* $Id$ 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