2007/04/30 by Fournier, Nicolas
#60H10 #60J75 #FOS: Mathematics #Probability (math.PR)
paper · doi:10.48550/arxiv.0704.3922
We consider a one-dimensional jumping Markov process \Xxt\t ≥ 0, solving a Poisson-driven stochastic differential equation. We prove that the law of Xxt admits a smooth density for t>0, under some regularity and non-degeneracy assumptions on the coefficients of the S.D.E. To our knowledge, our result is the first one including the important case of a non-constant rate of jump. The main difficulty is that in such a case, the map x ↦ Xxt is not smooth. This seems to make impossible the use of Malliavin calculus techniques. To overcome this problem, we introduce a new method, in which the propagation of the smoothness of the density is obtained by analytic arguments.