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e74335a4 | 1 | * $Id$ |
2 | ||
3 | C********************************************************************* | |
4 | ||
5 | SUBROUTINE LUONIA_HIJING(KFL,ECM) | |
6 | ||
7 | C...Purpose: to generate Upsilon and toponium decays into three | |
8 | C...gluons or two gluons and a photon. | |
9 | #include "lujets_hijing.inc" | |
10 | #include "ludat1_hijing.inc" | |
11 | #include "ludat2_hijing.inc" | |
12 | ||
13 | C...Printout. Check input parameters. | |
14 | IF(MSTU(12).GE.1) CALL LULIST_HIJING(0) | |
15 | IF(KFL.LT.0.OR.KFL.GT.8) THEN | |
16 | CALL LUERRM_HIJING(16 | |
17 | $ ,'(LUONIA_HIJING:) called with unknown flavour code') | |
18 | IF(MSTU(21).GE.1) RETURN | |
19 | ENDIF | |
20 | IF(ECM.LT.PARJ(127)+2.02*PARF(101)) THEN | |
21 | CALL LUERRM_HIJING(16 | |
22 | $ ,'(LUONIA_HIJING:) called with too small CM energy') | |
23 | IF(MSTU(21).GE.1) RETURN | |
24 | ENDIF | |
25 | ||
26 | C...Initial e+e- and onium state (optional). | |
27 | NC=0 | |
28 | IF(MSTJ(115).GE.2) THEN | |
29 | NC=NC+2 | |
30 | CALL LU1ENT_HIJING(NC-1,11,0.5*ECM,0.,0.) | |
31 | K(NC-1,1)=21 | |
32 | CALL LU1ENT_HIJING(NC,-11,0.5*ECM,PARU(1),0.) | |
33 | K(NC,1)=21 | |
34 | ENDIF | |
35 | KFLC=IABS(KFL) | |
36 | IF(MSTJ(115).GE.3.AND.KFLC.GE.5) THEN | |
37 | NC=NC+1 | |
38 | KF=110*KFLC+3 | |
39 | MSTU10=MSTU(10) | |
40 | MSTU(10)=1 | |
41 | P(NC,5)=ECM | |
42 | CALL LU1ENT_HIJING(NC,KF,ECM,0.,0.) | |
43 | K(NC,1)=21 | |
44 | K(NC,3)=1 | |
45 | MSTU(10)=MSTU10 | |
46 | ENDIF | |
47 | ||
48 | C...Choose x1 and x2 according to matrix element. | |
49 | NTRY=0 | |
50 | 100 X1=RLU_HIJING(0) | |
51 | X2=RLU_HIJING(0) | |
52 | X3=2.-X1-X2 | |
53 | IF(X3.GE.1..OR.((1.-X1)/(X2*X3))**2+((1.-X2)/(X1*X3))**2+ | |
54 | &((1.-X3)/(X1*X2))**2.LE.2.*RLU_HIJING(0)) GOTO 100 | |
55 | NTRY=NTRY+1 | |
56 | NJET=3 | |
57 | IF(MSTJ(101).LE.4) CALL LU3ENT_HIJING(NC+1,21,21,21,ECM,X1,X3) | |
58 | IF(MSTJ(101).GE.5) CALL LU3ENT_HIJING(-(NC+1),21,21,21,ECM,X1,X3) | |
59 | ||
60 | C...Photon-gluon-gluon events. Small system modifications. Jet origin. | |
61 | MSTU(111)=MSTJ(108) | |
62 | IF(MSTJ(108).EQ.2.AND.(MSTJ(101).EQ.0.OR.MSTJ(101).EQ.1)) | |
63 | &MSTU(111)=1 | |
64 | PARU(112)=PARJ(121) | |
65 | IF(MSTU(111).EQ.2) PARU(112)=PARJ(122) | |
66 | QF=0. | |
67 | IF(KFLC.NE.0) QF=KCHG(KFLC,1)/3. | |
68 | RGAM=7.2*QF**2*PARU(101)/ULALPS_HIJING(ECM**2) | |
69 | MK=0 | |
70 | ECMC=ECM | |
71 | IF(RLU_HIJING(0).GT.RGAM/(1.+RGAM)) THEN | |
72 | IF(1.-MAX(X1,X2,X3).LE.MAX((PARJ(126)/ECM)**2,PARJ(125))) | |
73 | & NJET=2 | |
74 | IF(NJET.EQ.2.AND.MSTJ(101).LE.4) CALL LU2ENT_HIJING(NC+1,21,21 | |
75 | $ ,ECM) | |
76 | IF(NJET.EQ.2.AND.MSTJ(101).GE.5) CALL LU2ENT_HIJING(-(NC+1),21 | |
77 | $ ,21,ECM) | |
78 | ELSE | |
79 | MK=1 | |
80 | ECMC=SQRT(1.-X1)*ECM | |
81 | IF(ECMC.LT.2.*PARJ(127)) GOTO 100 | |
82 | K(NC+1,1)=1 | |
83 | K(NC+1,2)=22 | |
84 | K(NC+1,4)=0 | |
85 | K(NC+1,5)=0 | |
86 | IF(MSTJ(101).GE.5) K(NC+2,4)=MSTU(5)*(NC+3) | |
87 | IF(MSTJ(101).GE.5) K(NC+2,5)=MSTU(5)*(NC+3) | |
88 | IF(MSTJ(101).GE.5) K(NC+3,4)=MSTU(5)*(NC+2) | |
89 | IF(MSTJ(101).GE.5) K(NC+3,5)=MSTU(5)*(NC+2) | |
90 | NJET=2 | |
91 | IF(ECMC.LT.4.*PARJ(127)) THEN | |
92 | MSTU10=MSTU(10) | |
93 | MSTU(10)=1 | |
94 | P(NC+2,5)=ECMC | |
95 | CALL LU1ENT_HIJING(NC+2,83,0.5*(X2+X3)*ECM,PARU(1),0.) | |
96 | MSTU(10)=MSTU10 | |
97 | NJET=0 | |
98 | ENDIF | |
99 | ENDIF | |
100 | DO 110 IP=NC+1,N | |
101 | 110 K(IP,3)=K(IP,3)+(MSTJ(115)/2)+(KFLC/5)*(MSTJ(115)/3)*(NC-1) | |
102 | ||
103 | C...Differential cross-sections. Upper limit for cross-section. | |
104 | IF(MSTJ(106).EQ.1) THEN | |
105 | SQ2=SQRT(2.) | |
106 | HF1=1.-PARJ(131)*PARJ(132) | |
107 | HF3=PARJ(133)**2 | |
108 | CT13=(X1*X3-2.*X1-2.*X3+2.)/(X1*X3) | |
109 | ST13=SQRT(1.-CT13**2) | |
110 | SIGL=0.5*X3**2*((1.-X2)**2+(1.-X3)**2)*ST13**2 | |
111 | SIGU=(X1*(1.-X1))**2+(X2*(1.-X2))**2+(X3*(1.-X3))**2-SIGL | |
112 | SIGT=0.5*SIGL | |
113 | SIGI=(SIGL*CT13/ST13+0.5*X1*X3*(1.-X2)**2*ST13)/SQ2 | |
114 | SIGMAX=(2.*HF1+HF3)*ABS(SIGU)+2.*(HF1+HF3)*ABS(SIGL)+2.*(HF1+ | |
115 | & 2.*HF3)*ABS(SIGT)+2.*SQ2*(HF1+2.*HF3)*ABS(SIGI) | |
116 | ||
117 | C...Angular orientation of event. | |
118 | 120 CHI=PARU(2)*RLU_HIJING(0) | |
119 | CTHE=2.*RLU_HIJING(0)-1. | |
120 | PHI=PARU(2)*RLU_HIJING(0) | |
121 | CCHI=COS(CHI) | |
122 | SCHI=SIN(CHI) | |
123 | C2CHI=COS(2.*CHI) | |
124 | S2CHI=SIN(2.*CHI) | |
125 | THE=ACOS(CTHE) | |
126 | STHE=SIN(THE) | |
127 | C2PHI=COS(2.*(PHI-PARJ(134))) | |
128 | S2PHI=SIN(2.*(PHI-PARJ(134))) | |
129 | SIG=((1.+CTHE**2)*HF1+STHE**2*C2PHI*HF3)*SIGU+2.*(STHE**2*HF1- | |
130 | & STHE**2*C2PHI*HF3)*SIGL+2.*(STHE**2*C2CHI*HF1+((1.+CTHE**2)* | |
131 | & C2CHI*C2PHI-2.*CTHE*S2CHI*S2PHI)*HF3)*SIGT-2.*SQ2*(2.*STHE*CTHE* | |
132 | & CCHI*HF1-2.*STHE*(CTHE*CCHI*C2PHI-SCHI*S2PHI)*HF3)*SIGI | |
133 | IF(SIG.LT.SIGMAX*RLU_HIJING(0)) GOTO 120 | |
134 | CALL LUDBRB_HIJING(NC+1,N,0.,CHI,0D0,0D0,0D0) | |
135 | CALL LUDBRB_HIJING(NC+1,N,THE,PHI,0D0,0D0,0D0) | |
136 | ENDIF | |
137 | ||
138 | C...Generate parton shower. Rearrange along strings and check. | |
139 | IF(MSTJ(101).GE.5.AND.NJET.GE.2) THEN | |
140 | CALL LUSHOW_HIJING(NC+MK+1,-NJET,ECMC) | |
141 | MSTJ14=MSTJ(14) | |
142 | IF(MSTJ(105).EQ.-1) MSTJ(14)=0 | |
143 | IF(MSTJ(105).GE.0) MSTU(28)=0 | |
144 | CALL LUPREP_HIJING(0) | |
145 | MSTJ(14)=MSTJ14 | |
146 | IF(MSTJ(105).GE.0.AND.MSTU(28).NE.0) GOTO 100 | |
147 | ENDIF | |
148 | ||
149 | C...Generate fragmentation. Information for LUTABU_HIJING: | |
150 | IF(MSTJ(105).EQ.1) CALL LUEXEC_HIJING | |
151 | MSTU(161)=110*KFLC+3 | |
152 | MSTU(162)=0 | |
153 | ||
154 | RETURN | |
155 | END |