On the non-existence of hyperbolic polygonal relative equilibria for the   negative curved $n$--body problem with equal masses
  We consider the $n$--body problem defined on surfaces of constant negative curvature. For the case of $n$--equal masses we prove that the hyperbolic relative equilibria with a regular polygonal shape do not exist. In particular the Lagrangian (three equal distances) hyperbolic relative equilibria do not exist. We also show the existence of a new class of hyperbolic collinear relative equilibria for the five body problem on surfaces of constant negative curvature. 
Ernesto Perez-Chavela and Juan Manuel Sanchez-Cerritos
math.DS