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Non-uniqueness times for the maximizer of the KPZ fixed point

Probability 2022-02-04 v1 Mathematical Physics math.MP

Abstract

Let ht\mathfrak h_t be the KPZ fixed point started from any initial condition that guarantees ht\mathfrak h_t has a maximum at every time tt almost surely. For any fixed tt, almost surely maxht\max \mathfrak h_t is uniquely attained. However, there are exceptional times t(0,)t \in (0, \infty) when maxht\max \mathfrak h_t is achieved at multiple points. Let Tk(0,)\mathcal T_k \subset (0, \infty) denote the set of times when maxht\max \mathfrak h_t is achieved at exactly kk points. We show that almost surely T2\mathcal T_2 has Hausdorff dimension 2/32/3 and is dense, T3\mathcal T_3 has Hausdorff dimension 1/31/3 and is dense, T4\mathcal T_4 has Hausdorff dimension 00, and there are no times when maxht\max \mathfrak h_t is achieved at 55 or more points. This resolves two conjectures of Corwin, Hammond, Hegde, and Matetski.

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Cite

@article{arxiv.2202.01700,
  title  = {Non-uniqueness times for the maximizer of the KPZ fixed point},
  author = {Duncan Dauvergne},
  journal= {arXiv preprint arXiv:2202.01700},
  year   = {2022}
}

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33 pages