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fe4da5cc | 1 | *CMZ : 17/07/98 15.44.35 by Federico Carminati |
2 | *-- Author : | |
3 | C********************************************************************* | |
4 | ||
5 | SUBROUTINE LUEEVT(KFL,ECM) | |
6 | ||
7 | C...Purpose: to handle the generation of an e+e- annihilation jet event. | |
8 | IMPLICIT DOUBLE PRECISION(D) | |
9 | *KEEP,LUJETS. | |
10 | COMMON /LUJETS/ N,K(200000,5),P(200000,5),V(200000,5) | |
11 | SAVE /LUJETS/ | |
12 | *KEEP,LUDAT1. | |
13 | COMMON /LUDAT1/ MSTU(200),PARU(200),MSTJ(200),PARJ(200) | |
14 | SAVE /LUDAT1/ | |
15 | *KEEP,LUDAT2. | |
16 | COMMON /LUDAT2/ KCHG(500,3),PMAS(500,4),PARF(2000),VCKM(4,4) | |
17 | SAVE /LUDAT2/ | |
18 | *KEND. | |
19 | ||
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 | |
25 | ENDIF | |
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 | |
31 | ENDIF | |
32 | ||
33 | C...Check consistency of MSTJ options set. | |
34 | IF(MSTJ(109).EQ.2.AND.MSTJ(110).NE.1) THEN | |
35 | CALL LUERRM(6, | |
36 | & '(LUEEVT:) MSTJ(109) value requires MSTJ(110) = 1') | |
37 | MSTJ(110)=1 | |
38 | ENDIF | |
39 | IF(MSTJ(109).EQ.2.AND.MSTJ(111).NE.0) THEN | |
40 | CALL LUERRM(6, | |
41 | & '(LUEEVT:) MSTJ(109) value requires MSTJ(111) = 0') | |
42 | MSTJ(111)=0 | |
43 | ENDIF | |
44 | ||
45 | C...Initialize alpha_strong and total cross-section. | |
46 | MSTU(111)=MSTJ(108) | |
47 | IF(MSTJ(108).EQ.2.AND.(MSTJ(101).EQ.0.OR.MSTJ(101).EQ.1)) | |
48 | &MSTU(111)=1 | |
49 | PARU(112)=PARJ(121) | |
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, | |
53 | &XTOT) | |
54 | IF(MSTJ(116).GE.3) MSTJ(116)=1 | |
55 | ||
56 | C...Add initial e+e- to event record (documentation only). | |
57 | NTRY=0 | |
58 | 100 NTRY=NTRY+1 | |
59 | IF(NTRY.GT.100) THEN | |
60 | CALL LUERRM(14,'(LUEEVT:) caught in an infinite loop') | |
61 | RETURN | |
62 | ENDIF | |
63 | NC=0 | |
64 | IF(MSTJ(115).GE.2) THEN | |
65 | NC=NC+2 | |
66 | CALL LU1ENT(NC-1,11,0.5*ECM,0.,0.) | |
67 | K(NC-1,1)=21 | |
68 | CALL LU1ENT(NC,-11,0.5*ECM,PARU(1),0.) | |
69 | K(NC,1)=21 | |
70 | ENDIF | |
71 | ||
72 | C...Radiative photon (in initial state). | |
73 | MK=0 | |
74 | ECMC=ECM | |
75 | IF(MSTJ(107).GE.1.AND.MSTJ(116).GE.1) CALL LURADK(ECM,MK,PAK, | |
76 | &THEK,PHIK,ALPK) | |
77 | IF(MK.EQ.1) ECMC=SQRT(ECM*(ECM-2.*PAK)) | |
78 | IF(MSTJ(115).GE.1.AND.MK.EQ.1) THEN | |
79 | NC=NC+1 | |
80 | CALL LU1ENT(NC,22,PAK,THEK,PHIK) | |
81 | K(NC,3)=MIN(MSTJ(115)/2,1) | |
82 | ENDIF | |
83 | ||
84 | C...Virtual exchange boson (gamma or Z0). | |
85 | IF(MSTJ(115).GE.3) THEN | |
86 | NC=NC+1 | |
87 | KF=22 | |
88 | IF(MSTJ(102).EQ.2) KF=23 | |
89 | MSTU10=MSTU(10) | |
90 | MSTU(10)=1 | |
91 | P(NC,5)=ECMC | |
92 | CALL LU1ENT(NC,KF,ECMC,0.,0.) | |
93 | K(NC,1)=21 | |
94 | K(NC,3)=1 | |
95 | MSTU(10)=MSTU10 | |
96 | ENDIF | |
97 | ||
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) | |
102 | KFLN=21 | |
103 | IF(NJET.EQ.4) CALL LUX4JT(NJET,CUT,KFLC,ECMC,KFLN,X1,X2,X4, | |
104 | &X12,X14) | |
105 | IF(NJET.EQ.3) CALL LUX3JT(NJET,CUT,KFLC,ECMC,X1,X3) | |
106 | IF(NJET.EQ.2) MSTJ(120)=1 | |
107 | ||
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, | |
111 | &ECMC) | |
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) | |
117 | DO 110 IP=NC+1,N | |
118 | 110 K(IP,3)=K(IP,3)+MIN(MSTJ(115)/2,1)+(MSTJ(115)/3)*(NC-1) | |
119 | ||
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) | |
125 | ENDIF | |
126 | ||
127 | C...Rotation and boost from radiative photon. | |
128 | IF(MK.EQ.1) THEN | |
129 | DBEK=-PAK/(ECM-PAK) | |
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) | |
134 | ENDIF | |
135 | ||
136 | C...Generate parton shower. Rearrange along strings and check. | |
137 | IF(MSTJ(101).EQ.5) THEN | |
138 | CALL LUSHOW(N-1,N,ECMC) | |
139 | MSTJ14=MSTJ(14) | |
140 | IF(MSTJ(105).EQ.-1) MSTJ(14)=0 | |
141 | IF(MSTJ(105).GE.0) MSTU(28)=0 | |
142 | CALL LUPREP(0) | |
143 | MSTJ(14)=MSTJ14 | |
144 | IF(MSTJ(105).GE.0.AND.MSTU(28).NE.0) GOTO 100 | |
145 | ENDIF | |
146 | ||
147 | C...Fragmentation/decay generation. Information for LUTABU. | |
148 | IF(MSTJ(105).EQ.1) CALL LUEXEC | |
149 | MSTU(161)=KFLC | |
150 | MSTU(162)=-KFLC | |
151 | ||
152 | RETURN | |
153 | END |