  In this article, we study the potential theory of normal tempered stable
process which is obtained by time-changing the Brownian motion with a tempered
stable subordinator. Precisely, we study the asymptotic behavior of potential
density and Levy density associated with tempered stable subordinator and the
Green function and the Levy density associated with the normal tempered stable
process. We also provide the corresponding results for normal inverse Gaussian
process which is a well studied process in literature.
