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hijsft.f
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hijsft.f
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C
C
C*******************************************************************
C *
C Subroutine HIJSFT *
C *
C Scatter two excited strings, JP from proj and JT from target *
C*******************************************************************
SUBROUTINE HIJSFT(JP,JT,JOUT,IERROR)
COMMON/HIJCRDN/YP(3,300),YT(3,300)
SAVE /HIJCRDN/
COMMON/HIPARNT/HIPR1(100),IHPR2(50),HINT1(100),IHNT2(50)
SAVE /HIPARNT/
COMMON/HIJDAT/HIDAT0(10,10),HIDAT(10)
SAVE /HIJDAT/
COMMON/RANSEED/NSEED
SAVE /RANSEED/
COMMON/HIJJET1/NPJ(300),KFPJ(300,500),PJPX(300,500),
& PJPY(300,500),PJPZ(300,500),PJPE(300,500),
& PJPM(300,500),NTJ(300),KFTJ(300,500),
& PJTX(300,500),PJTY(300,500),PJTZ(300,500),
& PJTE(300,500),PJTM(300,500)
SAVE /HIJJET1/
COMMON/HIJJET2/NSG,NJSG(900),IASG(900,3),K1SG(900,100),
& K2SG(900,100),PXSG(900,100),PYSG(900,100),
& PZSG(900,100),PESG(900,100),PMSG(900,100)
SAVE /HIJJET2/
COMMON/HISTRNG/NFP(300,15),PP(300,15),NFT(300,15),PT(300,15)
SAVE /HISTRNG/
COMMON/DPMCOM1/JJP,JJT,AMP,AMT,APX0,ATX0,AMPN,AMTN,AMP0,AMT0,
& NFDP,NFDT,WP,WM,SW,XREMP,XREMT,DPKC1,DPKC2,PP11,PP12,
& PT11,PT12,PTP2,PTT2
SAVE /DPMCOM1/
COMMON/DPMCOM2/NDPM,KDPM(20,2),PDPM1(20,5),PDPM2(20,5)
SAVE /DPMCOM2/
C*******************************************************************
C JOUT-> the number
C of hard scatterings preceding this soft collision.
C IHNT2(13)-> 1=
C double diffrac 2=single diffrac, 3=non-single diffrac.
C*******************************************************************
IERROR=0
JJP=JP
JJT=JT
NDPM=0
IOPMAIN=0
IF(JP.GT.IHNT2(1) .OR. JT.GT.IHNT2(3)) RETURN
EPP=PP(JP,4)+PP(JP,3)
EPM=PP(JP,4)-PP(JP,3)
ETP=PT(JT,4)+PT(JT,3)
ETM=PT(JT,4)-PT(JT,3)
WP=EPP+ETP
WM=EPM+ETM
SW=WP*WM
C ********total W+,W- and center-of-mass energy
IF(WP.LT.0.0 .OR. WM.LT.0.0) GO TO 1000
IF(JOUT.EQ.0) THEN
IF(EPP.LT.0.0) GO TO 1000
IF(EPM.LT.0.0) GO TO 1000
IF(ETP.LT.0.0) GO TO 1000
IF(ETM.LT.0.0) GO TO 1000
IF(EPP/(EPM+0.01).LE.ETP/(ETM+0.01)) RETURN
ENDIF
C ********For strings which does not follow a jet-prod,
C scatter only if Ycm(JP)>Ycm(JT). When jets
C are produced just before this collision
C this requirement has already be enforced
C (see SUBROUTINE HIJHRD)
IHNT2(11)=JP
IHNT2(12)=JT
C
C
C
MISS=0
PKC1=0.0
PKC2=0.0
PKC11=0.0
PKC12=0.0
PKC21=0.0
PKC22=0.0
DPKC11=0.0
DPKC12=0.0
DPKC21=0.0
DPKC22=0.0
IF(NFP(JP,10).EQ.1.OR.NFT(JT,10).EQ.1) THEN
IF(NFP(JP,10).EQ.1) THEN
PHI1=ULANGL(PP(JP,10),PP(JP,11))
PPJET=SQRT(PP(JP,10)**2+PP(JP,11)**2)
PKC1=PPJET
PKC11=PP(JP,10)
PKC12=PP(JP,11)
ENDIF
IF(NFT(JT,10).EQ.1) THEN
PHI2=ULANGL(PT(JT,10),PT(JT,11))
PTJET=SQRT(PT(JT,10)**2+PT(JT,11)**2)
PKC2=PTJET
PKC21=PT(JT,10)
PKC22=PT(JT,11)
ENDIF
IF(IHPR2(4).GT.0.AND.IHNT2(1).GT.1.AND.IHNT2(3).GT.1) THEN
IF(NFP(JP,10).EQ.0) THEN
PHI=-PHI2
ELSE IF(NFT(JT,10).EQ.0) THEN
PHI=PHI1
ELSE
PHI=(PHI1+PHI2-HIPR1(40))/2.0
ENDIF
BX=HINT1(19)*COS(HINT1(20))
BY=HINT1(19)*SIN(HINT1(20))
XP0=YP(1,JP)
YP0=YP(2,JP)
XT0=YT(1,JT)+BX
YT0=YT(2,JT)+BY
R1=MAX(1.2*IHNT2(1)**0.3333333,
& SQRT(XP0**2+YP0**2))
R2=MAX(1.2*IHNT2(3)**0.3333333,
& SQRT((XT0-BX)**2+(YT0-BY)**2))
IF(ABS(COS(PHI)).LT.1.0E-5) THEN
DD1=R1
DD2=R1
DD3=ABS(BY+SQRT(R2**2-(XP0-BX)**2)-YP0)
DD4=ABS(BY-SQRT(R2**2-(XP0-BX)**2)-YP0)
GO TO 5
ENDIF
BB=2.0*SIN(PHI)*(COS(PHI)*YP0-SIN(PHI)*XP0)
CC=(YP0**2-R1**2)*COS(PHI)**2+XP0*SIN(PHI)*(
& XP0*SIN(PHI)-2.0*YP0*COS(PHI))
DD=BB**2-4.0*CC
IF(DD.LT.0.0) GO TO 10
XX1=(-BB+SQRT(DD))/2.0
XX2=(-BB-SQRT(DD))/2.0
DD1=ABS((XX1-XP0)/COS(PHI))
DD2=ABS((XX2-XP0)/COS(PHI))
C
BB=2.0*SIN(PHI)*(COS(PHI)*(YT0-BY)-SIN(PHI)*XT0)-2.0*BX
CC=(BX**2+(YT0-BY)**2-R2**2)*COS(PHI)**2+XT0*SIN(PHI)
& *(XT0*SIN(PHI)-2.0*COS(PHI)*(YT0-BY))
& -2.0*BX*SIN(PHI)*(COS(PHI)*(YT0-BY)-SIN(PHI)*XT0)
DD=BB**2-4.0*CC
IF(DD.LT.0.0) GO TO 10
XX1=(-BB+SQRT(DD))/2.0
XX2=(-BB-SQRT(DD))/2.0
DD3=ABS((XX1-XT0)/COS(PHI))
DD4=ABS((XX2-XT0)/COS(PHI))
C
5 DD1=MIN(DD1,DD3)
DD2=MIN(DD2,DD4)
IF(DD1.LT.HIPR1(13)) DD1=0.0
IF(DD2.LT.HIPR1(13)) DD2=0.0
IF(NFP(JP,10).EQ.1.AND.PPJET.GT.HIPR1(11)) THEN
DP1=DD1*HIPR1(14)/2.0
DP1=MIN(DP1,PPJET-HIPR1(11))
PKC1=PPJET-DP1
DPX1=COS(PHI1)*DP1
DPY1=SIN(PHI1)*DP1
PKC11=PP(JP,10)-DPX1
PKC12=PP(JP,11)-DPY1
IF(DP1.GT.0.0) THEN
CTHEP=PP(JP,12)/SQRT(PP(JP,12)**2+PPJET**2)
DPZ1=DP1*CTHEP/SQRT(1.0-CTHEP**2)
DPE1=SQRT(DPX1**2+DPY1**2+DPZ1**2)
EPPPRM=PP(JP,4)+PP(JP,3)-DPE1-DPZ1
EPMPRM=PP(JP,4)-PP(JP,3)-DPE1+DPZ1
IF(EPPPRM.LE.0.0.OR.EPMPRM.LE.0.0) GO TO 15
EPP=EPPPRM
EPM=EPMPRM
PP(JP,10)=PKC11
PP(JP,11)=PKC12
NPJ(JP)=NPJ(JP)+1
KFPJ(JP,NPJ(JP))=21
PJPX(JP,NPJ(JP))=DPX1
PJPY(JP,NPJ(JP))=DPY1
PJPZ(JP,NPJ(JP))=DPZ1
PJPE(JP,NPJ(JP))=DPE1
PJPM(JP,NPJ(JP))=0.0
PP(JP,3)=PP(JP,3)-DPZ1
PP(JP,4)=PP(JP,4)-DPE1
ENDIF
ENDIF
15 IF(NFT(JT,10).EQ.1.AND.PTJET.GT.HIPR1(11)) THEN
DP2=DD2*HIPR1(14)/2.0
DP2=MIN(DP2,PTJET-HIPR1(11))
PKC2=PTJET-DP2
DPX2=COS(PHI2)*DP2
DPY2=SIN(PHI2)*DP2
PKC21=PT(JT,10)-DPX2
PKC22=PT(JT,11)-DPY2
IF(DP2.GT.0.0) THEN
CTHET=PT(JT,12)/SQRT(PT(JT,12)**2+PTJET**2)
DPZ2=DP2*CTHET/SQRT(1.0-CTHET**2)
DPE2=SQRT(DPX2**2+DPY2**2+DPZ2**2)
ETPPRM=PT(JT,4)+PT(JT,3)-DPE2-DPZ2
ETMPRM=PT(JT,4)-PT(JT,3)-DPE2+DPZ2
IF(ETPPRM.LE.0.0.OR.ETMPRM.LE.0.0) GO TO 16
ETP=ETPPRM
ETM=ETMPRM
PT(JT,10)=PKC21
PT(JT,11)=PKC22
NTJ(JT)=NTJ(JT)+1
KFTJ(JT,NTJ(JT))=21
PJTX(JT,NTJ(JT))=DPX2
PJTY(JT,NTJ(JT))=DPY2
PJTZ(JT,NTJ(JT))=DPZ2
PJTE(JT,NTJ(JT))=DPE2
PJTM(JT,NTJ(JT))=0.0
PT(JT,3)=PT(JT,3)-DPZ2
PT(JT,4)=PT(JT,4)-DPE2
ENDIF
ENDIF
16 DPKC11=-(PP(JP,10)-PKC11)/2.0
DPKC12=-(PP(JP,11)-PKC12)/2.0
DPKC21=-(PT(JT,10)-PKC21)/2.0
DPKC22=-(PT(JT,11)-PKC22)/2.0
WP=EPP+ETP
WM=EPM+ETM
SW=WP*WM
ENDIF
ENDIF
C ********If jet is quenched the pt from valence quark
C hard scattering has to reduced by d*kapa
C
C
10 PTP02=PP(JP,1)**2+PP(JP,2)**2
PTT02=PT(JT,1)**2+PT(JT,2)**2
C
AMQ=MAX(PP(JP,14)+PP(JP,15),PT(JT,14)+PT(JT,15))
AMX=HIPR1(1)+AMQ
C ********consider mass cut-off for strings which
C must also include quark's mass
AMP0=AMX
DPM0=AMX
NFDP=0
IF(NFP(JP,5).LE.2.AND.NFP(JP,3).NE.0) THEN
AMP0=ULMASS(NFP(JP,3))
NFDP=NFP(JP,3)+2*NFP(JP,3)/ABS(NFP(JP,3))
DPM0=ULMASS(NFDP)
IF(DPM0.LE.0.0) THEN
NFDP=NFDP-2*NFDP/ABS(NFDP)
DPM0=ULMASS(NFDP)
ENDIF
ENDIF
AMT0=AMX
DTM0=AMX
NFDT=0
IF(NFT(JT,5).LE.2.AND.NFT(JT,3).NE.0) THEN
AMT0=ULMASS(NFT(JT,3))
NFDT=NFT(JT,3)+2*NFT(JT,3)/ABS(NFT(JT,3))
DTM0=ULMASS(NFDT)
IF(DTM0.LE.0.0) THEN
NFDT=NFDT-2*NFDT/ABS(NFDT)
DTM0=ULMASS(NFDT)
ENDIF
ENDIF
C
AMPN=SQRT(AMP0**2+PTP02)
AMTN=SQRT(AMT0**2+PTT02)
SNN=(AMPN+AMTN)**2+0.001
C
IF(SW.LT.SNN+0.001) GO TO 4000
C ********Scatter only if SW>SNN
C*****give some PT kick to the two exited strings******************
20 SWPTN=4.0*(MAX(AMP0,AMT0)**2+MAX(PTP02,PTT02))
SWPTD=4.0*(MAX(DPM0,DTM0)**2+MAX(PTP02,PTT02))
SWPTX=4.0*(AMX**2+MAX(PTP02,PTT02))
IF(SW.LE.SWPTN) THEN
PKCMX=0.0
ELSE IF(SW.GT.SWPTN .AND. SW.LE.SWPTD
& .AND.NPJ(JP).EQ.0.AND.NTJ(JT).EQ.0) THEN
PKCMX=SQRT(SW/4.0-MAX(AMP0,AMT0)**2)
& -SQRT(MAX(PTP02,PTT02))
ELSE IF(SW.GT.SWPTD .AND. SW.LE.SWPTX
& .AND.NPJ(JP).EQ.0.AND.NTJ(JT).EQ.0) THEN
PKCMX=SQRT(SW/4.0-MAX(DPM0,DTM0)**2)
& -SQRT(MAX(PTP02,PTT02))
ELSE IF(SW.GT.SWPTX) THEN
PKCMX=SQRT(SW/4.0-AMX**2)-SQRT(MAX(PTP02,PTT02))
ENDIF
C ********maximun PT kick
C*********************************************************
C
IF(NFP(JP,10).EQ.1.OR.NFT(JT,10).EQ.1) THEN
IF(PKC1.GT.PKCMX) THEN
PKC1=PKCMX
PKC11=PKC1*COS(PHI1)
PKC12=PKC1*SIN(PHI1)
DPKC11=-(PP(JP,10)-PKC11)/2.0
DPKC12=-(PP(JP,11)-PKC12)/2.0
ENDIF
IF(PKC2.GT.PKCMX) THEN
PKC2=PKCMX
PKC21=PKC2*COS(PHI2)
PKC22=PKC2*SIN(PHI2)
DPKC21=-(PT(JT,10)-PKC21)/2.0
DPKC22=-(PT(JT,11)-PKC22)/2.0
ENDIF
DPKC1=DPKC11+DPKC21
DPKC2=DPKC12+DPKC22
NFP(JP,10)=-NFP(JP,10)
NFT(JT,10)=-NFT(JT,10)
GO TO 40
ENDIF
C ********If the valence quarks had a hard-collision
C the pt kick is the pt from hard-collision.
I_SNG=0
IF(IHPR2(13).NE.0 .AND. ATL_RAN(NSEED).LE.HIDAT(4)) I_SNG=1
IF((NFP(JP,5).EQ.3 .OR.NFT(JT,5).EQ.3).OR.
& (NPJ(JP).NE.0.OR.NFP(JP,10).NE.0).OR.
& (NTJ(JT).NE.0.OR.NFT(JT,10).NE.0)) I_SNG=0
C
C ********decite whether to have single-diffractive
IF(IHPR2(5).EQ.0) THEN
PKC=HIPR1(2)*SQRT(-ALOG(1.0-ATL_RAN(NSEED)
& *(1.0-EXP(-PKCMX**2/HIPR1(2)**2))))
GO TO 30
ENDIF
PKC=HIRND2(3,0.0,PKCMX**2)
PKC=SQRT(PKC)
IF(PKC.GT.HIPR1(20))
& PKC=HIPR1(2)*SQRT(-ALOG(EXP(-HIPR1(20)**2/HIPR1(2)**2)
& -ATL_RAN(NSEED)*(EXP(-HIPR1(20)**2/HIPR1(2)**2)-
& EXP(-PKCMX**2/HIPR1(2)**2))))
C
IF(I_SNG.EQ.1) PKC=0.65*SQRT(
& -ALOG(1.0-ATL_RAN(NSEED)*(1.0-EXP(-PKCMX**2/0.65**2))))
C ********select PT kick
30 PHI0=2.0*HIPR1(40)*ATL_RAN(NSEED)
PKC11=PKC*SIN(PHI0)
PKC12=PKC*COS(PHI0)
PKC21=-PKC11
PKC22=-PKC12
DPKC1=0.0
DPKC2=0.0
40 PP11=PP(JP,1)+PKC11-DPKC1
PP12=PP(JP,2)+PKC12-DPKC2
PT11=PT(JT,1)+PKC21-DPKC1
PT12=PT(JT,2)+PKC22-DPKC2
PTP2=PP11**2+PP12**2
PTT2=PT11**2+PT12**2
C
AMPN=SQRT(AMP0**2+PTP2)
AMTN=SQRT(AMT0**2+PTT2)
SNN=(AMPN+AMTN)**2+0.001
C***************************************
WP=EPP+ETP
WM=EPM+ETM
SW=WP*WM
C****************************************
IF(SW.LT.SNN) THEN
MISS=MISS+1
IF(MISS.LE.100) then
PKC=0.0
GO TO 30
ENDIF
IF(IHPR2(10).NE.0)
&WRITE(6,*) 'Error occured in Pt kick section of HIJSFT'
GO TO 4000
ENDIF
C******************************************************************
AMPD=SQRT(DPM0**2+PTP2)
AMTD=SQRT(DTM0**2+PTT2)
AMPX=SQRT(AMX**2+PTP2)
AMTX=SQRT(AMX**2+PTT2)
DPN=AMPN**2/SW
DTN=AMTN**2/SW
DPD=AMPD**2/SW
DTD=AMTD**2/SW
DPX=AMPX**2/SW
DTX=AMTX**2/SW
C
SPNTD=(AMPN+AMTD)**2
SPNTX=(AMPN+AMTX)**2
C ********CM energy if proj=N,targ=N*
SPDTN=(AMPD+AMTN)**2
SPXTN=(AMPX+AMTN)**2
C ********CM energy if proj=N*,targ=N
SPDTX=(AMPD+AMTX)**2
SPXTD=(AMPX+AMTD)**2
SDD=(AMPD+AMTD)**2
SXX=(AMPX+AMTX)**2
C
C
C ********CM energy if proj=delta, targ=delta
C****************There are many different cases**********
c IF(IHPR2(15).EQ.1) GO TO 500
C
C ********to have DPM type soft interactions
C
45 CONTINUE
IF(SW.GT.SXX+0.001) THEN
IF(I_SNG.EQ.0) THEN
D1=DPX
D2=DTX
NFP3=0
NFT3=0
GO TO 400
ELSE
c**** 5/30/1998 this is identical to the above statement. Added to
c**** avoid questional branching to block.
IF((NFP(JP,5).EQ.3 .AND.NFT(JT,5).EQ.3).OR.
& (NPJ(JP).NE.0.OR.NFP(JP,10).NE.0).OR.
& (NTJ(JT).NE.0.OR.NFT(JT,10).NE.0)) THEN
D1=DPX
D2=DTX
NFP3=0
NFT3=0
GO TO 400
ENDIF
C ********do not allow excited strings to have
C single-diffr
IF(ATL_RAN(NSEED).GT.0.5.OR.(NFT(JT,5).GT.2.OR.
& NTJ(JT).NE.0.OR.NFT(JT,10).NE.0)) THEN
D1=DPN
D2=DTX
NFP3=NFP(JP,3)
NFT3=0
GO TO 220
ELSE
D1=DPX
D2=DTN
NFP3=0
NFT3=NFT(JT,3)
GO TO 240
ENDIF
C ********have single diffractive collision
ENDIF
ELSE IF(SW.GT.MAX(SPDTX,SPXTD)+0.001 .AND.
& SW.LE.SXX+0.001) THEN
IF(((NPJ(JP).EQ.0.AND.NTJ(JT).EQ.0.AND.
& ATL_RAN(NSEED).GT.0.5).OR.(NPJ(JP).EQ.0
& .AND.NTJ(JT).NE.0)).AND.NFP(JP,5).LE.2) THEN
D1=DPD
D2=DTX
NFP3=NFDP
NFT3=0
GO TO 220
ELSE IF(NTJ(JT).EQ.0.AND.NFT(JT,5).LE.2) THEN
D1=DPX
D2=DTD
NFP3=0
NFT3=NFDT
GO TO 240
ENDIF
GO TO 4000
ELSE IF(SW.GT.MIN(SPDTX,SPXTD)+0.001.AND.
& SW.LE.MAX(SPDTX,SPXTD)+0.001) THEN
IF(SPDTX.LE.SPXTD.AND.NPJ(JP).EQ.0
& .AND.NFP(JP,5).LE.2) THEN
D1=DPD
D2=DTX
NFP3=NFDP
NFT3=0
GO TO 220
ELSE IF(SPDTX.GT.SPXTD.AND.NTJ(JT).EQ.0
& .AND.NFT(JT,5).LE.2) THEN
D1=DPX
D2=DTD
NFP3=0
NFT3=NFDT
GO TO 240
ENDIF
c*** 5/30/1998 added to avoid questional branching to another block
c*** this is identical to the statement following the next ELSE IF
IF(((NPJ(JP).EQ.0.AND.NTJ(JT).EQ.0
& .AND.ATL_RAN(NSEED).GT.0.5).OR.(NPJ(JP).EQ.0
& .AND.NTJ(JT).NE.0)).AND.NFP(JP,5).LE.2) THEN
D1=DPN
D2=DTX
NFP3=NFP(JP,3)
NFT3=0
GO TO 220
ELSE IF(NTJ(JT).EQ.0.AND.NFT(JT,5).LE.2) THEN
D1=DPX
D2=DTN
NFP3=0
NFT3=NFT(JT,3)
GO TO 240
ENDIF
GO TO 4000
ELSE IF(SW.GT.MAX(SPNTX,SPXTN)+0.001 .AND.
& SW.LE.MIN(SPDTX,SPXTD)+0.001) THEN
IF(((NPJ(JP).EQ.0.AND.NTJ(JT).EQ.0
& .AND.ATL_RAN(NSEED).GT.0.5).OR.(NPJ(JP).EQ.0
& .AND.NTJ(JT).NE.0)).AND.NFP(JP,5).LE.2) THEN
D1=DPN
D2=DTX
NFP3=NFP(JP,3)
NFT3=0
GO TO 220
ELSE IF(NTJ(JT).EQ.0.AND.NFT(JT,5).LE.2) THEN
D1=DPX
D2=DTN
NFP3=0
NFT3=NFT(JT,3)
GO TO 240
ENDIF
GO TO 4000
ELSE IF(SW.GT.MIN(SPNTX,SPXTN)+0.001 .AND.
& SW.LE.MAX(SPNTX,SPXTN)+0.001) THEN
IF(SPNTX.LE.SPXTN.AND.NPJ(JP).EQ.0
& .AND.NFP(JP,5).LE.2) THEN
D1=DPN
D2=DTX
NFP3=NFP(JP,3)
NFT3=0
GO TO 220
ELSEIF(SPNTX.GT.SPXTN.AND.NTJ(JT).EQ.0
& .AND.NFT(JT,5).LE.2) THEN
D1=DPX
D2=DTN
NFP3=0
NFT3=NFT(JT,3)
GO TO 240
ENDIF
GO TO 4000
ELSE IF(SW.LE.MIN(SPNTX,SPXTN)+0.001 .AND.
& (NPJ(JP).NE.0 .OR.NTJ(JT).NE.0)) THEN
GO TO 4000
ELSE IF(SW.LE.MIN(SPNTX,SPXTN)+0.001 .AND.
& NFP(JP,5).GT.2.AND.NFT(JT,5).GT.2) THEN
GO TO 4000
ELSE IF(SW.GT.SDD+0.001.AND.SW.LE.
& MIN(SPNTX,SPXTN)+0.001) THEN
D1=DPD
D2=DTD
NFP3=NFDP
NFT3=NFDT
GO TO 100
ELSE IF(SW.GT.MAX(SPNTD,SPDTN)+0.001
& .AND. SW.LE.SDD+0.001) THEN
IF(ATL_RAN(NSEED).GT.0.5) THEN
D1=DPD
D2=DTN
NFP3=NFDP
NFT3=NFT(JT,3)
GO TO 100
ELSE
D1=DPN
D2=DTD
NFP3=NFP(JP,3)
NFT3=NFDT
GO TO 100
ENDIF
ELSE IF(SW.GT.MIN(SPNTD,SPDTN)+0.001
& .AND. SW.LE.MAX(SPNTD,SPDTN)+0.001) THEN
IF(SPNTD.GT.SPDTN) THEN
D1=DPD
D2=DTN
NFP3=NFDP
NFT3=NFT(JT,3)
GO TO 100
ELSE
D1=DPN
D2=DTD
NFP3=NFP(JP,3)
NFT3=NFDT
GO TO 100
ENDIF
ELSE IF(SW.LE.MIN(SPNTD,SPDTN)+0.001) THEN
D1=DPN
D2=DTN
NFP3=NFP(JP,3)
NFT3=NFT(JT,3)
GO TO 100
ENDIF
WRITE(6,*) 'Error in HIJSFT: There is no path to here'
RETURN
C
C*************** elastic scattering ***************
C this is like elastic, both proj and targ mass
C must be fixed
C***************************************************
100 NFP5=MAX(2,NFP(JP,5))
NFT5=MAX(2,NFT(JT,5))
BB1=1.0+D1-D2
BB2=1.0+D2-D1
IF(BB1**2.LT.4.0*D1 .OR. BB2**2.LT.4.0*D2) THEN
MISS=MISS+1
IF(MISS.GT.100.OR.PKC.EQ.0.0) GO TO 3000
PKC=PKC*0.5
GO TO 30
ENDIF
IF(ATL_RAN(NSEED).LT.0.5) THEN
X1=(BB1-SQRT(BB1**2-4.0*D1))/2.0
X2=(BB2-SQRT(BB2**2-4.0*D2))/2.0
ELSE
X1=(BB1+SQRT(BB1**2-4.0*D1))/2.0
X2=(BB2+SQRT(BB2**2-4.0*D2))/2.0
ENDIF
IHNT2(13)=2
GO TO 600
C
C********** Single diffractive ***********************
C either proj or targ's mass is fixed
C*****************************************************
220 NFP5=MAX(2,NFP(JP,5))
NFT5=3
IF(NFP3.EQ.0) NFP5=3
BB2=1.0+D2-D1
IF(BB2**2.LT.4.0*D2) THEN
MISS=MISS+1
IF(MISS.GT.100.OR.PKC.EQ.0.0) GO TO 3000
PKC=PKC*0.5
GO TO 30
ENDIF
XMIN=(BB2-SQRT(BB2**2-4.0*D2))/2.0
XMAX=(BB2+SQRT(BB2**2-4.0*D2))/2.0
MISS4=0
222 X2=HIRND2(6,XMIN,XMAX)
X1=D1/(1.0-X2)
IF(X2*(1.0-X1).LT.(D2+1.E-4/SW)) THEN
MISS4=MISS4+1
IF(MISS4.LE.1000) GO TO 222
GO TO 5000
ENDIF
IHNT2(13)=2
GO TO 600
C ********Fix proj mass*********
240 NFP5=3
NFT5=MAX(2,NFT(JT,5))
IF(NFT3.EQ.0) NFT5=3
BB1=1.0+D1-D2
IF(BB1**2.LT.4.0*D1) THEN
MISS=MISS+1
IF(MISS.GT.100.OR.PKC.EQ.0.0) GO TO 3000
PKC=PKC*0.5
GO TO 30
ENDIF
XMIN=(BB1-SQRT(BB1**2-4.0*D1))/2.0
XMAX=(BB1+SQRT(BB1**2-4.0*D1))/2.0
MISS4=0
242 X1=HIRND2(6,XMIN,XMAX)
X2=D2/(1.0-X1)
IF(X1*(1.0-X2).LT.(D1+1.E-4/SW)) THEN
MISS4=MISS4+1
IF(MISS4.LE.1000) GO TO 242
GO TO 5000
ENDIF
IHNT2(13)=2
GO TO 600
C ********Fix targ mass*********
C
C*************non-single diffractive**********************
C both proj and targ may not be fixed in mass
C*********************************************************
C
400 NFP5=3
NFT5=3
BB1=1.0+D1-D2
BB2=1.0+D2-D1
IF(BB1**2.LT.4.0*D1 .OR. BB2**2.LT.4.0*D2) THEN
MISS=MISS+1
IF(MISS.GT.100.OR.PKC.EQ.0.0) GO TO 3000
PKC=PKC*0.5
GO TO 30
ENDIF
XMIN1=(BB1-SQRT(BB1**2-4.0*D1))/2.0
XMAX1=(BB1+SQRT(BB1**2-4.0*D1))/2.0
XMIN2=(BB2-SQRT(BB2**2-4.0*D2))/2.0
XMAX2=(BB2+SQRT(BB2**2-4.0*D2))/2.0
MISS4=0
410 X1=HIRND2(4,XMIN1,XMAX1)
X2=HIRND2(4,XMIN2,XMAX2)
IF(NFP(JP,5).EQ.3.OR.NFT(JT,5).EQ.3) THEN
X1=HIRND2(6,XMIN1,XMAX1)
X2=HIRND2(6,XMIN2,XMAX2)
ENDIF
C ********
IF(ABS(NFP(JP,1)*NFP(JP,2)).GT.1000000.OR.
& ABS(NFP(JP,1)*NFP(JP,2)).LT.100) THEN
X1=HIRND2(5,XMIN1,XMAX1)
ENDIF
IF(ABS(NFT(JT,1)*NFT(JT,2)).GT.1000000.OR.
& ABS(NFT(JT,1)*NFT(JT,2)).LT.100) THEN
X2=HIRND2(5,XMIN2,XMAX2)
ENDIF
c IF(IOPMAIN.EQ.3) X1=HIRND2(6,XMIN1,XMAX1)
c IF(IOPMAIN.EQ.2) X2=HIRND2(6,XMIN2,XMAX2)
C ********For q-qbar or (qq)-(qq)bar system use symetric
C distribution, for q-(qq) or qbar-(qq)bar use
C unsymetrical distribution
C
IF(ABS(NFP(JP,1)*NFP(JP,2)).GT.1000000) X1=1.0-X1
XXP=X1*(1.0-X2)
XXT=X2*(1.0-X1)
IF(XXP.LT.(D1+1.E-4/SW) .OR. XXT.LT.(D2+1.E-4/SW)) THEN
MISS4=MISS4+1
IF(MISS4.LE.1000) GO TO 410
GO TO 5000
ENDIF
IHNT2(13)=3
C***************************************************
C***************************************************
600 CONTINUE
IF(X1*(1.0-X2).LT.(AMPN**2-1.E-4)/SW.OR.
& X2*(1.0-X1).LT.(AMTN**2-1.E-4)/SW) THEN
MISS=MISS+1
IF(MISS.GT.100.OR.PKC.EQ.0.0) GO TO 2000
PKC=0.0
GO TO 30
ENDIF
C
EPP=(1.0-X2)*WP
EPM=X1*WM
ETP=X2*WP
ETM=(1.0-X1)*WM
PP(JP,3)=(EPP-EPM)/2.0
PP(JP,4)=(EPP+EPM)/2.0
IF(EPP*EPM-PTP2.LT.0.0) GO TO 6000
PP(JP,5)=SQRT(EPP*EPM-PTP2)
NFP(JP,3)=NFP3
NFP(JP,5)=NFP5
PT(JT,3)=(ETP-ETM)/2.0
PT(JT,4)=(ETP+ETM)/2.0
IF(ETP*ETM-PTT2.LT.0.0) GO TO 6000
PT(JT,5)=SQRT(ETP*ETM-PTT2)
NFT(JT,3)=NFT3
NFT(JT,5)=NFT5
C*****recoil PT from hard-inter is shared by two end-partons
C so that pt=p1+p2
PP(JP,1)=PP11-PKC11
PP(JP,2)=PP12-PKC12
KICKDIP=1
KICKDIT=1
IF(ABS(NFP(JP,1)*NFP(JP,2)).GT.1000000.OR.
& ABS(NFP(JP,1)*NFP(JP,2)).LT.100) THEN
KICKDIP=0
ENDIF
IF(ABS(NFT(JT,1)*NFT(JT,2)).GT.1000000.OR.
& ABS(NFT(JT,1)*NFT(JT,2)).LT.100) THEN
KICKDIT=0
ENDIF
IF((KICKDIP.EQ.0.AND.ATL_RAN(NSEED).LT.0.5)
& .OR.(KICKDIP.NE.0.AND.ATL_RAN(NSEED)
& .LT.0.5/(1.0+(PKC11**2+PKC12**2)/HIPR1(22)**2))) THEN
PP(JP,6)=(PP(JP,1)-PP(JP,6)-PP(JP,8)-DPKC1)/2.0+PP(JP,6)
PP(JP,7)=(PP(JP,2)-PP(JP,7)-PP(JP,9)-DPKC2)/2.0+PP(JP,7)
PP(JP,8)=(PP(JP,1)-PP(JP,6)-PP(JP,8)-DPKC1)/2.0
& +PP(JP,8)+PKC11
PP(JP,9)=(PP(JP,2)-PP(JP,7)-PP(JP,9)-DPKC2)/2.0
& +PP(JP,9)+PKC12
ELSE
PP(JP,8)=(PP(JP,1)-PP(JP,6)-PP(JP,8)-DPKC1)/2.0+PP(JP,8)
PP(JP,9)=(PP(JP,2)-PP(JP,7)-PP(JP,9)-DPKC2)/2.0+PP(JP,9)
PP(JP,6)=(PP(JP,1)-PP(JP,6)-PP(JP,8)-DPKC1)/2.0
& +PP(JP,6)+PKC11
PP(JP,7)=(PP(JP,2)-PP(JP,7)-PP(JP,9)-DPKC2)/2.0
& +PP(JP,7)+PKC12
ENDIF
PP(JP,1)=PP(JP,6)+PP(JP,8)
PP(JP,2)=PP(JP,7)+PP(JP,9)
C ********pt kick for proj
PT(JT,1)=PT11-PKC21
PT(JT,2)=PT12-PKC22
IF((KICKDIT.EQ.0.AND.ATL_RAN(NSEED).LT.0.5)
& .OR.(KICKDIT.NE.0.AND.ATL_RAN(NSEED)
& .LT.0.5/(1.0+(PKC21**2+PKC22**2)/HIPR1(22)**2))) THEN
PT(JT,6)=(PT(JT,1)-PT(JT,6)-PT(JT,8)-DPKC1)/2.0+PT(JT,6)
PT(JT,7)=(PT(JT,2)-PT(JT,7)-PT(JT,9)-DPKC2)/2.0+PT(JT,7)
PT(JT,8)=(PT(JT,1)-PT(JT,6)-PT(JT,8)-DPKC1)/2.0
& +PT(JT,8)+PKC21
PT(JT,9)=(PT(JT,2)-PT(JT,7)-PT(JT,9)-DPKC2)/2.0
& +PT(JT,9)+PKC22
ELSE
PT(JT,8)=(PT(JT,1)-PT(JT,6)-PT(JT,8)-DPKC1)/2.0+PT(JT,8)
PT(JT,9)=(PT(JT,2)-PT(JT,7)-PT(JT,9)-DPKC2)/2.0+PT(JT,9)
PT(JT,6)=(PT(JT,1)-PT(JT,6)-PT(JT,8)-DPKC1)/2.0
& +PT(JT,6)+PKC21
PT(JT,7)=(PT(JT,2)-PT(JT,7)-PT(JT,9)-DPKC2)/2.0
& +PT(JT,7)+PKC22
ENDIF
PT(JT,1)=PT(JT,6)+PT(JT,8)
PT(JT,2)=PT(JT,7)+PT(JT,9)
C ********pt kick for targ
IF(NPJ(JP).NE.0) NFP(JP,5)=3
IF(NTJ(JT).NE.0) NFT(JT,5)=3
C ********jets must be connected to string
IF(EPP/(EPM+0.0001).LT.ETP/(ETM+0.0001).AND.
& ABS(NFP(JP,1)*NFP(JP,2)).LT.1000000)THEN
DO 620 JSB=1,15
PSB=PP(JP,JSB)
PP(JP,JSB)=PT(JT,JSB)
PT(JT,JSB)=PSB
NSB=NFP(JP,JSB)
NFP(JP,JSB)=NFT(JT,JSB)
NFT(JT,JSB)=NSB
620 CONTINUE
C ********when Ycm(JP)<Ycm(JT) after the collision
C exchange the positions of the two
ENDIF
C
RETURN
C**************************************************
C**************************************************
1000 IERROR=1
IF(IHPR2(10).EQ.0) RETURN
WRITE(6,*) ' Fatal HIJSFT start error,abandon this event'
WRITE(6,*) ' PROJ E+,E-,W+',EPP,EPM,WP
WRITE(6,*) ' TARG E+,E-,W-',ETP,ETM,WM
WRITE(6,*) ' W+*W-, (APN+ATN)^2',SW,SNN
RETURN
2000 IERROR=0
IF(IHPR2(10).EQ.0) RETURN
WRITE(6,*) ' (2)energy partition fail,'
WRITE(6,*) ' HIJSFT not performed, but continue'
WRITE(6,*) ' MP1,MPN',X1*(1.0-X2)*SW,AMPN**2
WRITE(6,*) ' MT2,MTN',X2*(1.0-X1)*SW,AMTN**2
RETURN
3000 IERROR=0
IF(IHPR2(10).EQ.0) RETURN
WRITE(6,*) ' (3)something is wrong with the pt kick, '
WRITE(6,*) ' HIJSFT not performed, but continue'
WRITE(6,*) ' D1=',D1,' D2=',D2,' SW=',SW
WRITE(6,*) ' HISTORY NFP5=',NFP(JP,5),' NFT5=',NFT(JT,5)
WRITE(6,*) ' THIS COLLISON NFP5=',NFP5, ' NFT5=',NFT5
WRITE(6,*) ' # OF JET IN PROJ',NPJ(JP),' IN TARG',NTJ(JT)
RETURN
4000 IERROR=0
IF(IHPR2(10).EQ.0) RETURN
WRITE(6,*) ' (4)unable to choose process, but not harmful'
WRITE(6,*) ' HIJSFT not performed, but continue'
WRITE(6,*) ' PTP=',SQRT(PTP2),' PTT=',SQRT(PTT2),' SW=',SW
WRITE(6,*) ' AMCUT=',AMX,' JP=',JP,' JT=',JT
WRITE(6,*) ' HISTORY NFP5=',NFP(JP,5),' NFT5=',NFT(JT,5)
RETURN
5000 IERROR=0
IF(IHPR2(10).EQ.0) RETURN
WRITE(6,*) ' energy partition failed(5),for limited try'
WRITE(6,*) ' HIJSFT not performed, but continue'
WRITE(6,*) ' NFP5=',NFP5,' NFT5=',NFT5
WRITE(6,*) ' D1',D1,' X1(1-X2)',X1*(1.0-X2)
WRITE(6,*) ' D2',D2,' X2(1-X1)',X2*(1.0-X1)
RETURN
6000 PKC=0.0
MISS=MISS+1
IF(MISS.LT.100) GO TO 30
IERROR=1
IF(IHPR2(10).EQ.0) RETURN
WRITE(6,*) 'ERROR OCCURED, HIJSFT NOT PERFORMED'
WRITE(6,*) ' Abort this event'
WRITE(6,*) 'MTP,PTP2',EPP*EPM,PTP2,' MTT,PTT2',ETP*ETM,PTT2
RETURN
END