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Commit | Line | Data |
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3820ca8e | 1 | |
2 | CDECK ID>, HWHIGA. | |
3 | ||
4 | *CMZ :- -23/08/94 13.22.29 by Mike Seymour | |
5 | ||
6 | *-- Author : Ulrich Baur & Nigel Glover, adapted by Ian Knowles | |
7 | ||
8 | C----------------------------------------------------------------------- | |
9 | ||
10 | SUBROUTINE HWHIGA(S,T,U,EMH2,WTQQ,WTQG,WTGQ,WTGG) | |
11 | ||
12 | C----------------------------------------------------------------------- | |
13 | ||
14 | C Gives amplitudes squared for q-qbar, q(bar)-g and gg -> Higgs +jet | |
15 | ||
16 | C IAPHIG (set in HWIGIN)=0: zero mass approximation =1: exact result | |
17 | ||
18 | C =2: infinite mass limit. | |
19 | ||
20 | C Only top loop included. A factor (alpha_s**3*alpha_W) is extracted | |
21 | ||
22 | C----------------------------------------------------------------------- | |
23 | ||
24 | INCLUDE 'HERWIG61.INC' | |
25 | ||
26 | DOUBLE COMPLEX HWHIGB,HWHIGC,HWHIGD,HWHIG5,HWHIG1,HWHIG2,BI(4), | |
27 | ||
28 | & CI(7),DI(3),EPSI,TAMP(7) | |
29 | ||
30 | DOUBLE PRECISION S,T,U,EMH2,WTQQ,WTQG,WTGQ,WTGG,EMW2,RNGLU,RNQRK, | |
31 | ||
32 | & FLUXGG,FLUXGQ,FLUXQQ,EMQ2,TAMPI(7),TAMPR(7) | |
33 | ||
34 | INTEGER I | |
35 | ||
36 | LOGICAL NOMASS | |
37 | ||
38 | EXTERNAL HWHIGB,HWHIGC,HWHIGD,HWHIG5,HWHIG1,HWHIG2 | |
39 | ||
40 | COMMON/SMALL/EPSI | |
41 | ||
42 | COMMON/CINTS/BI,CI,DI | |
43 | ||
44 | EPSI=CMPLX(ZERO,-1.D-10) | |
45 | ||
46 | EMW2=RMASS(198)**2 | |
47 | ||
48 | C Spin and colour flux factors plus enhancement factor | |
49 | ||
50 | RNGLU=1./FLOAT(NCOLO**2-1) | |
51 | ||
52 | RNQRK=1./FLOAT(NCOLO) | |
53 | ||
54 | FLUXGG=.25*RNGLU**2*ENHANC(6)**2 | |
55 | ||
56 | FLUXGQ=.25*RNGLU*RNQRK*ENHANC(6)**2 | |
57 | ||
58 | FLUXQQ=.25*RNQRK**2*ENHANC(6)**2 | |
59 | ||
60 | IF (IAPHIG.EQ.2) THEN | |
61 | ||
62 | C Infinite mass limit in loops | |
63 | ||
64 | WTGG=2./3.*FLOAT(NCOLO*(NCOLO**2-1)) | |
65 | ||
66 | & *(EMH2**4+S**4+T**4+U**4)/(S*T*U*EMW2)*FLUXGG | |
67 | ||
68 | WTQQ= 16./9.*(U**2+T**2)/(S*EMW2)*FLUXQQ | |
69 | ||
70 | WTQG=-16./9.*(U**2+S**2)/(T*EMW2)*FLUXGQ | |
71 | ||
72 | WTGQ=-16./9.*(S**2+T**2)/(U*EMW2)*FLUXGQ | |
73 | ||
74 | RETURN | |
75 | ||
76 | ELSEIF (IAPHIG.EQ.1) THEN | |
77 | ||
78 | C Exact result for loops | |
79 | ||
80 | NOMASS=.FALSE. | |
81 | ||
82 | ELSEIF (IAPHIG.EQ.0) THEN | |
83 | ||
84 | C Small mass approximation in loops | |
85 | ||
86 | NOMASS=.TRUE. | |
87 | ||
88 | ELSE | |
89 | ||
90 | CALL HWWARN('HWHIGA',500,*999) | |
91 | ||
92 | ENDIF | |
93 | ||
94 | C Include only top quark contribution | |
95 | ||
96 | EMQ2=RMASS(6)**2 | |
97 | ||
98 | BI(1)=HWHIGB(NOMASS,S,ZERO,ZERO,EMQ2) | |
99 | ||
100 | BI(2)=HWHIGB(NOMASS,T,ZERO,ZERO,EMQ2) | |
101 | ||
102 | BI(3)=HWHIGB(NOMASS,U,ZERO,ZERO,EMQ2) | |
103 | ||
104 | BI(4)=HWHIGB(NOMASS,EMH2,ZERO,ZERO,EMQ2) | |
105 | ||
106 | BI(1)=BI(1)-BI(4) | |
107 | ||
108 | BI(2)=BI(2)-BI(4) | |
109 | ||
110 | BI(3)=BI(3)-BI(4) | |
111 | ||
112 | CI(1)=HWHIGC(NOMASS,S,ZERO,ZERO,EMQ2) | |
113 | ||
114 | CI(2)=HWHIGC(NOMASS,T,ZERO,ZERO,EMQ2) | |
115 | ||
116 | CI(3)=HWHIGC(NOMASS,U,ZERO,ZERO,EMQ2) | |
117 | ||
118 | CI(7)=HWHIGC(NOMASS,EMH2,ZERO,ZERO,EMQ2) | |
119 | ||
120 | CI(4)=(S*CI(1)-EMH2*CI(7))/(S-EMH2) | |
121 | ||
122 | CI(5)=(T*CI(2)-EMH2*CI(7))/(T-EMH2) | |
123 | ||
124 | CI(6)=(U*CI(3)-EMH2*CI(7))/(U-EMH2) | |
125 | ||
126 | DI(1)=HWHIGD(NOMASS,U,T,EMH2,EMQ2) | |
127 | ||
128 | DI(2)=HWHIGD(NOMASS,S,U,EMH2,EMQ2) | |
129 | ||
130 | DI(3)=HWHIGD(NOMASS,S,T,EMH2,EMQ2) | |
131 | ||
132 | C Compute complex amplitudes | |
133 | ||
134 | TAMP(1)=HWHIG1(S,T,U,EMH2,EMQ2,1,2,3,4,5,6) | |
135 | ||
136 | TAMP(2)=HWHIG2(S,T,U,EMH2,EMQ2,1,2,3,0,0,0) | |
137 | ||
138 | TAMP(3)=HWHIG1(T,S,U,EMH2,EMQ2,2,1,3,5,4,6) | |
139 | ||
140 | TAMP(4)=HWHIG1(U,T,S,EMH2,EMQ2,3,2,1,6,5,4) | |
141 | ||
142 | TAMP(5)=HWHIG5(S,T,U,EMH2,EMQ2,1,0,4,0,0,0) | |
143 | ||
144 | TAMP(6)=HWHIG5(T,S,U,EMH2,EMQ2,2,0,5,0,0,0) | |
145 | ||
146 | TAMP(7)=HWHIG5(U,T,S,EMH2,EMQ2,3,0,6,0,0,0) | |
147 | ||
148 | DO 20 I=1,7 | |
149 | ||
150 | TAMPI(I)= DBLE(TAMP(I)) | |
151 | ||
152 | 20 TAMPR(I)=-IMAG(TAMP(I)) | |
153 | ||
154 | C Square and add prefactors | |
155 | ||
156 | WTGG=0.03125*FLOAT(NCOLO*(NCOLO**2-1)) | |
157 | ||
158 | & *(TAMPR(1)**2+TAMPI(1)**2+TAMPR(2)**2+TAMPI(2)**2 | |
159 | ||
160 | & +TAMPR(3)**2+TAMPI(3)**2+TAMPR(4)**2+TAMPI(4)**2)*FLUXGG | |
161 | ||
162 | WTQQ= 16.*(U**2+T**2)/(U+T)**2*EMQ2**2/(S*EMW2) | |
163 | ||
164 | & *(TAMPR(5)**2+TAMPI(5)**2)*FLUXQQ | |
165 | ||
166 | WTQG=-16.*(U**2+S**2)/(U+S)**2*EMQ2**2/(T*EMW2) | |
167 | ||
168 | & *(TAMPR(6)**2+TAMPI(6)**2)*FLUXGQ | |
169 | ||
170 | WTGQ=-16.*(S**2+T**2)/(S+T)**2*EMQ2**2/(U*EMW2) | |
171 | ||
172 | & *(TAMPR(7)**2+TAMPI(7)**2)*FLUXGQ | |
173 | ||
174 | 999 RETURN | |
175 | ||
176 | END |