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Manuscript Title: Numerical solution of Q**2 evolution equations in a brute-force
method. | ||

Authors: M. Miyama, S. Kumano | ||

Program title: BF1 | ||

Catalogue identifier: ADDB_v1_0Distribution format: gz | ||

Journal reference: Comput. Phys. Commun. 94(1996)185 | ||

Programming language: Fortran. | ||

Computer: AlphaServer 2100 4/200. | ||

Operating system: OpenVMS V6.1. | ||

Keywords: Particle physics, Elementary, Qcd, Structure function, Parton distribution, Q**2 evolution, Numerical solution. | ||

Classification: 11.5. | ||

Nature of problem:This program solves Altarelli-Parisi Equations or modified evolution equations (Mueller-Qiu) with or without next-to-leading-order alphas effects for a spin-independent structure function or quark distribution. Both flavor-nonsinglet and singlet cases are provided, so that the distributions, xq , xq , xq+ = xq + xqbar (i=quark flavor), xg, xF , NS S i - i i NS xF , and xF+ in the nucleon and in nuclei can be evolved. S i | ||

Solution method:We divide the variable x (and Q**2) into very small steps, and integration and differentiation are defined by df(x) [f(x )-f(x )] m+1 m ---- = --------------- and dx Delta x m Integral(dxf(x)) = Zigma (m=1, Nx) Delta x f(x ). m mThen, the integro-differerential equations are simply solved step by step, and this method is so called brute-force method. If the step numbers are increased, accurate results should be obtained. | ||

Restrictions:This program is used for calculating Q**2 evolution of a spin- independent flavor-nonsinglet-quark, singlet-quark, qi+, and gluon distributions (and corresponding structure functions) in the leading order or in the next-to-leading-order of alphas. Q**2 evolution equations are the Altarelli-Parisi equations and the modified ones (Mueller-Qiu). The double precision aithmetic is used. The renormalization scheme is the modified minimal subtraction scheme (MSbar). A user provides the initial structure function or quark distribution as a subroutine or as a data file. Examples are explained in sections 4.2 and 4.3. Then, the user inputs twenty-one parameters in section 4.1. | ||

Running time:Approximately five minutes on AlphaSever 2100 4/200 in the nonsinglet case, sixty minutes in the singlet-quark evolution, and eighty minutes in the singlet evolution with recombination effects. |

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