3 papers
math.DS2026
Poncelet property of planar elliptic integrable Kepler billiards
Daniel Jaud, Lei Zhao
We consider the integrable dynamics of a Kepler billiard in the plane bounded by a branch of a conic section focused at the Kepler center. We show that in this case, for non-zero-e…
math.SG2026
Birkhoff normal forms, Dirac brackets and symplectic reduction
Jose Lamas, Lei Zhao
Dirac brackets are widely used to study constrained Hamiltonian dynamics. In this paper we develop a Dirac-bracket approach to normal forms on momentum levels and relate it to symp…
math.DS2025
Integrability of Kepler Billiards at Zero-Energy
Lei Zhao
We consider a Kepler billiard with zero-energy in the plane defined inside a smooth closed connected simple curve which intersects all focused parabola at at most two points. {We s…