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50.9.3
by Johan Alwall
Added Template and HELAS into bzr |
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subroutine jggxxx(v1,v2,g, jvv) |
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c
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c This subroutine computes an off-shell vector current from the three-
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c point gauge boson coupling. The vector propagator is given in Feynman
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c gauge for a massless vector and in unitary gauge for a massive vector.
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c
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c input:
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c complex v1(6) : first vector v1
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c complex v2(6) : second vector v2
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c real g : coupling constant (see the table below)
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c
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c output:
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c complex jvv(6) : vector current j^mu(v:v1,v2)
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c
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implicit none |
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double complex v1(6),v2(6),jvv(6),j12(0:3) |
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double complex sv1,sv2,v12 |
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double precision p1(0:3),p2(0:3),q(0:3),g,gs,s |
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#ifdef HELAS_CHECK
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double precision rZero |
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parameter( rZero = 0.0d0 ) |
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integer stdo |
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parameter( stdo = 6 ) |
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#endif
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c
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#ifdef HELAS_CHECK
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if ( abs(v1(1))+abs(v1(2))+abs(v1(3))+abs(v1(4)).eq.rZero ) then |
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write(stdo,*) ' helas-warn : v1 in jggxxx is zero vector' |
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endif |
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if ( abs(v1(5))+abs(v1(6)).eq.rZero ) then |
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write(stdo,*) |
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& ' helas-error : v1 in jggxxx has zero momentum' |
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endif |
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if (abs(v2(1))+abs(v2(2))+abs(v2(3))+abs(v2(4)).eq.rZero ) then |
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write(stdo,*) ' helas-warn : v2 in jggxxx is zero vector' |
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endif |
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if ( abs(v2(5))+abs(v2(6)).eq.rZero ) then |
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write(stdo,*) |
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& ' helas-error : v2 in jggxxx has zero momentum' |
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endif |
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if ( g.eq.rZero ) then |
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write(stdo,*) ' helas-error : g in jggxxx is zero coupling' |
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endif |
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#endif
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jvv(5) = v1(5) + v2(5) |
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jvv(6) = v1(6) + v2(6) |
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p1(0) = dble( v1(5)) |
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p1(1) = dble( v1(6)) |
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p1(2) = dimag(v1(6)) |
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p1(3) = dimag(v1(5)) |
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p2(0) = dble( v2(5)) |
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p2(1) = dble( v2(6)) |
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p2(2) = dimag(v2(6)) |
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p2(3) = dimag(v2(5)) |
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q(0) = -dble( jvv(5)) |
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q(1) = -dble( jvv(6)) |
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q(2) = -dimag(jvv(6)) |
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q(3) = -dimag(jvv(5)) |
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s = q(0)**2-(q(1)**2+q(2)**2+q(3)**2) |
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v12 = v1(1)*v2(1)-v1(2)*v2(2)-v1(3)*v2(3)-v1(4)*v2(4) |
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sv1 = (p2(0)-q(0))*v1(1) -(p2(1)-q(1))*v1(2) |
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& - (p2(2)-q(2))*v1(3) -(p2(3)-q(3))*v1(4) |
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sv2 = - (p1(0)-q(0))*v2(1) +(p1(1)-q(1))*v2(2) |
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& + (p1(2)-q(2))*v2(3) +(p1(3)-q(3))*v2(4) |
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j12(0) = (p1(0)-p2(0))*v12 +sv1*v2(1) +sv2*v1(1) |
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j12(1) = (p1(1)-p2(1))*v12 +sv1*v2(2) +sv2*v1(2) |
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j12(2) = (p1(2)-p2(2))*v12 +sv1*v2(3) +sv2*v1(3) |
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j12(3) = (p1(3)-p2(3))*v12 +sv1*v2(4) +sv2*v1(4) |
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gs = -g/s |
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jvv(1) = gs*j12(0) |
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jvv(2) = gs*j12(1) |
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jvv(3) = gs*j12(2) |
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jvv(4) = gs*j12(3) |
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c
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return |
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end |