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e74335a4 | 1 | * $Id$ |
2 | ||
3 | C********************************************************************* | |
4 | ||
5 | SUBROUTINE LUJMAS_HIJING(PMH,PML) | |
6 | ||
7 | C...Purpose: to determine, approximately, the two jet masses that | |
8 | C...minimize the sum m_H|2 + m_L|2, a la Clavelli and Wyler. | |
9 | #include "lujets_hijing.inc" | |
10 | #include "ludat1_hijing.inc" | |
11 | #include "ludat2_hijing.inc" | |
12 | DIMENSION SM(3,3),SAX(3),PS(3,5) | |
13 | ||
14 | C...Reset. | |
15 | NP=0 | |
16 | DO 110 J1=1,3 | |
17 | DO 100 J2=J1,3 | |
18 | 100 SM(J1,J2)=0. | |
19 | DO 110 J2=1,4 | |
20 | 110 PS(J1,J2)=0. | |
21 | PSS=0. | |
22 | ||
23 | C...Take copy of particles that are to be considered in mass analysis. | |
24 | DO 150 I=1,N | |
25 | IF(K(I,1).LE.0.OR.K(I,1).GT.10) GOTO 150 | |
26 | IF(MSTU(41).GE.2) THEN | |
27 | KC=LUCOMP_HIJING(K(I,2)) | |
28 | IF(KC.EQ.0.OR.KC.EQ.12.OR.KC.EQ.14.OR.KC.EQ.16.OR. | |
29 | & KC.EQ.18) GOTO 150 | |
30 | IF(MSTU(41).GE.3.AND.KCHG(KC,2).EQ.0.AND.LUCHGE_HIJING(K(I,2)) | |
31 | $ .EQ.0)GOTO 150 | |
32 | ENDIF | |
33 | IF(N+NP+1.GE.MSTU(4)-MSTU(32)-5) THEN | |
34 | CALL LUERRM_HIJING(11 | |
35 | $ ,'(LUJMAS_HIJING:) no more memory left in LUJETS_HIJING') | |
36 | PMH=-2. | |
37 | PML=-2. | |
38 | RETURN | |
39 | ENDIF | |
40 | NP=NP+1 | |
41 | DO 120 J=1,5 | |
42 | 120 P(N+NP,J)=P(I,J) | |
43 | IF(MSTU(42).EQ.0) P(N+NP,5)=0. | |
44 | IF(MSTU(42).EQ.1.AND.K(I,2).NE.22) P(N+NP,5)=PMAS(101,1) | |
45 | P(N+NP,4)=SQRT(P(N+NP,5)**2+P(I,1)**2+P(I,2)**2+P(I,3)**2) | |
46 | ||
47 | C...Fill information in sphericity tensor and total momentum vector. | |
48 | DO 130 J1=1,3 | |
49 | DO 130 J2=J1,3 | |
50 | 130 SM(J1,J2)=SM(J1,J2)+P(I,J1)*P(I,J2) | |
51 | PSS=PSS+(P(I,1)**2+P(I,2)**2+P(I,3)**2) | |
52 | DO 140 J=1,4 | |
53 | 140 PS(3,J)=PS(3,J)+P(N+NP,J) | |
54 | 150 CONTINUE | |
55 | ||
56 | C...Very low multiplicities (0 or 1) not considered. | |
57 | IF(NP.LE.1) THEN | |
58 | CALL LUERRM_HIJING(8 | |
59 | $ ,'(LUJMAS_HIJING:) too few particles for analysis') | |
60 | PMH=-1. | |
61 | PML=-1. | |
62 | RETURN | |
63 | ENDIF | |
64 | PARU(61)=SQRT(MAX(0.,PS(3,4)**2-PS(3,1)**2-PS(3,2)**2-PS(3,3)**2)) | |
65 | ||
66 | C...Find largest eigenvalue to matrix (third degree equation). | |
67 | DO 160 J1=1,3 | |
68 | DO 160 J2=J1,3 | |
69 | 160 SM(J1,J2)=SM(J1,J2)/PSS | |
70 | SQ=(SM(1,1)*SM(2,2)+SM(1,1)*SM(3,3)+SM(2,2)*SM(3,3)-SM(1,2)**2- | |
71 | &SM(1,3)**2-SM(2,3)**2)/3.-1./9. | |
72 | SR=-0.5*(SQ+1./9.+SM(1,1)*SM(2,3)**2+SM(2,2)*SM(1,3)**2+SM(3,3)* | |
73 | &SM(1,2)**2-SM(1,1)*SM(2,2)*SM(3,3))+SM(1,2)*SM(1,3)*SM(2,3)+1./27. | |
74 | SP=COS(ACOS(MAX(MIN(SR/SQRT(-SQ**3),1.),-1.))/3.) | |
75 | SMA=1./3.+SQRT(-SQ)*MAX(2.*SP,SQRT(3.*(1.-SP**2))-SP) | |
76 | ||
77 | C...Find largest eigenvector by solving equation system. | |
78 | DO 170 J1=1,3 | |
79 | SM(J1,J1)=SM(J1,J1)-SMA | |
80 | DO 170 J2=J1+1,3 | |
81 | 170 SM(J2,J1)=SM(J1,J2) | |
82 | SMAX=0. | |
83 | DO 180 J1=1,3 | |
84 | DO 180 J2=1,3 | |
85 | IF(ABS(SM(J1,J2)).LE.SMAX) GOTO 180 | |
86 | JA=J1 | |
87 | JB=J2 | |
88 | SMAX=ABS(SM(J1,J2)) | |
89 | 180 CONTINUE | |
90 | SMAX=0. | |
91 | DO 190 J3=JA+1,JA+2 | |
92 | J1=J3-3*((J3-1)/3) | |
93 | RL=SM(J1,JB)/SM(JA,JB) | |
94 | DO 190 J2=1,3 | |
95 | SM(J1,J2)=SM(J1,J2)-RL*SM(JA,J2) | |
96 | IF(ABS(SM(J1,J2)).LE.SMAX) GOTO 190 | |
97 | JC=J1 | |
98 | SMAX=ABS(SM(J1,J2)) | |
99 | 190 CONTINUE | |
100 | JB1=JB+1-3*(JB/3) | |
101 | JB2=JB+2-3*((JB+1)/3) | |
102 | SAX(JB1)=-SM(JC,JB2) | |
103 | SAX(JB2)=SM(JC,JB1) | |
104 | SAX(JB)=-(SM(JA,JB1)*SAX(JB1)+SM(JA,JB2)*SAX(JB2))/SM(JA,JB) | |
105 | ||
106 | C...Divide particles into two initial clusters by hemisphere. | |
107 | DO 200 I=N+1,N+NP | |
108 | PSAX=P(I,1)*SAX(1)+P(I,2)*SAX(2)+P(I,3)*SAX(3) | |
109 | IS=1 | |
110 | IF(PSAX.LT.0.) IS=2 | |
111 | K(I,3)=IS | |
112 | DO 200 J=1,4 | |
113 | 200 PS(IS,J)=PS(IS,J)+P(I,J) | |
114 | PMS=(PS(1,4)**2-PS(1,1)**2-PS(1,2)**2-PS(1,3)**2)+ | |
115 | &(PS(2,4)**2-PS(2,1)**2-PS(2,2)**2-PS(2,3)**2) | |
116 | ||
117 | C...Reassign one particle at a time; find maximum decrease of m|2 sum. | |
118 | 210 PMD=0. | |
119 | IM=0 | |
120 | DO 220 J=1,4 | |
121 | 220 PS(3,J)=PS(1,J)-PS(2,J) | |
122 | DO 230 I=N+1,N+NP | |
123 | PPS=P(I,4)*PS(3,4)-P(I,1)*PS(3,1)-P(I,2)*PS(3,2)-P(I,3)*PS(3,3) | |
124 | IF(K(I,3).EQ.1) PMDI=2.*(P(I,5)**2-PPS) | |
125 | IF(K(I,3).EQ.2) PMDI=2.*(P(I,5)**2+PPS) | |
126 | IF(PMDI.LT.PMD) THEN | |
127 | PMD=PMDI | |
128 | IM=I | |
129 | ENDIF | |
130 | 230 CONTINUE | |
131 | ||
132 | C...Loop back if significant reduction in sum of m|2. | |
133 | IF(PMD.LT.-PARU(48)*PMS) THEN | |
134 | PMS=PMS+PMD | |
135 | IS=K(IM,3) | |
136 | DO 240 J=1,4 | |
137 | PS(IS,J)=PS(IS,J)-P(IM,J) | |
138 | 240 PS(3-IS,J)=PS(3-IS,J)+P(IM,J) | |
139 | K(IM,3)=3-IS | |
140 | GOTO 210 | |
141 | ENDIF | |
142 | ||
143 | C...Final masses and output. | |
144 | MSTU(61)=N+1 | |
145 | MSTU(62)=NP | |
146 | PS(1,5)=SQRT(MAX(0.,PS(1,4)**2-PS(1,1)**2-PS(1,2)**2-PS(1,3)**2)) | |
147 | PS(2,5)=SQRT(MAX(0.,PS(2,4)**2-PS(2,1)**2-PS(2,2)**2-PS(2,3)**2)) | |
148 | PMH=MAX(PS(1,5),PS(2,5)) | |
149 | PML=MIN(PS(1,5),PS(2,5)) | |
150 | ||
151 | RETURN | |
152 | END |