HIJING/hijing1_36/ghvq.F

   1 * $Id$
   2 C
   3 C
   4 C
   5         FUNCTION GHVQ(Y1,Y2,AMT2)
   6         IMPLICIT REAL*8 (A-H,O-Z)
   7 #include "hiparnt.inc"
   8         DIMENSION F(2,7)
   9         SAVE
  10         XT=2.0*DSQRT(AMT2)/HINT1(1)
  11         X1=0.50*XT*(DEXP(Y1)+DEXP(Y2))
  12         X2=0.50*XT*(DEXP(-Y1)+DEXP(-Y2))
  13         SS=X1*X2*HINT1(1)**2
  14         AF=4.0
  15         IF(IHPR2(18).NE.0) AF=5.0
  16         DLAM=HIPR1(15)
  17         APH=12.0*3.1415926/(33.0-2.0*AF)/DLOG(AMT2/DLAM**2)
  18 C
  19         CALL PARTON(F,X1,X2,AMT2)
  20 C
  21         Gqq=4.0*(COSH(Y1-Y2)+HIPR1(7)**2/AMT2)/(1.D0+COSH(Y1-Y2))/9.0
  22      &      *(F(1,1)*F(2,2)+F(1,2)*F(2,1)+F(1,3)*F(2,4)
  23      &        +F(1,4)*F(2,3)+F(1,5)*F(2,6)+F(1,6)*F(2,5))
  24         Ggg=(8.D0*COSH(Y1-Y2)-1.D0)*(COSH(Y1-Y2)+2.0*HIPR1(7)**2/AMT2
  25      &      -2.0*HIPR1(7)**4/AMT2**2)/(1.0+COSH(Y1-Y2))/24.D0
  26      &      *F(1,7)*F(2,7)
  27 C
  28         GHVQ=(Gqq+Ggg)*HIPR1(23)*3.14159*APH**2/SS**2
  29         RETURN
  30         END