Unexpected tunneling current from downstream neutral modes

We analyze transport through a quantum point contact in fractional quantum Hall states with counter-propagating neutral edge modes. We show that both the noise (as expected and previously calculated by other authors) and (perhaps surprisingly) the average transmitted current are affected by downstream perturbations within the standard edge state model. We consider two scenarios for downstream perturbations. We argue that the change in transmitted current should be observable in experiments that have shown increased noise.