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YRM: Elia Bisi
A central limit theorem for point-to-line last passage percolation
We derive the thermodynamic limit of a discrete probabilistic model inspired by statistical
mechanics. Suppose there are independent exponentially distributed times attached to all
vertices of the 2-dimensional integer lattice. Starting from a given vertex, perform a path
made of N steps taken as follows: wait for the random time attached to the vertex where you
are, then move either to the rightwards or to the downwards neighbouring vertex. The
longest waiting time over all N-step paths is called point-to-line last passage percolation, and
is strongly connected to an interacting particle system called totally asymmetric simple
exclusion process (TASEP). We show that the model is exactly solvable, by expressing the
distribution of the last passage time in terms of an integral of symplectic Schur functions. The
rich algebraic structure behind this formula permits deriving a central limit theorem (very
different from the classical Gaussian one!), characterised by cube root of N fluctuations and
a limiting distribution from random matrix theory. Techniques to obtain asymptotics include:
infinite-dimensional determinants, contour integrals, and steepest descent method.
Based on arXiv:1703.07337 and arXiv:1711.05120, joint work with Nikos Zygouras