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HELAS/httaxx.F
 
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      subroutine httaxx(tc1,tc2,gc,mass,width,jsc)
 
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c
 
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c- by RF - Mar. 2006 
 
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c
 
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c This subroutine computes an off-shell scalar from the tts coupling.
 
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c
 
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c     input:
 
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c          complex tc1(18)           : Incoming tensor particle
 
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c          complex tc2(18)           : Incoming tensor particle
 
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c          complex gc(2)             : coupling constant: gt(1) scalar
 
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c                                                         gt(2) not used
 
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c          real    mass              : mass of the outgoing scalar
 
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c          real    width             : width of the outgoing scalar
 
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c
 
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c     output:
 
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c          complex sc(3)             : Incoming scalar particle
 
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c
 
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c
 
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      implicit none
 
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c--   dimension of the current set to arbitrary length
 
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c      INTEGER DIM
 
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c      PARAMETER(DIM=18)
 
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      include "dimension.inc"
 
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      double complex tc1(DIM),tc2(DIM),jsc(DIM)
 
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      double complex vertex,dj,gc(2)
 
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      double precision mass,width,q2,q(4)
 
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c Take the inner product between the tensor particles. The 
 
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c Note that the tensor particle is antisymmetric, thus all diagonal terms
 
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c are zero.
 
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      jsc(2)=tc1(17)+tc2(17)
 
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      jsc(3)=tc1(18)+tc2(18)
 
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      if (gc(1).NE.(0D0,0D0)) then
 
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      q(1) = -dble( jsc(2))
 
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      q(2) = -dble( jsc(3))
 
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      q(3) = -dimag(jsc(3))
 
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      q(4) = -dimag(jsc(2))
 
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      q2 = q(1)**2 - q(2)**2 - q(3)**2 - q(4)**2
 
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      dj = gc(1) /dcmplx( q2-mass**2, mass*width )
 
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      jsc(1) = dj* (
 
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c     &                       + tc1( 1) * tc2( 1)
 
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     &                       - tc1( 2) * tc2( 2)
 
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     &                       - tc1( 3) * tc2( 3)
 
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     &                       - tc1( 4) * tc2( 4)
 
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     &                       - tc1( 5) * tc2( 5)
 
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c     &                       + tc1( 6) * tc2( 6)
 
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     &                       + tc1( 7) * tc2( 7)
 
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     &                       + tc1( 8) * tc2( 8)
 
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     &                       - tc1( 9) * tc2( 9)
 
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     &                       + tc1(10) * tc2(10)
 
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c     &                       + tc1(11) * tc2(11)
 
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     &                       + tc1(12) * tc2(12)
 
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     &                       - tc1(13) * tc2(13)
 
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     &                       + tc1(14) * tc2(14)
 
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     &                       + tc1(15) * tc2(15)
 
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c     &                       + tc1(16) * tc2(16)
 
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     &                                           )
 
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      else
 
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         jsc( 1)=(0D0,0D0)
 
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      endif
 
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      return
 
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      end