1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
|
subroutine ssssxx(s1,s2,s3,s4,gc , vertex)
c
c This subroutine computes an amplitude of the four-scalar coupling.
c
c input:
c complex s1(3) : first scalar s1
c complex s2(3) : second scalar s2
c complex s3(3) : third scalar s3
c complex s4(3) : fourth scalar s4
c complex gc : coupling constant ghhhh
c
c output:
c complex vertex : amplitude gamma(s1,s2,s3,s4)
c
implicit none
double complex s1(3),s2(3),s3(3),s4(3),gc,vertex
#ifdef HELAS_CHECK
double precision p0,p1,p2,p3,q0,q1,q2,q3,r0,r1,r2,r3,o0,o1,o2,o3,
& pm
double precision epsi
parameter( epsi = 4.0d-5 )
double precision rZero
parameter( rZero = 0.0d0 )
double complex cZero
parameter( cZero = ( 0.0d0, 0.0d0 ) )
integer stdo
parameter( stdo = 6 )
#endif
c
#ifdef HELAS_CHECK
p0 = dble( s1(2))
p1 = dble( s1(3))
p2 = dimag(s1(3))
p3 = dimag(s1(2))
q0 = dble( s2(2))
q1 = dble( s2(3))
q2 = dimag(s2(3))
q3 = dimag(s2(2))
r0 = dble( s3(2))
r1 = dble( s3(3))
r2 = dimag(s3(3))
r3 = dimag(s3(2))
o0 = dble( s4(2))
o1 = dble( s4(3))
o2 = dimag(s4(3))
o3 = dimag(s4(2))
if ( s1(1).eq.cZero ) then
write(stdo,*) ' helas-warn : s1 in ssssxx is zero scalar'
endif
if ( abs(s1(2))+abs(s1(3)).eq.rZero ) then
write(stdo,*)
& ' helas-error : s1 in ssssxx has zero momentum'
endif
if ( s2(1).eq.cZero ) then
write(stdo,*) ' helas-warn : s2 in ssssxx is zero scalar'
endif
if ( abs(s2(2))+abs(s2(3)).eq.rZero ) then
write(stdo,*)
& ' helas-error : s2 in ssssxx has zero momentum'
endif
if ( s3(1).eq.cZero ) then
write(stdo,*) ' helas-warn : s3 in ssssxx is zero scalar'
endif
if ( abs(s3(2))+abs(s3(3)).eq.rZero ) then
write(stdo,*)
& ' helas-error : s3 in ssssxx has zero momentum'
endif
if ( s4(1).eq.cZero ) then
write(stdo,*) ' helas-warn : s4 in ssssxx is zero scalar'
endif
if ( abs(s4(2))+abs(s4(3)).eq.rZero ) then
write(stdo,*)
& ' helas-error : s4 in ssssxx has zero momentum'
endif
pm = max( abs(p0),abs(q0),abs(r0),abs(o0),
& abs(p1),abs(q1),abs(r1),abs(o1),
& abs(p2),abs(q2),abs(r2),abs(o2),
& abs(p3),abs(q3),abs(r3),abs(o3) )
if ( abs(s1(2)+s2(2)+s3(2)+s4(2))
& +abs(s1(3)+s2(3)+s3(3)+s4(3)).ge.pm*epsi ) then
write(stdo,*)
& ' helas-error : s1,s2,s3,s4 in ssssxx'
write(stdo,*)
& ' : have not balanced momenta'
endif
if ( gc.eq.cZero ) then
write(stdo,*) ' helas-error : g in ssssxx is zero coupling'
endif
#endif
vertex = gc*s1(1)*s2(1)*s3(1)*s4(1)
c
return
end
|