d9/d54/ghvq_8f_source.html

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