PDF/spdf/sfgrvl.F

   1 *
   2 * $Id$
   3 *
   4 * $Log$
   5 * Revision 1.1.1.2  1996/10/30 08:29:48  cernlib
   6 * Version 7.04
   7 *
   8 * Revision 1.1.1.1  1996/04/12 15:29:35  plothow
   9 * Version 7.01
  10 *
  11 *
  12 #include "pdf/pilot.h"
  13 C-----------------------------------------------------------------------
  14       SUBROUTINE SFGRVL(DX,DSCAL,DUPV,DDNV,DSEA,DSTR,DCHM,DBOT,DTOP,DGL)
  15 C
  16 C :::::::::::: Structure functions from Glueck, Reya and Vogt  (LO)
  17 C :::::::::::: Lambda(NF=3) = 0.250 GeV
  18 C
  19       DIMENSION XQ(7)
  20 #include "pdf/expdp.inc"
  21      +       DX,DSCAL,DUPV,DDNV,DSEA,DSTR,DCHM,DBOT,DTOP,DGL
  22       PARAMETER (ALAM=0.250)
  23 C
  24       X = DX
  25       Q2 = DSCAL**2
  26 C
  27 C     generate the individual structure fcn calls
  28 C
  29 C...Lowest order parametrization of Gluck, Reya, Vogt.
  30 C...Allowed variable range: 0.2 GeV^2 < Q2 < 1E6 GeV^2; 1E-4 < x < 1;
  31 C...extended to 0.2 GeV^2 < Q2 < 1E8 GeV^2; 1E-6 < x < 1
  32 C...after consultation with the authors.
  33
  34 C...Determine s and x.
  35           Q2IN=MIN(1E8,MAX(0.2,Q2))
  36           SD=LOG(LOG(Q2IN/ALAM**2)/LOG(0.2/ALAM**2))
  37         XC=MAX(1E-6,X)
  38         XL=-LOG(XC)
  39
  40 C...Calculate structure functions.
  41         XQ(1)=(0.794+0.312*SD)*XC**(0.427-0.011*SD)*
  42      &  (1.+(6.887-2.227*SD)*XC+(-11.083+2.136*SD)*XC**2+
  43      &  (3.900+1.079*SD)*XC**3)*(1.-XC)**(1.037+1.077*SD)
  44         XQ(2)=(0.486+0.139*SD)*XC**(0.434-0.018*SD)*
  45      &  (1.+(7.716-2.684*SD)*XC+(-12.768+3.122*SD)*XC**2+
  46      &  (4.564+0.470*SD)*XC**3)*(1.-XC)**(1.889+1.129*SD)
  47         XQ(3)=(XC**(0.415+0.186*SD)*((0.786+0.942*SD)+
  48      &  (5.256-5.810*SD)*XC+(-4.599+5.842*SD)*XC**2)+SD**0.592*
  49      &  EXP(-(0.398+2.135*SD)+SQRT(3.779*SD**1.250*XL)))*
  50      &  (1.-XC)**(1.622+1.980*SD)
  51         XQ(4)=SD**0.448*(1.-XC)**(5.540-0.445*SD)*
  52      &  EXP(-(4.668+1.230*SD)+SQRT((13.173-1.361*SD)*SD**0.442*XL))/
  53      &  XL**(3.181-0.862*SD)
  54         XQ(5)=0.
  55         IF(SD.GT.1.125) XQ(5)=(SD-1.125)*(1.-XC)**(2.038+1.022*SD)*
  56      &  EXP(-(4.290+1.569*SD)+SQRT((2.982+1.452*SD)*SD**0.5*XL))
  57         XQ(6)=0.
  58         IF(SD.GT.1.603) XQ(6)=(SD-1.603)*(1.-XC)**(2.230+1.052*SD)*
  59      &  EXP(-(4.566+1.559*SD)+SQRT((4.147+1.268*SD)*SD**0.5*XL))
  60
  61 C...Put into output array - special factor for small x.
  62         CXS=1.
  63 C       IF(X.LT.1E-4.AND.ABS(XLOWPW-1.).GT.0.01)
  64 C    &  CXS=(1E-4/X)**(XLOWPW-1.)
  65       UPV = CXS*XQ(1)
  66       DUPV = UPV
  67       DNV = CXS*XQ(2)
  68       DDNV = DNV
  69       SEA = CXS*XQ(4)
  70       DSEA = SEA
  71       STR = CXS*XQ(4)
  72       DSTR = STR
  73       CHM = CXS*XQ(5)
  74       DCHM = CHM
  75       DBOT = 0.0D0
  76       DTOP = 0.0D0
  77       GL = CXS*XQ(3)
  78       DGL = GL
  79 C
  80       RETURN
  81       END