=(PP(JP,1)-PP(JP,6)-PP(JP,8)-DPKC1)/2.0
 738      &              +PP(JP,6)+PKC11
 739            PP(JP,7)=(PP(JP,2)-PP(JP,7)-PP(JP,9)-DPKC2)/2.0
 740      &              +PP(JP,7)+PKC12
 741         ENDIF
 742         PP(JP,1)=PP(JP,6)+PP(JP,8)
 743         PP(JP,2)=PP(JP,7)+PP(JP,9)
 744 C                               ********pt kick for proj
 745         PT(JT,1)=PT11-PKC21
 746         PT(JT,2)=PT12-PKC22
 747         IF((KICKDIT.EQ.0.AND.RLU_HIJING(0).LT.0.5)
 748      &     .OR.(KICKDIT.NE.0.AND.RLU_HIJING(0)
 749      &     .LT.0.5/(1.0+(PKC21**2+PKC22**2)/HIPR1(22)**2))) THEN
 750            PT(JT,6)=(PT(JT,1)-PT(JT,6)-PT(JT,8)-DPKC1)/2.0+PT(JT,6)
 751            PT(JT,7)=(PT(JT,2)-PT(JT,7)-PT(JT,9)-DPKC2)/2.0+PT(JT,7)
 752            PT(JT,8)=(PT(JT,1)-PT(JT,6)-PT(JT,8)-DPKC1)/2.0
 753      &              +PT(JT,8)+PKC21
 754            PT(JT,9)=(PT(JT,2)-PT(JT,7)-PT(JT,9)-DPKC2)/2.0
 755      &              +PT(JT,9)+PKC22
 756         ELSE
 757            PT(JT,8)=(PT(JT,1)-PT(JT,6)-PT(JT,8)-DPKC1)/2.0+PT(JT,8)
 758            PT(JT,9)=(PT(JT,2)-PT(JT,7)-PT(JT,9)-DPKC2)/2.0+PT(JT,9)
 759            PT(JT,6)=(PT(JT,1)-PT(JT,6)-PT(JT,8)-DPKC1)/2.0
 760      &              +PT(JT,6)+PKC21
 761            PT(JT,7)=(PT(JT,2)-PT(JT,7)-PT(JT,9)-DPKC2)/2.0
 762      &              +PT(JT,7)+PKC22
 763         ENDIF
 764         PT(JT,1)=PT(JT,6)+PT(JT,8)
 765         PT(JT,2)=PT(JT,7)+PT(JT,9)
 766 C                       ********pt kick for targ
 767
 768         IF(NPJ(JP).NE.0) NFP(JP,5)=3
 769         IF(NTJ(JT).NE.0) NFT(JT,5)=3
 770 C                       ********jets must be connected to string
 771         IF(EPP/(EPM+0.0001).LT.ETP/(ETM+0.0001).AND.
 772      &                  ABS(NFP(JP,1)*NFP(JP,2)).LT.1000000)THEN
 773                 DO 620 JSB=1,15
 774                 PSB=PP(JP,JSB)
 775                 PP(JP,JSB)=PT(JT,JSB)
 776                 PT(JT,JSB)=PSB
 777                 NSB=NFP(JP,JSB)
 778                 NFP(JP,JSB)=NFT(JT,JSB)
 779                 NFT(JT,JSB)=NSB
 780 620             CONTINUE
 781 C               ********when Ycm(JP)<Ycm(JT) after the collision
 782 C                       exchange the positions of the two
 783         ENDIF
 784 C
 785         RETURN
 786 C**************************************************
 787 C**************************************************
 788 1000    IERROR=1
 789         IF(IHPR2(10).EQ.0) RETURN
 790         WRITE(6,*) '    Fatal HIJSFT start error,abandon this event'
 791         WRITE(6,*) '    PROJ E+,E-,W+',EPP,EPM,WP
 792         WRITE(6,*) '    TARG E+,E-,W-',ETP,ETM,WM
 793         WRITE(6,*) '    W+*W-, (APN+ATN)^2',SW,SNN
 794         RETURN
 795 2000    IERROR=0
 796         IF(IHPR2(10).EQ.0) RETURN
 797         WRITE(6,*) '    (2)energy partition fail,'
 798         WRITE(6,*) '    HIJSFT not performed, but continue'
 799         WRITE(6,*) '    MP1,MPN',X1*(1.0-X2)*SW,AMPN**2
 800         WRITE(6,*) '    MT2,MTN',X2*(1.0-X1)*SW,AMTN**2
 801         RETURN
 802 3000    IERROR=0
 803         IF(IHPR2(10).EQ.0) RETURN
 804         WRITE(6,*) '    (3)something is wrong with the pt kick, '
 805         WRITE(6,*) '    HIJSFT not performed, but continue'
 806         WRITE(6,*) '    D1=',D1,' D2=',D2,' SW=',SW
 807         WRITE(6,*) '    HISTORY NFP5=',NFP(JP,5),' NFT5=',NFT(JT,5)
 808         WRITE(6,*) '    THIS COLLISON NFP5=',NFP5, ' NFT5=',NFT5
 809         WRITE(6,*) '    # OF JET IN PROJ',NPJ(JP),' IN TARG',NTJ(JT)
 810         RETURN
 811 4000    IERROR=0
 812         IF(IHPR2(10).EQ.0) RETURN
 813         WRITE(6,*) '    (4)unable to choose process, but not harmful'
 814         WRITE(6,*) '    HIJSFT not performed, but continue'
 815         WRITE(6,*) '    PTP=',SQRT(PTP2),' PTT=',SQRT(PTT2),' SW=',SW
 816         WRITE(6,*) '    AMCUT=',AMX,' JP=',JP,' JT=',JT
 817         WRITE(6,*) '    HISTORY NFP5=',NFP(JP,5),' NFT5=',NFT(JT,5)
 818         RETURN
 819 5000    IERROR=0
 820         IF(IHPR2(10).EQ.0) RETURN
 821         WRITE(6,*) '    energy partition failed(5),for limited try'
 822         WRITE(6,*) '    HIJSFT not performed, but continue'
 823         WRITE(6,*) '    NFP5=',NFP5,' NFT5=',NFT5
 824         WRITE(6,*) '    D1',D1,' X1(1-X2)',X1*(1.0-X2)
 825         WRITE(6,*) '    D2',D2,' X2(1-X1)',X2*(1.0-X1)
 826         RETURN
 827 6000    PKC=0.0
 828         MISS=MISS+1
 829         IF(MISS.LT.100) GO TO 30
 830         IERROR=1
 831         IF(IHPR2(10).EQ.0) RETURN
 832         WRITE(6,*) ' ERROR OCCURED, HIJSFT NOT PERFORMED'
 833         WRITE(6,*) ' Abort this event'
 834         WRITE(6,*) 'MTP,PTP2',EPP*EPM,PTP2,'  MTT,PTT2',ETP*ETM,PTT2
 835         RETURN
 836         END