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50.9.3
by Johan Alwall
Added Template and HELAS into bzr |
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subroutine wwwwxx(wm1,wp1,wm2,wp2,gwwa,gwwz , vertex) |
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c
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c This subroutine computes an amplitude of the four-point W-/W+ coupling.
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c
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c input:
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c complex wm1(0:3) : first flow-out W- wm1
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c complex wp1(0:3) : first flow-out W+ wp1
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c complex wm2(0:3) : second flow-out W- wm2
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c complex wp2(0:3) : second flow-out W+ wp2
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c real gwwa : coupling constant of W and A gwwa
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c real gwwz : coupling constant of W and Z gwwz
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c real zmass : mass of Z
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c real zwidth : width of Z
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c
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c output:
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c complex vertex : amplitude gamma(wm1,wp1,wm2,wp2)
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c
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implicit none |
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double complex wm1(6),wp1(6),wm2(6),wp2(6),vertex |
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double complex dv1(0:3),dv2(0:3),dv3(0:3),dv4(0:3),dvertx |
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double complex v12,v13,v14,v23,v24,v34 |
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double precision pwm1(0:3),pwp1(0:3),pwm2(0:3),pwp2(0:3) |
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double precision gwwa,gwwz |
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double precision rZero, rOne, rTwo |
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parameter( rZero = 0.0d0, rOne = 1.0d0, rTwo = 2.0d0 ) |
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#ifdef HELAS_CHECK
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double precision pm |
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double precision epsi |
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parameter( epsi = 2.0d-5 ) |
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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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pwm1(0) = dble( wm1(5)) |
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pwm1(1) = dble( wm1(6)) |
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pwm1(2) = dimag(wm1(6)) |
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pwm1(3) = dimag(wm1(5)) |
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pwp1(0) = dble( wp1(5)) |
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pwp1(1) = dble( wp1(6)) |
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pwp1(2) = dimag(wp1(6)) |
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pwp1(3) = dimag(wp1(5)) |
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pwm2(0) = dble( wm2(5)) |
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pwm2(1) = dble( wm2(6)) |
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pwm2(2) = dimag(wm2(6)) |
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pwm2(3) = dimag(wm2(5)) |
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pwp2(0) = dble( wp2(5)) |
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pwp2(1) = dble( wp2(6)) |
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pwp2(2) = dimag(wp2(6)) |
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pwp2(3) = dimag(wp2(5)) |
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#ifdef HELAS_CHECK
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if ( abs(wm1(1))+abs(wm1(2)) |
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& +abs(wm1(3))+abs(wm1(4)).eq.rZero ) then |
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write(stdo,*) ' helas-warn : wm1 in wwwwxx is zero vector' |
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endif |
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if ( abs(wm1(5))+abs(wm1(5)).eq.rZero ) then |
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write(stdo,*) |
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& ' helas-error : wm1 in wwwwxx has zero momentum' |
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endif |
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if ( abs(wp1(1))+abs(wp1(2)) |
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& +abs(wp1(3))+abs(wp1(4)).eq.rZero ) then |
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write(stdo,*) ' helas-warn : wp1 in wwwwxx is zero vector' |
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endif |
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if ( abs(wp1(5))+abs(wp1(5)).eq.rZero ) then |
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write(stdo,*) |
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& ' helas-error : wp1 in wwwwxx has zero momentum' |
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endif |
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if ( abs(wm2(1))+abs(wm2(2)) |
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& +abs(wm2(3))+abs(wm2(4)).eq.rZero ) then |
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write(stdo,*) ' helas-warn : wm2 in wwwwxx is zero vector' |
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endif |
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if ( abs(wm2(5))+abs(wm2(5)).eq.rZero ) then |
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write(stdo,*) |
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& ' helas-error : wm2 in wwwwxx has zero momentum' |
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endif |
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if ( abs(wp2(1))+abs(wp2(2)) |
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& +abs(wp2(3))+abs(wp2(4)).eq.rZero ) then |
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write(stdo,*) ' helas-warn : wp2 in wwwwxx is zero vector' |
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endif |
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if ( abs(wp2(5))+abs(wp2(5)).eq.rZero ) then |
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write(stdo,*) |
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& ' helas-error : wp2 in wwwwxx has zero momentum' |
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endif |
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pm = max( abs(pwm1(0)),abs(pwp1(0)),abs(pwm2(0)),abs(pwp2(0)), |
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& abs(pwm1(1)),abs(pwp1(1)),abs(pwm2(1)),abs(pwp2(1)), |
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& abs(pwm1(2)),abs(pwp1(2)),abs(pwm2(2)),abs(pwp2(2)), |
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& abs(pwm1(3)),abs(pwp1(3)),abs(pwm2(3)),abs(pwp2(3)) ) |
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if ( abs(wm1(5)+wp1(5)+wm2(5)+wp2(5)) |
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& +abs(wm1(6)+wp1(6)+wm2(6)+wp2(6)).ge.pm*epsi ) then |
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write(stdo,*) |
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& ' helas-error : wm1,wp1,wm2,wp2 in wwwwxx' |
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write(stdo,*) |
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& ' : have not balanced momenta' |
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endif |
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if ( gwwa.eq.rZero ) then |
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write(stdo,*) ' helas-error : gwwa in wwwwxx is zero coupling' |
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endif |
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if ( gwwz.eq.rZero ) then |
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write(stdo,*) |
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& ' helas-error : gwwz in wwwwxx is zero coupling' |
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endif |
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if ( gwwa.lt.rZero .or. gwwa.ge.gwwz ) then |
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write(stdo,*) |
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& ' helas-warn : gwwa/gwwz in wwwwxx are non-standard couplings' |
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write(stdo,*) |
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& ' : gwwa = ',gwwa,' gwwz = ',gwwz |
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endif |
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#endif
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dv1(0) = dcmplx(wm1(1)) |
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dv1(1) = dcmplx(wm1(2)) |
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dv1(2) = dcmplx(wm1(3)) |
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dv1(3) = dcmplx(wm1(4)) |
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dv2(0) = dcmplx(wp1(1)) |
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dv2(1) = dcmplx(wp1(2)) |
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dv2(2) = dcmplx(wp1(3)) |
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dv2(3) = dcmplx(wp1(4)) |
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dv3(0) = dcmplx(wm2(1)) |
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dv3(1) = dcmplx(wm2(2)) |
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dv3(2) = dcmplx(wm2(3)) |
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dv3(3) = dcmplx(wm2(4)) |
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dv4(0) = dcmplx(wp2(1)) |
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dv4(1) = dcmplx(wp2(2)) |
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dv4(2) = dcmplx(wp2(3)) |
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dv4(3) = dcmplx(wp2(4)) |
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v12 = dv1(0)*dv2(0)-dv1(1)*dv2(1)-dv1(2)*dv2(2)-dv1(3)*dv2(3) |
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v13 = dv1(0)*dv3(0)-dv1(1)*dv3(1)-dv1(2)*dv3(2)-dv1(3)*dv3(3) |
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v14 = dv1(0)*dv4(0)-dv1(1)*dv4(1)-dv1(2)*dv4(2)-dv1(3)*dv4(3) |
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v23 = dv2(0)*dv3(0)-dv2(1)*dv3(1)-dv2(2)*dv3(2)-dv2(3)*dv3(3) |
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v24 = dv2(0)*dv4(0)-dv2(1)*dv4(1)-dv2(2)*dv4(2)-dv2(3)*dv4(3) |
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v34 = dv3(0)*dv4(0)-dv3(1)*dv4(1)-dv3(2)*dv4(2)-dv3(3)*dv4(3) |
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dvertx = (v12*v34 + v14*v23 - rTwo*v13*v24)*(gwwa**2+gwwz**2) |
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vertex = -dcmplx( dvertx ) |
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c
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return |
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end |