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Commit | Line | Data |
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fe4da5cc | 1 | |
2 | C********************************************************************* | |
3 | ||
4 | SUBROUTINE LU4ENT(IP,KF1,KF2,KF3,KF4,PECM,X1,X2,X4,X12,X14) | |
5 | ||
6 | C...Purpose: to store four partons or particles in their CM frame, with | |
7 | C...the first along the +z axis, the last in the xz plane with x > 0 | |
8 | C...and the second having y < 0 and y > 0 with equal probability. | |
9 | COMMON/LUJETS/N,K(4000,5),P(4000,5),V(4000,5) | |
10 | COMMON/LUDAT1/MSTU(200),PARU(200),MSTJ(200),PARJ(200) | |
11 | COMMON/LUDAT2/KCHG(500,3),PMAS(500,4),PARF(2000),VCKM(4,4) | |
12 | SAVE /LUJETS/,/LUDAT1/,/LUDAT2/ | |
13 | ||
14 | C...Standard checks. | |
15 | MSTU(28)=0 | |
16 | IF(MSTU(12).GE.1) CALL LULIST(0) | |
17 | IPA=MAX(1,IABS(IP)) | |
18 | IF(IPA.GT.MSTU(4)-3) CALL LUERRM(21, | |
19 | &'(LU4ENT:) writing outside LUJETS momory') | |
20 | KC1=LUCOMP(KF1) | |
21 | KC2=LUCOMP(KF2) | |
22 | KC3=LUCOMP(KF3) | |
23 | KC4=LUCOMP(KF4) | |
24 | IF(KC1.EQ.0.OR.KC2.EQ.0.OR.KC3.EQ.0.OR.KC4.EQ.0) CALL LUERRM(12, | |
25 | &'(LU4ENT:) unknown flavour code') | |
26 | ||
27 | C...Find masses. Reset K, P and V vectors. | |
28 | PM1=0. | |
29 | IF(MSTU(10).EQ.1) PM1=P(IPA,5) | |
30 | IF(MSTU(10).GE.2) PM1=ULMASS(KF1) | |
31 | PM2=0. | |
32 | IF(MSTU(10).EQ.1) PM2=P(IPA+1,5) | |
33 | IF(MSTU(10).GE.2) PM2=ULMASS(KF2) | |
34 | PM3=0. | |
35 | IF(MSTU(10).EQ.1) PM3=P(IPA+2,5) | |
36 | IF(MSTU(10).GE.2) PM3=ULMASS(KF3) | |
37 | PM4=0. | |
38 | IF(MSTU(10).EQ.1) PM4=P(IPA+3,5) | |
39 | IF(MSTU(10).GE.2) PM4=ULMASS(KF4) | |
40 | DO 110 I=IPA,IPA+3 | |
41 | DO 100 J=1,5 | |
42 | K(I,J)=0 | |
43 | P(I,J)=0. | |
44 | V(I,J)=0. | |
45 | 100 CONTINUE | |
46 | 110 CONTINUE | |
47 | ||
48 | C...Check flavours. | |
49 | KQ1=KCHG(KC1,2)*ISIGN(1,KF1) | |
50 | KQ2=KCHG(KC2,2)*ISIGN(1,KF2) | |
51 | KQ3=KCHG(KC3,2)*ISIGN(1,KF3) | |
52 | KQ4=KCHG(KC4,2)*ISIGN(1,KF4) | |
53 | IF(MSTU(19).EQ.1) THEN | |
54 | MSTU(19)=0 | |
55 | ELSEIF(KQ1.EQ.0.AND.KQ2.EQ.0.AND.KQ3.EQ.0.AND.KQ4.EQ.0) THEN | |
56 | ELSEIF(KQ1.NE.0.AND.KQ2.EQ.2.AND.KQ3.EQ.2.AND.(KQ1+KQ4.EQ.0.OR. | |
57 | &KQ1+KQ4.EQ.4)) THEN | |
58 | ELSEIF(KQ1.NE.0.AND.KQ1+KQ2.EQ.0.AND.KQ3.NE.0.AND.KQ3+KQ4.EQ.0.) | |
59 | &THEN | |
60 | ELSE | |
61 | CALL LUERRM(2,'(LU4ENT:) unphysical flavour combination') | |
62 | ENDIF | |
63 | K(IPA,2)=KF1 | |
64 | K(IPA+1,2)=KF2 | |
65 | K(IPA+2,2)=KF3 | |
66 | K(IPA+3,2)=KF4 | |
67 | ||
68 | C...Store partons/particles in K vectors for normal case. | |
69 | IF(IP.GE.0) THEN | |
70 | K(IPA,1)=1 | |
71 | IF(KQ1.NE.0.AND.(KQ2.NE.0.OR.KQ3.NE.0.OR.KQ4.NE.0)) K(IPA,1)=2 | |
72 | K(IPA+1,1)=1 | |
73 | IF(KQ2.NE.0.AND.KQ1+KQ2.NE.0.AND.(KQ3.NE.0.OR.KQ4.NE.0)) | |
74 | & K(IPA+1,1)=2 | |
75 | K(IPA+2,1)=1 | |
76 | IF(KQ3.NE.0.AND.KQ4.NE.0) K(IPA+2,1)=2 | |
77 | K(IPA+3,1)=1 | |
78 | ||
79 | C...Store partons for parton shower evolution from q-g-g-qbar or | |
80 | C...g-g-g-g event. | |
81 | ELSEIF(KQ1+KQ2.NE.0) THEN | |
82 | K(IPA,1)=3 | |
83 | K(IPA+1,1)=3 | |
84 | K(IPA+2,1)=3 | |
85 | K(IPA+3,1)=3 | |
86 | KCS=4 | |
87 | IF(KQ1.EQ.-1) KCS=5 | |
88 | K(IPA,KCS)=MSTU(5)*(IPA+1) | |
89 | K(IPA,9-KCS)=MSTU(5)*(IPA+3) | |
90 | K(IPA+1,KCS)=MSTU(5)*(IPA+2) | |
91 | K(IPA+1,9-KCS)=MSTU(5)*IPA | |
92 | K(IPA+2,KCS)=MSTU(5)*(IPA+3) | |
93 | K(IPA+2,9-KCS)=MSTU(5)*(IPA+1) | |
94 | K(IPA+3,KCS)=MSTU(5)*IPA | |
95 | K(IPA+3,9-KCS)=MSTU(5)*(IPA+2) | |
96 | ||
97 | C...Store partons for parton shower evolution from q-qbar-q-qbar event. | |
98 | ELSE | |
99 | K(IPA,1)=3 | |
100 | K(IPA+1,1)=3 | |
101 | K(IPA+2,1)=3 | |
102 | K(IPA+3,1)=3 | |
103 | K(IPA,4)=MSTU(5)*(IPA+1) | |
104 | K(IPA,5)=K(IPA,4) | |
105 | K(IPA+1,4)=MSTU(5)*IPA | |
106 | K(IPA+1,5)=K(IPA+1,4) | |
107 | K(IPA+2,4)=MSTU(5)*(IPA+3) | |
108 | K(IPA+2,5)=K(IPA+2,4) | |
109 | K(IPA+3,4)=MSTU(5)*(IPA+2) | |
110 | K(IPA+3,5)=K(IPA+3,4) | |
111 | ENDIF | |
112 | ||
113 | C...Check kinematics. | |
114 | MKERR=0 | |
115 | IF(0.5*X1*PECM.LE.PM1.OR.0.5*X2*PECM.LE.PM2.OR.0.5*(2.-X1-X2-X4)* | |
116 | &PECM.LE.PM3.OR.0.5*X4*PECM.LE.PM4) MKERR=1 | |
117 | PA1=SQRT(MAX(1E-10,(0.5*X1*PECM)**2-PM1**2)) | |
118 | PA2=SQRT(MAX(1E-10,(0.5*X2*PECM)**2-PM2**2)) | |
119 | PA4=SQRT(MAX(1E-10,(0.5*X4*PECM)**2-PM4**2)) | |
120 | X24=X1+X2+X4-1.-X12-X14+(PM3**2-PM1**2-PM2**2-PM4**2)/PECM**2 | |
121 | CTHE4=(X1*X4-2.*X14)*PECM**2/(4.*PA1*PA4) | |
122 | IF(ABS(CTHE4).GE.1.002) MKERR=1 | |
123 | CTHE4=MAX(-1.,MIN(1.,CTHE4)) | |
124 | STHE4=SQRT(1.-CTHE4**2) | |
125 | CTHE2=(X1*X2-2.*X12)*PECM**2/(4.*PA1*PA2) | |
126 | IF(ABS(CTHE2).GE.1.002) MKERR=1 | |
127 | CTHE2=MAX(-1.,MIN(1.,CTHE2)) | |
128 | STHE2=SQRT(1.-CTHE2**2) | |
129 | CPHI2=((X2*X4-2.*X24)*PECM**2-4.*PA2*CTHE2*PA4*CTHE4)/ | |
130 | &MAX(1E-8*PECM**2,4.*PA2*STHE2*PA4*STHE4) | |
131 | IF(ABS(CPHI2).GE.1.05) MKERR=1 | |
132 | CPHI2=MAX(-1.,MIN(1.,CPHI2)) | |
133 | IF(MKERR.EQ.1) CALL LUERRM(13, | |
134 | &'(LU4ENT:) unphysical kinematical variable setup') | |
135 | ||
136 | C...Store partons/particles in P vectors. | |
137 | P(IPA,3)=PA1 | |
138 | P(IPA,4)=SQRT(PA1**2+PM1**2) | |
139 | P(IPA,5)=PM1 | |
140 | P(IPA+3,1)=PA4*STHE4 | |
141 | P(IPA+3,3)=PA4*CTHE4 | |
142 | P(IPA+3,4)=SQRT(PA4**2+PM4**2) | |
143 | P(IPA+3,5)=PM4 | |
144 | P(IPA+1,1)=PA2*STHE2*CPHI2 | |
145 | P(IPA+1,2)=PA2*STHE2*SQRT(1.-CPHI2**2)*(-1.)**INT(RLU(0)+0.5) | |
146 | P(IPA+1,3)=PA2*CTHE2 | |
147 | P(IPA+1,4)=SQRT(PA2**2+PM2**2) | |
148 | P(IPA+1,5)=PM2 | |
149 | P(IPA+2,1)=-P(IPA+1,1)-P(IPA+3,1) | |
150 | P(IPA+2,2)=-P(IPA+1,2) | |
151 | P(IPA+2,3)=-P(IPA,3)-P(IPA+1,3)-P(IPA+3,3) | |
152 | P(IPA+2,4)=SQRT(P(IPA+2,1)**2+P(IPA+2,2)**2+P(IPA+2,3)**2+PM3**2) | |
153 | P(IPA+2,5)=PM3 | |
154 | ||
155 | C...Set N. Optionally fragment/decay. | |
156 | N=IPA+3 | |
157 | IF(IP.EQ.0) CALL LUEXEC | |
158 | ||
159 | RETURN | |
160 | END |