English

No hyperbolic pants for the 4-body problem

Dynamical Systems 2015-02-03 v1 Differential Geometry

Abstract

The NN-body problem with a 1/r21/r^2 potential has, in addition to translation and rotational symmetry, an effective scale symmetry which allows its zero energy flow to be reduced to a geodesic flow on complex projective N2N-2-space, minus a hyperplane arrangement. When N=3N=3 we get a geodesic flow on the two-sphere minus three points. If, in addition we assume that the three masses are equal, then it was proved in [1] that the corresponding metric is hyperbolic: its Gaussian curvature is negative except at two points. Does the negative curvature property persist for N=4N=4, that is, in the equal mass 1/r21/r^2 4-body problem? Here we prove `no' by computing that the corresponding Riemannian metric in this N=4N=4 case has positive sectional curvature at some two-planes. This `no' answer dashes hopes of naively extending hyperbolicity from N=3N=3 to N>3N>3.

Keywords

Cite

@article{arxiv.1502.00606,
  title  = {No hyperbolic pants for the 4-body problem},
  author = {Connor Jackman and Richard Montgomery},
  journal= {arXiv preprint arXiv:1502.00606},
  year   = {2015}
}

Comments

10 pages, 1 figure

R2 v1 2026-06-22T08:19:32.452Z