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Small deviation estimates and small ball probabilities for geodesics in last passage percolation

2021/01/05 by Basu, Riddhipratim, Bhatia, Manan
#FOS: Mathematics #FOS: Physical sciences #Mathematical Physics (math-ph) #Probability (math.PR)

paper · doi:10.48550/arxiv.2101.01717

Abstract

For the exactly solvable model of exponential last passage percolation on ℤ2, consider the geodesic Γn joining (0,0) and (n,n) for large n. It is well known that the transversal fluctuation of Γn around the line x=y is n2/3+o(1) with high probability. We obtain the exponent governing the decay of the small ball probability for Γn and establish that for small δ, the probability that Γn is contained in a strip of width δn2/3 around the diagonal is exp (-Θ(δ-3/2)) uniformly in high n. We also obtain optimal small deviation estimates for the one point distribution of the geodesic showing that for (t)/(2n) bounded away from 0 and 1, we have ℙ(|x(t)-y(t)|≤ δn2/3)=Θ(δ) uniformly in high n, where (x(t),y(t)) is the unique point where Γn intersects the line x+y=t. Our methods are expected to go through for other exactly solvable models of planar last passage percolation and, upon taking the n→ ∞ limit, provide analogous estimates for geodesics in the directed landscape.

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