The lower tail problem for homogeneous functionals of stable processes with no negative jumps

Abstract

Let Z be a strictly a-stable real Levy process (a>1) and X be a fluctuating b-homogeneous additive functional of Z. We investigate the asymptotics of the first passage-time of X above 1, and give a general upper bound. When Z has no negative jumps, we prove that this bound is optimal and does not depend on the homogeneity parameter b. This extends a result of Y. Isozaki and solves partially a conjecture of Z. Shi.Comment: Revised version. To appear in ALEA Latin American Journal of Probability and Mathematical Statistic