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pygrvl.f
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1 
2 C*********************************************************************
3 
4 C...PYGRVL
5 C...Gives the GRV 94 L (leading order) parton distribution function set
6 C...in parametrized form.
7 C...Authors: M. Glueck, E. Reya and A. Vogt.
8 
9  SUBROUTINE pygrvl (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 = 0.23d0
16  lam2 = 0.2322d0 * 0.2322d0
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 = 2.284d0 + 0.802d0 * s + 0.055d0 * s2
24  aku = 0.590d0 - 0.024d0 * s
25  bku = 0.131d0 + 0.063d0 * s
26  au = -0.449d0 - 0.138d0 * s - 0.076d0 * s2
27  bu = 0.213d0 + 2.669d0 * s - 0.728d0 * s2
28  cu = 8.854d0 - 9.135d0 * s + 1.979d0 * s2
29  du = 2.997d0 + 0.753d0 * s - 0.076d0 * s2
30  uv = pygrvv(x, nu, aku, bku, au, bu, cu, du)
31 
32 C...dv :
33  nd = 0.371d0 + 0.083d0 * s + 0.039d0 * s2
34  akd = 0.376d0
35  bkd = 0.486d0 + 0.062d0 * s
36  ad = -0.509d0 + 3.310d0 * s - 1.248d0 * s2
37  bd = 12.41d0 - 10.52d0 * s + 2.267d0 * s2
38  cd = 6.373d0 - 6.208d0 * s + 1.418d0 * s2
39  dd = 3.691d0 + 0.799d0 * s - 0.071d0 * s2
40  dv = pygrvv(x, nd, akd, bkd, ad, bd, cd, dd)
41 
42 C...del :
43  ne = 0.082d0 + 0.014d0 * s + 0.008d0 * s2
44  ake = 0.409d0 - 0.005d0 * s
45  bke = 0.799d0 + 0.071d0 * s
46  ae = -38.07d0 + 36.13d0 * s - 0.656d0 * s2
47  be = 90.31d0 - 74.15d0 * s + 7.645d0 * s2
48  ce = 0.0d0
49  de = 7.486d0 + 1.217d0 * s - 0.159d0 * s2
50  del = pygrvv(x, ne, ake, bke, ae, be, ce, de)
51 
52 C...udb :
53  alx = 1.451d0
54  bex = 0.271d0
55  akx = 0.410d0 - 0.232d0 * s
56  bkx = 0.534d0 - 0.457d0 * s
57  agx = 0.890d0 - 0.140d0 * s
58  bgx = -0.981d0
59  cx = 0.320d0 + 0.683d0 * s
60  dx = 4.752d0 + 1.164d0 * s + 0.286d0 * s2
61  ex = 4.119d0 + 1.713d0 * s
62  esx = 0.682d0 + 2.978d0 * 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 = 0.914d0
69  bes = 0.577d0
70  aks = 1.798d0 - 0.596d0 * s
71  as = -5.548d0 + 3.669d0 * ds - 0.616d0 * s
72  bs = 18.92d0 - 16.73d0 * ds + 5.168d0 * s
73  dst = 6.379d0 - 0.350d0 * s + 0.142d0 * s2
74  est = 3.981d0 + 1.638d0 * s
75  ess = 6.402d0
76  sb = pygrvs(x, s, sts, als, bes, aks, as, bs, dst, est, ess)
77 
78 C...cb :
79  stc = 0.888d0
80  alc = 1.01d0
81  bec = 0.37d0
82  akc = 0d0
83  ac = 0d0
84  bc = 4.24d0 - 0.804d0 * s
85  dct = 3.46d0 - 1.076d0 * s
86  ect = 4.61d0 + 1.49d0 * s
87  esc = 2.555d0 + 1.961d0 * s
88  chm = pygrvs(x, s, stc, alc, bec, akc, ac, bc, dct, ect, esc)
89 
90 C...bb :
91  stb = 1.351d0
92  alb = 1.00d0
93  beb = 0.51d0
94  akb = 0d0
95  ab = 0d0
96  bb = 1.848d0
97  dbt = 2.929d0 + 1.396d0 * s
98  ebt = 4.71d0 + 1.514d0 * s
99  esb = 4.02d0 + 1.239d0 * s
100  bot = pygrvs(x, s, stb, alb, beb, akb, ab, bb, dbt, ebt, esb)
101 
102 C...gl :
103  alg = 0.524d0
104  beg = 1.088d0
105  akg = 1.742d0 - 0.930d0 * s
106  bkg = - 0.399d0 * s2
107  ag = 7.486d0 - 2.185d0 * s
108  bg = 16.69d0 - 22.74d0 * s + 5.779d0 * s2
109  cg = -25.59d0 + 29.71d0 * s - 7.296d0 * s2
110  dg = 2.792d0 + 2.215d0 * s + 0.422d0 * s2 - 0.104d0 * s3
111  eg = 0.807d0 + 2.005d0 * s
112  esg = 3.841d0 + 0.316d0 * s
113  gl = pygrvw(x, s, alg, beg, akg, bkg, ag, bg, cg,
114  & dg, eg, esg)
115 
116  RETURN
117  END