PDF/spdf/dgpho1.F

   1 *
   2 * $Id$
   3 *
   4 * $Log$
   5 * Revision 1.1.1.2  1996/10/30 08:28:02  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 DGPHO1(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...         nf=3 for   1< Q2 <32  GeV2
  42 C...         nf=4 for  32< Q2 <200 GeV2
  43 C...         nf=5 for 200< Q2 <1D4 GeV2
  44 C...--------------------------------------------------
  45 C
  46 C...initialization of gluon parameters array for DG
  47         DATA (((A(I,J,K),I=1,3),J=1,4),K=1,3)/
  48      >    -0.20700, -0.19870,  5.1190,
  49      >     0.61580,  0.62570, -0.2752,
  50      >     1.07400,  8.35200, -6.9930,
  51      >     0.00000,  5.02400,  2.2980,
  52      >     0.8926D-2,0.0509,  -0.2313,
  53      >     0.65940,  0.27740,  0.1382,
  54      >     0.47660, -0.39060,  6.5420,
  55      >     0.01975, -0.32120,  0.5162,
  56      >     0.03197, -0.618D-2,-0.1216,
  57      >     1.01800,  0.94760,  0.9047,
  58      >     0.24610, -0.60940,  2.6530,
  59      >     0.02707, -0.01067,  0.2003D-2/
  60 C
  61 C...initialization of quark parameters array for DG
  62         DATA (((B(I,J,K,1),I=1,5),J=1,4),K=1,2)/
  63      >     2.2850,   6.0730,  -0.4202,   -0.0808,  0.0553,
  64      >    -0.0153,  -0.8132,   0.0178,    0.6346,  1.1360,
  65      >     1.33D3, -41.310,    0.9216,    1.2080,  0.9512,
  66      >     4.2190,   3.1650,   0.1800,    0.2030,  0.0116,
  67      >    16.690,    0.1760,  -0.0208,   -0.0168, -0.1986,
  68      >    -0.7916,   0.0479,   0.3386D-2, 1.3530,  1.1000,
  69      >     1.0990D3, 1.0470,   4.8530,    1.4260,  1.1360,
  70      >     4.4280,   0.0250,   0.8404,    1.2390, -0.2779/
  71         DATA (((B(I,J,K,2),I=1,5),J=1,4),K=1,2)/
  72      >    -0.3711,  -0.1717,   0.08766,  -0.8915, -0.1816,
  73      >     1.0610,   0.7815,   0.02197,   0.2857,  0.5866,
  74      >     4.7580,   1.5350,   0.10960,   2.9730,  2.4210,
  75      >    -0.0150,   0.7067D-2,0.20400,   0.1185,  0.4059,
  76      >    -0.1207,  25.000,   -0.01230,  -0.0919,  0.02015,
  77      >     1.0710,  -1.6480,   1.16200,   0.7912,  0.9869,
  78      >     1.9770,  -0.01563,  0.48240,   0.6397, -0.07036,
  79      >    -0.8625D-2,6.4380,  -0.01100,   2.3270,  0.01694/
  80         DATA (((B(I,J,K,3),I=1,5),J=1,4),K=1,2)/
  81      >    15.8,      2.742,    0.02917,  -0.0342, -0.02302,
  82      >    -0.9464,  -0.7332,   0.04657,   0.7196,  0.9229,
  83      >    -0.5,      0.7148,   0.1785,    0.7338,  0.5873,
  84      >    -0.2118,   3.287,    0.04811,   0.08139,-0.79D-4,
  85      >     6.734,   59.88,    -0.3226D-2,-0.03321, 0.1059,
  86      >    -1.008,   -2.983,    0.8432,    0.9475,  0.6954,
  87      >    -0.08594,  4.48,     0.3616,   -0.3198, -0.6663,
  88      >     0.07625,  0.9686,   0.1383D-2, 0.02132, 0.3683/
  89 C
  90 C...specification of sets
  91        Q2 = DQ*DQ
  92          IF (Q2.LT.32.0D0) NFL=3
  93          IF((Q2.GE.32.0D0).AND.(Q2.LT.200.0D0)) NFL=4
  94          IF (Q2.GE.200.0D0) NFL=5
  95 C
  96 C...calculations
  97        ALAM2=ALAM**2
  98        T=LOG(Q2/ALAM2)
  99        LF=NFL-2
 100 C
 101 C...gluons
 102         DO 11 I=1,3
 103           AT(I)=A(I,1,LF)*T**A(I,2,LF)+A(I,3,LF)*T**(-A(I,4,LF))
 104  11     CONTINUE
 105         POMG=AT(1)*DX**AT(2)*(1.D0-DX)**AT(3)
 106         DGL=POMG*ALPEM
 107 C
 108 C...quarks
 109         E(1)=1.0D0
 110         IF(NFL.EQ.3) THEN
 111           E(2)=9.0D0
 112         ELSEIF(NFL.EQ.4) THEN
 113           E(2)=10.0D0
 114         ELSEIF(NFL.EQ.5) THEN
 115           E(2)=55.0D0/6.0D0
 116         ENDIF
 117         DO 13 J=1,2
 118           DO 15 I=1,5
 119             BTP=B(I,1,J,LF)*T**B(I,2,J,LF)
 120             BT(I,J)=BTP+B(I,3,J,LF)*T**(-B(I,4,J,LF))
 121  15       CONTINUE
 122  13     CONTINUE
 123 C
 124 C...singlet & non-singlet combinations
 125         DO 17 J=1,2
 126           POM1=DX*(DX*DX+(1.D0-DX)**2)/(BT(1,J)-BT(2,J)*LOG(1.D0-DX))
 127           POM2=BT(3,J)*DX**BT(4,J)*(1.D0-DX)**BT(5,J)
 128           XQPOM(J)=E(J)*POM1+POM2
 129  17     CONTINUE
 130 C
 131 C...quarks flavours
 132         IF (NFL.EQ.3) THEN
 133             DUB=ALPEM*1.D0/6.D0*(XQPOM(2)+9.D0*XQPOM(1))
 134             DDB=ALPEM*1.D0/6.D0*(XQPOM(2)-9.D0/2.D0*XQPOM(1))
 135             DSB=DDB
 136             DCB=0.D0
 137             DBB=0.D0
 138         ELSEIF (NFL.EQ.4) THEN
 139             DUB=ALPEM*1.D0/8.D0*(XQPOM(2)+6.D0*XQPOM(1))
 140             DCB=DUB
 141             DDB=ALPEM*1.D0/8.D0*(XQPOM(2)-6.D0*XQPOM(1))
 142             DSB=DDB
 143             DBB=0.D0
 144         ELSEIF (NFL.EQ.5) THEN
 145             DUB=ALPEM*1.D0/10.D0*(XQPOM(2)+15.D0/2.D0*XQPOM(1))
 146             DCB=DUB
 147             DDB=ALPEM*1.D0/10.D0*(XQPOM(2)-5.D0*XQPOM(1))
 148             DSB=DDB
 149             DBB=DDB
 150         ENDIF
 151       DUV=DUB
 152       DDV=DDB
 153 C
 154       RETURN
 155       END