1 *CMZ : 17/07/98 15.44.35 by Federico Carminati
3 C*********************************************************************
5 SUBROUTINE LUEEVT(KFL,ECM)
7 C...Purpose: to handle the generation of an e+e- annihilation jet event.
8 IMPLICIT DOUBLE PRECISION(D)
10 COMMON /LUJETS/ N,K(200000,5),P(200000,5),V(200000,5)
13 COMMON /LUDAT1/ MSTU(200),PARU(200),MSTJ(200),PARJ(200)
16 COMMON /LUDAT2/ KCHG(500,3),PMAS(500,4),PARF(2000),VCKM(4,4)
20 C...Check input parameters.
21 IF(MSTU(12).GE.1) CALL LULIST(0)
22 IF(KFL.LT.0.OR.KFL.GT.8) THEN
23 CALL LUERRM(16,'(LUEEVT:) called with unknown flavour code')
24 IF(MSTU(21).GE.1) RETURN
26 IF(KFL.LE.5) ECMMIN=PARJ(127)+2.02*PARF(100+MAX(1,KFL))
27 IF(KFL.GE.6) ECMMIN=PARJ(127)+2.02*PMAS(KFL,1)
28 IF(ECM.LT.ECMMIN) THEN
29 CALL LUERRM(16,'(LUEEVT:) called with too small CM energy')
30 IF(MSTU(21).GE.1) RETURN
33 C...Check consistency of MSTJ options set.
34 IF(MSTJ(109).EQ.2.AND.MSTJ(110).NE.1) THEN
36 & '(LUEEVT:) MSTJ(109) value requires MSTJ(110) = 1')
39 IF(MSTJ(109).EQ.2.AND.MSTJ(111).NE.0) THEN
41 & '(LUEEVT:) MSTJ(109) value requires MSTJ(111) = 0')
45 C...Initialize alpha_strong and total cross-section.
47 IF(MSTJ(108).EQ.2.AND.(MSTJ(101).EQ.0.OR.MSTJ(101).EQ.1))
50 IF(MSTU(111).EQ.2) PARU(112)=PARJ(122)
51 IF(MSTJ(116).GT.0.AND.(MSTJ(116).GE.2.OR.ABS(ECM-PARJ(151)).GE.
52 &PARJ(139).OR.10*MSTJ(102)+KFL.NE.MSTJ(119))) CALL LUXTOT(KFL,ECM,
54 IF(MSTJ(116).GE.3) MSTJ(116)=1
56 C...Add initial e+e- to event record (documentation only).
60 CALL LUERRM(14,'(LUEEVT:) caught in an infinite loop')
64 IF(MSTJ(115).GE.2) THEN
66 CALL LU1ENT(NC-1,11,0.5*ECM,0.,0.)
68 CALL LU1ENT(NC,-11,0.5*ECM,PARU(1),0.)
72 C...Radiative photon (in initial state).
75 IF(MSTJ(107).GE.1.AND.MSTJ(116).GE.1) CALL LURADK(ECM,MK,PAK,
77 IF(MK.EQ.1) ECMC=SQRT(ECM*(ECM-2.*PAK))
78 IF(MSTJ(115).GE.1.AND.MK.EQ.1) THEN
80 CALL LU1ENT(NC,22,PAK,THEK,PHIK)
81 K(NC,3)=MIN(MSTJ(115)/2,1)
84 C...Virtual exchange boson (gamma or Z0).
85 IF(MSTJ(115).GE.3) THEN
88 IF(MSTJ(102).EQ.2) KF=23
92 CALL LU1ENT(NC,KF,ECMC,0.,0.)
98 C...Choice of flavour and jet configuration.
99 CALL LUXKFL(KFL,ECM,ECMC,KFLC)
100 IF(KFLC.EQ.0) GOTO 100
101 CALL LUXJET(ECMC,NJET,CUT)
103 IF(NJET.EQ.4) CALL LUX4JT(NJET,CUT,KFLC,ECMC,KFLN,X1,X2,X4,
105 IF(NJET.EQ.3) CALL LUX3JT(NJET,CUT,KFLC,ECMC,X1,X3)
106 IF(NJET.EQ.2) MSTJ(120)=1
108 C...Fill jet configuration and origin.
109 IF(NJET.EQ.2.AND.MSTJ(101).NE.5) CALL LU2ENT(NC+1,KFLC,-KFLC,ECMC)
110 IF(NJET.EQ.2.AND.MSTJ(101).EQ.5) CALL LU2ENT(-(NC+1),KFLC,-KFLC,
112 IF(NJET.EQ.3) CALL LU3ENT(NC+1,KFLC,21,-KFLC,ECMC,X1,X3)
113 IF(NJET.EQ.4.AND.KFLN.EQ.21) CALL LU4ENT(NC+1,KFLC,KFLN,KFLN,
114 &-KFLC,ECMC,X1,X2,X4,X12,X14)
115 IF(NJET.EQ.4.AND.KFLN.NE.21) CALL LU4ENT(NC+1,KFLC,-KFLN,KFLN,
116 &-KFLC,ECMC,X1,X2,X4,X12,X14)
118 110 K(IP,3)=K(IP,3)+MIN(MSTJ(115)/2,1)+(MSTJ(115)/3)*(NC-1)
120 C...Angular orientation according to matrix element.
121 IF(MSTJ(106).EQ.1) THEN
122 CALL LUXDIF(NC,NJET,KFLC,ECMC,CHI,THE,PHI)
123 CALL LUDBRB(NC+1,N,0.,CHI,0D0,0D0,0D0)
124 CALL LUDBRB(NC+1,N,THE,PHI,0D0,0D0,0D0)
127 C...Rotation and boost from radiative photon.
130 NMIN=NC+1-MSTJ(115)/3
131 CALL LUDBRB(NMIN,N,0.,-PHIK,0D0,0D0,0D0)
132 CALL LUDBRB(NMIN,N,ALPK,0.,DBEK*SIN(THEK),0D0,DBEK*COS(THEK))
133 CALL LUDBRB(NMIN,N,0.,PHIK,0D0,0D0,0D0)
136 C...Generate parton shower. Rearrange along strings and check.
137 IF(MSTJ(101).EQ.5) THEN
138 CALL LUSHOW(N-1,N,ECMC)
140 IF(MSTJ(105).EQ.-1) MSTJ(14)=0
141 IF(MSTJ(105).GE.0) MSTU(28)=0
144 IF(MSTJ(105).GE.0.AND.MSTU(28).NE.0) GOTO 100
147 C...Fragmentation/decay generation. Information for LUTABU.
148 IF(MSTJ(105).EQ.1) CALL LUEXEC