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Manuscript Title: Efficient evolution of unpolarized and polarized parton distributions with QCD-PEGASUS | ||

Authors: A. Vogt | ||

Program title: QCD-Pegasus Version: 1.0 | ||

Catalogue identifier: ADVN_v1_0Distribution format: tar.gz | ||

Journal reference: Comput. Phys. Commun. 170(2005)65 | ||

Programming language: FORTRAN 77 (using the common compiler extension of procedure names with more than six characters). | ||

Computer: All. | ||

Operating system: All. | ||

RAM: negligible (< 1 MB) | ||

Keywords: unpolarized and longitudinally polarized parton distributions, Altarelli-Parisi evolution equations, Mellin-space solutions. | ||

PACS: 12.38.-t, 12.38.Bx. | ||

Classification: 11.5. | ||

Nature of problem:Solution of the evolution equations for the unpolarized and polarized parton distributions of hadrons at leading order (LO), next-to-leading order and next-to-next-to-leading order of perturbative QCD. Evolution performed either with a fixed number n of effectively massless quark flavours or in the variable-_{f}n scheme. The calculation of observables from the parton distributions is not part of the present package._{f} | ||

Solution method:Analytic solution in Mellin space (beyond LO in general by power-expansion around the lowest-order expansion) followed by a fast Mellin inversion to x-space using a fixed one-fits-all contour. | ||

Restrictions:The initial distributions for the evolution are required in a form facilitating an efficient calculation of their complex Mellin moments. The ratio of the renormalization and factorization scales μ _{τ}/μ has to be a fixed number. | ||

Running time:One to ten seconds, on a PC with a 2.0 GHz Pentium-IV processor, for performing the evolution of 200 initial distributions to 500 ( x, μ) points each. For more details see section 6 of the manuscript. |

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