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.
6 DATA PMC/1.3/, PMB/4.6/, AEM2PI/0.0011614/
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))
17 C...d, u, s part by simple charge factor.
22 C...Also fill for antiquarks.