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Manuscript Title: PANN: partial-wave analysis of nucleon-nucleon scattering in wide- energy region.
Authors: M. Matsuda, J. Nagata, H. Yoshino, Y. Yoshino
Program title: PANN
Catalogue identifier: ADMN_v1_0
Distribution format: tar.gz
Journal reference: Comput. Phys. Commun. 131(2000)225
Programming language: Fortran.
Word size: 32
Keywords: Elementary particle physics, Empirical model, Partial-wave analysis, Nucleon-nucleon scattering, Regge amplitudes, Multi-pole, Dibaryon, One-boson-exchange.
Classification: 11.6.

Nature of problem:
Partial-wave analysis (PWA) is a model independent method to determine the scattering amplitudes by means of fitting the experimental data on many kinds of observables. PANN carries out the energy-independent PWA of nucleon-nucleon scattering [1]. The obtained phase-shifts can be used to construct the potential model at low energies and to determine the coupling constants of the interactions in various models for nucleon-nucleon system at intermediate energies [2]. Unlike the usual PWA program, PANN is extended to make it available to analyze the nucleon-nucleon scattering data up to a few ten GeV using Veneziano-type amplitudes [3]. The nucleon-nucleon interaction at very short range can be studied by PANN, which are expected to detect some new dynamics.

Solution method:
The available experimental data are stored in the input file for PANN. The chi-square-minimization is carried out [4] and the free searched parameters are varied so as to reproduce the experimental data. After completing the chi-square-minimization, the user obtains the best-fit values of parameters (phase shifts, mixing parameters and reflection parameters) together with their uncertainties simultaneously. PANN provides the solution of phase shifts, mixing parameters, reflection parameters and also the determined helicity amplitudes. In addition, the calculated values of the differential cross section and various spin observables are provided. New experiments may be proposed by studying the predicted values for spin observables by PANN.

The program is developed to perform the PWAs of the elastic pp scattering and the elastic np scattering, where their effects from inelastic channels are evaluated by the reflection coefficients of S-matrix. The inelastic nucleon-nucleon scattering, for instance, one-pion production process cannot be treated.

Running time:
From several seconds to several ten minutes depending upon the number of experimental data and searched parameters. The computer time will increase if one takes smaller step size in the gradient of chi-square-space.

[1] M. Matsuda, J. Nagata, H. Yoshino, K. Harada, S. Ohara, Prog. Theor. Phys. 93 (1995) 1059; J. Nagata, H. Yoshino, M. Matsuda, Prog. Theor. Phys. 95 (1996) 691; H. Yoshino, J. Nagata, Y. Yoshino, M. Matsuda, N. Hiroshige, T. Ueda, Prog. Theor. Phys. 95 (1996) 577.
[2] See, for instance, S. Sawada, T. Ueda, W. Watari, M. Yonezawa, Prog. Theor. Phys. 28 (1962) 28.
[3] M. Kawasaki, Y. Susuki, M. Yonezawa, Prog. Theor. Phys. 47 (1972) 589.
[4] Y. Oyanagi, Library of Computer Center of University of Tokyo.