[u/mrichter/AliRoot.git] / HIJING / hipyset1_35 / lux4jt_hijing.F

* $Id$
    
C*********************************************************************  
    
      SUBROUTINE LUX4JT_HIJING(NJET,CUT,KFL,ECM,KFLN,X1,X2,X4,X12,X14) 
    
C...Purpose: to select the kinematical variables of four-jet events.    
#include "ludat1_hijing.inc"
      DIMENSION WTA(4),WTB(4),WTC(4),WTD(4),WTE(4)  
    
C...Common constants. Colour factors for QCD and Abelian gluon theory.  
      PMQ=ULMASS_HIJING(KFL)   
      QME=(2.*PMQ/ECM)**2   
      CT=LOG(1./CUT-5.) 
      IF(MSTJ(109).EQ.0) THEN   
        CF=4./3.    
        CN=3.   
        TR=2.   
      ELSE  
        CF=1.   
        CN=0.   
        TR=12.  
      ENDIF 
    
C...Choice of process (qqbargg or qqbarqqbar).  
  100 NJET=4    
      IT=1  
      IF(PARJ(155).GT.RLU_HIJING(0)) IT=2  
      IF(MSTJ(101).LE.-3) IT=-MSTJ(101)-2   
      IF(IT.EQ.1) WTMX=0.7/CUT**2   
      IF(IT.EQ.1.AND.MSTJ(109).EQ.2) WTMX=0.6/CUT**2    
      IF(IT.EQ.2) WTMX=0.1125*CF*TR/CUT**2  
      ID=1  
    
C...Sample the five kinematical variables (for qqgg preweighted in y34).    
  110 Y134=3.*CUT+(1.-6.*CUT)*RLU_HIJING(0)    
      Y234=3.*CUT+(1.-6.*CUT)*RLU_HIJING(0)    
      IF(IT.EQ.1) Y34=(1.-5.*CUT)*EXP(-CT*RLU_HIJING(0))   
      IF(IT.EQ.2) Y34=CUT+(1.-6.*CUT)*RLU_HIJING(0)    
      IF(Y34.LE.Y134+Y234-1..OR.Y34.GE.Y134*Y234) GOTO 110  
      VT=RLU_HIJING(0) 
      CP=COS(PARU(1)*RLU_HIJING(0))    
      Y14=(Y134-Y34)*VT 
      Y13=Y134-Y14-Y34  
      VB=Y34*(1.-Y134-Y234+Y34)/((Y134-Y34)*(Y234-Y34)) 
      Y24=0.5*(Y234-Y34)*(1.-4.*SQRT(MAX(0.,VT*(1.-VT)*VB*(1.-VB)))*    
     &CP-(1.-2.*VT)*(1.-2.*VB)) 
      Y23=Y234-Y34-Y24  
      Y12=1.-Y134-Y23-Y24   
      IF(MIN(Y12,Y13,Y14,Y23,Y24).LE.CUT) GOTO 110  
      Y123=Y12+Y13+Y23  
      Y124=Y12+Y14+Y24  
    
C...Calculate matrix elements for qqgg or qqqq process. 
      IC=0  
      WTTOT=0.  
  120 IC=IC+1   
      IF(IT.EQ.1) THEN  
        WTA(IC)=(Y12*Y34**2-Y13*Y24*Y34+Y14*Y23*Y34+3.*Y12*Y23*Y34+ 
     &  3.*Y12*Y14*Y34+4.*Y12**2*Y34-Y13*Y23*Y24+2.*Y12*Y23*Y24-    
     &  Y13*Y14*Y24-2.*Y12*Y13*Y24+2.*Y12**2*Y24+Y14*Y23**2+2.*Y12* 
     &  Y23**2+Y14**2*Y23+4.*Y12*Y14*Y23+4.*Y12**2*Y23+2.*Y12*Y14**2+   
     &  2.*Y12*Y13*Y14+4.*Y12**2*Y14+2.*Y12**2*Y13+2.*Y12**3)/(2.*Y13*  
     &  Y134*Y234*Y24)+(Y24*Y34+Y12*Y34+Y13*Y24-Y14*Y23+Y12*Y13)/(Y13*  
     &  Y134**2)+2.*Y23*(1.-Y13)/(Y13*Y134*Y24)+Y34/(2.*Y13*Y24)    
        WTB(IC)=(Y12*Y24*Y34+Y12*Y14*Y34-Y13*Y24**2+Y13*Y14*Y24+2.*Y12* 
     &  Y14*Y24)/(Y13*Y134*Y23*Y14)+Y12*(1.+Y34)*Y124/(Y134*Y234*Y14*   
     &  Y24)-(2.*Y13*Y24+Y14**2+Y13*Y23+2.*Y12*Y13)/(Y13*Y134*Y14)+ 
     &  Y12*Y123*Y124/(2.*Y13*Y14*Y23*Y24)  
        WTC(IC)=-(5.*Y12*Y34**2+2.*Y12*Y24*Y34+2.*Y12*Y23*Y34+2.*Y12*   
     &  Y14*Y34+2.*Y12*Y13*Y34+4.*Y12**2*Y34-Y13*Y24**2+Y14*Y23*Y24+    
     &  Y13*Y23*Y24+Y13*Y14*Y24-Y12*Y14*Y24-Y13**2*Y24-3.*Y12*Y13*Y24-  
     &  Y14*Y23**2-Y14**2*Y23+Y13*Y14*Y23-3.*Y12*Y14*Y23-Y12*Y13*Y23)/  
     &  (4.*Y134*Y234*Y34**2)+(3.*Y12*Y34**2-3.*Y13*Y24*Y34+3.*Y12*Y24* 
     &  Y34+3.*Y14*Y23*Y34-Y13*Y24**2-Y12*Y23*Y34+6.*Y12*Y14*Y34+2.*Y12*    
     &  Y13*Y34-2.*Y12**2*Y34+Y14*Y23*Y24-3.*Y13*Y23*Y24-2.*Y13*Y14*    
     &  Y24+4.*Y12*Y14*Y24+2.*Y12*Y13*Y24+3.*Y14*Y23**2+2.*Y14**2*Y23+  
     &  2.*Y14**2*Y12+2.*Y12**2*Y14+6.*Y12*Y14*Y23-2.*Y12*Y13**2-   
     &  2.*Y12**2*Y13)/(4.*Y13*Y134*Y234*Y34)   
        WTC(IC)=WTC(IC)+(2.*Y12*Y34**2-2.*Y13*Y24*Y34+Y12*Y24*Y34+  
     &  4.*Y13*Y23*Y34+4.*Y12*Y14*Y34+2.*Y12*Y13*Y34+2.*Y12**2*Y34- 
     &  Y13*Y24**2+3.*Y14*Y23*Y24+4.*Y13*Y23*Y24-2.*Y13*Y14*Y24+    
     &  4.*Y12*Y14*Y24+2.*Y12*Y13*Y24+2.*Y14*Y23**2+4.*Y13*Y23**2+  
     &  2.*Y13*Y14*Y23+2.*Y12*Y14*Y23+4.*Y12*Y13*Y23+2.*Y12*Y14**2+4.*  
     &  Y12**2*Y13+4.*Y12*Y13*Y14+2.*Y12**2*Y14)/(4.*Y13*Y134*Y24*Y34)- 
     &  (Y12*Y34**2-2.*Y14*Y24*Y34-2.*Y13*Y24*Y34-Y14*Y23*Y34+Y13*Y23*  
     &  Y34+Y12*Y14*Y34+2.*Y12*Y13*Y34-2.*Y14**2*Y24-4.*Y13*Y14*Y24-    
     &  4.*Y13**2*Y24-Y14**2*Y23-Y13**2*Y23+Y12*Y13*Y14-Y12*Y13**2)/    
     &  (2.*Y13*Y34*Y134**2)+(Y12*Y34**2-4.*Y14*Y24*Y34-2.*Y13*Y24*Y34- 
     &  2.*Y14*Y23*Y34-4.*Y13*Y23*Y34-4.*Y12*Y14*Y34-4.*Y12*Y13*Y34-    
     &  2.*Y13*Y14*Y24+2.*Y13**2*Y24+2.*Y14**2*Y23-2.*Y13*Y14*Y23-  
     &  Y12*Y14**2-6.*Y12*Y13*Y14-Y12*Y13**2)/(4.*Y34**2*Y134**2)   
        WTTOT=WTTOT+Y34*CF*(CF*WTA(IC)+(CF-0.5*CN)*WTB(IC)+CN*WTC(IC))/ 
     &  8.  
      ELSE  
        WTD(IC)=(Y13*Y23*Y34+Y12*Y23*Y34-Y12**2*Y34+Y13*Y23*Y24+2.*Y12* 
     &  Y23*Y24-Y14*Y23**2+Y12*Y13*Y24+Y12*Y14*Y23+Y12*Y13*Y14)/(Y13**2*    
     &  Y123**2)-(Y12*Y34**2-Y13*Y24*Y34+Y12*Y24*Y34-Y14*Y23*Y34-Y12*   
     &  Y23*Y34-Y13*Y24**2+Y14*Y23*Y24-Y13*Y23*Y24-Y13**2*Y24+Y14*  
     &  Y23**2)/(Y13**2*Y123*Y134)+(Y13*Y14*Y12+Y34*Y14*Y12-Y34**2*Y12+ 
     &  Y13*Y14*Y24+2.*Y34*Y14*Y24-Y23*Y14**2+Y34*Y13*Y24+Y34*Y23*Y14+  
     &  Y34*Y13*Y23)/(Y13**2*Y134**2)-(Y34*Y12**2-Y13*Y24*Y12+Y34*Y24*  
     &  Y12-Y23*Y14*Y12-Y34*Y14*Y12-Y13*Y24**2+Y23*Y14*Y24-Y13*Y14*Y24- 
     &  Y13**2*Y24+Y23*Y14**2)/(Y13**2*Y134*Y123)   
        WTE(IC)=(Y12*Y34*(Y23-Y24+Y14+Y13)+Y13*Y24**2-Y14*Y23*Y24+Y13*  
     &  Y23*Y24+Y13*Y14*Y24+Y13**2*Y24-Y14*Y23*(Y14+Y23+Y13))/(Y13*Y23* 
     &  Y123*Y134)-Y12*(Y12*Y34-Y23*Y24-Y13*Y24-Y14*Y23-Y14*Y13)/(Y13*  
     &  Y23*Y123**2)-(Y14+Y13)*(Y24+Y23)*Y34/(Y13*Y23*Y134*Y234)+   
     &  (Y12*Y34*(Y14-Y24+Y23+Y13)+Y13*Y24**2-Y23*Y14*Y24+Y13*Y14*Y24+  
     &  Y13*Y23*Y24+Y13**2*Y24-Y23*Y14*(Y14+Y23+Y13))/(Y13*Y14*Y134*    
     &  Y123)-Y34*(Y34*Y12-Y14*Y24-Y13*Y24-Y23*Y14-Y23*Y13)/(Y13*Y14*   
     &  Y134**2)-(Y23+Y13)*(Y24+Y14)*Y12/(Y13*Y14*Y123*Y124)    
        WTTOT=WTTOT+CF*(TR*WTD(IC)+(CF-0.5*CN)*WTE(IC))/16. 
      ENDIF 
    
C...Permutations of momenta in matrix element. Weighting.   
  130 IF(IC.EQ.1.OR.IC.EQ.3.OR.ID.EQ.2.OR.ID.EQ.3) THEN 
        YSAV=Y13    
        Y13=Y14 
        Y14=YSAV    
        YSAV=Y23    
        Y23=Y24 
        Y24=YSAV    
        YSAV=Y123   
        Y123=Y124   
        Y124=YSAV   
      ENDIF 
      IF(IC.EQ.2.OR.IC.EQ.4.OR.ID.EQ.3.OR.ID.EQ.4) THEN 
        YSAV=Y13    
        Y13=Y23 
        Y23=YSAV    
        YSAV=Y14    
        Y14=Y24 
        Y24=YSAV    
        YSAV=Y134   
        Y134=Y234   
        Y234=YSAV   
      ENDIF 
      IF(IC.LE.3) GOTO 120  
      IF(ID.EQ.1.AND.WTTOT.LT.RLU_HIJING(0)*WTMX) GOTO 110 
      IC=5  
    
C...qqgg events: string configuration and event type.   
      IF(IT.EQ.1) THEN  
        IF(MSTJ(109).EQ.0.AND.ID.EQ.1) THEN 
          PARJ(156)=Y34*(2.*(WTA(1)+WTA(2)+WTA(3)+WTA(4))+4.*(WTC(1)+   
     &    WTC(2)+WTC(3)+WTC(4)))/(9.*WTTOT) 
          IF(WTA(2)+WTA(4)+2.*(WTC(2)+WTC(4)).GT.RLU_HIJING(0)*(WTA(1)
     $         +WTA(2)+WTA(3)+WTA(4)+2.*(WTC(1)+WTC(2)+WTC(3)+WTC(4))))
     $         ID=2 
          IF(ID.EQ.2) GOTO 130  
        ELSEIF(MSTJ(109).EQ.2.AND.ID.EQ.1) THEN 
          PARJ(156)=Y34*(WTA(1)+WTA(2)+WTA(3)+WTA(4))/(8.*WTTOT)    
          IF(WTA(2)+WTA(4).GT.RLU_HIJING(0)*(WTA(1)+WTA(2)+WTA(3)+WTA(4)
     $         )) ID=2    
          IF(ID.EQ.2) GOTO 130  
        ENDIF   
        MSTJ(120)=3 
        IF(MSTJ(109).EQ.0.AND.0.5*Y34*(WTC(1)+WTC(2)+WTC(3)+WTC(4)).GT. 
     &  RLU_HIJING(0)*WTTOT) MSTJ(120)=4   
        KFLN=21 
    
C...Mass cuts. Kinematical variables out.   
        IF(Y12.LE.CUT+QME) NJET=2   
        IF(NJET.EQ.2) GOTO 150  
        Q12=0.5*(1.-SQRT(1.-QME/Y12))   
        X1=1.-(1.-Q12)*Y234-Q12*Y134    
        X4=1.-(1.-Q12)*Y134-Q12*Y234    
        X2=1.-Y124  
        X12=(1.-Q12)*Y13+Q12*Y23    
        X14=Y12-0.5*QME 
        IF(Y134*Y234/((1.-X1)*(1.-X4)).LE.RLU_HIJING(0)) NJET=2    
    
C...qqbarqqbar events: string configuration, choose new flavour.    
      ELSE  
        IF(ID.EQ.1) THEN    
          WTR=RLU_HIJING(0)*(WTD(1)+WTD(2)+WTD(3)+WTD(4))  
          IF(WTR.LT.WTD(2)+WTD(3)+WTD(4)) ID=2  
          IF(WTR.LT.WTD(3)+WTD(4)) ID=3 
          IF(WTR.LT.WTD(4)) ID=4    
          IF(ID.GE.2) GOTO 130  
        ENDIF   
        MSTJ(120)=5 
        PARJ(156)=CF*TR*(WTD(1)+WTD(2)+WTD(3)+WTD(4))/(16.*WTTOT)   
  140   KFLN=1+INT(5.*RLU_HIJING(0))   
        IF(KFLN.NE.KFL.AND.0.2*PARJ(156).LE.RLU_HIJING(0)) GOTO 140    
        IF(KFLN.EQ.KFL.AND.1.-0.8*PARJ(156).LE.RLU_HIJING(0)) GOTO 140 
        IF(KFLN.GT.MSTJ(104)) NJET=2    
        PMQN=ULMASS_HIJING(KFLN)   
        QMEN=(2.*PMQN/ECM)**2   
    
C...Mass cuts. Kinematical variables out.   
        IF(Y24.LE.CUT+QME.OR.Y13.LE.1.1*QMEN) NJET=2    
        IF(NJET.EQ.2) GOTO 150  
        Q24=0.5*(1.-SQRT(1.-QME/Y24))   
        Q13=0.5*(1.-SQRT(1.-QMEN/Y13))  
        X1=1.-(1.-Q24)*Y123-Q24*Y134    
        X4=1.-(1.-Q24)*Y134-Q24*Y123    
        X2=1.-(1.-Q13)*Y234-Q13*Y124    
        X12=(1.-Q24)*((1.-Q13)*Y14+Q13*Y34)+Q24*((1.-Q13)*Y12+Q13*Y23)  
        X14=Y24-0.5*QME 
        X34=(1.-Q24)*((1.-Q13)*Y23+Q13*Y12)+Q24*((1.-Q13)*Y34+Q13*Y14)  
        IF(PMQ**2+PMQN**2+MIN(X12,X34)*ECM**2.LE.   
     &  (PARJ(127)+PMQ+PMQN)**2) NJET=2 
        IF(Y123*Y134/((1.-X1)*(1.-X4)).LE.RLU_HIJING(0)) NJET=2    
      ENDIF 
  150 IF(MSTJ(101).LE.-2.AND.NJET.EQ.2) GOTO 100    
    
      RETURN    
      END
Commit	Line	Data
e74335a4	1	* $Id$
	2
	3	C*********************************************************************
	4
	5	SUBROUTINE LUX4JT_HIJING(NJET,CUT,KFL,ECM,KFLN,X1,X2,X4,X12,X14)
	6
	7	C...Purpose: to select the kinematical variables of four-jet events.
	8	#include "ludat1_hijing.inc"
	9	DIMENSION WTA(4),WTB(4),WTC(4),WTD(4),WTE(4)
	10
	11	C...Common constants. Colour factors for QCD and Abelian gluon theory.
	12	PMQ=ULMASS_HIJING(KFL)
	13	QME=(2.PMQ/ECM)*2
	14	CT=LOG(1./CUT-5.)
	15	IF(MSTJ(109).EQ.0) THEN
	16	CF=4./3.
	17	CN=3.
	18	TR=2.
	19	ELSE
	20	CF=1.
	21	CN=0.
	22	TR=12.
	23	ENDIF
	24
	25	C...Choice of process (qqbargg or qqbarqqbar).
	26	100 NJET=4
	27	IT=1
	28	IF(PARJ(155).GT.RLU_HIJING(0)) IT=2
	29	IF(MSTJ(101).LE.-3) IT=-MSTJ(101)-2
	30	IF(IT.EQ.1) WTMX=0.7/CUT**2
	31	IF(IT.EQ.1.AND.MSTJ(109).EQ.2) WTMX=0.6/CUT**2
	32	IF(IT.EQ.2) WTMX=0.1125CFTR/CUT**2
	33	ID=1
	34
	35	C...Sample the five kinematical variables (for qqgg preweighted in y34).
	36	110 Y134=3.CUT+(1.-6.CUT)*RLU_HIJING(0)
	37	Y234=3.CUT+(1.-6.CUT)*RLU_HIJING(0)
	38	IF(IT.EQ.1) Y34=(1.-5.CUT)EXP(-CT*RLU_HIJING(0))
	39	IF(IT.EQ.2) Y34=CUT+(1.-6.CUT)RLU_HIJING(0)
	40	IF(Y34.LE.Y134+Y234-1..OR.Y34.GE.Y134*Y234) GOTO 110
	41	VT=RLU_HIJING(0)
	42	CP=COS(PARU(1)*RLU_HIJING(0))
	43	Y14=(Y134-Y34)*VT
	44	Y13=Y134-Y14-Y34
	45	VB=Y34(1.-Y134-Y234+Y34)/((Y134-Y34)(Y234-Y34))
	46	Y24=0.5(Y234-Y34)(1.-4.SQRT(MAX(0.,VT(1.-VT)VB(1.-VB)))*
	47	&CP-(1.-2.VT)(1.-2.*VB))
	48	Y23=Y234-Y34-Y24
	49	Y12=1.-Y134-Y23-Y24
	50	IF(MIN(Y12,Y13,Y14,Y23,Y24).LE.CUT) GOTO 110
	51	Y123=Y12+Y13+Y23
	52	Y124=Y12+Y14+Y24
	53
	54	C...Calculate matrix elements for qqgg or qqqq process.
	55	IC=0
	56	WTTOT=0.
	57	120 IC=IC+1
	58	IF(IT.EQ.1) THEN
	59	WTA(IC)=(Y12Y342-Y13Y24Y34+Y14Y23Y34+3.Y12Y23Y34+
	60	& 3.Y12Y14Y34+4.Y12*2Y34-Y13Y23Y24+2.Y12Y23*Y24-
	61	& Y13Y14Y24-2.Y12Y13Y24+2.Y12*2Y24+Y14Y232+2.Y12*
	62	& Y232+Y142Y23+4.Y12Y14Y23+4.Y122Y23+2.Y12Y14**2+
	63	& 2.Y12Y13Y14+4.Y12*2Y14+2.Y122Y13+2.Y123)/(2.Y13*
	64	& Y134Y234Y24)+(Y24Y34+Y12Y34+Y13Y24-Y14Y23+Y12Y13)/(Y13
65	& Y134*2)+2.Y23(1.-Y13)/(Y13Y134Y24)+Y34/(2.Y13*Y24)
66	WTB(IC)=(Y12Y24Y34+Y12Y14Y34-Y13Y242+Y13Y14Y24+2.Y12*
67	& Y14Y24)/(Y13Y134Y23Y14)+Y12(1.+Y34)Y124/(Y134Y234Y14*
68	& Y24)-(2.Y13Y24+Y14*2+Y13Y23+2.Y12Y13)/(Y13Y134Y14)+
69	& Y12Y123Y124/(2.Y13Y14Y23Y24)
70	WTC(IC)=-(5.Y12Y34*2+2.Y12Y24Y34+2.Y12Y23Y34+2.Y12*
71	& Y14Y34+2.Y12Y13Y34+4.Y122Y34-Y13Y242+Y14Y23*Y24+
72	& Y13Y23Y24+Y13Y14Y24-Y12Y14Y24-Y13*2Y24-3.Y12Y13*Y24-
73	& Y14Y232-Y142Y23+Y13Y14Y23-3.Y12Y14Y23-Y12Y13*Y23)/
74	& (4.Y134Y234Y342)+(3.Y12Y342-3.Y13Y24Y34+3.Y12Y24*
75	& Y34+3.Y14Y23Y34-Y13Y24*2-Y12Y23Y34+6.Y12Y14Y34+2.Y12
76	& Y13Y34-2.Y12*2Y34+Y14Y23Y24-3.Y13Y23Y24-2.Y13Y14
77	& Y24+4.Y12Y14Y24+2.Y12Y13Y24+3.Y14Y23*2+2.Y14*2Y23+
78	& 2.Y142Y12+2.Y122Y14+6.Y12Y14Y23-2.Y12Y13*2-
79	& 2.Y122Y13)/(4.Y13Y134Y234Y34)
80	WTC(IC)=WTC(IC)+(2.Y12Y34*2-2.Y13Y24Y34+Y12Y24Y34+
81	& 4.Y13Y23Y34+4.Y12Y14Y34+2.Y12Y13Y34+2.Y12*2Y34-
82	& Y13Y242+3.Y14Y23Y24+4.Y13Y23Y24-2.Y13Y14Y24+
83	& 4.Y12Y14Y24+2.Y12Y13Y24+2.Y14Y23*2+4.Y13Y23*2+
84	& 2.Y13Y14Y23+2.Y12Y14Y23+4.Y12Y13Y23+2.Y12Y142+4.
85	& Y12*2Y13+4.Y12Y13Y14+2.Y12*2Y14)/(4.Y13Y134Y24Y34)-
86	& (Y12Y342-2.Y14Y24Y34-2.Y13Y24Y34-Y14Y23Y34+Y13Y23*
87	& Y34+Y12Y14Y34+2.Y12Y13Y34-2.Y14*2Y24-4.Y13Y14*Y24-
88	& 4.Y132Y24-Y14*2Y23-Y13*2Y23+Y12Y13Y14-Y12Y13*2)/
89	& (2.Y13Y34Y1342)+(Y12Y34*2-4.Y14Y24Y34-2.Y13Y24*Y34-
90	& 2.Y14Y23Y34-4.Y13Y23Y34-4.Y12Y14Y34-4.Y12Y13Y34-
91	& 2.Y13Y14Y24+2.Y13*2Y24+2.Y142Y23-2.Y13Y14*Y23-
92	& Y12Y142-6.Y12Y13Y14-Y12Y132)/(4.Y34*2Y134**2)
93	WTTOT=WTTOT+Y34CF(CFWTA(IC)+(CF-0.5CN)WTB(IC)+CNWTC(IC))/
94	& 8.
95	ELSE
96	WTD(IC)=(Y13Y23Y34+Y12Y23Y34-Y12*2Y34+Y13Y23Y24+2.Y12
97	& Y23Y24-Y14Y23*2+Y12Y13Y24+Y12Y14Y23+Y12Y13Y14)/(Y132
98	& Y123*2)-(Y12Y34*2-Y13Y24Y34+Y12Y24Y34-Y14Y23Y34-Y12
99	& Y23Y34-Y13Y24*2+Y14Y23Y24-Y13Y23Y24-Y132Y24+Y14*
100	& Y232)/(Y132Y123Y134)+(Y13Y14Y12+Y34Y14Y12-Y34*2Y12+
101	& Y13Y14Y24+2.Y34Y14Y24-Y23Y14*2+Y34Y13Y24+Y34Y23*Y14+
102	& Y34Y13Y23)/(Y13*2Y134*2)-(Y34Y12*2-Y13Y24Y12+Y34Y24*
103	& Y12-Y23Y14Y12-Y34Y14Y12-Y13Y242+Y23Y14Y24-Y13Y14*Y24-
104	& Y13*2Y24+Y23Y142)/(Y132Y134*Y123)
105	WTE(IC)=(Y12Y34(Y23-Y24+Y14+Y13)+Y13Y242-Y14Y23Y24+Y13
106	& Y23Y24+Y13Y14Y24+Y132Y24-Y14Y23(Y14+Y23+Y13))/(Y13Y23
107	& Y123Y134)-Y12(Y12Y34-Y23Y24-Y13Y24-Y14Y23-Y14Y13)/(Y13
108	& Y23Y1232)-(Y14+Y13)(Y24+Y23)Y34/(Y13Y23Y134Y234)+
109	& (Y12Y34(Y14-Y24+Y23+Y13)+Y13Y242-Y23Y14Y24+Y13Y14*Y24+
110	& Y13Y23Y24+Y13*2Y24-Y23Y14(Y14+Y23+Y13))/(Y13Y14Y134*
111	& Y123)-Y34(Y34Y12-Y14Y24-Y13Y24-Y23Y14-Y23Y13)/(Y13Y14
112	& Y134*2)-(Y23+Y13)(Y24+Y14)Y12/(Y13Y14Y123Y124)
113	WTTOT=WTTOT+CF(TRWTD(IC)+(CF-0.5CN)WTE(IC))/16.
114	ENDIF
115
116	C...Permutations of momenta in matrix element. Weighting.
117	130 IF(IC.EQ.1.OR.IC.EQ.3.OR.ID.EQ.2.OR.ID.EQ.3) THEN
118	YSAV=Y13
119	Y13=Y14
120	Y14=YSAV
121	YSAV=Y23
122	Y23=Y24
123	Y24=YSAV
124	YSAV=Y123
125	Y123=Y124
126	Y124=YSAV
127	ENDIF
128	IF(IC.EQ.2.OR.IC.EQ.4.OR.ID.EQ.3.OR.ID.EQ.4) THEN
129	YSAV=Y13
130	Y13=Y23
131	Y23=YSAV
132	YSAV=Y14
133	Y14=Y24
134	Y24=YSAV
135	YSAV=Y134
136	Y134=Y234
137	Y234=YSAV
138	ENDIF
139	IF(IC.LE.3) GOTO 120
140	IF(ID.EQ.1.AND.WTTOT.LT.RLU_HIJING(0)*WTMX) GOTO 110
141	IC=5
142
143	C...qqgg events: string configuration and event type.
144	IF(IT.EQ.1) THEN
145	IF(MSTJ(109).EQ.0.AND.ID.EQ.1) THEN
146	PARJ(156)=Y34(2.(WTA(1)+WTA(2)+WTA(3)+WTA(4))+4.*(WTC(1)+
147	& WTC(2)+WTC(3)+WTC(4)))/(9.*WTTOT)
148	IF(WTA(2)+WTA(4)+2.(WTC(2)+WTC(4)).GT.RLU_HIJING(0)(WTA(1)
149	$ +WTA(2)+WTA(3)+WTA(4)+2.*(WTC(1)+WTC(2)+WTC(3)+WTC(4))))
150	$ ID=2
151	IF(ID.EQ.2) GOTO 130
152	ELSEIF(MSTJ(109).EQ.2.AND.ID.EQ.1) THEN
153	PARJ(156)=Y34(WTA(1)+WTA(2)+WTA(3)+WTA(4))/(8.WTTOT)
154	IF(WTA(2)+WTA(4).GT.RLU_HIJING(0)*(WTA(1)+WTA(2)+WTA(3)+WTA(4)
155	$ )) ID=2
156	IF(ID.EQ.2) GOTO 130
157	ENDIF
158	MSTJ(120)=3
159	IF(MSTJ(109).EQ.0.AND.0.5Y34(WTC(1)+WTC(2)+WTC(3)+WTC(4)).GT.
160	& RLU_HIJING(0)*WTTOT) MSTJ(120)=4
161	KFLN=21
162
163	C...Mass cuts. Kinematical variables out.
164	IF(Y12.LE.CUT+QME) NJET=2
165	IF(NJET.EQ.2) GOTO 150
166	Q12=0.5*(1.-SQRT(1.-QME/Y12))
167	X1=1.-(1.-Q12)Y234-Q12Y134
168	X4=1.-(1.-Q12)Y134-Q12Y234
169	X2=1.-Y124
170	X12=(1.-Q12)Y13+Q12Y23
171	X14=Y12-0.5*QME
172	IF(Y134Y234/((1.-X1)(1.-X4)).LE.RLU_HIJING(0)) NJET=2
173
174	C...qqbarqqbar events: string configuration, choose new flavour.
175	ELSE
176	IF(ID.EQ.1) THEN
177	WTR=RLU_HIJING(0)*(WTD(1)+WTD(2)+WTD(3)+WTD(4))
178	IF(WTR.LT.WTD(2)+WTD(3)+WTD(4)) ID=2
179	IF(WTR.LT.WTD(3)+WTD(4)) ID=3
180	IF(WTR.LT.WTD(4)) ID=4
181	IF(ID.GE.2) GOTO 130
182	ENDIF
183	MSTJ(120)=5
184	PARJ(156)=CFTR(WTD(1)+WTD(2)+WTD(3)+WTD(4))/(16.*WTTOT)
185	140 KFLN=1+INT(5.*RLU_HIJING(0))
186	IF(KFLN.NE.KFL.AND.0.2*PARJ(156).LE.RLU_HIJING(0)) GOTO 140
187	IF(KFLN.EQ.KFL.AND.1.-0.8*PARJ(156).LE.RLU_HIJING(0)) GOTO 140
188	IF(KFLN.GT.MSTJ(104)) NJET=2
189	PMQN=ULMASS_HIJING(KFLN)
190	QMEN=(2.PMQN/ECM)*2
191
192	C...Mass cuts. Kinematical variables out.
193	IF(Y24.LE.CUT+QME.OR.Y13.LE.1.1*QMEN) NJET=2
194	IF(NJET.EQ.2) GOTO 150
195	Q24=0.5*(1.-SQRT(1.-QME/Y24))
196	Q13=0.5*(1.-SQRT(1.-QMEN/Y13))
197	X1=1.-(1.-Q24)Y123-Q24Y134
198	X4=1.-(1.-Q24)Y134-Q24Y123
199	X2=1.-(1.-Q13)Y234-Q13Y124
200	X12=(1.-Q24)((1.-Q13)Y14+Q13Y34)+Q24((1.-Q13)Y12+Q13Y23)
201	X14=Y24-0.5*QME
202	X34=(1.-Q24)((1.-Q13)Y23+Q13Y12)+Q24((1.-Q13)Y34+Q13Y14)
203	IF(PMQ2+PMQN2+MIN(X12,X34)ECM*2.LE.
204	& (PARJ(127)+PMQ+PMQN)**2) NJET=2
205	IF(Y123Y134/((1.-X1)(1.-X4)).LE.RLU_HIJING(0)) NJET=2
206	ENDIF
207	150 IF(MSTJ(101).LE.-2.AND.NJET.EQ.2) GOTO 100
208
209	RETURN
210	END