A Yaglom type asymptotic result for subcritical branching Brownian motion with absorption

We consider a slightly subcritical branching Brownian motion with absorption, where particles move as Brownian motions with drift - root 2 + 2 epsilon, undergo dyadic fission at rate 1, and are killed when they reach the origin. We obtain a Yaglom type asymptotic result, showing that the long run expected number of particles conditioned on survival grows exponentially as 1/ root epsilon as the process approaches criticality. (C) 2021 The Author(s). Published by Elsevier B.V.