Numerical solution of Q2 evolution equations for polarized structure functions Original Research Article

We investigate numerical solution of Dokshitzer-Gribov-Lipatov-Altarelli-Parisi (DGLAP) Q2 evolution equations for longitudinally polarized structure functions. Flavor nonsinglet and singlet equations with next-to-leading-order αs corrections are studied. A brute-force method is employed. Dividing the variables x and Q2 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 Q2 steps and more than one thousand x steps are taken. Our evolution results are compared with polarized experimental data of the spin asymmetry A1 by the SLAC-E130, SLAC-E143, EMC, and SMC collaborations. The comparison indicates that we cannot assume A1 is independent of Q2. We provide a FORTRAN program for the Q2 evolution and devolution of polarized nonsinglet-quark, singlet-quark, Δqi+Δqi, and gluon distributions (and corresponding structure functions).