  We consider a model of branching Brownian motion with self repulsion.
Self-repulsion is introduced via change of measure that penalises particles
spending time in an $\e$-neighbourhood of each other. We derive a simplified
version of the model where only branching events are penalised. This model is
almost exactly solvable and we derive a precise description of the particle
numbers and branching times. In the limit of weak penalty, an interesting
universal time-inhomogeneous branching process emerges. The position of the
maximum is governed by a F-KPP type reaction-diffusion equation with a time
dependent reaction term.
