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MA(1) processes with Laplace innovations conditioned to stay positive

Year: 2026
Type: preprint
Abstract: We study a moving-average process with (not necessarily symmetric) Laplace innovations under the constraint of positivity. In the three nondegenerate parameter regimes $0<θ<1$, $θ>1$, and $θ<0$, we prove convergence of the conditioned finite-dimensional distributions and identify the limit as a Doob $h$-transform. The regimes lead to qualitatively different limiting dynamics: the invariant law is supported on the positive half-line for $0<θ<1$, the conditioned chain is confined to the negative half-line for $θ>1$, and the dynamics are genuinely two-sided and governed by $q$-trigonometric functions for $θ<0$. In each case, the persistence exponent, sharp persistence asymptotics, the defining eigenfunction, and the unique invariant distribution are obtained explicitly.
Language: English
Open Access status: green
OpenAlex ID: W7212023145
Cites: 4
Cited by: 1
Related to: 10