Another New Solvable Many-Body Model of Goldfish Type

A new solvable many-body problem is identified. It is characterized by nonlinear Newtonian equations of motion (''acceleration equal force'') featuring one-body and two-body velocity-dependent forces ''of goldfish type'' which determine the motion ofan arbitra...

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Main Author: Francesco Calogero
Format: Article
Language:English
Published: National Academy of Science of Ukraine 2012-07-01
Series:Symmetry, Integrability and Geometry: Methods and Applications
Subjects:
Online Access:http://dx.doi.org/10.3842/SIGMA.2012.046
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author Francesco Calogero
author_facet Francesco Calogero
author_sort Francesco Calogero
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description A new solvable many-body problem is identified. It is characterized by nonlinear Newtonian equations of motion (''acceleration equal force'') featuring one-body and two-body velocity-dependent forces ''of goldfish type'' which determine the motion ofan arbitrary number $N$ of unit-mass point-particles in a plane. The $N$ (generally complex) values $z_{n}(t)$ at time $t$ ofthe $N$ coordinates of these moving particles are given by the $N$eigenvalues of a time-dependent $Nimes N$ matrix $U(t)$explicitly known in terms of the $2N$ initial data $z_{n}(0)$and $dot{z}_{n}(0) $. This model comes in two dif/ferentvariants, one featuring 3 arbitrary coupling constants, the other only 2; for special values of these parameters all solutions are completely periodic with the same period independent of the initial data (''isochrony''); for other special values of these parameters this property holds up to corrections vanishing exponentially as $tightarrow infty$ (''asymptotic isochrony''). Other isochronous variants of these models are also reported. Alternative formulations, obtained by changing the dependent variables from the $N$ zeros of a monic polynomial of degree $N$ to its $N$ coefficients, are also exhibited. Some mathematical findings implied by some of these results - such as Diophantine properties of the zeros of certain polynomials - are outlined, but their analysis is postponed to a separate paper.
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spelling doaj.art-2f6ad3c5f37a4bb69c156d73d6ab4ce42022-12-21T18:01:48ZengNational Academy of Science of UkraineSymmetry, Integrability and Geometry: Methods and Applications1815-06592012-07-018046Another New Solvable Many-Body Model of Goldfish TypeFrancesco CalogeroA new solvable many-body problem is identified. It is characterized by nonlinear Newtonian equations of motion (''acceleration equal force'') featuring one-body and two-body velocity-dependent forces ''of goldfish type'' which determine the motion ofan arbitrary number $N$ of unit-mass point-particles in a plane. The $N$ (generally complex) values $z_{n}(t)$ at time $t$ ofthe $N$ coordinates of these moving particles are given by the $N$eigenvalues of a time-dependent $Nimes N$ matrix $U(t)$explicitly known in terms of the $2N$ initial data $z_{n}(0)$and $dot{z}_{n}(0) $. This model comes in two dif/ferentvariants, one featuring 3 arbitrary coupling constants, the other only 2; for special values of these parameters all solutions are completely periodic with the same period independent of the initial data (''isochrony''); for other special values of these parameters this property holds up to corrections vanishing exponentially as $tightarrow infty$ (''asymptotic isochrony''). Other isochronous variants of these models are also reported. Alternative formulations, obtained by changing the dependent variables from the $N$ zeros of a monic polynomial of degree $N$ to its $N$ coefficients, are also exhibited. Some mathematical findings implied by some of these results - such as Diophantine properties of the zeros of certain polynomials - are outlined, but their analysis is postponed to a separate paper.http://dx.doi.org/10.3842/SIGMA.2012.046nonlinear discrete-time dynamical systemsintegrable and solvable mapsisochronous discrete-time dynamical systemsdiscrete-time dynamical systems of goldfish type
spellingShingle Francesco Calogero
Another New Solvable Many-Body Model of Goldfish Type
Symmetry, Integrability and Geometry: Methods and Applications
nonlinear discrete-time dynamical systems
integrable and solvable maps
isochronous discrete-time dynamical systems
discrete-time dynamical systems of goldfish type
title Another New Solvable Many-Body Model of Goldfish Type
title_full Another New Solvable Many-Body Model of Goldfish Type
title_fullStr Another New Solvable Many-Body Model of Goldfish Type
title_full_unstemmed Another New Solvable Many-Body Model of Goldfish Type
title_short Another New Solvable Many-Body Model of Goldfish Type
title_sort another new solvable many body model of goldfish type
topic nonlinear discrete-time dynamical systems
integrable and solvable maps
isochronous discrete-time dynamical systems
discrete-time dynamical systems of goldfish type
url http://dx.doi.org/10.3842/SIGMA.2012.046
work_keys_str_mv AT francescocalogero anothernewsolvablemanybodymodelofgoldfishtype