+++ /dev/null
-
-C*********************************************************************
-
- SUBROUTINE LU4ENT(IP,KF1,KF2,KF3,KF4,PECM,X1,X2,X4,X12,X14)
-
-C...Purpose: to store four partons or particles in their CM frame, with
-C...the first along the +z axis, the last in the xz plane with x > 0
-C...and the second having y < 0 and y > 0 with equal probability.
- 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/
-
-C...Standard checks.
- MSTU(28)=0
- IF(MSTU(12).GE.1) CALL LULIST(0)
- IPA=MAX(1,IABS(IP))
- IF(IPA.GT.MSTU(4)-3) CALL LUERRM(21,
- &'(LU4ENT:) writing outside LUJETS momory')
- KC1=LUCOMP(KF1)
- KC2=LUCOMP(KF2)
- KC3=LUCOMP(KF3)
- KC4=LUCOMP(KF4)
- IF(KC1.EQ.0.OR.KC2.EQ.0.OR.KC3.EQ.0.OR.KC4.EQ.0) CALL LUERRM(12,
- &'(LU4ENT:) unknown flavour code')
-
-C...Find masses. Reset K, P and V vectors.
- PM1=0.
- IF(MSTU(10).EQ.1) PM1=P(IPA,5)
- IF(MSTU(10).GE.2) PM1=ULMASS(KF1)
- PM2=0.
- IF(MSTU(10).EQ.1) PM2=P(IPA+1,5)
- IF(MSTU(10).GE.2) PM2=ULMASS(KF2)
- PM3=0.
- IF(MSTU(10).EQ.1) PM3=P(IPA+2,5)
- IF(MSTU(10).GE.2) PM3=ULMASS(KF3)
- PM4=0.
- IF(MSTU(10).EQ.1) PM4=P(IPA+3,5)
- IF(MSTU(10).GE.2) PM4=ULMASS(KF4)
- DO 110 I=IPA,IPA+3
- DO 100 J=1,5
- K(I,J)=0
- P(I,J)=0.
- V(I,J)=0.
- 100 CONTINUE
- 110 CONTINUE
-
-C...Check flavours.
- KQ1=KCHG(KC1,2)*ISIGN(1,KF1)
- KQ2=KCHG(KC2,2)*ISIGN(1,KF2)
- KQ3=KCHG(KC3,2)*ISIGN(1,KF3)
- KQ4=KCHG(KC4,2)*ISIGN(1,KF4)
- IF(MSTU(19).EQ.1) THEN
- MSTU(19)=0
- ELSEIF(KQ1.EQ.0.AND.KQ2.EQ.0.AND.KQ3.EQ.0.AND.KQ4.EQ.0) THEN
- ELSEIF(KQ1.NE.0.AND.KQ2.EQ.2.AND.KQ3.EQ.2.AND.(KQ1+KQ4.EQ.0.OR.
- &KQ1+KQ4.EQ.4)) THEN
- ELSEIF(KQ1.NE.0.AND.KQ1+KQ2.EQ.0.AND.KQ3.NE.0.AND.KQ3+KQ4.EQ.0.)
- &THEN
- ELSE
- CALL LUERRM(2,'(LU4ENT:) unphysical flavour combination')
- ENDIF
- K(IPA,2)=KF1
- K(IPA+1,2)=KF2
- K(IPA+2,2)=KF3
- K(IPA+3,2)=KF4
-
-C...Store partons/particles in K vectors for normal case.
- IF(IP.GE.0) THEN
- K(IPA,1)=1
- IF(KQ1.NE.0.AND.(KQ2.NE.0.OR.KQ3.NE.0.OR.KQ4.NE.0)) K(IPA,1)=2
- K(IPA+1,1)=1
- IF(KQ2.NE.0.AND.KQ1+KQ2.NE.0.AND.(KQ3.NE.0.OR.KQ4.NE.0))
- & K(IPA+1,1)=2
- K(IPA+2,1)=1
- IF(KQ3.NE.0.AND.KQ4.NE.0) K(IPA+2,1)=2
- K(IPA+3,1)=1
-
-C...Store partons for parton shower evolution from q-g-g-qbar or
-C...g-g-g-g event.
- ELSEIF(KQ1+KQ2.NE.0) THEN
- K(IPA,1)=3
- K(IPA+1,1)=3
- K(IPA+2,1)=3
- K(IPA+3,1)=3
- KCS=4
- IF(KQ1.EQ.-1) KCS=5
- K(IPA,KCS)=MSTU(5)*(IPA+1)
- K(IPA,9-KCS)=MSTU(5)*(IPA+3)
- K(IPA+1,KCS)=MSTU(5)*(IPA+2)
- K(IPA+1,9-KCS)=MSTU(5)*IPA
- K(IPA+2,KCS)=MSTU(5)*(IPA+3)
- K(IPA+2,9-KCS)=MSTU(5)*(IPA+1)
- K(IPA+3,KCS)=MSTU(5)*IPA
- K(IPA+3,9-KCS)=MSTU(5)*(IPA+2)
-
-C...Store partons for parton shower evolution from q-qbar-q-qbar event.
- ELSE
- K(IPA,1)=3
- K(IPA+1,1)=3
- K(IPA+2,1)=3
- K(IPA+3,1)=3
- K(IPA,4)=MSTU(5)*(IPA+1)
- K(IPA,5)=K(IPA,4)
- K(IPA+1,4)=MSTU(5)*IPA
- K(IPA+1,5)=K(IPA+1,4)
- K(IPA+2,4)=MSTU(5)*(IPA+3)
- K(IPA+2,5)=K(IPA+2,4)
- K(IPA+3,4)=MSTU(5)*(IPA+2)
- K(IPA+3,5)=K(IPA+3,4)
- ENDIF
-
-C...Check kinematics.
- MKERR=0
- IF(0.5*X1*PECM.LE.PM1.OR.0.5*X2*PECM.LE.PM2.OR.0.5*(2.-X1-X2-X4)*
- &PECM.LE.PM3.OR.0.5*X4*PECM.LE.PM4) MKERR=1
- PA1=SQRT(MAX(1E-10,(0.5*X1*PECM)**2-PM1**2))
- PA2=SQRT(MAX(1E-10,(0.5*X2*PECM)**2-PM2**2))
- PA4=SQRT(MAX(1E-10,(0.5*X4*PECM)**2-PM4**2))
- X24=X1+X2+X4-1.-X12-X14+(PM3**2-PM1**2-PM2**2-PM4**2)/PECM**2
- CTHE4=(X1*X4-2.*X14)*PECM**2/(4.*PA1*PA4)
- IF(ABS(CTHE4).GE.1.002) MKERR=1
- CTHE4=MAX(-1.,MIN(1.,CTHE4))
- STHE4=SQRT(1.-CTHE4**2)
- CTHE2=(X1*X2-2.*X12)*PECM**2/(4.*PA1*PA2)
- IF(ABS(CTHE2).GE.1.002) MKERR=1
- CTHE2=MAX(-1.,MIN(1.,CTHE2))
- STHE2=SQRT(1.-CTHE2**2)
- CPHI2=((X2*X4-2.*X24)*PECM**2-4.*PA2*CTHE2*PA4*CTHE4)/
- &MAX(1E-8*PECM**2,4.*PA2*STHE2*PA4*STHE4)
- IF(ABS(CPHI2).GE.1.05) MKERR=1
- CPHI2=MAX(-1.,MIN(1.,CPHI2))
- IF(MKERR.EQ.1) CALL LUERRM(13,
- &'(LU4ENT:) unphysical kinematical variable setup')
-
-C...Store partons/particles in P vectors.
- P(IPA,3)=PA1
- P(IPA,4)=SQRT(PA1**2+PM1**2)
- P(IPA,5)=PM1
- P(IPA+3,1)=PA4*STHE4
- P(IPA+3,3)=PA4*CTHE4
- P(IPA+3,4)=SQRT(PA4**2+PM4**2)
- P(IPA+3,5)=PM4
- P(IPA+1,1)=PA2*STHE2*CPHI2
- P(IPA+1,2)=PA2*STHE2*SQRT(1.-CPHI2**2)*(-1.)**INT(RLU(0)+0.5)
- P(IPA+1,3)=PA2*CTHE2
- P(IPA+1,4)=SQRT(PA2**2+PM2**2)
- P(IPA+1,5)=PM2
- P(IPA+2,1)=-P(IPA+1,1)-P(IPA+3,1)
- P(IPA+2,2)=-P(IPA+1,2)
- P(IPA+2,3)=-P(IPA,3)-P(IPA+1,3)-P(IPA+3,3)
- P(IPA+2,4)=SQRT(P(IPA+2,1)**2+P(IPA+2,2)**2+P(IPA+2,3)**2+PM3**2)
- P(IPA+2,5)=PM3
-
-C...Set N. Optionally fragment/decay.
- N=IPA+3
- IF(IP.EQ.0) CALL LUEXEC
-
- RETURN
- END
git://git.uio.no / u / mrichter / AliRoot.git / blobdiff