paper

Numerical solution of evolution equations in a brute-force method

arXiv:hep-ph/9508246 · doi:10.1016/0010-4655(96)00013-6

Abstract

We investigate numerical solution of evolution equations for structure functions in the nucleon and in nuclei. (Dokshitzer-Gribov-Lipatov-)Altarelli-Parisi and Mueller-Qiu evolution equations are solved in a brute-force method. Spin-independent flavor-nonsinglet and singlet equations with next-to-leading-order corrections are studied. Dividing the variables and into small steps, we simply solve the integrodifferential equations. Numerical results indicate that accuracy is better than 2\% in the region if more than two-hundred steps and more than one-thousand steps are taken. The numerical solution is discussed in detail, and evolution results are compared with dependent data in CDHSW, SLAC, BCDMS, EMC, NMC, Fermilab-E665, ZEUS, and H1 experiments. We provide a FORTRAN program for Q evolution (and ``devolution'') of nonsinglet-quark, singlet-quark, , and gluon distributions (and corresponding structure functions) in the nucleon and in nuclei. This is a very useful program for studying spin-independent structure functions.

48 pages, LATEX, figs. 1-6. Complete postscript file including the figure is available at ftp://ftp.cc.saga-u.ac.jp/pub/paper/riko/quantum1/saga-he-81.ps.gz or at http://www.cc.saga-u.ac.jp/saga-u/riko/physics/quantum1/structure.html (We had a problem in taking a file in WWW, but the problem was fixed recently.) Email: 94sm10 or [email protected]

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