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pygrvm.f
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1 
2 C*********************************************************************
3 
4 C...PYGRVM
5 C...Gives the GRV 94 M (MSbar) parton distribution function set
6 C...in parametrized form.
7 C...Authors: M. Glueck, E. Reya and A. Vogt.
8 
9  SUBROUTINE pygrvm (X, Q2, UV, DV, DEL, UDB, SB, CHM, BOT, GL)
10 
11 C...Double precision declaration.
12  IMPLICIT DOUBLE PRECISION (a - z)
13 
14 C...Common expressions.
15  mu2 = 0.34d0
16  lam2 = 0.248d0 * 0.248d0
17  s = log(log(q2/lam2) / log(mu2/lam2))
18  ds = sqrt(s)
19  s2 = s * s
20  s3 = s2 * s
21 
22 C...uv :
23  nu = 1.304d0 + 0.863d0 * s
24  aku = 0.558d0 - 0.020d0 * s
25  bku = 0.183d0 * s
26  au = -0.113d0 + 0.283d0 * s - 0.321d0 * s2
27  bu = 6.843d0 - 5.089d0 * s + 2.647d0 * s2 - 0.527d0 * s3
28  cu = 7.771d0 - 10.09d0 * s + 2.630d0 * s2
29  du = 3.315d0 + 1.145d0 * s - 0.583d0 * s2 + 0.154d0 * s3
30  uv = pygrvv(x, nu, aku, bku, au, bu, cu, du)
31 
32 C...dv :
33  nd = 0.102d0 - 0.017d0 * s + 0.005d0 * s2
34  akd = 0.270d0 - 0.019d0 * s
35  bkd = 0.260d0
36  ad = 2.393d0 + 6.228d0 * s - 0.881d0 * s2
37  bd = 46.06d0 + 4.673d0 * s - 14.98d0 * s2 + 1.331d0 * s3
38  cd = 17.83d0 - 53.47d0 * s + 21.24d0 * s2
39  dd = 4.081d0 + 0.976d0 * s - 0.485d0 * s2 + 0.152d0 * s3
40  dv = pygrvv(x, nd, akd, bkd, ad, bd, cd, dd)
41 
42 C...del :
43  ne = 0.070d0 + 0.042d0 * s - 0.011d0 * s2 + 0.004d0 * s3
44  ake = 0.409d0 - 0.007d0 * s
45  bke = 0.782d0 + 0.082d0 * s
46  ae = -29.65d0 + 26.49d0 * s + 5.429d0 * s2
47  be = 90.20d0 - 74.97d0 * s + 4.526d0 * s2
48  ce = 0.0d0
49  de = 8.122d0 + 2.120d0 * s - 1.088d0 * s2 + 0.231d0 * s3
50  del = pygrvv(x, ne, ake, bke, ae, be, ce, de)
51 
52 C...udb :
53  alx = 0.877d0
54  bex = 0.561d0
55  akx = 0.275d0
56  bkx = 0.0d0
57  agx = 0.997d0
58  bgx = 3.210d0 - 1.866d0 * s
59  cx = 7.300d0
60  dx = 9.010d0 + 0.896d0 * ds + 0.222d0 * s2
61  ex = 3.077d0 + 1.446d0 * s
62  esx = 3.173d0 - 2.445d0 * ds + 2.207d0 * s
63  udb = pygrvw(x, s, alx, bex, akx, bkx, agx, bgx, cx,
64  & dx, ex, esx)
65 
66 C...sb :
67  sts = 0d0
68  als = 0.756d0
69  bes = 0.216d0
70  aks = 1.690d0 + 0.650d0 * ds - 0.922d0 * s
71  as = -4.329d0 + 1.131d0 * s
72  bs = 9.568d0 - 1.744d0 * s
73  dst = 9.377d0 + 1.088d0 * ds - 1.320d0 * s + 0.130d0 * s2
74  est = 3.031d0 + 1.639d0 * s
75  ess = 5.837d0 + 0.815d0 * s
76  sb = pygrvs(x, s, sts, als, bes, aks, as, bs, dst, est, ess)
77 
78 C...cb :
79  stc = 0.820d0
80  alc = 0.98d0
81  bec = 0d0
82  akc = -0.625d0 - 0.523d0 * s
83  ac = 0d0
84  bc = 1.896d0 + 1.616d0 * s
85  dct = 4.12d0 + 0.683d0 * s
86  ect = 4.36d0 + 1.328d0 * s
87  esc = 0.677d0 + 0.679d0 * s
88  chm = pygrvs(x, s, stc, alc, bec, akc, ac, bc, dct, ect, esc)
89 
90 C...bb :
91  stb = 1.297d0
92  alb = 0.99d0
93  beb = 0d0
94  akb = - 0.193d0 * s
95  ab = 0d0
96  bb = 0d0
97  dbt = 3.447d0 + 0.927d0 * s
98  ebt = 4.68d0 + 1.259d0 * s
99  esb = 1.892d0 + 2.199d0 * s
100  bot = pygrvs(x, s, stb, alb, beb, akb, ab, bb, dbt, ebt, esb)
101 
102 C...gl :
103  alg = 1.014d0
104  beg = 1.738d0
105  akg = 1.724d0 + 0.157d0 * s
106  bkg = 0.800d0 + 1.016d0 * s
107  ag = 7.517d0 - 2.547d0 * s
108  bg = 34.09d0 - 52.21d0 * ds + 17.47d0 * s
109  cg = 4.039d0 + 1.491d0 * s
110  dg = 3.404d0 + 0.830d0 * s
111  eg = -1.112d0 + 3.438d0 * s - 0.302d0 * s2
112  esg = 3.256d0 - 0.436d0 * s
113  gl = pygrvw(x, s, alg, beg, akg, bkg, ag, bg, cg, dg, eg, esg)
114 
115  RETURN
116  END