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