Subcritical catalytic branching random walk with finite or infinite variance of offspring number

Abstract

Subcritical catalytic branching random walk on d-dimensional lattice is studied. New theorems concerning the asymptotic behavior of distributions of local particles numbers are established. To prove the results different approaches are used including the connection between fractional moments of random variables and fractional derivatives of their Laplace transforms. In the previous papers on this subject only supercritical and critical regimes were investigated assuming finiteness of the first moment of offspring number and finiteness of the variance of offspring number, respectively. In the present paper for the offspring number in subcritical regime finiteness of the moment of order 1+\delta is required where \delta is some positive number. Keywords and phrases: branching random walk, subcritical regime, finite variance of offspring number, infinite variance of offspring number, local particles numbers, limit theorems, fractional moments, fractional derivatives.