g.f

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C
C
C
C
  FUNCTION g(Y1,Y2,PT2)
  IMPLICIT REAL*8 (a-h,o-z)
  REAL hipr1(100),hint1(100)
        common/hiparnt/hipr1,ihpr2(50),hint1,ihnt2(50)
        SAVE  /hiparnt/
  dimension f(2,7)
  xt=2.0*dsqrt(pt2)/hint1(1)
  x1=0.50*xt*(dexp(y1)+dexp(y2))
  x2=0.50*xt*(dexp(-y1)+dexp(-y2))
  z=dsqrt(1.d0-xt**2/x1/x2)
  ss=x1*x2*hint1(1)**2
  t=-(1.0-z)/2.0
  u=-(1.0+z)/2.0
  af=3.0
  dlam=hipr1(15)
  aph=12.0*3.1415926/(33.0-2.0*af)/dlog(pt2/dlam**2)
C
  CALL parton(f,x1,x2,pt2)
C
  g11=( (f(1,1)+f(1,2))*(f(2,3)+f(2,4)+f(2,5)+f(2,6))
     &      +(f(1,3)+f(1,4))*(f(2,5)+f(2,6)) )*subcrs1(t,u)
C
  g12=( (f(2,1)+f(2,2))*(f(1,3)+f(1,4)+f(1,5)+f(1,6))
     &      +(f(2,3)+f(2,4))*(f(1,5)+f(1,6)) )*subcrs1(u,t)
C
  g13=(f(1,1)*f(2,1)+f(1,2)*f(2,2)+f(1,3)*f(2,3)+f(1,4)*f(2,4)
     &      +f(1,5)*f(2,5)+f(1,6)*f(2,6))*(subcrs1(u,t)
     &      +subcrs1(t,u)-8.d0/t/u/27.d0)
C
  g2=(af-1)*(f(1,1)*f(2,2)+f(2,1)*f(1,2)+f(1,3)*f(2,4)
     &     +f(2,3)*f(1,4)+f(1,5)*f(2,6)+f(2,5)*f(1,6))*subcrs2(t,u)
C
  g31=(f(1,1)*f(2,2)+f(1,3)*f(2,4)+f(1,5)*f(2,6))*subcrs3(t,u)
  g32=(f(2,1)*f(1,2)+f(2,3)*f(1,4)+f(2,5)*f(1,6))*subcrs3(u,t)
C
  g4=(f(1,1)*f(2,2)+f(2,1)*f(1,2)+f(1,3)*f(2,4)+f(2,3)*f(1,4)+
     1  f(1,5)*f(2,6)+f(2,5)*f(1,6))*subcrs4(t,u)
C
  g5=af*f(1,7)*f(2,7)*subcrs5(t,u)
C
  g61=f(1,7)*(f(2,1)+f(2,2)+f(2,3)+f(2,4)+f(2,5)
     &      +f(2,6))*subcrs6(t,u)
  g62=f(2,7)*(f(1,1)+f(1,2)+f(1,3)+f(1,4)+f(1,5)
     &      +f(1,6))*subcrs6(u,t)
C
  g7=f(1,7)*f(2,7)*subcrs7(t,u)
C
  g=(g11+g12+g13+g2+g31+g32+g4+g5+g61+g62+g7)*hipr1(17)*
     1  3.14159d0*aph**2/ss**2

  RETURN
  END