Linear-order dynamical hitsets with uniform tails

Determine whether the expected dynamical hitset for Brownian last passage percolation, between the endpoint regions \(\mathscr R_n^-\) and \(\mathscr R_n^+\) and over the critical time interval \([0,n^{-1/3}]\) in the bulk slab \([-n/2,n/2]\), is bounded by \(Cn\) for an absolute constant \(C\); additionally, establish whether there are constants \(C,c>0\) and \(\gamma\in(0,1)\), independent of \(n\) and \(\alpha\), such that the corresponding hitset exceeds \(\alpha n\) with probability at most \(Ce^{-c\alpha^\gamma}\) for every integer \(n\ge1\) and \(\alpha\ge1\).

Background

Theorem 1 establishes an expected hitset bound of order nexp⁡{C(log⁡log⁡n)2}n\exp\{C(\log\log n)^2\} on the critical dynamical time interval, together with a stretched-exponential failure estimate at a comparable threshold. The question asks whether the subpolynomial correction can be removed, yielding a genuinely linear expected hitset size, and whether a uniform tail bound in the excess factor α\alpha holds.

A positive answer to the expectation bound would substantially strengthen the control of geodesic traces and, as discussed immediately afterward, is expected to imply almost-sure nonexistence of exceptional times supporting bigeodesics with random directions. The authors explain that their current multiscale argument incurs scale-dependent branching and terminal costs, and does not provide the required uniform-in-nn tail estimate.

References

In view of this, we have the following natural question. Is the expected dynamical hitset on the critical time interval of linear order? More precisely, is there an absolute constant C such that, for every integer n\ge1, E\left|HitSet_{\mathscr R_n-}{\mathscr R_n+,[0,n{-1/3}]} \bigl(#1{-n/2}{n/2}\bigr)\right|\le Cn? Further, do there exist constants C,c>0 and \gamma\in(0,1), independent of n and \alpha, such that, for every integer n\ge1 and every \alpha\ge1, P\left( \left|HitSet_{\mathscr R_n-}{\mathscr R_n+,[0,n{-1/3}]} \bigl(#1{-n/2}{n/2}\bigr)\right|>\alpha n \right)\le Ce{-c\alpha\gamma}?

— Geodesic traces in dynamical Brownian last passage percolation  (2609.35103 - Bhatia, 28 Sep 2026) in Question 1, Section Further questions