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Periodic KPZ fixed point with general initial conditions

Jinho Baik, Yuchen Liao, Zhipeng Liu

Abstract

We consider the periodic totally asymmetric simple exclusion process with a general initial condition that properly approximates a periodic upper-semicontinuous function. We find the large time limit of the rescaled space-time multipoint distribution of the height function in the relaxation time scale. The limiting functions form a consistent family of finite-dimensional distributions; thus, they define the periodic KPZ fixed point with a general upper-semicontinuous initial condition. The main technical novelty of the paper is a hitting expectation representation of the energy function and the characteristic function in the finite-time multipoint distribution formula obtained in arXiv:1912.10143. The representation of the characteristic function is partly inspired by the work of arXiv:1701.00018, arXiv:2509.03246, while the representation of the energy function is based on an extensive guess-and-check exploration.

Periodic KPZ fixed point with general initial conditions

Abstract

We consider the periodic totally asymmetric simple exclusion process with a general initial condition that properly approximates a periodic upper-semicontinuous function. We find the large time limit of the rescaled space-time multipoint distribution of the height function in the relaxation time scale. The limiting functions form a consistent family of finite-dimensional distributions; thus, they define the periodic KPZ fixed point with a general upper-semicontinuous initial condition. The main technical novelty of the paper is a hitting expectation representation of the energy function and the characteristic function in the finite-time multipoint distribution formula obtained in arXiv:1912.10143. The representation of the characteristic function is partly inspired by the work of arXiv:1701.00018, arXiv:2509.03246, while the representation of the energy function is based on an extensive guess-and-check exploration.
Paper Structure (32 sections, 24 theorems, 309 equations, 2 figures)

This paper contains 32 sections, 24 theorems, 309 equations, 2 figures.

Key Result

Theorem 1.2

Assume that $\mathfrak{h}\in\mathrm{UC}_\mathrm{p}$, and $H^{\mathrm{PTASEP}}_{L;\mathfrak{h}}(x,0)$ after rescaling converges to $\mathfrak{h}$ in the space $\mathrm{UC}_\mathrm{p}$ as $L\to \infty$ as described above. For any $m\ge 1$, and any $m$ distinct points $(\beta_\ell,\alpha_\ell,\tau_\ell for $1\leq i\leq m$. Then we have The limit $\mathbb{F}^{(\mathrm{p})}_\mathfrak{h}$ is defined by

Figures (2)

  • Figure 1: The roots of $\mathrm{e}^{-\zeta^2/2}=\mathrm{z}$ for $\mathrm{z}=0.3\mathrm{e}^{\mathrm{i}\pi/4}$. The dashed line is the level curve $|\mathrm{e}^{-\zeta^2/2}|=|\mathrm{z}|$.
  • Figure 2: Roots and level sets for $w^N(w+1)^{L-N} = z^L$ with $N=6, L=18$. Here $\mathbf{r}_0 =\frac{4^{1/3}}{3}$.

Theorems & Definitions (55)

  • Definition 1.1: Space of the initial height functions
  • Theorem 1.2
  • Remark 1.3
  • Theorem 1.5
  • proof : Proof of Theorem \ref{['thm:main2']}
  • Definition 2.1
  • Proposition 2.2
  • Definition 2.3
  • Remark 2.4
  • Proposition 2.5: Shift invariane of $\mathrm{C}_\mathfrak{h}(\mathbf{z})$
  • ...and 45 more