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e74335a4 | 1 | * $Id$ |
2 | ||
3 | C********************************************************************* | |
4 | ||
5 | SUBROUTINE LUX3JT_HIJING(NJET,CUT,KFL,ECM,X1,X2) | |
6 | ||
7 | C...Purpose: to select the kinematical variables of three-jet events. | |
8 | #include "ludat1_hijing.inc" | |
9 | DIMENSION ZHUP(5,12) | |
10 | ||
11 | C...Coefficients of Zhu second order parametrization. | |
12 | DATA ((ZHUP(IC1,IC2),IC2=1,12),IC1=1,5)/ | |
13 | & 18.29, 89.56, 4.541, -52.09, -109.8, 24.90, | |
14 | & 11.63, 3.683, 17.50, 0.002440, -1.362, -0.3537, | |
15 | & 11.42, 6.299, -22.55, -8.915, 59.25, -5.855, | |
16 | & -32.85, -1.054, -16.90, 0.006489, -0.8156, 0.01095, | |
17 | & 7.847, -3.964, -35.83, 1.178, 29.39, 0.2806, | |
18 | & 47.82, -12.36, -56.72, 0.04054, -0.4365, 0.6062, | |
19 | & 5.441, -56.89, -50.27, 15.13, 114.3, -18.19, | |
20 | & 97.05, -1.890, -139.9, 0.08153, -0.4984, 0.9439, | |
21 | & -17.65, 51.44, -58.32, 70.95, -255.7, -78.99, | |
22 | & 476.9, 29.65, -239.3, 0.4745, -1.174, 6.081/ | |
23 | ||
24 | C...Dilogarithm of x for x<0.5 (x>0.5 obtained by analytic trick). | |
25 | DILOG(X)=X+X**2/4.+X**3/9.+X**4/16.+X**5/25.+X**6/36.+X**7/49. | |
26 | ||
27 | C...Event type. Mass effect factors and other common constants. | |
28 | MSTJ(120)=2 | |
29 | MSTJ(121)=0 | |
30 | PMQ=ULMASS_HIJING(KFL) | |
31 | QME=(2.*PMQ/ECM)**2 | |
32 | IF(MSTJ(109).NE.1) THEN | |
33 | CUTL=LOG(CUT) | |
34 | CUTD=LOG(1./CUT-2.) | |
35 | IF(MSTJ(109).EQ.0) THEN | |
36 | CF=4./3. | |
37 | CN=3. | |
38 | TR=2. | |
39 | WTMX=MIN(20.,37.-6.*CUTD) | |
40 | IF(MSTJ(110).EQ.2) WTMX=2.*(7.5+80.*CUT) | |
41 | ELSE | |
42 | CF=1. | |
43 | CN=0. | |
44 | TR=12. | |
45 | WTMX=0. | |
46 | ENDIF | |
47 | ||
48 | C...Alpha_strong and effects of optimized Q^2 scale. Maximum weight. | |
49 | ALS2PI=PARU(118)/PARU(2) | |
50 | WTOPT=0. | |
51 | IF(MSTJ(111).EQ.1) WTOPT=(33.-2.*MSTU(112))/6.*LOG(PARJ(169))* | |
52 | & ALS2PI | |
53 | WTMAX=MAX(0.,1.+WTOPT+ALS2PI*WTMX) | |
54 | ||
55 | C...Choose three-jet events in allowed region. | |
56 | 100 NJET=3 | |
57 | 110 Y13L=CUTL+CUTD*RLU_HIJING(0) | |
58 | Y23L=CUTL+CUTD*RLU_HIJING(0) | |
59 | Y13=EXP(Y13L) | |
60 | Y23=EXP(Y23L) | |
61 | Y12=1.-Y13-Y23 | |
62 | IF(Y12.LE.CUT) GOTO 110 | |
63 | IF(Y13**2+Y23**2+2.*Y12.LE.2.*RLU_HIJING(0)) GOTO 110 | |
64 | ||
65 | C...Second order corrections. | |
66 | IF(MSTJ(101).EQ.2.AND.MSTJ(110).LE.1) THEN | |
67 | Y12L=LOG(Y12) | |
68 | Y13M=LOG(1.-Y13) | |
69 | Y23M=LOG(1.-Y23) | |
70 | Y12M=LOG(1.-Y12) | |
71 | IF(Y13.LE.0.5) Y13I=DILOG(Y13) | |
72 | IF(Y13.GE.0.5) Y13I=1.644934-Y13L*Y13M-DILOG(1.-Y13) | |
73 | IF(Y23.LE.0.5) Y23I=DILOG(Y23) | |
74 | IF(Y23.GE.0.5) Y23I=1.644934-Y23L*Y23M-DILOG(1.-Y23) | |
75 | IF(Y12.LE.0.5) Y12I=DILOG(Y12) | |
76 | IF(Y12.GE.0.5) Y12I=1.644934-Y12L*Y12M-DILOG(1.-Y12) | |
77 | WT1=(Y13**2+Y23**2+2.*Y12)/(Y13*Y23) | |
78 | WT2=CF*(-2.*(CUTL-Y12L)**2-3.*CUTL-1.+3.289868+ | |
79 | & 2.*(2.*CUTL-Y12L)*CUT/Y12)+ | |
80 | & CN*((CUTL-Y12L)**2-(CUTL-Y13L)**2-(CUTL-Y23L)**2-11.*CUTL/6.+ | |
81 | & 67./18.+1.644934-(2.*CUTL-Y12L)*CUT/Y12+(2.*CUTL-Y13L)* | |
82 | & CUT/Y13+(2.*CUTL-Y23L)*CUT/Y23)+ | |
83 | & TR*(2.*CUTL/3.-10./9.)+ | |
84 | & CF*(Y12/(Y12+Y13)+Y12/(Y12+Y23)+(Y12+Y23)/Y13+(Y12+Y13)/Y23+ | |
85 | & Y13L*(4.*Y12**2+2.*Y12*Y13+4.*Y12*Y23+Y13*Y23)/(Y12+Y23)**2+ | |
86 | & Y23L*(4.*Y12**2+2.*Y12*Y23+4.*Y12*Y13+Y13*Y23)/(Y12+Y13)**2)/ | |
87 | & WT1+ | |
88 | & CN*(Y13L*Y13/(Y12+Y23)+Y23L*Y23/(Y12+Y13))/WT1+ | |
89 | & (CN-2.*CF)*((Y12**2+(Y12+Y13)**2)*(Y12L*Y23L-Y12L*Y12M-Y23L* | |
90 | & Y23M+1.644934-Y12I-Y23I)/(Y13*Y23)+(Y12**2+(Y12+Y23)**2)* | |
91 | & (Y12L*Y13L-Y12L*Y12M-Y13L*Y13M+1.644934-Y12I-Y13I)/ | |
92 | & (Y13*Y23)+(Y13**2+Y23**2)/(Y13*Y23*(Y13+Y23))- | |
93 | & 2.*Y12L*Y12**2/(Y13+Y23)**2-4.*Y12L*Y12/(Y13+Y23))/WT1- | |
94 | & CN*(Y13L*Y23L-Y13L*Y13M-Y23L*Y23M+1.644934-Y13I-Y23I) | |
95 | IF(1.+WTOPT+ALS2PI*WT2.LE.0.) MSTJ(121)=1 | |
96 | IF(1.+WTOPT+ALS2PI*WT2.LE.WTMAX*RLU_HIJING(0)) GOTO 110 | |
97 | PARJ(156)=(WTOPT+ALS2PI*WT2)/(1.+WTOPT+ALS2PI*WT2) | |
98 | ||
99 | ELSEIF(MSTJ(101).EQ.2.AND.MSTJ(110).EQ.2) THEN | |
100 | C...Second order corrections; Zhu parametrization of ERT. | |
101 | ZX=(Y23-Y13)**2 | |
102 | ZY=1.-Y12 | |
103 | IZA=0 | |
104 | DO 120 IY=1,5 | |
105 | 120 IF(ABS(CUT-0.01*IY).LT.0.0001) IZA=IY | |
106 | IF(IZA.NE.0) THEN | |
107 | IZ=IZA | |
108 | WT2=ZHUP(IZ,1)+ZHUP(IZ,2)*ZX+ZHUP(IZ,3)*ZX**2+(ZHUP(IZ,4)+ | |
109 | & ZHUP(IZ,5)*ZX)*ZY+(ZHUP(IZ,6)+ZHUP(IZ,7)*ZX)*ZY**2+ | |
110 | & (ZHUP(IZ,8)+ZHUP(IZ,9)*ZX)*ZY**3+ZHUP(IZ,10)/(ZX-ZY**2)+ | |
111 | & ZHUP(IZ,11)/(1.-ZY)+ZHUP(IZ,12)/ZY | |
112 | ELSE | |
113 | IZ=100.*CUT | |
114 | WTL=ZHUP(IZ,1)+ZHUP(IZ,2)*ZX+ZHUP(IZ,3)*ZX**2+(ZHUP(IZ,4)+ | |
115 | & ZHUP(IZ,5)*ZX)*ZY+(ZHUP(IZ,6)+ZHUP(IZ,7)*ZX)*ZY**2+ | |
116 | & (ZHUP(IZ,8)+ZHUP(IZ,9)*ZX)*ZY**3+ZHUP(IZ,10)/(ZX-ZY**2)+ | |
117 | & ZHUP(IZ,11)/(1.-ZY)+ZHUP(IZ,12)/ZY | |
118 | IZ=IZ+1 | |
119 | WTU=ZHUP(IZ,1)+ZHUP(IZ,2)*ZX+ZHUP(IZ,3)*ZX**2+(ZHUP(IZ,4)+ | |
120 | & ZHUP(IZ,5)*ZX)*ZY+(ZHUP(IZ,6)+ZHUP(IZ,7)*ZX)*ZY**2+ | |
121 | & (ZHUP(IZ,8)+ZHUP(IZ,9)*ZX)*ZY**3+ZHUP(IZ,10)/(ZX-ZY**2)+ | |
122 | & ZHUP(IZ,11)/(1.-ZY)+ZHUP(IZ,12)/ZY | |
123 | WT2=WTL+(WTU-WTL)*(100.*CUT+1.-IZ) | |
124 | ENDIF | |
125 | IF(1.+WTOPT+2.*ALS2PI*WT2.LE.0.) MSTJ(121)=1 | |
126 | IF(1.+WTOPT+2.*ALS2PI*WT2.LE.WTMAX*RLU_HIJING(0)) GOTO 110 | |
127 | PARJ(156)=(WTOPT+2.*ALS2PI*WT2)/(1.+WTOPT+2.*ALS2PI*WT2) | |
128 | ENDIF | |
129 | ||
130 | C...Impose mass cuts (gives two jets). For fixed jet number new try. | |
131 | X1=1.-Y23 | |
132 | X2=1.-Y13 | |
133 | X3=1.-Y12 | |
134 | IF(4.*Y23*Y13*Y12/X3**2.LE.QME) NJET=2 | |
135 | IF(MOD(MSTJ(103),4).GE.2.AND.IABS(MSTJ(101)).LE.1.AND.QME*X3+ | |
136 | & 0.5*QME**2+(0.5*QME+0.25*QME**2)*((1.-X2)/(1.-X1)+ | |
137 | & (1.-X1)/(1.-X2)).GT.(X1**2+X2**2)*RLU_HIJING(0)) NJET=2 | |
138 | IF(MSTJ(101).EQ.-1.AND.NJET.EQ.2) GOTO 100 | |
139 | ||
140 | C...Scalar gluon model (first order only, no mass effects). | |
141 | ELSE | |
142 | 130 NJET=3 | |
143 | 140 Y12=SQRT(4.*CUT**2+RLU_HIJING(0)*((1.-CUT)**2-4.*CUT**2)) | |
144 | IF(LOG((Y12-CUT)/CUT).LE.RLU_HIJING(0)*LOG((1.-2.*CUT)/CUT)) | |
145 | $ GOTO 140 | |
146 | YD=SIGN(2.*CUT*((Y12-CUT)/CUT)**RLU_HIJING(0)-Y12,RLU_HIJING(0) | |
147 | $ -0.5) | |
148 | X1=1.-0.5*(Y12+YD) | |
149 | X2=1.-0.5*(Y12-YD) | |
150 | IF(4.*(1.-X1)*(1.-X2)*Y12/(1.-Y12)**2.LE.QME) NJET=2 | |
151 | IF(MSTJ(101).EQ.-1.AND.NJET.EQ.2) GOTO 130 | |
152 | ENDIF | |
153 | ||
154 | RETURN | |
155 | END |