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Manuscript Title: Soliton bag model.
Authors: R. Saly
Program title: SOLITON
Catalogue identifier: AAVQ_v1_0
Distribution format: gz
Journal reference: Comput. Phys. Commun. 30(1983)411
Programming language: Fortran.
Computer: VAX-11/780.
Operating system: VAX/VMS.
RAM: 40K words
Word size: 32
Keywords: Elementary, Particle physics, Empirical model, Nonlinear differential Equations, Soliton, Bag model, Dirac equation.
Classification: 11.6.

Nature of problem:
The soliton bag model is a generalization of the MIT and SLAC bag models. Mathematically the problem equals to boundary and eigenvalue problems for a system of coupled linear ordinary differential equations, integral equations and a nonlinear differential equation. The calculated quantities include: quark energy, bag energy, total hadron energy, magnetic moment, charge radius, ratio of axial-vector/ vector coupling, etc.

Solution method:
The problem is solved by iteration whose cycle involves the following three steps:
1) solution of the radial Dirac equations (eigenvalue problem),
2) renormalization of the quark wave functions,
3) solution of the nonlinear differential equation by the Newton method (two point boundary value problem).
The main tool in all three steps is a direct Taylor series expansion of the functions involved. The boundary (eigenvalue) problems are solved using a shooting method based on bi-section and parabola iteration.

Running time:
Execution of the program in the test case (accuracy 0.5% or 12 iterations) takes 1 min on the VAX-11 computer.