Effective equidistribution of expanding translates in the space of affine lattices
Wooyeon Kim
TL;DR
The paper proves a polynomially effective equidistribution result for expanding translates in the space of $d$-dimensional affine lattices, $Y=\operatorname{SL}_d(\mathbb{R})\ltimes \mathbb{R}^d/\operatorname{SL}_d(\mathbb{Z})\ltimes \mathbb{Z}^d$, for all $d\ge 2$. Its approach blends an effective base equidistribution on $X=\operatorname{SL}_d(\mathbb{R})/\operatorname{SL}_d(\mathbb{Z})$ with a fiber-wise Fourier analysis on the torus fiber $\mathbb{T}^d$, using a partition of unity on $X$ and a geometric decomposition of $Y$. A key innovation is a Diophantine-geometry mechanism that translates large nonzero Fourier coefficients into high-concentration scenarios on auxiliary measures, which is then ruled out by a Weyl-type argument together with an effective equidistribution on $X$. The main quantitative bound is expressed in terms of a Diophantine growth function $\zeta(b,T)$, yielding explicit polynomial rates depending on the Diophantine type of the torus coordinate $b$, and it extends to general diagonal subgroups. This advances effective measure rigidity in the affine-lattice setting and opens avenues for quantitative homogeneous dynamics in related semi-direct product actions.
Abstract
We prove a polynomially effective equidistribution result for expanding translates in the space of $d$-dimensional affine lattices for any $d\ge 2$.
