  We give an explicit description of the law of terminal value $W$ of additive
martingales in a remarkable branching stable process. We show that the right
tail probability of the terminal value decays exponentially fast and the left
tail probability follows that $-\log \mathbb{P}(W<x) \sim \frac{1}{2} (\log
x)^2$ as $x \rightarrow 0+$. These are in sharp contrast with results in the
literature such as Liu (2000, 2001) and Buraczewski (2009). We further show
that the law of $W$ is self-decomposable, and therefore, possesses a unimodal
density. We specify the asymptotic behavior at $0$ and at $+\infty$ of the
latter.

Probability