Numerical solution of Q2 evolution equations for polarized structure functions

We investigate numerical solution of Dokshitzer-Gribov-Lipatov-Altarelli-Paris (DGLAP) Q(2) evolution equations for longitudinally polarized structure functions. Flavor nonsinglet and singlet equations with next-to-leading-order alpha(s) corrections are studied. A brute-force method is employed. Dividing the variables x and Q(2) into small steps, we simply solve the integrodifferential equations. Numerical results indicate that accuracy is better than 1% in the region 10(-5) < x < 0.8 if more than two hundred Q(2) steps and more than one thousand x steps are taken. Our evolution results are compared with polarized experimental data of the spin asymmetry A(1) by the SLAC-E130, SLAC-E143, EMC, and SMC collaborations. The comparison indicates that we cannot assume A(1) is independent of Q(2). We provide a FORTRAN program for the Q(2) evolution and devolution of polarized nonsinglet-quark, singlet-quark, Delta q(i)+Delta (q) over bar(i), and gluon distributions (and corresponding structure functions). (C) 1998 Published by Elsevier Science B.V.