2 C*********************************************************************
4 SUBROUTINE LUEEVT(KFL,ECM)
6 C...Purpose: to handle the generation of an e+e- annihilation jet event.
7 IMPLICIT DOUBLE PRECISION(D)
8 COMMON/LUJETS/N,K(4000,5),P(4000,5),V(4000,5)
9 COMMON/LUDAT1/MSTU(200),PARU(200),MSTJ(200),PARJ(200)
10 COMMON/LUDAT2/KCHG(500,3),PMAS(500,4),PARF(2000),VCKM(4,4)
11 SAVE /LUJETS/,/LUDAT1/,/LUDAT2/
13 C...Check input parameters.
14 IF(MSTU(12).GE.1) CALL LULIST(0)
15 IF(KFL.LT.0.OR.KFL.GT.8) THEN
16 CALL LUERRM(16,'(LUEEVT:) called with unknown flavour code')
17 IF(MSTU(21).GE.1) RETURN
19 IF(KFL.LE.5) ECMMIN=PARJ(127)+2.02*PARF(100+MAX(1,KFL))
20 IF(KFL.GE.6) ECMMIN=PARJ(127)+2.02*PMAS(KFL,1)
21 IF(ECM.LT.ECMMIN) THEN
22 CALL LUERRM(16,'(LUEEVT:) called with too small CM energy')
23 IF(MSTU(21).GE.1) RETURN
26 C...Check consistency of MSTJ options set.
27 IF(MSTJ(109).EQ.2.AND.MSTJ(110).NE.1) THEN
29 & '(LUEEVT:) MSTJ(109) value requires MSTJ(110) = 1')
32 IF(MSTJ(109).EQ.2.AND.MSTJ(111).NE.0) THEN
34 & '(LUEEVT:) MSTJ(109) value requires MSTJ(111) = 0')
38 C...Initialize alpha_strong and total cross-section.
40 IF(MSTJ(108).EQ.2.AND.(MSTJ(101).EQ.0.OR.MSTJ(101).EQ.1))
43 IF(MSTU(111).EQ.2) PARU(112)=PARJ(122)
44 IF(MSTJ(116).GT.0.AND.(MSTJ(116).GE.2.OR.ABS(ECM-PARJ(151)).GE.
45 &PARJ(139).OR.10*MSTJ(102)+KFL.NE.MSTJ(119))) CALL LUXTOT(KFL,ECM,
47 IF(MSTJ(116).GE.3) MSTJ(116)=1
50 C...Add initial e+e- to event record (documentation only).
54 CALL LUERRM(14,'(LUEEVT:) caught in an infinite loop')
59 IF(MSTJ(115).GE.2) THEN
61 CALL LU1ENT(NC-1,11,0.5*ECM,0.,0.)
63 CALL LU1ENT(NC,-11,0.5*ECM,PARU(1),0.)
67 C...Radiative photon (in initial state).
70 IF(MSTJ(107).GE.1.AND.MSTJ(116).GE.1) CALL LURADK(ECM,MK,PAK,
72 IF(MK.EQ.1) ECMC=SQRT(ECM*(ECM-2.*PAK))
73 IF(MSTJ(115).GE.1.AND.MK.EQ.1) THEN
75 CALL LU1ENT(NC,22,PAK,THEK,PHIK)
76 K(NC,3)=MIN(MSTJ(115)/2,1)
79 C...Virtual exchange boson (gamma or Z0).
80 IF(MSTJ(115).GE.3) THEN
83 IF(MSTJ(102).EQ.2) KF=23
87 CALL LU1ENT(NC,KF,ECMC,0.,0.)
93 C...Choice of flavour and jet configuration.
94 CALL LUXKFL(KFL,ECM,ECMC,KFLC)
95 IF(KFLC.EQ.0) GOTO 100
96 CALL LUXJET(ECMC,NJET,CUT)
98 IF(NJET.EQ.4) CALL LUX4JT(NJET,CUT,KFLC,ECMC,KFLN,X1,X2,X4,
100 IF(NJET.EQ.3) CALL LUX3JT(NJET,CUT,KFLC,ECMC,X1,X3)
101 IF(NJET.EQ.2) MSTJ(120)=1
103 C...Fill jet configuration and origin.
104 IF(NJET.EQ.2.AND.MSTJ(101).NE.5) CALL LU2ENT(NC+1,KFLC,-KFLC,ECMC)
105 IF(NJET.EQ.2.AND.MSTJ(101).EQ.5) CALL LU2ENT(-(NC+1),KFLC,-KFLC,
107 IF(NJET.EQ.3) CALL LU3ENT(NC+1,KFLC,21,-KFLC,ECMC,X1,X3)
108 IF(NJET.EQ.4.AND.KFLN.EQ.21) CALL LU4ENT(NC+1,KFLC,KFLN,KFLN,
109 &-KFLC,ECMC,X1,X2,X4,X12,X14)
110 IF(NJET.EQ.4.AND.KFLN.NE.21) CALL LU4ENT(NC+1,KFLC,-KFLN,KFLN,
111 &-KFLC,ECMC,X1,X2,X4,X12,X14)
112 IF(MSTU(24).NE.0) GOTO 100
114 K(IP,3)=K(IP,3)+MIN(MSTJ(115)/2,1)+(MSTJ(115)/3)*(NC-1)
117 C...Angular orientation according to matrix element.
118 IF(MSTJ(106).EQ.1) THEN
119 CALL LUXDIF(NC,NJET,KFLC,ECMC,CHI,THE,PHI)
120 CALL LUDBRB(NC+1,N,0.,CHI,0D0,0D0,0D0)
121 CALL LUDBRB(NC+1,N,THE,PHI,0D0,0D0,0D0)
124 C...Rotation and boost from radiative photon.
127 NMIN=NC+1-MSTJ(115)/3
128 CALL LUDBRB(NMIN,N,0.,-PHIK,0D0,0D0,0D0)
129 CALL LUDBRB(NMIN,N,ALPK,0.,DBEK*SIN(THEK),0D0,DBEK*COS(THEK))
130 CALL LUDBRB(NMIN,N,0.,PHIK,0D0,0D0,0D0)
133 C...Generate parton shower. Rearrange along strings and check.
134 IF(MSTJ(101).EQ.5) THEN
135 CALL LUSHOW(N-1,N,ECMC)
137 IF(MSTJ(105).EQ.-1) MSTJ(14)=-1
138 IF(MSTJ(105).GE.0) MSTU(28)=0
141 IF(MSTJ(105).GE.0.AND.MSTU(28).NE.0) GOTO 100
144 C...Fragmentation/decay generation. Information for LUTABU.
145 IF(MSTJ(105).EQ.1) CALL LUEXEC