English

Equal masses results for choreographies $n$-body problems

Classical Analysis and ODEs 2020-08-12 v4

Abstract

We prove that equally spaced choreography solutions of a large class of nn-body problems including the classical nn-body problem and a subset of quasi-homogeneous nn-body problems, have equal masses if the dimension of the space spanned by the point masses is n1n-1, n2n-2, or, if nn is odd, if the dimension is n3n-3. If nn is even and the dimension is n3n-3, then all masses with an odd label are equal and all masses with an even label are equal. Additionally, we prove that the same results hold true for any solution of an n+1n+1-body problem for which nn of the point masses behave like an equally spaced choreography and the n+1n+1st point mass is fixed at the origin. Furthermore, we deduce that if the curve along which the point masses of a choreography move has an axis of symmetry, the masses have to be equal if n=3n=3 and that if n=4n=4, if three of the point masses behave as stated and the fourth mass is fixed at a point, the masses of the first three point masses are all equal. Finally, we prove for the nn-body problem in spaces of negative constant Gaussian curvature that if n<6n<6, n4n\neq 4, equally spaced choreography solutions have to have equal masses, and for n=4n=4 the even labeled masses are equal and the odd labeled masses are equal and that the same holds true for the nn-body problem in spaces of positive constant Gaussian curvature, as long as the point masses do not move along a great circle. Additionally, we show that these last two results are also true for any solution to the n+1n+1-body problem in spaces of negative constant Gaussian curvature and the n+1n+1-body problem in spaces of positive constant Gaussian curvature respectively, for the case that nn of the point masses behave like an equally spaced choreography and the n+1n+1st is fixed at a point.

Keywords

Cite

@article{arxiv.2003.10694,
  title  = {Equal masses results for choreographies $n$-body problems},
  author = {Pieter Tibboel},
  journal= {arXiv preprint arXiv:2003.10694},
  year   = {2020}
}

Comments

Remark 1.1. added, details added to proof of Theorem 1.6

R2 v1 2026-06-23T14:25:02.155Z