5 * Revision 1.1.1.2 1996/10/30 08:31:48 cernlib
8 * Revision 1.1.1.1 1996/04/12 15:30:05 plothow
12 #include "pdf/pilot.h"
13 C*********************************************************************
15 SUBROUTINE STROWP2(X,SCALE,UPV,DNV,SEA,STR,CHM,GL)
16 C :::::::::::::: OWENS SET 2 PION STRUCTURE FUNCTION :::::::::::::::
17 #include "pdf/impdp.inc"
18 #if defined(CERNLIB_DOUBLE)
19 DOUBLE PRECISION DGAMMA
21 #include "pdf/expdp.inc"
22 + COW(3,5,4),TS(6),XQ(9)
24 C...Expansion coefficients for up and down valence quark distributions.
25 DATA ((COW(IP,IS,1),IS=1,5),IP=1,3)/
26 1 4.0000D-01, 6.2800D-01, 0.0000D+00, 0.0000D+00, 0.0000D+00,
27 2 -5.9090D-02, 6.4360D-01, 0.0000D+00, 0.0000D+00, 0.0000D+00,
28 3 -6.5240D-03, 1.4510D-02, 0.0000D+00, 0.0000D+00, 0.0000D+00/
29 C...Expansion coefficients for gluon distribution.
30 DATA ((COW(IP,IS,2),IS=1,5),IP=1,3)/
31 1 7.9400D-01, 0.0000D+00, 2.8900D+00, 6.0000D+00, 0.0000D+00,
32 2 -9.1440D-01, -1.2370D+00, 5.9660D-01, -3.6710D+00, -8.1910D+00,
33 3 5.9660D-01, 6.5820D-01, -2.5500D-01, -2.3040D+00, 7.7580D+00/
34 C...Expansion coefficients for (up+down+strange) quark sea distribution.
35 DATA ((COW(IP,IS,3),IS=1,5),IP=1,3)/
36 1 9.0000D-01, 0.0000D+00, 5.0000D+00, 0.0000D+00, 0.0000D+00,
37 2 -1.4170D-01, -1.6970D-01, -2.4740D+00, -2.5340D+00, 5.6210D-01,
38 3 -1.7400D-01, -9.6230D-02, 1.5750D+00, 1.3780D+00, -2.7010D-01/
39 C...Expansion coefficients for charm quark sea distribution.
40 DATA ((COW(IP,IS,4),IS=1,5),IP=1,3)/
41 1 0.0000D+00, -8.8200D-02, 1.9240D+00, 0.0000D+00, 0.0000D+00,
42 2 6.2290D-02, -2.8920D-01, 2.4240D-01, -4.4630D+00, -8.3670D-01,
43 3 -4.0990D-02, -1.0820D-01, 2.0360D+00, 5.2090D+00, -4.8400D-02/
45 DATA ZEROD/0.D0/, ONED/1.D0/, SIXD/6.D0/
46 DATA ALAM/0.4D0/, Q02/4.D0/, QMAX2/2.D3/
47 C...Pion structure functions from Owens.
48 C...Allowed variable range: 4 GeV^2 < Q^2 < approx 2000 GeV^2.
50 C...Determine set, Lambda and s expansion variable.
52 Q2IN = MIN( QMAX2,MAX( Q02,Q2))
53 SD = LOG( LOG( Q2IN/ALAM**2)/ LOG( Q02/ALAM**2))
55 C...Calculate structure functions.
58 20 TS(IS)=COW(1,IS,KFL)+COW(2,IS,KFL)*SD+
61 #if defined(CERNLIB_SINGLE)
62 DENOM = GAMMA(TS(1))*GAMMA(TS(2)+ONED)/GAMMA(TS(1)+TS(2)+ONED)
64 #if defined(CERNLIB_DOUBLE)
65 DENOM = DGAMMA(TS(1))*DGAMMA(TS(2)+ONED)/
66 + DGAMMA(TS(1)+TS(2)+ONED)
68 XQ(KFL)=X**TS(1)*(1.-X)**TS(2)/DENOM
70 XQ(KFL)=TS(1)*X**TS(2)*(1.-X)**TS(3)*(1.+TS(4)*X+TS(5)*X**2)