PDF/spdf/sfwhi3.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 08:30:44  cernlib
   9 * Version 7.04
  10 *
  11 * Revision 1.1.1.1  1996/04/12 15:29:46  plothow
  12 * Version 7.01
  13 *
  14 *
  15 #include "pdf/pilot.h"
  16 c-------------------------------------------------------
  17       subroutine SFWHI3(ZX,ZQ,ZUV,ZDV,ZUB,ZDB,ZSB,ZCB,ZGL)
  18 c-------------------------------------------------------
  19 c     WHIT3 parton distribution in the photon
  20 c
  21 c     INPUT:  integer ic  : if ic=0 then qc=0
  22 c                           else qc is calculated
  23 c             DOUBLE PRECISION  Q2  : energy scale Q^2 (GeV^2)
  24 c             DOUBLE PRECISION  x   : energy fraction
  25 c
  26 c     OUTPUT: DOUBLE PRECISION  qu  : up-quark dist.
  27 c             DOUBLE PRECISION  qd  : down- or strange-quark dist.
  28 c             DOUBLE PRECISION  qc  : charm-quark dist.
  29 c             DOUBLE PRECISION  g   : gluon dist.
  30 c-------------------------------------------------------
  31 c     Modified by M.Tanaka on July 22, 1994.
  32 c     The bug pointed out by M.Drees is fixed.
  33 c-------------------------------------------------------
  34 c     Modified by I.Watanabe on July 22, 1994.
  35 c-------------------------------------------------------
  36       implicit none
  37       external whit3g
  38 #if defined(CERNLIB_DOUBLE)
  39       DOUBLE PRECISION
  40 #endif
  41 #if defined(CERNLIB_SINGLE)
  42       REAL
  43 #endif
  44      +       ZX,ZQ,ZUV,ZDV,ZUB,ZDB,ZSB,ZCB,ZGL
  45 c arg
  46       integer ic
  47       DOUBLE PRECISION Q2,x
  48       DOUBLE PRECISION qu,qd,qc,g
  49 c const
  50       DOUBLE PRECISION q42it,q52it,lam42,lam52
  51       DOUBLE PRECISION alinv,mc,PI
  52 c local
  53       DOUBLE PRECISION qv,qsea,cv,cs,dcv,dcs
  54       DOUBLE PRECISION A0val,A1val,A2val,Bval,Cval,
  55      $       A0sea,B0sea,BB0sea,C0sea
  56       DOUBLE PRECISION A0dcv,A1dcv,A2dcv,A3dcv,Bdcv,Cdcv
  57       DOUBLE PRECISION Adcs, B0dcs, B1dcs, Cdcs
  58       DOUBLE PRECISION x1,x2,mc2q2
  59       DOUBLE PRECISION s,s2,s3,s4,prsccf,alstpi
  60       DOUBLE PRECISION WHIT3g
  61 c parameters
  62       parameter(lam42=0.16d0, lam52=0.091411319d0)
  63       parameter(Q42IT=4.0d0, Q52IT=100.0d0)
  64       parameter(alinv=137.036d0, mc=1.5d0)
  65       parameter(pi=3.14159265358979323846d0)
  66       common /scale/ s,s2,s3,s4,prsccf
  67 c
  68 c begin
  69       x=ZX
  70       Q2=ZQ*ZQ
  71       ic=1
  72 c
  73       x1=1.0d0-x
  74       x2=x**2
  75       mc2q2=mc**2/Q2
  76 c
  77       if(Q2.lt.100.0d0) then
  78 c  under 100 GeV^2
  79 c
  80 c  set  scale s
  81          if(Q2.lt.4.0d0) then
  82 cccc  for under 4GeV^2 prescription
  83             s=  0.0d0
  84             prsccf =  log(Q2/LAM42)/ log(Q42IT/LAM42)
  85             alstpi = 6.0d0/25.0d0/ log(Q42IT/LAM42)
  86          else
  87             s=   log(  log(Q2/LAM42)/ log(Q42IT/LAM42))
  88             prsccf = 1.0d0
  89             alstpi = 6.0d0/25.0d0/ log(Q2/LAM42)
  90          endif
  91             s2=s**2
  92             s3=s2*s
  93             s4=s2**2
  94 c
  95 cccccc   WHIT3 quark (U100)
  96 c
  97       A0val= 1.882000d+00+s*( 1.213000d+00)+s2*( 6.970000d-01)
  98       A1val=              s*(-2.361000d+00)+s2*(-1.136000d+00)
  99       A2val=              s*( 5.280000d-01)+s2*( 2.406000d+00)
 100       Bval = 5.000000d-01+s*( 2.107000d-02)+s2*( 4.130000d-03)
 101       Cval = 2.500000d-01+s*(-2.376000d-01)+s2*( 2.018000d-01)
 102      $           +s3*(-5.040000d-02)
 103       A0sea= 1.587000d+00+s*( 5.050000d+00)+s2*(-1.126000d+01)
 104      $           +s3*( 7.560000d+00)+s4*(-1.471000d+00)
 105       B0sea=-1.006000d-01+s*( 2.259000d-01)+s2*(-1.195000d+00)
 106      $           +s3*( 1.175000d+00)+s4*(-4.460000d-01)
 107       BB0sea=5.730000d+00+s*( 2.564000d+01)+s2*(-5.870000d+01)
 108      $           +s3*( 6.320000d+01)+s4*(-2.577000d+01)
 109       C0sea= 2.136000d+01+s*(-7.290000d+01)+s2*( 1.532000d+02)
 110      $           +s3*(-1.679000d+02)+s4*( 6.740000d+01)
 111 c
 112          qv  = prsccf/alinv/x*
 113      $         (A0val+A1val*x+A2val*x2) * x**Bval * x1**Cval
 114          qsea= prsccf/alinv/x*
 115      $         A0sea * x**(B0sea+BB0sea*x) * x1**C0sea
 116 c
 117          qu  = qv/3.0d0  + qsea/6.0d0
 118          qu  = qu*x
 119          ZUV=qu
 120          ZUB=qu
 121          qd  = qv/12.0d0 + qsea/6.0d0
 122          qd  = qd*x
 123          ZDV=qd
 124          ZDB=qd
 125          ZSB=qd
 126 c
 127          if((ic.ne.0) .and. (x*(1.0d0+4.0d0*mc2q2).lt.1.0d0)) then
 128             call WHIT3Q(x,mc2q2,cv,cs)
 129             qc = cv/alinv/2.0d0/PI + cs*alstpi
 130             qc  = qc*x
 131             ZCB=qc
 132          else
 133             qc = 0.0d0
 134             ZCB=qc
 135          endif
 136 c
 137          g   = WHIT3G(x,Q2)
 138          g   = g*x
 139          ZGL=g
 140 c
 141       else
 142 c over 100 GeV^2
 143 c
 144 c set scale s
 145          s=   log(  log(Q2/LAM52)/ log(Q52IT/LAM52))
 146          prsccf = 1.0d0
 147          alstpi = 6.0d0/23.0d0/ log(Q2/LAM52)
 148             s2=s**2
 149             s3=s2*s
 150             s4=s2**2
 151 c
 152 cccccc   WHIT3 quark (O100)
 153 c
 154       A0val= 3.058000d+00+s*( 2.474000d+00)+s2*( 1.002000d+00)
 155       A1val=-2.182000d+00+s*(-4.480000d+00)+s2*(-2.264000d-01)
 156       A2val= 1.522000d+00+s*( 4.300000d+00)+s2*( 1.315000d+00)
 157       Bval = 5.170000d-01+s*( 4.030000d-02)+s2*(-2.097000d-02)
 158       Cval = 1.655000d-01+s*(-2.064000d-02)+s2*( 5.370000d-02)
 159       A0sea= 1.850000d+00+s*(-3.670000d+00)+s2*( 2.714000d+01)
 160      $           +s3*(-1.066000d+02)+s4*( 1.309000d+02)
 161       B0sea=-2.299000d-01+s*(-4.970000d-01)+s2*( 2.464000d+00)
 162      $           +s3*(-9.950000d+00)+s4*( 1.232000d+01)
 163       BB0sea=1.042000d+01+s*(-1.074000d+01)+s2*( 1.327000d+02)
 164      $           +s3*(-5.390000d+02)+s4*( 6.560000d+02)
 165       C0sea= 4.070000d+00+s*( 4.110000d+00)+s2*(-1.719000d+02)
 166      $           +s3*( 7.070000d+02)+s4*(-8.590000d+02)
 167 c
 168          qv  = 1.0d0/alinv/x*
 169      $         (A0val+A1val*x+A2val*x2) * x**Bval * x1**Cval
 170          qsea= 1.0d0/alinv/x*
 171      $         A0sea * x**(B0sea+BB0sea*x) * x1**C0sea
 172 c
 173          qu  = qv/3.0d0  + qsea/6.0d0
 174          qu  = qu*x
 175          ZUV=qu
 176          ZUB=qu
 177          qd  = qv/12.0d0 + qsea/6.0d0
 178          qd  = qd*x
 179          ZDV=qd
 180          ZDB=qd
 181          ZSB=qd
 182          g   = WHIT3G(x,Q2)
 183          g   = g*x
 184          ZGL=g
 185 c
 186          if((ic.ne.0) .and. (x*(1.0d0+4.0d0*mc2q2).lt.1.0d0)) then
 187       A0dcv=              s*( 1.219000d-01)+s2*( 6.200000d+00)
 188      $           +s3*(-2.504000d+01)+s4*( 3.098000d+01)
 189       A1dcv=              s*( 1.913000d+00)+s2*(-7.690000d+01)
 190      $           +s3*( 3.180000d+02)+s4*(-3.920000d+02)
 191       A2dcv=              s*(-7.160000d+00)+s2*( 2.503000d+02)
 192      $           +s3*(-1.062000d+03)+s4*( 1.308000d+03)
 193       A3dcv=              s*( 3.190000d+00)+s2*(-2.301000d+02)
 194      $           +s3*( 1.012000d+03)+s4*(-1.250000d+03)
 195       Bdcv = 4.990000d-01+s*( 3.470000d+00)+s2*(-1.526000d+01)
 196      $           +s3*( 1.967000d+01)
 197       Cdcv = 3.290000d-01+s*( 8.240000d+00)+s2*(-3.800000d+01)
 198      $           +s3*( 4.630000d+01)
 199       Adcs =              s*(-1.948000d-02)+s2*( 2.861000d-02)
 200      $           +s3*(-2.036000d-02)
 201       B0dcs=-4.130000d-01+s*(-4.390000d-01)+s2*( 1.810000d-01)
 202       B1dcs= 5.190000d+00+s*(-7.400000d+00)+s2*( 3.400000d+00)
 203       Cdcs = 2.359000d+00+s*( 9.770000d-01)+s2*(-7.730000d+00)
 204      $           +s3*( 9.480000d+00)
 205 c
 206          dcv = 1.0d0/alinv/x*
 207      $         (A0dcv+x*A1dcv+x2*A2dcv+x2*x*A3dcv) * x**Bdcv * x1**Cdcv
 208          dcs = 1.0d0/alinv/x*
 209      $         Adcs * x**(B0dcs+B1dcs*x) * x1**Cdcs
 210 c
 211            call WHIT3Q(x,mc*mc/Q2,cv,cs)
 212            qc = cv/alinv/2.0d0/PI + cs*alstpi + dcs + dcv
 213            qc  = qc*x
 214            ZCB=qc
 215          else
 216            qc = 0.0d0
 217            ZCB=qc
 218          endif
 219       endif
 220 c
 221       return
 222       end