Based on some evaluation techniques for Feynman integrals we deduce th
e distribution of annuities with random interest rate derived from a p
articular Lagrangian. A linear risk free interest intensity as well as
an arbitrary function describing the risk free intensity is considere
d. In addition, a transformation of Feynman integrals, related to some
time changes in stochastic processes, provides us with a connection t
o Bessel processes.