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  • Committer: andrew.lifson at lu
  • Date: 2021-09-02 13:57:34 UTC
  • Revision ID: andrew.lifson@thep.lu.se-20210902135734-4eybgli0iljkax9b
added fresh copy of MG5_aMC_v3.2.0

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HELAS/iovtkk.F
 
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      subroutine iovtkk(fi,fo,vc,tc,g , vertex)
 
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c
 
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c This subroutine computes an amplitude of the three-point coupling of
 
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c two gauge bosons and a Kaluza-Klein tensor boson.
 
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c
 
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c input:
 
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c       complex fi(6)          : flow-in  fermion     SM |fi>
 
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c       complex fo(6)          : flow-out fermion     SM <fo|
 
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c       complex vc(6)          : vector               SM   v
 
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c       complex tc(6,4)        : tensor               KK   t
 
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c       real    g(2)           : coupling constant    -g(L,R)*kappa/4
 
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c
 
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c output:
 
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c       complex vertex         : amplitude            gamma(fi,fo,vc,tc)
 
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c     
 
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      implicit none
 
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      double complex fi(6), fo(6), vc(6), tc(6,4), vertex
 
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      double precision g(2)
 
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      double complex f13, f14, f23, f24, f31, f32, f41, f42
 
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      double complex fs1L, fs1R, fs2L, fs2R, fs3L, fs3R, fs4L, fs4R
 
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      double complex T12, T13, T14, T23, T24, T34
 
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      double precision rZero, rTwo
 
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      parameter( rZero = 0.0d0, rTwo = 2.0d0 )
 
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      double complex ci
 
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      parameter( ci = ( 0.0d0, 1.0d0 ) )
 
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c
 
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      f31 = fo(3)*fi(1)*g(1)
 
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      f32 = fo(3)*fi(2)*g(1)
 
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      f41 = fo(4)*fi(1)*g(1)
 
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      f42 = fo(4)*fi(2)*g(1)
 
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      fs1L =  f31 + f42
 
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      fs2L = -f32 - f41
 
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      fs3L = (f32 - f41)*ci
 
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      fs4L = -f31 + f42
 
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      if ( g(2).ne.rZero ) then
 
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         f14 = fo(1)*fi(4)*g(2)
 
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         f13 = fo(1)*fi(3)*g(2)
 
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         f23 = fo(2)*fi(3)*g(2)
 
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         f24 = fo(2)*fi(4)*g(2)
 
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         fs1R =  f13 + f24
 
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         fs2R =  f23 + f14
 
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         fs3R = (f23 - f14)*ci
 
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         fs4R =  f13 - f24
 
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      end if
 
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      T12 = tc(1,2) + tc(2,1)
 
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      T13 = tc(1,3) + tc(3,1)
 
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      T14 = tc(1,4) + tc(4,1)
 
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      T23 = tc(2,3) + tc(3,2)
 
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      T24 = tc(2,4) + tc(4,2)
 
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      T34 = tc(3,4) + tc(4,3)
 
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      if ( g(2).ne.rZero ) then
 
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         vertex =  (fs1L + fs1R)*(  vc(1)*rTwo*tc(1,1)
 
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     &                            - vc(2)*T12 - vc(3)*T13 - vc(4)*T14 )
 
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     &           + (fs2L + fs2R)*(  vc(2)*rTwo*tc(2,2)
 
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     &                            - vc(1)*T12 + vc(3)*T23 + vc(4)*T24 )
 
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     &           + (fs3L + fs3R)*(  vc(3)*rTwo*tc(3,3)
 
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     &                            - vc(1)*T13 + vc(2)*T23 + vc(4)*T34 )
 
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     &           + (fs4L + fs4R)*(  vc(4)*rTwo*tc(4,4)
 
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     &                            - vc(1)*T14 + vc(2)*T24 + vc(3)*T34 )
 
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         vertex = vertex - rTwo*( tc(1,1)-tc(2,2)-tc(3,3)-tc(4,4) )
 
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     &                         *(  (vc(1)+      vc(4))*(f31+f24)
 
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     &                           + (vc(1)-      vc(4))*(f13+f42)
 
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     &                           + (vc(2)+ci*vc(3))*(f41-f23)
 
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     &                           + (vc(2)-ci*vc(3))*(f32-f14) )
 
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      else
 
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         vertex =  fs1L*(  vc(1)*rTwo*tc(1,1)
 
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     &                   - vc(2)*T12 - vc(3)*T13 - vc(4)*T14 )
 
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     &           + fs2L*(  vc(2)*rTwo*tc(2,2)
 
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     &                   - vc(1)*T12 + vc(3)*T23 + vc(4)*T24 )
 
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     &           + fs3L*(  vc(3)*rTwo*tc(3,3)
 
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     &                   - vc(1)*T13 + vc(2)*T23 + vc(4)*T34 )
 
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     &           + fs4L*(  vc(4)*rTwo*tc(4,4)
 
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     &                   - vc(1)*T14 + vc(2)*T24 + vc(3)*T34 )
 
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         vertex = vertex - rTwo*( tc(1,1)-tc(2,2)-tc(3,3)-tc(4,4) )
 
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     &                         *(  (vc(1)+      vc(4))*f31
 
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     &                           + (vc(1)-      vc(4))*f42
 
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     &                           + (vc(2)+ci*vc(3))*f41
 
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     &                           + (vc(2)-ci*vc(3))*f32 )
 
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      end if
 
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c
 
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      return
 
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      end