The KPZ Upper-Tail Field as a KPZ Fixed Point with Brownian Initial Data
Abstract
The KPZ upper-tail field introduced by Liu and Zhang arises as the scaling limit of the narrow-wedge KPZ fixed point in a microscopic neighborhood of a conditioned large height. In this paper, we give a direct probabilistic identification of the upper-tail field. We identify the grounded positive-time sector with the KPZ fixed point started from the two-sided Brownian V-profile Bts(2x)−2|x|, while the negative-time sector is represented through an explicit exponential tilt of the same evolution. The argument uses the directed-landscape variational structure and the local Brownian comparison under upper-tail conditioning. As consequences of these representations, we recover probabilistically the positive- and negative-time large-scale limits of the KPZ upper-tail field.
Related
- Ballistic aggregation for one-sided Brownian initial velocity
- Backward and reflected backward stochastic differential equations under initial enlargement of Brownian filtrations
- Super-Brownian limits and the k-point function for high-dimensional percolation
- Optimal Reinsurance-Dividend Strategy with Fixed Transaction Costs in a Regime-Switching Brownian Risk Model: A Viscosity Solution to the Impulse Control Problem
- Point Configurations in Brownian Traces
BibTeX
@misc{zhang2026uppertail,
title = {{The KPZ Upper-Tail Field as a KPZ Fixed Point with Brownian Initial Data}},
author = {Ruixuan Zhang},
howpublished = {arXiv},
year = {2026},
month = sep,
doi = {10.48550/arxiv.2609.26424},
eprint = {2609.26424},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2609.26424},
note = {CC BY-NC-ND 4.0},
}
RIS
TY - UNPB
TI - The KPZ Upper-Tail Field as a KPZ Fixed Point with Brownian Initial Data
AU - Ruixuan Zhang
PY - 2026
DA - 2026/09/22
PB - arXiv
DO - 10.48550/arxiv.2609.26424
UR - https://arxiv.org/abs/2609.26424
AB - The KPZ upper-tail field introduced by Liu and Zhang arises as the scaling limit of the narrow-wedge KPZ fixed point in a microscopic neighborhood of a conditioned large height. In this paper, we give a direct probabilistic identification of the upper-tail field. We identify the grounded positive-time sector with the KPZ fixed point started from the two-sided Brownian V-profile B_ts(2x)−2|x|, while the negative-time sector is represented through an explicit exponential tilt of the same evolution. The argument uses the directed-landscape variational structure and the local Brownian comparison under upper-tail conditioning. As consequences of these representations, we recover probabilistically the positive- and negative-time large-scale limits of the KPZ upper-tail field.
ER -