PDF/spdf/dopho1.F

   1 *
   2 * $Id$
   3 *
   4 * $Log$
   5 * Revision 1.4  2000/09/18 10:02:35  hristov
   6 * Makefile added to PDF8
   7 *
   8 * Revision 1.1.1.2  1996/10/30 08:28:06  cernlib
   9 * Version 7.04
  10 *
  11 * Revision 1.2  1996/10/28 14:59:08  pdflib
  12 * PDFLIB new version 7.04
  13 *
  14 * Revision 1.1.1.1  1996/04/12 15:29:17  plothow
  15 * Version 7.01
  16 *
  17 *
  18 #include "pdf/pilot.h"
  19        SUBROUTINE DOPHO1(DX,DQ,DUV,DDV,DUB,DDB,DSB,DCB,DBB,DGL)
  20 C********************************************************************
  21 C*                                                                  *
  22 C*    Parametrization of parton distribution functions              *
  23 C*    in the photon (LO analysis) - asymptotic solution of AP eq.!  *
  24 C*                                                                  *
  25 C* authors:  D.Duke and H.Owens (DO)                                *
  26 C*           /Phys.Rev. D26 (1982) 1600/                            *
  27 C*                                                                  *
  28 C* Prepared by:                                                     *
  29 C*             Krzysztof Charchula, DESY                            *
  30 C*             bitnet: F1PCHA@DHHDESY3                              *
  31 C*             decnet: 13313::CHARCHULA                             *
  32 C*                                                                  *
  33 C* Modified by:                                                     *
  34 C*             H. Plothow-Besch/CERN-PPE                            *
  35 C*                                                                  *
  36 C********************************************************************
  37 C
  38 #include "pdf/impdp.inc"
  39 #if defined(CERNLIB_DOUBLE)
  40       DOUBLE PRECISION
  41 #endif
  42 #if defined(CERNLIB_SINGLE)
  43       REAL
  44 #endif
  45      +        CQ(5),
  46      +        DX,DQ,DUV,DDV,DUB,DDB,DSB,DCB,DBB,DGL
  47       PARAMETER (ALPEM=7.29927D-3, PI=3.141592D0)
  48       PARAMETER (ALAM=0.2D0)
  49       DATA CQ/0.33333D0,0.66666D0,0.33333D0,0.66666D0,0.33333D0/
  50 C
  51        Q2 = DQ*DQ
  52        ALAM2=ALAM**2
  53        FQ=ALPEM/(2.*PI)*LOG(Q2/ALAM2)
  54 C
  55 C...gluons
  56        POMG=0.194*(1.-DX)**1.03/(DX**0.97)
  57        DGL=POMG*FQ
  58 C
  59 C...quarks
  60         POM1=(1.81-1.67*DX+2.16*DX**2)
  61         POM2=DX**0.7/(1.-0.4*LOG(1.-DX))
  62         POM3=38.D-4*(1.-DX)**1.82/(DX**1.18)
  63           DDB=(CQ(1)**2*POM1*POM2+POM3)*FQ
  64           DDV=DDB
  65           DUB=(CQ(2)**2*POM1*POM2+POM3)*FQ
  66           DUV=DUB
  67           DSB=(CQ(3)**2*POM1*POM2+POM3)*FQ
  68           DCB=(CQ(4)**2*POM1*POM2+POM3)*FQ
  69           DBB=(CQ(5)**2*POM1*POM2+POM3)*FQ
  70        RETURN
  71        END