text: We consider the totally asymmetric simple exclusion process in a critical scaling parametrized by @math , which creates a shock in the particle density of order @math @math the observation time. When starting from step initial data, we provide bounds on the limiting law which in particular imply that in the double limit @math one recovers the product limit law and the degeneration of the correlation length observed at shocks of order @math . This result is shown to apply to a general last-passage percolation model. We also obtain bounds on the two-point functions of several @math processes.
  @cite_20: Coalescence of semi-infinite geodesics remains a central question in planar first passage percolation. In this paper we study finer properties of the coalescence structure of finite and semi-infinite geodesics for exactly solvable models of last passage percolation. Consider directed last passage percolation on @math with i.i.d. exponential weights on the vertices. Fix two points @math and @math for some @math , and consider the maximal paths @math and @math starting at @math and @math respectively to the point @math for @math . Our object of study is the point of coalescence, i.e., the point @math with smallest @math . We establish that the distance to coalescence @math scales as @math , by showing the upper tail bound @math for some @math . We also consider the problem of coalescence for semi-infinite geodesics. For the almost surely unique semi-infinite geodesics in the direction @math starting from @math and @math , we establish the optimal tail estimate @math , for the point of coalescence @math . This answers a question left open by Pimentel (Ann. Probab., 2016) who proved the corresponding lower bound.
summary: Here we rehash some of the known results that we will use in this paper, and describe the method of proof from @cite_20 , which is relevant to this paper.