C********************************************************************* SUBROUTINE LUSHOW(IP1,IP2,QMAX) C...Purpose: to generate timelike parton showers from given partons. IMPLICIT DOUBLE PRECISION(D) COMMON/LUJETS/N,K(4000,5),P(4000,5),V(4000,5) COMMON/LUDAT1/MSTU(200),PARU(200),MSTJ(200),PARJ(200) COMMON/LUDAT2/KCHG(500,3),PMAS(500,4),PARF(2000),VCKM(4,4) SAVE /LUJETS/,/LUDAT1/,/LUDAT2/ DIMENSION PMTH(5,50),PS(5),PMA(4),PMSD(4),IEP(4),IPA(4), &KFLA(4),KFLD(4),KFL(4),ITRY(4),ISI(4),ISL(4),DP(4),DPT(5,4), &KSH(0:40),KCII(2),NIIS(2),IIIS(2,2),THEIIS(2,2),PHIIIS(2,2), &ISII(2) C...Initialization of cutoff masses etc. IF(MSTJ(41).LE.0.OR.(MSTJ(41).EQ.1.AND.QMAX.LE.PARJ(82)).OR. &QMAX.LE.MIN(PARJ(82),PARJ(83))) RETURN DO 100 IFL=0,40 KSH(IFL)=0 100 CONTINUE KSH(21)=1 PMTH(1,21)=ULMASS(21) PMTH(2,21)=SQRT(PMTH(1,21)**2+0.25*PARJ(82)**2) PMTH(3,21)=2.*PMTH(2,21) PMTH(4,21)=PMTH(3,21) PMTH(5,21)=PMTH(3,21) PMTH(1,22)=ULMASS(22) PMTH(2,22)=SQRT(PMTH(1,22)**2+0.25*PARJ(83)**2) PMTH(3,22)=2.*PMTH(2,22) PMTH(4,22)=PMTH(3,22) PMTH(5,22)=PMTH(3,22) PMQTH1=PARJ(82) IF(MSTJ(41).GE.2) PMQTH1=MIN(PARJ(82),PARJ(83)) PMQTH2=PMTH(2,21) IF(MSTJ(41).GE.2) PMQTH2=MIN(PMTH(2,21),PMTH(2,22)) DO 110 IFL=1,8 KSH(IFL)=1 PMTH(1,IFL)=ULMASS(IFL) PMTH(2,IFL)=SQRT(PMTH(1,IFL)**2+0.25*PMQTH1**2) PMTH(3,IFL)=PMTH(2,IFL)+PMQTH2 PMTH(4,IFL)=SQRT(PMTH(1,IFL)**2+0.25*PARJ(82)**2)+PMTH(2,21) PMTH(5,IFL)=SQRT(PMTH(1,IFL)**2+0.25*PARJ(83)**2)+PMTH(2,22) 110 CONTINUE DO 120 IFL=11,17,2 IF(MSTJ(41).GE.2) KSH(IFL)=1 PMTH(1,IFL)=ULMASS(IFL) PMTH(2,IFL)=SQRT(PMTH(1,IFL)**2+0.25*PARJ(83)**2) PMTH(3,IFL)=PMTH(2,IFL)+PMTH(2,22) PMTH(4,IFL)=PMTH(3,IFL) PMTH(5,IFL)=PMTH(3,IFL) 120 CONTINUE PT2MIN=MAX(0.5*PARJ(82),1.1*PARJ(81))**2 ALAMS=PARJ(81)**2 ALFM=LOG(PT2MIN/ALAMS) C...Store positions of shower initiating partons. IF(IP1.GT.0.AND.IP1.LE.MIN(N,MSTU(4)-MSTU(32)).AND.IP2.EQ.0) THEN NPA=1 IPA(1)=IP1 ELSEIF(MIN(IP1,IP2).GT.0.AND.MAX(IP1,IP2).LE.MIN(N,MSTU(4)- &MSTU(32))) THEN NPA=2 IPA(1)=IP1 IPA(2)=IP2 ELSEIF(IP1.GT.0.AND.IP1.LE.MIN(N,MSTU(4)-MSTU(32)).AND.IP2.LT.0 &.AND.IP2.GE.-3) THEN NPA=IABS(IP2) DO 130 I=1,NPA IPA(I)=IP1+I-1 130 CONTINUE ELSE CALL LUERRM(12, & '(LUSHOW:) failed to reconstruct showering system') IF(MSTU(21).GE.1) RETURN ENDIF C...Check on phase space available for emission. IREJ=0 DO 140 J=1,5 PS(J)=0. 140 CONTINUE PM=0. DO 160 I=1,NPA KFLA(I)=IABS(K(IPA(I),2)) PMA(I)=P(IPA(I),5) C...Special cutoff masses for t, l, h with variable masses. IFLA=KFLA(I) IF(KFLA(I).GE.6.AND.KFLA(I).LE.8) THEN IFLA=37+KFLA(I)+ISIGN(2,K(IPA(I),2)) PMTH(1,IFLA)=PMA(I) PMTH(2,IFLA)=SQRT(PMTH(1,IFLA)**2+0.25*PMQTH1**2) PMTH(3,IFLA)=PMTH(2,IFLA)+PMQTH2 PMTH(4,IFLA)=SQRT(PMTH(1,IFLA)**2+0.25*PARJ(82)**2)+PMTH(2,21) PMTH(5,IFLA)=SQRT(PMTH(1,IFLA)**2+0.25*PARJ(83)**2)+PMTH(2,22) ENDIF IF(KFLA(I).LE.40) THEN IF(KSH(KFLA(I)).EQ.1) PMA(I)=PMTH(3,IFLA) ENDIF PM=PM+PMA(I) IF(KFLA(I).GT.40) THEN IREJ=IREJ+1 ELSE IF(KSH(KFLA(I)).EQ.0.OR.PMA(I).GT.QMAX) IREJ=IREJ+1 ENDIF DO 150 J=1,4 PS(J)=PS(J)+P(IPA(I),J) 150 CONTINUE 160 CONTINUE IF(IREJ.EQ.NPA) RETURN PS(5)=SQRT(MAX(0.,PS(4)**2-PS(1)**2-PS(2)**2-PS(3)**2)) IF(NPA.EQ.1) PS(5)=PS(4) IF(PS(5).LE.PM+PMQTH1) RETURN C...Check if 3-jet matrix elements to be used. M3JC=0 IF(NPA.EQ.2.AND.MSTJ(47).GE.1) THEN IF(KFLA(1).GE.1.AND.KFLA(1).LE.8.AND.KFLA(2).GE.1.AND. & KFLA(2).LE.8) M3JC=1 IF((KFLA(1).EQ.11.OR.KFLA(1).EQ.13.OR.KFLA(1).EQ.15.OR. & KFLA(1).EQ.17).AND.KFLA(2).EQ.KFLA(1)) M3JC=1 IF((KFLA(1).EQ.11.OR.KFLA(1).EQ.13.OR.KFLA(1).EQ.15.OR. & KFLA(1).EQ.17).AND.KFLA(2).EQ.KFLA(1)+1) M3JC=1 IF((KFLA(1).EQ.12.OR.KFLA(1).EQ.14.OR.KFLA(1).EQ.16.OR. & KFLA(1).EQ.18).AND.KFLA(2).EQ.KFLA(1)-1) M3JC=1 IF(MSTJ(47).EQ.2.OR.MSTJ(47).EQ.4) M3JC=1 M3JCM=0 IF(M3JC.EQ.1.AND.MSTJ(47).GE.3.AND.KFLA(1).EQ.KFLA(2)) THEN M3JCM=1 QME=(2.*PMTH(1,KFLA(1))/PS(5))**2 ENDIF ENDIF C...Find if interference with initial state partons. MIIS=0 IF(MSTJ(50).GE.1.AND.MSTJ(50).LE.3.AND.NPA.EQ.2) MIIS=MSTJ(50) IF(MIIS.NE.0) THEN DO 180 I=1,2 KCII(I)=0 KCA=LUCOMP(KFLA(I)) IF(KCA.NE.0) KCII(I)=KCHG(KCA,2)*ISIGN(1,K(IPA(I),2)) NIIS(I)=0 IF(KCII(I).NE.0) THEN DO 170 J=1,2 ICSI=MOD(K(IPA(I),3+J)/MSTU(5),MSTU(5)) IF(ICSI.GT.0.AND.ICSI.NE.IPA(1).AND.ICSI.NE.IPA(2).AND. & (KCII(I).EQ.(-1)**(J+1).OR.KCII(I).EQ.2)) THEN NIIS(I)=NIIS(I)+1 IIIS(I,NIIS(I))=ICSI ENDIF 170 CONTINUE ENDIF 180 CONTINUE IF(NIIS(1)+NIIS(2).EQ.0) MIIS=0 ENDIF C...Boost interfering initial partons to rest frame C...and reconstruct their polar and azimuthal angles. IF(MIIS.NE.0) THEN DO 200 I=1,2 DO 190 J=1,5 K(N+I,J)=K(IPA(I),J) P(N+I,J)=P(IPA(I),J) V(N+I,J)=0. 190 CONTINUE 200 CONTINUE DO 220 I=3,2+NIIS(1) DO 210 J=1,5 K(N+I,J)=K(IIIS(1,I-2),J) P(N+I,J)=P(IIIS(1,I-2),J) V(N+I,J)=0. 210 CONTINUE 220 CONTINUE DO 240 I=3+NIIS(1),2+NIIS(1)+NIIS(2) DO 230 J=1,5 K(N+I,J)=K(IIIS(2,I-2-NIIS(1)),J) P(N+I,J)=P(IIIS(2,I-2-NIIS(1)),J) V(N+I,J)=0. 230 CONTINUE 240 CONTINUE CALL LUDBRB(N+1,N+2+NIIS(1)+NIIS(2),0.,0.,-DBLE(PS(1)/PS(4)), & -DBLE(PS(2)/PS(4)),-DBLE(PS(3)/PS(4))) PHI=ULANGL(P(N+1,1),P(N+1,2)) CALL LUDBRB(N+1,N+2+NIIS(1)+NIIS(2),0.,-PHI,0D0,0D0,0D0) THE=ULANGL(P(N+1,3),P(N+1,1)) CALL LUDBRB(N+1,N+2+NIIS(1)+NIIS(2),-THE,0.,0D0,0D0,0D0) DO 250 I=3,2+NIIS(1) THEIIS(1,I-2)=ULANGL(P(N+I,3),SQRT(P(N+I,1)**2+P(N+I,2)**2)) PHIIIS(1,I-2)=ULANGL(P(N+I,1),P(N+I,2)) 250 CONTINUE DO 260 I=3+NIIS(1),2+NIIS(1)+NIIS(2) THEIIS(2,I-2-NIIS(1))=PARU(1)-ULANGL(P(N+I,3), & SQRT(P(N+I,1)**2+P(N+I,2)**2)) PHIIIS(2,I-2-NIIS(1))=ULANGL(P(N+I,1),P(N+I,2)) 260 CONTINUE ENDIF C...Define imagined single initiator of shower for parton system. NS=N IF(N.GT.MSTU(4)-MSTU(32)-5) THEN CALL LUERRM(11,'(LUSHOW:) no more memory left in LUJETS') IF(MSTU(21).GE.1) RETURN ENDIF IF(NPA.GE.2) THEN K(N+1,1)=11 K(N+1,2)=21 K(N+1,3)=0 K(N+1,4)=0 K(N+1,5)=0 P(N+1,1)=0. P(N+1,2)=0. P(N+1,3)=0. P(N+1,4)=PS(5) P(N+1,5)=PS(5) V(N+1,5)=PS(5)**2 N=N+1 ENDIF C...Loop over partons that may branch. NEP=NPA IM=NS IF(NPA.EQ.1) IM=NS-1 270 IM=IM+1 IF(N.GT.NS) THEN IF(IM.GT.N) GOTO 510 KFLM=IABS(K(IM,2)) IF(KFLM.GT.40) GOTO 270 IF(KSH(KFLM).EQ.0) GOTO 270 IFLM=KFLM IF(KFLM.GE.6.AND.KFLM.LE.8) IFLM=37+KFLM+ISIGN(2,K(IM,2)) IF(P(IM,5).LT.PMTH(2,IFLM)) GOTO 270 IGM=K(IM,3) ELSE IGM=-1 ENDIF IF(N+NEP.GT.MSTU(4)-MSTU(32)-5) THEN CALL LUERRM(11,'(LUSHOW:) no more memory left in LUJETS') IF(MSTU(21).GE.1) RETURN ENDIF C...Position of aunt (sister to branching parton). C...Origin and flavour of daughters. IAU=0 IF(IGM.GT.0) THEN IF(K(IM-1,3).EQ.IGM) IAU=IM-1 IF(N.GE.IM+1.AND.K(IM+1,3).EQ.IGM) IAU=IM+1 ENDIF IF(IGM.GE.0) THEN K(IM,4)=N+1 DO 280 I=1,NEP K(N+I,3)=IM 280 CONTINUE ELSE K(N+1,3)=IPA(1) ENDIF IF(IGM.LE.0) THEN DO 290 I=1,NEP K(N+I,2)=K(IPA(I),2) 290 CONTINUE ELSEIF(KFLM.NE.21) THEN K(N+1,2)=K(IM,2) K(N+2,2)=K(IM,5) ELSEIF(K(IM,5).EQ.21) THEN K(N+1,2)=21 K(N+2,2)=21 ELSE K(N+1,2)=K(IM,5) K(N+2,2)=-K(IM,5) ENDIF C...Reset flags on daughers and tries made. DO 300 IP=1,NEP K(N+IP,1)=3 K(N+IP,4)=0 K(N+IP,5)=0 KFLD(IP)=IABS(K(N+IP,2)) IF(KCHG(LUCOMP(KFLD(IP)),2).EQ.0) K(N+IP,1)=1 ITRY(IP)=0 ISL(IP)=0 ISI(IP)=0 IF(KFLD(IP).LE.40) THEN IF(KSH(KFLD(IP)).EQ.1) ISI(IP)=1 ENDIF 300 CONTINUE ISLM=0 C...Maximum virtuality of daughters. IF(IGM.LE.0) THEN DO 310 I=1,NPA IF(NPA.GE.3) P(N+I,4)=(PS(4)*P(IPA(I),4)-PS(1)*P(IPA(I),1)- & PS(2)*P(IPA(I),2)-PS(3)*P(IPA(I),3))/PS(5) P(N+I,5)=MIN(QMAX,PS(5)) IF(NPA.GE.3) P(N+I,5)=MIN(P(N+I,5),P(N+I,4)) IF(ISI(I).EQ.0) P(N+I,5)=P(IPA(I),5) 310 CONTINUE ELSE IF(MSTJ(43).LE.2) PEM=V(IM,2) IF(MSTJ(43).GE.3) PEM=P(IM,4) P(N+1,5)=MIN(P(IM,5),V(IM,1)*PEM) P(N+2,5)=MIN(P(IM,5),(1.-V(IM,1))*PEM) IF(K(N+2,2).EQ.22) P(N+2,5)=PMTH(1,22) ENDIF DO 320 I=1,NEP PMSD(I)=P(N+I,5) IF(ISI(I).EQ.1) THEN IFLD=KFLD(I) IF(KFLD(I).GE.6.AND.KFLD(I).LE.8) IFLD=37+KFLD(I)+ & ISIGN(2,K(N+I,2)) IF(P(N+I,5).LE.PMTH(3,IFLD)) P(N+I,5)=PMTH(1,IFLD) ENDIF V(N+I,5)=P(N+I,5)**2 320 CONTINUE C...Choose one of the daughters for evolution. 330 INUM=0 IF(NEP.EQ.1) INUM=1 DO 340 I=1,NEP IF(INUM.EQ.0.AND.ISL(I).EQ.1) INUM=I 340 CONTINUE DO 350 I=1,NEP IF(INUM.EQ.0.AND.ITRY(I).EQ.0.AND.ISI(I).EQ.1) THEN IFLD=KFLD(I) IF(KFLD(I).GE.6.AND.KFLD(I).LE.8) IFLD=37+KFLD(I)+ & ISIGN(2,K(N+I,2)) IF(P(N+I,5).GE.PMTH(2,IFLD)) INUM=I ENDIF 350 CONTINUE IF(INUM.EQ.0) THEN RMAX=0. DO 360 I=1,NEP IF(ISI(I).EQ.1.AND.PMSD(I).GE.PMQTH2) THEN RPM=P(N+I,5)/PMSD(I) IFLD=KFLD(I) IF(KFLD(I).GE.6.AND.KFLD(I).LE.8) IFLD=37+KFLD(I)+ & ISIGN(2,K(N+I,2)) IF(RPM.GT.RMAX.AND.P(N+I,5).GE.PMTH(2,IFLD)) THEN RMAX=RPM INUM=I ENDIF ENDIF 360 CONTINUE ENDIF C...Store information on choice of evolving daughter. INUM=MAX(1,INUM) IEP(1)=N+INUM DO 370 I=2,NEP IEP(I)=IEP(I-1)+1 IF(IEP(I).GT.N+NEP) IEP(I)=N+1 370 CONTINUE DO 380 I=1,NEP KFL(I)=IABS(K(IEP(I),2)) 380 CONTINUE ITRY(INUM)=ITRY(INUM)+1 IF(ITRY(INUM).GT.200) THEN CALL LUERRM(14,'(LUSHOW:) caught in infinite loop') IF(MSTU(21).GE.1) RETURN ENDIF Z=0.5 IF(KFL(1).GT.40) GOTO 430 IF(KSH(KFL(1)).EQ.0) GOTO 430 IFL=KFL(1) IF(KFL(1).GE.6.AND.KFL(1).LE.8) IFL=37+KFL(1)+ &ISIGN(2,K(IEP(1),2)) IF(P(IEP(1),5).LT.PMTH(2,IFL)) GOTO 430 C...Select side for interference with initial state partons. IF(MIIS.GE.1.AND.IEP(1).LE.NS+3) THEN III=IEP(1)-NS-1 ISII(III)=0 IF(IABS(KCII(III)).EQ.1.AND.NIIS(III).EQ.1) THEN ISII(III)=1 ELSEIF(KCII(III).EQ.2.AND.NIIS(III).EQ.1) THEN IF(RLU(0).GT.0.5) ISII(III)=1 ELSEIF(KCII(III).EQ.2.AND.NIIS(III).EQ.2) THEN ISII(III)=1 IF(RLU(0).GT.0.5) ISII(III)=2 ENDIF ENDIF C...Calculate allowed z range. IF(NEP.EQ.1) THEN PMED=PS(4) ELSEIF(IGM.EQ.0.OR.MSTJ(43).LE.2) THEN PMED=P(IM,5) ELSE IF(INUM.EQ.1) PMED=V(IM,1)*PEM IF(INUM.EQ.2) PMED=(1.-V(IM,1))*PEM ENDIF IF(MOD(MSTJ(43),2).EQ.1) THEN ZC=PMTH(2,21)/PMED ZCE=PMTH(2,22)/PMED ELSE ZC=0.5*(1.-SQRT(MAX(0.,1.-(2.*PMTH(2,21)/PMED)**2))) IF(ZC.LT.1E-4) ZC=(PMTH(2,21)/PMED)**2 ZCE=0.5*(1.-SQRT(MAX(0.,1.-(2.*PMTH(2,22)/PMED)**2))) IF(ZCE.LT.1E-4) ZCE=(PMTH(2,22)/PMED)**2 ENDIF ZC=MIN(ZC,0.491) ZCE=MIN(ZCE,0.491) IF((MSTJ(41).EQ.1.AND.ZC.GT.0.49).OR.(MSTJ(41).GE.2.AND. &MIN(ZC,ZCE).GT.0.49)) THEN P(IEP(1),5)=PMTH(1,IFL) V(IEP(1),5)=P(IEP(1),5)**2 GOTO 430 ENDIF C...Integral of Altarelli-Parisi z kernel for QCD. IF(MSTJ(49).EQ.0.AND.KFL(1).EQ.21) THEN FBR=6.*LOG((1.-ZC)/ZC)+MSTJ(45)*(0.5-ZC) ELSEIF(MSTJ(49).EQ.0) THEN FBR=(8./3.)*LOG((1.-ZC)/ZC) C...Integral of Altarelli-Parisi z kernel for scalar gluon. ELSEIF(MSTJ(49).EQ.1.AND.KFL(1).EQ.21) THEN FBR=(PARJ(87)+MSTJ(45)*PARJ(88))*(1.-2.*ZC) ELSEIF(MSTJ(49).EQ.1) THEN FBR=(1.-2.*ZC)/3. IF(IGM.EQ.0.AND.M3JC.EQ.1) FBR=4.*FBR C...Integral of Altarelli-Parisi z kernel for Abelian vector gluon. ELSEIF(KFL(1).EQ.21) THEN FBR=6.*MSTJ(45)*(0.5-ZC) ELSE FBR=2.*LOG((1.-ZC)/ZC) ENDIF C...Reset QCD probability for lepton. IF(KFL(1).GE.11.AND.KFL(1).LE.18) FBR=0. C...Integral of Altarelli-Parisi kernel for photon emission. IF(MSTJ(41).GE.2.AND.KFL(1).GE.1.AND.KFL(1).LE.18) THEN FBRE=(KCHG(KFL(1),1)/3.)**2*2.*LOG((1.-ZCE)/ZCE) IF(MSTJ(41).EQ.10) FBRE=PARJ(84)*FBRE ENDIF C...Inner veto algorithm starts. Find maximum mass for evolution. 390 PMS=V(IEP(1),5) IF(IGM.GE.0) THEN PM2=0. DO 400 I=2,NEP PM=P(IEP(I),5) IF(KFL(I).LE.40) THEN IFLI=KFL(I) IF(KFL(I).GE.6.AND.KFL(I).LE.8) IFLI=37+KFL(I)+ & ISIGN(2,K(IEP(I),2)) IF(KSH(KFL(I)).EQ.1) PM=PMTH(2,IFLI) ENDIF PM2=PM2+PM 400 CONTINUE PMS=MIN(PMS,(P(IM,5)-PM2)**2) ENDIF C...Select mass for daughter in QCD evolution. B0=27./6. DO 410 IFF=4,MSTJ(45) IF(PMS.GT.4.*PMTH(2,IFF)**2) B0=(33.-2.*IFF)/6. 410 CONTINUE IF(FBR.LT.1E-3) THEN PMSQCD=0. ELSEIF(MSTJ(44).LE.0) THEN PMSQCD=PMS*EXP(MAX(-50.,LOG(RLU(0))*PARU(2)/(PARU(111)*FBR))) ELSEIF(MSTJ(44).EQ.1) THEN PMSQCD=4.*ALAMS*(0.25*PMS/ALAMS)**(RLU(0)**(B0/FBR)) ELSE PMSQCD=PMS*EXP(MAX(-50.,ALFM*B0*LOG(RLU(0))/FBR)) ENDIF IF(ZC.GT.0.49.OR.PMSQCD.LE.PMTH(4,IFL)**2) PMSQCD=PMTH(2,IFL)**2 V(IEP(1),5)=PMSQCD MCE=1 C...Select mass for daughter in QED evolution. IF(MSTJ(41).GE.2.AND.KFL(1).GE.1.AND.KFL(1).LE.18) THEN PMSQED=PMS*EXP(MAX(-50.,LOG(RLU(0))*PARU(2)/(PARU(101)*FBRE))) IF(ZCE.GT.0.49.OR.PMSQED.LE.PMTH(5,IFL)**2) PMSQED= & PMTH(2,IFL)**2 IF(PMSQED.GT.PMSQCD) THEN V(IEP(1),5)=PMSQED MCE=2 ENDIF ENDIF C...Check whether daughter mass below cutoff. P(IEP(1),5)=SQRT(V(IEP(1),5)) IF(P(IEP(1),5).LE.PMTH(3,IFL)) THEN P(IEP(1),5)=PMTH(1,IFL) V(IEP(1),5)=P(IEP(1),5)**2 GOTO 430 ENDIF C...Select z value of branching: q -> qgamma. IF(MCE.EQ.2) THEN Z=1.-(1.-ZCE)*(ZCE/(1.-ZCE))**RLU(0) IF(1.+Z**2.LT.2.*RLU(0)) GOTO 390 K(IEP(1),5)=22 C...Select z value of branching: q -> qg, g -> gg, g -> qqbar. ELSEIF(MSTJ(49).NE.1.AND.KFL(1).NE.21) THEN Z=1.-(1.-ZC)*(ZC/(1.-ZC))**RLU(0) IF(1.+Z**2.LT.2.*RLU(0)) GOTO 390 K(IEP(1),5)=21 ELSEIF(MSTJ(49).EQ.0.AND.MSTJ(45)*(0.5-ZC).LT.RLU(0)*FBR) THEN Z=(1.-ZC)*(ZC/(1.-ZC))**RLU(0) IF(RLU(0).GT.0.5) Z=1.-Z IF((1.-Z*(1.-Z))**2.LT.RLU(0)) GOTO 390 K(IEP(1),5)=21 ELSEIF(MSTJ(49).NE.1) THEN Z=ZC+(1.-2.*ZC)*RLU(0) IF(Z**2+(1.-Z)**2.LT.RLU(0)) GOTO 390 KFLB=1+INT(MSTJ(45)*RLU(0)) PMQ=4.*PMTH(2,KFLB)**2/V(IEP(1),5) IF(PMQ.GE.1.) GOTO 390 PMQ0=4.*PMTH(2,21)**2/V(IEP(1),5) IF(MOD(MSTJ(43),2).EQ.0.AND.(1.+0.5*PMQ)*SQRT(1.-PMQ).LT. & RLU(0)*(1.+0.5*PMQ0)*SQRT(1.-PMQ0)) GOTO 390 K(IEP(1),5)=KFLB C...Ditto for scalar gluon model. ELSEIF(KFL(1).NE.21) THEN Z=1.-SQRT(ZC**2+RLU(0)*(1.-2.*ZC)) K(IEP(1),5)=21 ELSEIF(RLU(0)*(PARJ(87)+MSTJ(45)*PARJ(88)).LE.PARJ(87)) THEN Z=ZC+(1.-2.*ZC)*RLU(0) K(IEP(1),5)=21 ELSE Z=ZC+(1.-2.*ZC)*RLU(0) KFLB=1+INT(MSTJ(45)*RLU(0)) PMQ=4.*PMTH(2,KFLB)**2/V(IEP(1),5) IF(PMQ.GE.1.) GOTO 390 K(IEP(1),5)=KFLB ENDIF IF(MCE.EQ.1.AND.MSTJ(44).GE.2) THEN IF(Z*(1.-Z)*V(IEP(1),5).LT.PT2MIN) GOTO 390 IF(ALFM/LOG(V(IEP(1),5)*Z*(1.-Z)/ALAMS).LT.RLU(0)) GOTO 390 ENDIF C...Check if z consistent with chosen m. IF(KFL(1).EQ.21) THEN KFLGD1=IABS(K(IEP(1),5)) KFLGD2=KFLGD1 ELSE KFLGD1=KFL(1) KFLGD2=IABS(K(IEP(1),5)) ENDIF IF(NEP.EQ.1) THEN PED=PS(4) ELSEIF(NEP.GE.3) THEN PED=P(IEP(1),4) ELSEIF(IGM.EQ.0.OR.MSTJ(43).LE.2) THEN PED=0.5*(V(IM,5)+V(IEP(1),5)-PM2**2)/P(IM,5) ELSE IF(IEP(1).EQ.N+1) PED=V(IM,1)*PEM IF(IEP(1).EQ.N+2) PED=(1.-V(IM,1))*PEM ENDIF IF(MOD(MSTJ(43),2).EQ.1) THEN IFLGD1=KFLGD1 IF(KFLGD1.GE.6.AND.KFLGD1.LE.8) IFLGD1=IFL PMQTH3=0.5*PARJ(82) IF(KFLGD2.EQ.22) PMQTH3=0.5*PARJ(83) PMQ1=(PMTH(1,IFLGD1)**2+PMQTH3**2)/V(IEP(1),5) PMQ2=(PMTH(1,KFLGD2)**2+PMQTH3**2)/V(IEP(1),5) ZD=SQRT(MAX(0.,(1.-V(IEP(1),5)/PED**2)*((1.-PMQ1-PMQ2)**2- & 4.*PMQ1*PMQ2))) ZH=1.+PMQ1-PMQ2 ELSE ZD=SQRT(MAX(0.,1.-V(IEP(1),5)/PED**2)) ZH=1. ENDIF ZL=0.5*(ZH-ZD) ZU=0.5*(ZH+ZD) IF(Z.LT.ZL.OR.Z.GT.ZU) GOTO 390 IF(KFL(1).EQ.21) V(IEP(1),3)=LOG(ZU*(1.-ZL)/MAX(1E-20,ZL* &(1.-ZU))) IF(KFL(1).NE.21) V(IEP(1),3)=LOG((1.-ZL)/MAX(1E-10,1.-ZU)) C...Width suppression for q -> q + g. IF(MSTJ(40).NE.0.AND.KFL(1).NE.21) THEN IF(IGM.EQ.0) THEN EGLU=0.5*PS(5)*(1.-Z)*(1.+V(IEP(1),5)/V(NS+1,5)) ELSE EGLU=PMED*(1.-Z) ENDIF CHI=PARJ(89)**2/(PARJ(89)**2+EGLU**2) IF(MSTJ(40).EQ.1) THEN IF(CHI.LT.RLU(0)) GOTO 390 ELSEIF(MSTJ(40).EQ.2) THEN IF(1.-CHI.LT.RLU(0)) GOTO 390 ENDIF ENDIF C...Three-jet matrix element correction. IF(IGM.EQ.0.AND.M3JC.EQ.1) THEN X1=Z*(1.+V(IEP(1),5)/V(NS+1,5)) X2=1.-V(IEP(1),5)/V(NS+1,5) X3=(1.-X1)+(1.-X2) IF(MCE.EQ.2) THEN KI1=K(IPA(INUM),2) KI2=K(IPA(3-INUM),2) QF1=KCHG(IABS(KI1),1)*ISIGN(1,KI1)/3. QF2=KCHG(IABS(KI2),1)*ISIGN(1,KI2)/3. WSHOW=QF1**2*(1.-X1)/X3*(1.+(X1/(2.-X2))**2)+ & QF2**2*(1.-X2)/X3*(1.+(X2/(2.-X1))**2) WME=(QF1*(1.-X1)/X3-QF2*(1.-X2)/X3)**2*(X1**2+X2**2) ELSEIF(MSTJ(49).NE.1) THEN WSHOW=1.+(1.-X1)/X3*(X1/(2.-X2))**2+ & (1.-X2)/X3*(X2/(2.-X1))**2 WME=X1**2+X2**2 IF(M3JCM.EQ.1) WME=WME-QME*X3-0.5*QME**2- & (0.5*QME+0.25*QME**2)*((1.-X2)/MAX(1E-7,1.-X1)+ & (1.-X1)/MAX(1E-7,1.-X2)) ELSE WSHOW=4.*X3*((1.-X1)/(2.-X2)**2+(1.-X2)/(2.-X1)**2) WME=X3**2 IF(MSTJ(102).GE.2) WME=X3**2-2.*(1.+X3)*(1.-X1)*(1.-X2)* & PARJ(171) ENDIF IF(WME.LT.RLU(0)*WSHOW) GOTO 390 C...Impose angular ordering by rejection of nonordered emission. ELSEIF(MCE.EQ.1.AND.IGM.GT.0.AND.MSTJ(42).GE.2) THEN MAOM=1 ZM=V(IM,1) IF(IEP(1).EQ.N+2) ZM=1.-V(IM,1) THE2ID=Z*(1.-Z)*(ZM*P(IM,4))**2/V(IEP(1),5) IAOM=IM 420 IF(K(IAOM,5).EQ.22) THEN IAOM=K(IAOM,3) IF(K(IAOM,3).LE.NS) MAOM=0 IF(MAOM.EQ.1) GOTO 420 ENDIF IF(MAOM.EQ.1) THEN THE2IM=V(IAOM,1)*(1.-V(IAOM,1))*P(IAOM,4)**2/V(IAOM,5) IF(THE2ID.LT.THE2IM) GOTO 390 ENDIF ENDIF C...Impose user-defined maximum angle at first branching. IF(MSTJ(48).EQ.1) THEN IF(NEP.EQ.1.AND.IM.EQ.NS) THEN THE2ID=Z*(1.-Z)*PS(4)**2/V(IEP(1),5) IF(THE2ID.LT.1./PARJ(85)**2) GOTO 390 ELSEIF(NEP.EQ.2.AND.IEP(1).EQ.NS+2) THEN THE2ID=Z*(1.-Z)*(0.5*P(IM,4))**2/V(IEP(1),5) IF(THE2ID.LT.1./PARJ(85)**2) GOTO 390 ELSEIF(NEP.EQ.2.AND.IEP(1).EQ.NS+3) THEN THE2ID=Z*(1.-Z)*(0.5*P(IM,4))**2/V(IEP(1),5) IF(THE2ID.LT.1./PARJ(86)**2) GOTO 390 ENDIF ENDIF C...Impose angular constraint in first branching from interference C...with initial state partons. IF(MIIS.GE.2.AND.IEP(1).LE.NS+3) THEN THE2D=MAX((1.-Z)/Z,Z/(1.-Z))*V(IEP(1),5)/(0.5*P(IM,4))**2 IF(IEP(1).EQ.NS+2.AND.ISII(1).GE.1) THEN IF(THE2D.GT.THEIIS(1,ISII(1))**2) GOTO 390 ELSEIF(IEP(1).EQ.NS+3.AND.ISII(2).GE.1) THEN IF(THE2D.GT.THEIIS(2,ISII(2))**2) GOTO 390 ENDIF ENDIF C...End of inner veto algorithm. Check if only one leg evolved so far. 430 V(IEP(1),1)=Z ISL(1)=0 ISL(2)=0 IF(NEP.EQ.1) GOTO 460 IF(NEP.EQ.2.AND.P(IEP(1),5)+P(IEP(2),5).GE.P(IM,5)) GOTO 330 DO 440 I=1,NEP IF(ITRY(I).EQ.0.AND.KFLD(I).LE.40) THEN IF(KSH(KFLD(I)).EQ.1) THEN IFLD=KFLD(I) IF(KFLD(I).GE.6.AND.KFLD(I).LE.8) IFLD=37+KFLD(I)+ & ISIGN(2,K(N+I,2)) IF(P(N+I,5).GE.PMTH(2,IFLD)) GOTO 330 ENDIF ENDIF 440 CONTINUE C...Check if chosen multiplet m1,m2,z1,z2 is physical. IF(NEP.EQ.3) THEN PA1S=(P(N+1,4)+P(N+1,5))*(P(N+1,4)-P(N+1,5)) PA2S=(P(N+2,4)+P(N+2,5))*(P(N+2,4)-P(N+2,5)) PA3S=(P(N+3,4)+P(N+3,5))*(P(N+3,4)-P(N+3,5)) PTS=0.25*(2.*PA1S*PA2S+2.*PA1S*PA3S+2.*PA2S*PA3S- & PA1S**2-PA2S**2-PA3S**2)/PA1S IF(PTS.LE.0.) GOTO 330 ELSEIF(IGM.EQ.0.OR.MSTJ(43).LE.2.OR.MOD(MSTJ(43),2).EQ.0) THEN DO 450 I1=N+1,N+2 KFLDA=IABS(K(I1,2)) IF(KFLDA.GT.40) GOTO 450 IF(KSH(KFLDA).EQ.0) GOTO 450 IFLDA=KFLDA IF(KFLDA.GE.6.AND.KFLDA.LE.8) IFLDA=37+KFLDA+ & ISIGN(2,K(I1,2)) IF(P(I1,5).LT.PMTH(2,IFLDA)) GOTO 450 IF(KFLDA.EQ.21) THEN KFLGD1=IABS(K(I1,5)) KFLGD2=KFLGD1 ELSE KFLGD1=KFLDA KFLGD2=IABS(K(I1,5)) ENDIF I2=2*N+3-I1 IF(IGM.EQ.0.OR.MSTJ(43).LE.2) THEN PED=0.5*(V(IM,5)+V(I1,5)-V(I2,5))/P(IM,5) ELSE IF(I1.EQ.N+1) ZM=V(IM,1) IF(I1.EQ.N+2) ZM=1.-V(IM,1) PML=SQRT((V(IM,5)-V(N+1,5)-V(N+2,5))**2- & 4.*V(N+1,5)*V(N+2,5)) PED=PEM*(0.5*(V(IM,5)-PML+V(I1,5)-V(I2,5))+PML*ZM)/V(IM,5) ENDIF IF(MOD(MSTJ(43),2).EQ.1) THEN PMQTH3=0.5*PARJ(82) IF(KFLGD2.EQ.22) PMQTH3=0.5*PARJ(83) IFLGD1=KFLGD1 IF(KFLGD1.GE.6.AND.KFLGD1.LE.8) IFLGD1=IFLDA PMQ1=(PMTH(1,IFLGD1)**2+PMQTH3**2)/V(I1,5) PMQ2=(PMTH(1,KFLGD2)**2+PMQTH3**2)/V(I1,5) ZD=SQRT(MAX(0.,(1.-V(I1,5)/PED**2)*((1.-PMQ1-PMQ2)**2- & 4.*PMQ1*PMQ2))) ZH=1.+PMQ1-PMQ2 ELSE ZD=SQRT(MAX(0.,1.-V(I1,5)/PED**2)) ZH=1. ENDIF ZL=0.5*(ZH-ZD) ZU=0.5*(ZH+ZD) IF(I1.EQ.N+1.AND.(V(I1,1).LT.ZL.OR.V(I1,1).GT.ZU)) ISL(1)=1 IF(I1.EQ.N+2.AND.(V(I1,1).LT.ZL.OR.V(I1,1).GT.ZU)) ISL(2)=1 IF(KFLDA.EQ.21) V(I1,4)=LOG(ZU*(1.-ZL)/MAX(1E-20,ZL*(1.-ZU))) IF(KFLDA.NE.21) V(I1,4)=LOG((1.-ZL)/MAX(1E-10,1.-ZU)) 450 CONTINUE IF(ISL(1).EQ.1.AND.ISL(2).EQ.1.AND.ISLM.NE.0) THEN ISL(3-ISLM)=0 ISLM=3-ISLM ELSEIF(ISL(1).EQ.1.AND.ISL(2).EQ.1) THEN ZDR1=MAX(0.,V(N+1,3)/MAX(1E-6,V(N+1,4))-1.) ZDR2=MAX(0.,V(N+2,3)/MAX(1E-6,V(N+2,4))-1.) IF(ZDR2.GT.RLU(0)*(ZDR1+ZDR2)) ISL(1)=0 IF(ISL(1).EQ.1) ISL(2)=0 IF(ISL(1).EQ.0) ISLM=1 IF(ISL(2).EQ.0) ISLM=2 ENDIF IF(ISL(1).EQ.1.OR.ISL(2).EQ.1) GOTO 330 ENDIF IFLD1=KFLD(1) IF(KFLD(1).GE.6.AND.KFLD(1).LE.8) IFLD1=37+KFLD(1)+ &ISIGN(2,K(N+1,2)) IFLD2=KFLD(2) IF(KFLD(2).GE.6.AND.KFLD(2).LE.8) IFLD2=37+KFLD(2)+ &ISIGN(2,K(N+2,2)) IF(IGM.GT.0.AND.MOD(MSTJ(43),2).EQ.1.AND.(P(N+1,5).GE. &PMTH(2,IFLD1).OR.P(N+2,5).GE.PMTH(2,IFLD2))) THEN PMQ1=V(N+1,5)/V(IM,5) PMQ2=V(N+2,5)/V(IM,5) ZD=SQRT(MAX(0.,(1.-V(IM,5)/PEM**2)*((1.-PMQ1-PMQ2)**2- & 4.*PMQ1*PMQ2))) ZH=1.+PMQ1-PMQ2 ZL=0.5*(ZH-ZD) ZU=0.5*(ZH+ZD) IF(V(IM,1).LT.ZL.OR.V(IM,1).GT.ZU) GOTO 330 ENDIF C...Accepted branch. Construct four-momentum for initial partons. 460 MAZIP=0 MAZIC=0 IF(NEP.EQ.1) THEN P(N+1,1)=0. P(N+1,2)=0. P(N+1,3)=SQRT(MAX(0.,(P(IPA(1),4)+P(N+1,5))*(P(IPA(1),4)- & P(N+1,5)))) P(N+1,4)=P(IPA(1),4) V(N+1,2)=P(N+1,4) ELSEIF(IGM.EQ.0.AND.NEP.EQ.2) THEN PED1=0.5*(V(IM,5)+V(N+1,5)-V(N+2,5))/P(IM,5) P(N+1,1)=0. P(N+1,2)=0. P(N+1,3)=SQRT(MAX(0.,(PED1+P(N+1,5))*(PED1-P(N+1,5)))) P(N+1,4)=PED1 P(N+2,1)=0. P(N+2,2)=0. P(N+2,3)=-P(N+1,3) P(N+2,4)=P(IM,5)-PED1 V(N+1,2)=P(N+1,4) V(N+2,2)=P(N+2,4) ELSEIF(NEP.EQ.3) THEN P(N+1,1)=0. P(N+1,2)=0. P(N+1,3)=SQRT(MAX(0.,PA1S)) P(N+2,1)=SQRT(PTS) P(N+2,2)=0. P(N+2,3)=0.5*(PA3S-PA2S-PA1S)/P(N+1,3) P(N+3,1)=-P(N+2,1) P(N+3,2)=0. P(N+3,3)=-(P(N+1,3)+P(N+2,3)) V(N+1,2)=P(N+1,4) V(N+2,2)=P(N+2,4) V(N+3,2)=P(N+3,4) C...Construct transverse momentum for ordinary branching in shower. ELSE ZM=V(IM,1) PZM=SQRT(MAX(0.,(PEM+P(IM,5))*(PEM-P(IM,5)))) PMLS=(V(IM,5)-V(N+1,5)-V(N+2,5))**2-4.*V(N+1,5)*V(N+2,5) IF(PZM.LE.0.) THEN PTS=0. ELSEIF(MOD(MSTJ(43),2).EQ.1) THEN PTS=(PEM**2*(ZM*(1.-ZM)*V(IM,5)-(1.-ZM)*V(N+1,5)- & ZM*V(N+2,5))-0.25*PMLS)/PZM**2 ELSE PTS=PMLS*(ZM*(1.-ZM)*PEM**2/V(IM,5)-0.25)/PZM**2 ENDIF PT=SQRT(MAX(0.,PTS)) C...Find coefficient of azimuthal asymmetry due to gluon polarization. HAZIP=0. IF(MSTJ(49).NE.1.AND.MOD(MSTJ(46),2).EQ.1.AND.K(IM,2).EQ.21. & AND.IAU.NE.0) THEN IF(K(IGM,3).NE.0) MAZIP=1 ZAU=V(IGM,1) IF(IAU.EQ.IM+1) ZAU=1.-V(IGM,1) IF(MAZIP.EQ.0) ZAU=0. IF(K(IGM,2).NE.21) THEN HAZIP=2.*ZAU/(1.+ZAU**2) ELSE HAZIP=(ZAU/(1.-ZAU*(1.-ZAU)))**2 ENDIF IF(K(N+1,2).NE.21) THEN HAZIP=HAZIP*(-2.*ZM*(1.-ZM))/(1.-2.*ZM*(1.-ZM)) ELSE HAZIP=HAZIP*(ZM*(1.-ZM)/(1.-ZM*(1.-ZM)))**2 ENDIF ENDIF C...Find coefficient of azimuthal asymmetry due to soft gluon C...interference. HAZIC=0. IF(MSTJ(49).NE.2.AND.MSTJ(46).GE.2.AND.(K(N+1,2).EQ.21.OR. & K(N+2,2).EQ.21).AND.IAU.NE.0) THEN IF(K(IGM,3).NE.0) MAZIC=N+1 IF(K(IGM,3).NE.0.AND.K(N+1,2).NE.21) MAZIC=N+2 IF(K(IGM,3).NE.0.AND.K(N+1,2).EQ.21.AND.K(N+2,2).EQ.21.AND. & ZM.GT.0.5) MAZIC=N+2 IF(K(IAU,2).EQ.22) MAZIC=0 ZS=ZM IF(MAZIC.EQ.N+2) ZS=1.-ZM ZGM=V(IGM,1) IF(IAU.EQ.IM-1) ZGM=1.-V(IGM,1) IF(MAZIC.EQ.0) ZGM=1. IF(MAZIC.NE.0) HAZIC=(P(IM,5)/P(IGM,5))* & SQRT((1.-ZS)*(1.-ZGM)/(ZS*ZGM)) HAZIC=MIN(0.95,HAZIC) ENDIF ENDIF C...Construct kinematics for ordinary branching in shower. 470 IF(NEP.EQ.2.AND.IGM.GT.0) THEN IF(MOD(MSTJ(43),2).EQ.1) THEN P(N+1,4)=PEM*V(IM,1) ELSE P(N+1,4)=PEM*(0.5*(V(IM,5)-SQRT(PMLS)+V(N+1,5)-V(N+2,5))+ & SQRT(PMLS)*ZM)/V(IM,5) ENDIF PHI=PARU(2)*RLU(0) P(N+1,1)=PT*COS(PHI) P(N+1,2)=PT*SIN(PHI) IF(PZM.GT.0.) THEN P(N+1,3)=0.5*(V(N+2,5)-V(N+1,5)-V(IM,5)+2.*PEM*P(N+1,4))/PZM ELSE P(N+1,3)=0. ENDIF P(N+2,1)=-P(N+1,1) P(N+2,2)=-P(N+1,2) P(N+2,3)=PZM-P(N+1,3) P(N+2,4)=PEM-P(N+1,4) IF(MSTJ(43).LE.2) THEN V(N+1,2)=(PEM*P(N+1,4)-PZM*P(N+1,3))/P(IM,5) V(N+2,2)=(PEM*P(N+2,4)-PZM*P(N+2,3))/P(IM,5) ENDIF ENDIF C...Rotate and boost daughters. IF(IGM.GT.0) THEN IF(MSTJ(43).LE.2) THEN BEX=P(IGM,1)/P(IGM,4) BEY=P(IGM,2)/P(IGM,4) BEZ=P(IGM,3)/P(IGM,4) GA=P(IGM,4)/P(IGM,5) GABEP=GA*(GA*(BEX*P(IM,1)+BEY*P(IM,2)+BEZ*P(IM,3))/(1.+GA)- & P(IM,4)) ELSE BEX=0. BEY=0. BEZ=0. GA=1. GABEP=0. ENDIF THE=ULANGL(P(IM,3)+GABEP*BEZ,SQRT((P(IM,1)+GABEP*BEX)**2+ & (P(IM,2)+GABEP*BEY)**2)) PHI=ULANGL(P(IM,1)+GABEP*BEX,P(IM,2)+GABEP*BEY) DO 480 I=N+1,N+2 DP(1)=COS(THE)*COS(PHI)*P(I,1)-SIN(PHI)*P(I,2)+ & SIN(THE)*COS(PHI)*P(I,3) DP(2)=COS(THE)*SIN(PHI)*P(I,1)+COS(PHI)*P(I,2)+ & SIN(THE)*SIN(PHI)*P(I,3) DP(3)=-SIN(THE)*P(I,1)+COS(THE)*P(I,3) DP(4)=P(I,4) DBP=BEX*DP(1)+BEY*DP(2)+BEZ*DP(3) DGABP=GA*(GA*DBP/(1D0+GA)+DP(4)) P(I,1)=DP(1)+DGABP*BEX P(I,2)=DP(2)+DGABP*BEY P(I,3)=DP(3)+DGABP*BEZ P(I,4)=GA*(DP(4)+DBP) 480 CONTINUE ENDIF C...Weight with azimuthal distribution, if required. IF(MAZIP.NE.0.OR.MAZIC.NE.0) THEN DO 490 J=1,3 DPT(1,J)=P(IM,J) DPT(2,J)=P(IAU,J) DPT(3,J)=P(N+1,J) 490 CONTINUE DPMA=DPT(1,1)*DPT(2,1)+DPT(1,2)*DPT(2,2)+DPT(1,3)*DPT(2,3) DPMD=DPT(1,1)*DPT(3,1)+DPT(1,2)*DPT(3,2)+DPT(1,3)*DPT(3,3) DPMM=DPT(1,1)**2+DPT(1,2)**2+DPT(1,3)**2 DO 500 J=1,3 DPT(4,J)=DPT(2,J)-DPMA*DPT(1,J)/DPMM DPT(5,J)=DPT(3,J)-DPMD*DPT(1,J)/DPMM 500 CONTINUE DPT(4,4)=SQRT(DPT(4,1)**2+DPT(4,2)**2+DPT(4,3)**2) DPT(5,4)=SQRT(DPT(5,1)**2+DPT(5,2)**2+DPT(5,3)**2) IF(MIN(DPT(4,4),DPT(5,4)).GT.0.1*PARJ(82)) THEN CAD=(DPT(4,1)*DPT(5,1)+DPT(4,2)*DPT(5,2)+ & DPT(4,3)*DPT(5,3))/(DPT(4,4)*DPT(5,4)) IF(MAZIP.NE.0) THEN IF(1.+HAZIP*(2.*CAD**2-1.).LT.RLU(0)*(1.+ABS(HAZIP))) & GOTO 470 ENDIF IF(MAZIC.NE.0) THEN IF(MAZIC.EQ.N+2) CAD=-CAD IF((1.-HAZIC)*(1.-HAZIC*CAD)/(1.+HAZIC**2-2.*HAZIC*CAD) & .LT.RLU(0)) GOTO 470 ENDIF ENDIF ENDIF C...Azimuthal anisotropy due to interference with initial state partons. IF(MOD(MIIS,2).EQ.1.AND.IGM.EQ.NS+1.AND.(K(N+1,2).EQ.21.OR. &K(N+2,2).EQ.21)) THEN III=IM-NS-1 IF(ISII(III).GE.1) THEN IAZIID=N+1 IF(K(N+1,2).NE.21) IAZIID=N+2 IF(K(N+1,2).EQ.21.AND.K(N+2,2).EQ.21.AND. & P(N+1,4).GT.P(N+2,4)) IAZIID=N+2 THEIID=ULANGL(P(IAZIID,3),SQRT(P(IAZIID,1)**2+P(IAZIID,2)**2)) IF(III.EQ.2) THEIID=PARU(1)-THEIID PHIIID=ULANGL(P(IAZIID,1),P(IAZIID,2)) HAZII=MIN(0.95,THEIID/THEIIS(III,ISII(III))) CAD=COS(PHIIID-PHIIIS(III,ISII(III))) PHIREL=ABS(PHIIID-PHIIIS(III,ISII(III))) IF(PHIREL.GT.PARU(1)) PHIREL=PARU(2)-PHIREL IF((1.-HAZII)*(1.-HAZII*CAD)/(1.+HAZII**2-2.*HAZII*CAD) & .LT.RLU(0)) GOTO 470 ENDIF ENDIF C...Continue loop over partons that may branch, until none left. IF(IGM.GE.0) K(IM,1)=14 N=N+NEP NEP=2 IF(N.GT.MSTU(4)-MSTU(32)-5) THEN CALL LUERRM(11,'(LUSHOW:) no more memory left in LUJETS') IF(MSTU(21).GE.1) N=NS IF(MSTU(21).GE.1) RETURN ENDIF GOTO 270 C...Set information on imagined shower initiator. 510 IF(NPA.GE.2) THEN K(NS+1,1)=11 K(NS+1,2)=94 K(NS+1,3)=IP1 IF(IP2.GT.0.AND.IP2.LT.IP1) K(NS+1,3)=IP2 K(NS+1,4)=NS+2 K(NS+1,5)=NS+1+NPA IIM=1 ELSE IIM=0 ENDIF C...Reconstruct string drawing information. DO 520 I=NS+1+IIM,N IF(K(I,1).LE.10.AND.K(I,2).EQ.22) THEN K(I,1)=1 ELSEIF(K(I,1).LE.10.AND.IABS(K(I,2)).GE.11.AND. &IABS(K(I,2)).LE.18) THEN K(I,1)=1 ELSEIF(K(I,1).LE.10) THEN K(I,4)=MSTU(5)*(K(I,4)/MSTU(5)) K(I,5)=MSTU(5)*(K(I,5)/MSTU(5)) ELSEIF(K(MOD(K(I,4),MSTU(5))+1,2).NE.22) THEN ID1=MOD(K(I,4),MSTU(5)) IF(K(I,2).GE.1.AND.K(I,2).LE.8) ID1=MOD(K(I,4),MSTU(5))+1 ID2=2*MOD(K(I,4),MSTU(5))+1-ID1 K(I,4)=MSTU(5)*(K(I,4)/MSTU(5))+ID1 K(I,5)=MSTU(5)*(K(I,5)/MSTU(5))+ID2 K(ID1,4)=K(ID1,4)+MSTU(5)*I K(ID1,5)=K(ID1,5)+MSTU(5)*ID2 K(ID2,4)=K(ID2,4)+MSTU(5)*ID1 K(ID2,5)=K(ID2,5)+MSTU(5)*I ELSE ID1=MOD(K(I,4),MSTU(5)) ID2=ID1+1 K(I,4)=MSTU(5)*(K(I,4)/MSTU(5))+ID1 K(I,5)=MSTU(5)*(K(I,5)/MSTU(5))+ID1 IF(IABS(K(I,2)).LE.10.OR.K(ID1,1).GE.11) THEN K(ID1,4)=K(ID1,4)+MSTU(5)*I K(ID1,5)=K(ID1,5)+MSTU(5)*I ELSE K(ID1,4)=0 K(ID1,5)=0 ENDIF K(ID2,4)=0 K(ID2,5)=0 ENDIF 520 CONTINUE C...Transformation from CM frame. IF(NPA.GE.2) THEN BEX=PS(1)/PS(4) BEY=PS(2)/PS(4) BEZ=PS(3)/PS(4) GA=PS(4)/PS(5) GABEP=GA*(GA*(BEX*P(IPA(1),1)+BEY*P(IPA(1),2)+BEZ*P(IPA(1),3)) & /(1.+GA)-P(IPA(1),4)) ELSE BEX=0. BEY=0. BEZ=0. GABEP=0. ENDIF THE=ULANGL(P(IPA(1),3)+GABEP*BEZ,SQRT((P(IPA(1),1) &+GABEP*BEX)**2+(P(IPA(1),2)+GABEP*BEY)**2)) PHI=ULANGL(P(IPA(1),1)+GABEP*BEX,P(IPA(1),2)+GABEP*BEY) IF(NPA.EQ.3) THEN CHI=ULANGL(COS(THE)*COS(PHI)*(P(IPA(2),1)+GABEP*BEX)+COS(THE)* & SIN(PHI)*(P(IPA(2),2)+GABEP*BEY)-SIN(THE)*(P(IPA(2),3)+GABEP* & BEZ),-SIN(PHI)*(P(IPA(2),1)+GABEP*BEX)+COS(PHI)*(P(IPA(2),2)+ & GABEP*BEY)) MSTU(33)=1 CALL LUDBRB(NS+1,N,0.,CHI,0D0,0D0,0D0) ENDIF DBEX=DBLE(BEX) DBEY=DBLE(BEY) DBEZ=DBLE(BEZ) MSTU(33)=1 CALL LUDBRB(NS+1,N,THE,PHI,DBEX,DBEY,DBEZ) C...Decay vertex of shower. DO 540 I=NS+1,N DO 530 J=1,5 V(I,J)=V(IP1,J) 530 CONTINUE 540 CONTINUE C...Delete trivial shower, else connect initiators. IF(N.EQ.NS+NPA+IIM) THEN N=NS ELSE DO 550 IP=1,NPA K(IPA(IP),1)=14 K(IPA(IP),4)=K(IPA(IP),4)+NS+IIM+IP K(IPA(IP),5)=K(IPA(IP),5)+NS+IIM+IP K(NS+IIM+IP,3)=IPA(IP) IF(IIM.EQ.1.AND.MSTU(16).NE.2) K(NS+IIM+IP,3)=NS+1 IF(K(NS+IIM+IP,1).NE.1) THEN K(NS+IIM+IP,4)=MSTU(5)*IPA(IP)+K(NS+IIM+IP,4) K(NS+IIM+IP,5)=MSTU(5)*IPA(IP)+K(NS+IIM+IP,5) ENDIF 550 CONTINUE ENDIF RETURN END