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Commit | Line | Data |
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fe4da5cc | 1 | #include "pdf/pilot.h" |
2 | SUBROUTINE SASDIR(X,Q2,P2,Q02,XPGA) | |
3 | C...Purpose: to evaluate the direct contribution, i.e. the C^gamma term, | |
4 | C...as needed in MSbar parametrizations. | |
5 | DIMENSION XPGA(-6:6) | |
6 | DATA PMC/1.3/, PMB/4.6/, AEM2PI/0.0011614/ | |
7 | ||
8 | C...Reset output. | |
9 | DO 100 KFL=-6,6 | |
10 | XPGA(KFL)=0. | |
11 | 100 CONTINUE | |
12 | ||
13 | C...Evaluate common x-dependent expression. | |
14 | XTMP = (X**2+(1.-X)**2) * (-LOG(X)) - 1. | |
15 | CGAM = 3.*AEM2PI*X * (XTMP*(1.+P2/(P2+Q02)) + 6.*X*(1.-X)) | |
16 | ||
17 | C...d, u, s part by simple charge factor. | |
18 | XPGA(1)=(1./9.)*CGAM | |
19 | XPGA(2)=(4./9.)*CGAM | |
20 | XPGA(3)=(1./9.)*CGAM | |
21 | ||
22 | C...Also fill for antiquarks. | |
23 | DO 110 KF=1,5 | |
24 | XPGA(-KF)=XPGA(KF) | |
25 | 110 CONTINUE | |
26 | ||
27 | RETURN | |
28 | END |