PROGRAM SUMMARY
Title of program:
PANN
Catalogue identifier:
ADMN
Ref. in CPC:
131(2000)225
Distribution format: tar gzip file
Number of bits in a word:
32
Number of lines in distributed program, including test data, etc:
5361
Keywords:
Elementary particle physics, Empirical model, Partial-wave analysis,
Nucleon-nucleon scattering, Regge amplitudes, Multi-pole, Dibaryon,
One-boson-exchange.
Programming language used: Fortran
Nature of physical 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.
Method of solution
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.
Restrictions on the complexity of the problem
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.
Typical 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.
References
[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.