PDF/spdf/dopho2.F

   1 *
   2 * $Id$
   3 *
   4 * $Log$
   5 * Revision 1.1.1.2  1996/10/30 08:28:07  cernlib
   6 * Version 7.04
   7 *
   8 * Revision 1.2  1996/10/28 14:59:26  pdflib
   9 * PDFLIB new version 7.04
  10 *
  11 * Revision 1.1.1.1  1996/04/12 15:29:17  plothow
  12 * Version 7.01
  13 *
  14 *
  15 #include "pdf/pilot.h"
  16        SUBROUTINE DOPHO2(DX,DQ,DUV,DDV,DUB,DDB,DSB,DCB,DBB,DGL)
  17 C********************************************************************
  18 C*                                                                  *
  19 C*    Parametrization of parton distribution functions              *
  20 C*    in the photon (LO analysis) - asymptotic solution of AP eq.!  *
  21 C*                                                                  *
  22 C* authors:  D.Duke and H.Owens (DO)                                *
  23 C*           /Phys.Rev. D26 (1982) 1600/                            *
  24 C*                                                                  *
  25 C* Prepared by:                                                     *
  26 C*             Krzysztof Charchula, DESY                            *
  27 C*             bitnet: F1PCHA@DHHDESY3                              *
  28 C*             decnet: 13313::CHARCHULA                             *
  29 C*                                                                  *
  30 C* Modified by:                                                     *
  31 C*             H. Plothow-Besch/CERN-PPE                            *
  32 C*                                                                  *
  33 C********************************************************************
  34 C
  35 #include "pdf/impdp.inc"
  36 #include "pdf/expdp.inc"
  37      +        CQ(5),
  38      +        DX,DQ,DUV,DDV,DUB,DDB,DSB,DCB,DBB,DGL
  39       PARAMETER (ALPEM=7.29927D-3,PI=3.141592D0)
  40       PARAMETER (ALAM=0.4D0)
  41       DATA CQ/0.33333D0,0.66666D0,0.33333D0,0.66666D0,0.33333D0/
  42 C
  43        Q2 = DQ*DQ
  44        ALAM2=ALAM**2
  45        FQ=ALPEM/(2.*PI)*LOG(Q2/ALAM2)
  46 C
  47 C...gluons
  48        POMG=0.194*(1.-DX)**1.03/(DX**0.97)
  49        DGL=POMG*FQ
  50 C
  51 C...quarks
  52         POM1=(1.81-1.67*DX+2.16*DX**2)
  53         POM2=DX**0.7/(1.-0.4*LOG(1.-DX))
  54         POM3=38.D-4*(1.-DX)**1.82/(DX**1.18)
  55           DDB=(CQ(1)**2*POM1*POM2+POM3)*FQ
  56           DDV=DDB
  57           DUB=(CQ(2)**2*POM1*POM2+POM3)*FQ
  58           DUV=DUB
  59           DSB=(CQ(3)**2*POM1*POM2+POM3)*FQ
  60           DCB=(CQ(4)**2*POM1*POM2+POM3)*FQ
  61           DBB=(CQ(5)**2*POM1*POM2+POM3)*FQ
  62        RETURN
  63        END