PDF/spdf/dgpho2.F

   1 *
   2 * $Id$
   3 *
   4 * $Log$
   5 * Revision 1.1.1.2  1996/10/30 08:28:04  cernlib
   6 * Version 7.04
   7 *
   8 * Revision 1.1.1.1  1996/04/12 15:29:15  plothow
   9 * Version 7.01
  10 *
  11 *
  12 #include "pdf/pilot.h"
  13        SUBROUTINE DGPHO2(DX,DQ,DUV,DDV,DUB,DDB,DSB,DCB,DBB,DGL)
  14 C********************************************************************
  15 C*                                                                  *
  16 C*    Parametrization of parton distribution functions              *
  17 C*    in the photon (LO analysis) - full  solution of AP eq.!       *
  18 C*                                                                  *
  19 C* authors:  M.Drees and K.Grassie (DG)                             *
  20 C*          /Z. Phys. C28 (1985) 451/                               *
  21 C*                                                                  *
  22 C* Prepared by:                                                     *
  23 C*             Krzysztof Charchula, DESY                            *
  24 C*             bitnet: F1PCHA@DHHDESY3                              *
  25 C*             decnet: 13313::CHARCHULA                             *
  26 C*                                                                  *
  27 C* Modified by:                                                     *
  28 C*             H. Plothow-Besch/CERN-PPE                            *
  29 C*                                                                  *
  30 C********************************************************************
  31 C
  32 #include "pdf/impdp.inc"
  33 #include "pdf/expdp.inc"
  34      +        A(3,4,3),AT(3),
  35      +        B(5,4,2,3),BT(5,2),XQPOM(2),E(2),
  36      +        DX,DQ,DUV,DDV,DUB,DDB,DSB,DCB,DBB,DGL
  37       PARAMETER (ALPEM=7.29927D-3, PI=3.141592D0)
  38       PARAMETER (ALAM=0.4D0)
  39 C...comments
  40 C...--------------------------------------------------
  41 C...        with nf=3 (valid for   1< Q2 <50  GeV2)
  42 C...--------------------------------------------------
  43 C
  44 C...initialization of gluon parameters array for DG
  45         DATA (((A(I,J,K),I=1,3),J=1,4),K=1,3)/
  46      >    -0.20700, -0.19870,  5.1190,
  47      >     0.61580,  0.62570, -0.2752,
  48      >     1.07400,  8.35200, -6.9930,
  49      >     0.00000,  5.02400,  2.2980,
  50      >     0.8926D-2,0.0509,  -0.2313,
  51      >     0.65940,  0.27740,  0.1382,
  52      >     0.47660, -0.39060,  6.5420,
  53      >     0.01975, -0.32120,  0.5162,
  54      >     0.03197, -0.618D-2,-0.1216,
  55      >     1.01800,  0.94760,  0.9047,
  56      >     0.24610, -0.60940,  2.6530,
  57      >     0.02707, -0.01067,  0.2003D-2/
  58 C
  59 C...initialization of quark parameters array for DG
  60         DATA (((B(I,J,K,1),I=1,5),J=1,4),K=1,2)/
  61      >     2.2850,   6.0730,  -0.4202,   -0.0808,  0.0553,
  62      >    -0.0153,  -0.8132,   0.0178,    0.6346,  1.1360,
  63      >     1.33D3, -41.310,    0.9216,    1.2080,  0.9512,
  64      >     4.2190,   3.1650,   0.1800,    0.2030,  0.0116,
  65      >    16.690,    0.1760,  -0.0208,   -0.0168, -0.1986,
  66      >    -0.7916,   0.0479,   0.3386D-2, 1.3530,  1.1000,
  67      >     1.0990D3, 1.0470,   4.8530,    1.4260,  1.1360,
  68      >     4.4280,   0.0250,   0.8404,    1.2390, -0.2779/
  69         DATA (((B(I,J,K,2),I=1,5),J=1,4),K=1,2)/
  70      >    -0.3711,  -0.1717,   0.08766,  -0.8915, -0.1816,
  71      >     1.0610,   0.7815,   0.02197,   0.2857,  0.5866,
  72      >     4.7580,   1.5350,   0.10960,   2.9730,  2.4210,
  73      >    -0.0150,   0.7067D-2,0.20400,   0.1185,  0.4059,
  74      >    -0.1207,  25.000,   -0.01230,  -0.0919,  0.02015,
  75      >     1.0710,  -1.6480,   1.16200,   0.7912,  0.9869,
  76      >     1.9770,  -0.01563,  0.48240,   0.6397, -0.07036,
  77      >    -0.8625D-2,6.4380,  -0.01100,   2.3270,  0.01694/
  78         DATA (((B(I,J,K,3),I=1,5),J=1,4),K=1,2)/
  79      >    15.8,      2.742,    0.02917,  -0.0342, -0.02302,
  80      >    -0.9464,  -0.7332,   0.04657,   0.7196,  0.9229,
  81      >    -0.5,      0.7148,   0.1785,    0.7338,  0.5873,
  82      >    -0.2118,   3.287,    0.04811,   0.08139,-0.79D-4,
  83      >     6.734,   59.88,    -0.3226D-2,-0.03321, 0.1059,
  84      >    -1.008,   -2.983,    0.8432,    0.9475,  0.6954,
  85      >    -0.08594,  4.48,     0.3616,   -0.3198, -0.6663,
  86      >     0.07625,  0.9686,   0.1383D-2, 0.02132, 0.3683/
  87 C
  88 C...specification of sets
  89          NFL=3
  90 C
  91 C...calculations
  92        Q2 = DQ*DQ
  93        ALAM2=ALAM**2
  94        T=LOG(Q2/ALAM2)
  95        LF=NFL-2
  96 C
  97 C...gluons
  98         DO 11 I=1,3
  99           AT(I)=A(I,1,LF)*T**A(I,2,LF)+A(I,3,LF)*T**(-A(I,4,LF))
 100  11     CONTINUE
 101         POMG=AT(1)*DX**AT(2)*(1.D0-DX)**AT(3)
 102         DGL=POMG*ALPEM
 103 C
 104 C...quarks
 105         E(1)=1.D0
 106         E(2)=9.D0
 107         DO 13 J=1,2
 108           DO 15 I=1,5
 109             BTP=B(I,1,J,LF)*T**B(I,2,J,LF)
 110             BT(I,J)=BTP+B(I,3,J,LF)*T**(-B(I,4,J,LF))
 111  15       CONTINUE
 112  13     CONTINUE
 113 C
 114 C...singlet & non-singlet combinations
 115         DO 17 J=1,2
 116           POM1=DX*(DX*DX+(1.D0-DX)**2)/(BT(1,J)-BT(2,J)*LOG(1.D0-DX))
 117           POM2=BT(3,J)*DX**BT(4,J)*(1.D0-DX)**BT(5,J)
 118           XQPOM(J)=E(J)*POM1+POM2
 119  17     CONTINUE
 120 C
 121 C...quarks flavours
 122       DUB=ALPEM*1.D0/6.D0*(XQPOM(2)+9.D0*XQPOM(1))
 123       DUV=DUB
 124       DDB=ALPEM*1.D0/6.D0*(XQPOM(2)-9.D0/2.D0*XQPOM(1))
 125       DDV=DDB
 126       DSB=DDB
 127       DCB=0.D0
 128       DBB=0.D0
 129 C
 130       RETURN
 131       END