LETTER TO THE EDITOR: Particle dynamics in a mass-conserving coalescence process

We consider a fully asymmetric one-dimensional diffusion model with mass-conserving coalescence. Particles of unit mass enter at one edge of the chain and coalesce while performing a biased random walk towards the other edge where they exit. The conserved particle mass acts as a passive scalar in the reaction process A+Aicons/Journals/Common/rightarrow" ALT="rightarrow" ALIGN="TOP"/> A, and allows an exact mapping to a restricted ballistic surface deposition model for which exact results exist. In particular, the mass-mass correlation function is exactly known. These results complement earlier exact results for the A+Aicons/Journals/Common/rightarrow" ALT="rightarrow" ALIGN="TOP"/> A process without mass. We introduce a comprehensive scaling theory for this process. The exact analytical and numerical results confirm its validity.