Physical Review A
Exact evaluation of the propagator beyond and at caustics for a charged particle in a constant magnetic field
Bin Kang Cheng
Abstract
It is first shown that the propagator of a charged particle in a constant external magnetic field is related to the propagator of a one-dimensional driven harmonic oscillator with memory. The memory term can be removed by introducing the auxiliary force term and then by integrating it out. By using this new formula for a driven harmonic oscillator, a generalization of Horv\'athy-Feynman formula, we finally evaluate exactly the propagator beyond and at caustics of our dynamical system.