3 C*********************************************************************
5 SUBROUTINE LUONIA_HIJING(KFL,ECM)
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"
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
17 $ ,'(LUONIA_HIJING:) called with unknown flavour code')
18 IF(MSTU(21).GE.1) RETURN
20 IF(ECM.LT.PARJ(127)+2.02*PARF(101)) THEN
22 $ ,'(LUONIA_HIJING:) called with too small CM energy')
23 IF(MSTU(21).GE.1) RETURN
26 C...Initial e+e- and onium state (optional).
28 IF(MSTJ(115).GE.2) THEN
30 CALL LU1ENT_HIJING(NC-1,11,0.5*ECM,0.,0.)
32 CALL LU1ENT_HIJING(NC,-11,0.5*ECM,PARU(1),0.)
36 IF(MSTJ(115).GE.3.AND.KFLC.GE.5) THEN
42 CALL LU1ENT_HIJING(NC,KF,ECM,0.,0.)
48 C...Choose x1 and x2 according to matrix element.
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
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)
60 C...Photon-gluon-gluon events. Small system modifications. Jet origin.
62 IF(MSTJ(108).EQ.2.AND.(MSTJ(101).EQ.0.OR.MSTJ(101).EQ.1))
65 IF(MSTU(111).EQ.2) PARU(112)=PARJ(122)
67 IF(KFLC.NE.0) QF=KCHG(KFLC,1)/3.
68 RGAM=7.2*QF**2*PARU(101)/ULALPS_HIJING(ECM**2)
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)))
74 IF(NJET.EQ.2.AND.MSTJ(101).LE.4) CALL LU2ENT_HIJING(NC+1,21,21
76 IF(NJET.EQ.2.AND.MSTJ(101).GE.5) CALL LU2ENT_HIJING(-(NC+1),21
81 IF(ECMC.LT.2.*PARJ(127)) GOTO 100
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)
91 IF(ECMC.LT.4.*PARJ(127)) THEN
95 CALL LU1ENT_HIJING(NC+2,83,0.5*(X2+X3)*ECM,PARU(1),0.)
101 110 K(IP,3)=K(IP,3)+(MSTJ(115)/2)+(KFLC/5)*(MSTJ(115)/3)*(NC-1)
103 C...Differential cross-sections. Upper limit for cross-section.
104 IF(MSTJ(106).EQ.1) THEN
106 HF1=1.-PARJ(131)*PARJ(132)
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
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)
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)
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)
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)
142 IF(MSTJ(105).EQ.-1) MSTJ(14)=0
143 IF(MSTJ(105).GE.0) MSTU(28)=0
144 CALL LUPREP_HIJING(0)
146 IF(MSTJ(105).GE.0.AND.MSTU(28).NE.0) GOTO 100
149 C...Generate fragmentation. Information for LUTABU_HIJING:
150 IF(MSTJ(105).EQ.1) CALL LUEXEC_HIJING