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c
c ----------------------------------------------------------------------
c
subroutine fsigld(fi,sc,gc,fmass,fwidth,smass,mNLSP,idecay , fsi)
c
c This subroutine computes an off-shell fermion wavefunction from a
c flowing-in external fermion and a scalar boson, for the NLSP-boson-
c Goldstino vertex. The h.c. of the NLSP decay is handled via the
c input parameter idecay.
c
c input:
c complex fi(6) : flow-in fermion |fi>
c complex sc(3) : input scalar s
c complex gc(2) : coupling constants gsf
c real fmass : mass of output fermion f'
c real fwidth : width of output fermion f'
c integer idecay : 1 for NLSP decay to Goldstino
c : -1 for Goldstino to NLSP (h.c. of above)
c
c output:
c complex fsi(6) : off-shell fermion |f',s,fi>
c
implicit none
double complex fi(6), sc(3), gc(2), fsi(6), s1, s2, s3, s4, ds
double complex p14p, p14m, p23p, p23m
double precision pf(0:3), fmass, fwidth, mNLSP, smass, pf2
integer idecay
double complex ci, cZero
parameter( ci = ( 0.0d0, 1.0d0 ), cZero = ( 0.0d0, 0.0d0 ) )
c
fsi(5) = fi(5) - sc(2)
fsi(6) = fi(6) - sc(3)
pf(0) = dble( fsi(5))
pf(1) = dble( fsi(6))
pf(2) = dimag(fsi(6))
pf(3) = dimag(fsi(5))
pf2 = pf(0)**2 - pf(1)**2 - pf(2)**2 - pf(3)**2
if ( idecay.ne.1 .or. idecay.ne.-1 ) then
write(6,*) 'error in idecay of FSIGLD'
stop
end if
p14p = dble(sc(2)) + dimag(sc(2))
p14m = dble(sc(2)) - dimag(sc(2))
p23p = dble(sc(3)) + dimag(sc(3))*ci
p23m = dble(sc(3)) - dimag(sc(3))*ci
ds = -sc(1)/dcmplx( pf2-fmass**2, fmass*fwidth )
s1 = -idecay*gc(1)*fi(1)*smass**2
s2 = -idecay*gc(1)*fi(2)*smass**2
s3 = gc(1)*mNLSP*( fi(1)*p14p + fi(2)*p23m )
s4 = gc(1)*mNLSP*( fi(1)*p23p + fi(2)*p14m )
if ( gc(2).ne.cZero ) then
s1 = s1 + gc(2)*mNLSP*( fi(3)*p14m - fi(4)*p23m )
s2 = s2 + gc(2)*mNLSP*(-fi(3)*p23p + fi(4)*p14p )
s3 = s3 - gc(2)*idecay*fi(3)*smass**2
s4 = s4 - gc(2)*idecay*fi(4)*smass**2
end if
fsi(1) = ( (pf(0)-pf(3))*s3 - dconjg(fsi(6))*s4 + fmass*s1 )*ds
fsi(2) = ( -fsi(6)*s3 + (pf(0)+pf(3))*s4 + fmass*s2 )*ds
fsi(3) = ( (pf(0)+pf(3))*s1 + dconjg(fsi(6))*s2 + fmass*s3 )*ds
fsi(4) = ( fsi(6)*s1 + (pf(0)-pf(3))*s2 + fmass*s4 )*ds
c
return
end
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