HCM PROPERTY AND THE HALF-CAUCHY DISTRIBUTION
Abstract: Let and be two independent positive -stable random variables. It is known
that is distributed as the positive branch of a Cauchy random variable with drift.
We show that the density of the power transformation is hyperbolically
completely monotone in the sense of Thorin and Bondesson if and only if and
This clarifies a conjecture of Bondesson (1992) on positive stable densities.
2000 AMS Mathematics Subject Classification: Primary: 60E07; Secondary:
60E05.
Keywords and phrases: Half-Cauchy distribution, complete monotonicity, generalized
gamma convolution, hyperbolically completely monotone function, Pick function, positive
stable density.