Moser Regularization of a Stochastically Perturbed Kepler Problem
Archishman Saha
TL;DR
This work analyzes a Kepler problem perturbed by angular-momentum–oriented stochastic noise and shows that key invariants, specifically $||\mathbf{J}||$ and $||\mathbf{A}||$, remain constant in magnitude while the distance $||\mathbf{q}||$ and speed follow deterministic trajectories. By applying a Moser-type regularization, the stochastic dynamics are mapped to a stochastic geodesic flow on the 3-sphere, with the noise structure preserved by the map, enabling a geometric treatment of collisions. The study demonstrates that collision solutions correspond to great circles on $S^3$ through the north pole and that the regularization extends to general negative energy levels via scaling, maintaining a symplectic framework. This provides a robust bridge between stochastic Hamiltonian perturbations and classical geometric regularization, offering a deterministic backbone for certain stochastic Keplerian phenomena.
Abstract
We consider a stochastic Kepler problem perturbed by a Hamiltonian noise affecting the angular momentum vector. We show that the angular momentum and the Laplace-Runge-Lenz vectors are conserved in magnitude and as a consequence, the distance and speed of the particle follow deterministic dynamics. Further, in a procedure similar to Moser's regularization, we transform the stochastic Kepler problem to obtain its dynamics as a stochastic geodesic flow on a 3-sphere.
