On the collision between two PNG droplets
  In this article we study the interface generated by the collision between two cristals growing layer by layer on a one-dimensional substrate through random decomposition of particles. We relate this interface with the notion of beta-path in an equivalent directed polymer model and, by using asymptotics results from Baik and Rains (2000) and some hydrodynamic tools introduced by Cator and Groeenenboon (2005), we derive a law of large numbers for such a path and obtain some bounds for its fluctuations. 
Cristian Coletti and Leandro P. R. Pimentel