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Commit | Line | Data |
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fe4da5cc | 1 | * |
2 | * $Id$ | |
3 | * | |
4 | * $Log$ | |
5 | * Revision 1.1.1.2 1996/10/30 08:32:02 cernlib | |
6 | * Version 7.04 | |
7 | * | |
8 | * Revision 1.1.1.1 1996/04/12 15:30:16 plothow | |
9 | * Version 7.01 | |
10 | * | |
11 | * | |
12 | #include "pdf/pilot.h" | |
13 | c | |
14 | cccccccccccccccccccccccccccccc | |
15 | c QPM calculation | |
16 | subroutine WHIT3Q(x,r,cv,cs) | |
17 | ccc INPUTS : x,r=mc^2/Q^2 | |
18 | ccc OUTPUTS: cv,cs (valence- and sea- charm quark dist) | |
19 | ccc cv <-- cv / ( alpha / 2PI) | |
20 | ccc cs <-- cs / ( alpha_s/2PI) | |
21 | c | |
22 | implicit none | |
23 | c arg | |
24 | DOUBLE PRECISION x,r | |
25 | DOUBLE PRECISION cv,cs | |
26 | c CONST | |
27 | DOUBLE PRECISION ec,mc | |
28 | parameter(ec=2.0d0/3.0d0,mc=1.5d0) | |
29 | c N=15 Gauss int. weights and points | |
30 | integer GN,i | |
31 | parameter(GN=15) | |
32 | DOUBLE PRECISION XG(GN), XW(GN) | |
33 | DATA (XG(i),i=1,GN)/6.003741d-03, | |
34 | $ 3.136330d-02, 7.589671d-02, 1.377911d-01, 2.145139d-01, | |
35 | $ 3.029243d-01, 3.994030d-01, 5.000000d-01, 6.005970d-01, | |
36 | $ 6.970757d-01, 7.854861d-01, 8.622089d-01, 9.241033d-01, | |
37 | $ 9.686367d-01, 9.939963d-01/ | |
38 | DATA (XW(i),i=1,GN)/1.537662d-02, | |
39 | $ 3.518302d-02, 5.357961d-02, 6.978534d-02, 8.313460d-02, | |
40 | $ 9.308050d-02, 9.921574d-02, 1.012891d-01, 9.921574d-02, | |
41 | $ 9.308050d-02, 8.313460d-02, 6.978534d-02, 5.357961d-02, | |
42 | $ 3.518302d-02, 1.537662d-02/ | |
43 | c local | |
44 | DOUBLE PRECISION sum, y,z,beta,w,WHIT3G,L | |
45 | parameter(L=4.0d0) | |
46 | DOUBLE PRECISION x1,rx,z1,rz | |
47 | c | |
48 | c begin | |
49 | x1=1.0d0-x | |
50 | rx=4.0d0*r*x | |
51 | c | |
52 | c direct | |
53 | beta=dsqrt(1.0d0-rx/x1) | |
54 | w=x*( beta*(-1.0d0+8.0d0*x*x1-rx*x1) | |
55 | $ +(x**2+x1**2+rx*(1.0d0-3.0d0*x)-0.5d0*rx**2) | |
56 | $ * log( (1.0d0+beta)/(1.0d0-beta) )) | |
57 | cv = 3.0d0*ec**2 * w / x | |
58 | c | |
59 | c resolved | |
60 | sum=0.0d0 | |
61 | do 10 i=1,GN | |
62 | y= x+rx + (x1-rx)*XG(i)**L | |
63 | z=x/y | |
64 | z1=1.0d0-z | |
65 | rz=4.0d0*r*z | |
66 | beta=dsqrt(1.0d0-rz/z1) | |
67 | w=z*( beta*(-1.0d0+8.0d0*z*z1-rz*z1) | |
68 | $ +(z**2+z1**2+rz*(1.0d0-3.0d0*z)-0.5d0*rz**2) | |
69 | $ * log( (1.0d0+beta)/(1.0d0-beta) )) | |
70 | c | |
71 | sum= sum + w * WHIT3G(y,mc**2/r)* L*XG(i)**(L-1.0d0)*XW(i) | |
72 | c | |
73 | 10 continue | |
74 | c | |
75 | cs = 0.5d0/x * (x1-rx) * sum | |
76 | c | |
77 | return | |
78 | end |