PDF/spdf/sfgrvl.F

   1 *
   2 * $Id$
   3 *
   4 * $Log$
   5 * Revision 1.4  2000/09/18 10:02:36  hristov
   6 * Makefile added to PDF8
   7 *
   8 * Revision 1.1.1.2  1996/10/30 08:29:48  cernlib
   9 * Version 7.04
  10 *
  11 * Revision 1.1.1.1  1996/04/12 15:29:35  plothow
  12 * Version 7.01
  13 *
  14 *
  15 #include "pdf/pilot.h"
  16 C-----------------------------------------------------------------------
  17       SUBROUTINE SFGRVL(DX,DSCAL,DUPV,DDNV,DSEA,DSTR,DCHM,DBOT,DTOP,DGL)
  18 C
  19 C :::::::::::: Structure functions from Glueck, Reya and Vogt  (LO)
  20 C :::::::::::: Lambda(NF=3) = 0.250 GeV
  21 C
  22       DIMENSION XQ(7)
  23 #if defined(CERNLIB_DOUBLE)
  24       DOUBLE PRECISION
  25 #endif
  26 #if defined(CERNLIB_SINGLE)
  27       REAL
  28 #endif
  29      +       DX,DSCAL,DUPV,DDNV,DSEA,DSTR,DCHM,DBOT,DTOP,DGL
  30       PARAMETER (ALAM=0.250)
  31 C
  32       X = DX
  33       Q2 = DSCAL**2
  34 C
  35 C     generate the individual structure fcn calls
  36 C
  37 C...Lowest order parametrization of Gluck, Reya, Vogt.
  38 C...Allowed variable range: 0.2 GeV^2 < Q2 < 1E6 GeV^2; 1E-4 < x < 1;
  39 C...extended to 0.2 GeV^2 < Q2 < 1E8 GeV^2; 1E-6 < x < 1
  40 C...after consultation with the authors.
  41
  42 C...Determine s and x.
  43           Q2IN=MIN(1E8,MAX(0.2,Q2))
  44           SD=LOG(LOG(Q2IN/ALAM**2)/LOG(0.2/ALAM**2))
  45         XC=MAX(1E-6,X)
  46         XL=-LOG(XC)
  47
  48 C...Calculate structure functions.
  49         XQ(1)=(0.794+0.312*SD)*XC**(0.427-0.011*SD)*
  50      &  (1.+(6.887-2.227*SD)*XC+(-11.083+2.136*SD)*XC**2+
  51      &  (3.900+1.079*SD)*XC**3)*(1.-XC)**(1.037+1.077*SD)
  52         XQ(2)=(0.486+0.139*SD)*XC**(0.434-0.018*SD)*
  53      &  (1.+(7.716-2.684*SD)*XC+(-12.768+3.122*SD)*XC**2+
  54      &  (4.564+0.470*SD)*XC**3)*(1.-XC)**(1.889+1.129*SD)
  55         XQ(3)=(XC**(0.415+0.186*SD)*((0.786+0.942*SD)+
  56      &  (5.256-5.810*SD)*XC+(-4.599+5.842*SD)*XC**2)+SD**0.592*
  57      &  EXP(-(0.398+2.135*SD)+SQRT(3.779*SD**1.250*XL)))*
  58      &  (1.-XC)**(1.622+1.980*SD)
  59         XQ(4)=SD**0.448*(1.-XC)**(5.540-0.445*SD)*
  60      &  EXP(-(4.668+1.230*SD)+SQRT((13.173-1.361*SD)*SD**0.442*XL))/
  61      &  XL**(3.181-0.862*SD)
  62         XQ(5)=0.
  63         IF(SD.GT.1.125) XQ(5)=(SD-1.125)*(1.-XC)**(2.038+1.022*SD)*
  64      &  EXP(-(4.290+1.569*SD)+SQRT((2.982+1.452*SD)*SD**0.5*XL))
  65         XQ(6)=0.
  66         IF(SD.GT.1.603) XQ(6)=(SD-1.603)*(1.-XC)**(2.230+1.052*SD)*
  67      &  EXP(-(4.566+1.559*SD)+SQRT((4.147+1.268*SD)*SD**0.5*XL))
  68
  69 C...Put into output array - special factor for small x.
  70         CXS=1.
  71 C       IF(X.LT.1E-4.AND.ABS(XLOWPW-1.).GT.0.01)
  72 C    &  CXS=(1E-4/X)**(XLOWPW-1.)
  73       UPV = CXS*XQ(1)
  74       DUPV = UPV
  75       DNV = CXS*XQ(2)
  76       DDNV = DNV
  77       SEA = CXS*XQ(4)
  78       DSEA = SEA
  79       STR = CXS*XQ(4)
  80       DSTR = STR
  81       CHM = CXS*XQ(5)
  82       DCHM = CHM
  83       DBOT = 0.0D0
  84       DTOP = 0.0D0
  85       GL = CXS*XQ(3)
  86       DGL = GL
  87 C
  88       RETURN
  89       END