LAUSR

We study a minimal model of self-propelled particle in a crowded single-file environment. We extend classical models of exclusion processes (previously analyzed for diffusive and driven tracer particles) to the case where the tracer particle is a run-and-tumble particle (RTP), while all bath particles perform symmetric random walks. In the limit of high density of bath particles, we derive exact expressions for the full distribution of the RTP position X and all its cumulants, valid for arbitrary values of the tumbling probability α and time n. Our results highlight striking effects of crowding on the dynamics: even cumulants of the RTP position are increasing functions of α at intermediate timescales, and display a subdiffusive anomalous scaling independent of α in the limit of long times . These analytical results set the ground for a quantitative analysis of experimental trajectories of real biological or artificial microswimmers in extreme confinement.