ghvq.f

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C
C
C
  FUNCTION ghvq(Y1,Y2,AMT2)
  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(amt2)/hint1(1)
  x1=0.50*xt*(dexp(y1)+dexp(y2))
  x2=0.50*xt*(dexp(-y1)+dexp(-y2))
  ss=x1*x2*hint1(1)**2
  af=4.0
  IF(ihpr2(18).NE.0) af=5.0
  dlam=hipr1(15)
  aph=12.0*3.1415926/(33.0-2.0*af)/dlog(amt2/dlam**2)
C
  CALL parton(f,x1,x2,amt2)
C
  gqq=4.0*(cosh(y1-y2)+hipr1(7)**2/amt2)/(1.d0+cosh(y1-y2))/9.0
     &      *(f(1,1)*f(2,2)+f(1,2)*f(2,1)+f(1,3)*f(2,4)
     &        +f(1,4)*f(2,3)+f(1,5)*f(2,6)+f(1,6)*f(2,5))
  ggg=(8.d0*cosh(y1-y2)-1.d0)*(cosh(y1-y2)+2.0*hipr1(7)**2/amt2
     &      -2.0*hipr1(7)**4/amt2**2)/(1.0+cosh(y1-y2))/24.d0
     &      *f(1,7)*f(2,7)
C
  ghvq=(gqq+ggg)*hipr1(23)*3.14159*aph**2/ss**2
  RETURN
  END