Transport and fluctuations in mass aggregation processes: Mobility-driven clustering

We calculate the bulk-diffusion coefficient and conductivity in nonequilibrium conserved-mass aggregation processes on a ring. These involve chipping fragmentation of masses, which diffuse lattice aggregate with their neighboring masses contact, and, under certain conditions, they exhibit condensation transition. find that, even absence microscopic time reversibility, systems satisfy an Einstein relation, connects ratio to mass fluctuation. Interestingly, when dominates over chipping, or, equivalently, mobility is greatly enhanced. The enhancement conductivity, accordance results large fluctuations can induce mobility-driven clustering systems. Indeed, parameter regime, we show that along fluctuation, diverges beyond critical density, thus characterizing previously observed transition [Phys. Rev. Lett. 81, 3691 (1998)] terms instability conductivity. Notably, remains finite all cases. our analytic quite good agreement simulations.