Counting Lattice Points near Korányi Spheres via Generalized Radon Transforms

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Main Authors: Srivastava, Rajula, Taylor, Krystal
Format: Preprint
Published: 2025
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author Srivastava, Rajula
Taylor, Krystal
author_facet Srivastava, Rajula
Taylor, Krystal
contents In this note, we study a lattice point counting problem for spheres in Heisenberg groups, incorporating both the non-isotropic dilation structure and the non-commutative group law. More specifically, we establish an upper bound for the average number of lattice points in a $δ$-neighborhood of a Korányi sphere of large radius, where the average considered is over Heisenberg group translations of the sphere. This is in contrast with previous works, which either count lattice points on dilates of a fixed sphere (see \cites{GNT, Gath2}) or consider averages over Euclidean translations of the sphere (see \cites{CT}). We observe that incorporating the Heisenberg group structure allows us to circumvent the degeneracy arising from the vanishing of the Gaussian curvature at the poles of the Korányi sphere. In fact, in lower dimensions (the first and second Heisenberg group), our method establishes an upper bound for this number which gives a logarithmic improvement over the bound implied by the previously known results. Even for the higher dimensional Heisenberg groups, we recover the bounds implied by the main result of \cite{GNT} using a completely different approach of generalized Radon transforms. Further, we obtain upper bounds for the average number of lattice points near more general spheres described with respect to radial, Heisenberg homogeneous norms as considered in \cite{GNT}.
format Preprint
id arxiv_https___arxiv_org_abs_2502_05900
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Counting Lattice Points near Korányi Spheres via Generalized Radon Transforms
Srivastava, Rajula
Taylor, Krystal
Number Theory
Classical Analysis and ODEs
11P21, 42B20, 42B25, 22E25, 22E40
In this note, we study a lattice point counting problem for spheres in Heisenberg groups, incorporating both the non-isotropic dilation structure and the non-commutative group law. More specifically, we establish an upper bound for the average number of lattice points in a $δ$-neighborhood of a Korányi sphere of large radius, where the average considered is over Heisenberg group translations of the sphere. This is in contrast with previous works, which either count lattice points on dilates of a fixed sphere (see \cites{GNT, Gath2}) or consider averages over Euclidean translations of the sphere (see \cites{CT}). We observe that incorporating the Heisenberg group structure allows us to circumvent the degeneracy arising from the vanishing of the Gaussian curvature at the poles of the Korányi sphere. In fact, in lower dimensions (the first and second Heisenberg group), our method establishes an upper bound for this number which gives a logarithmic improvement over the bound implied by the previously known results. Even for the higher dimensional Heisenberg groups, we recover the bounds implied by the main result of \cite{GNT} using a completely different approach of generalized Radon transforms. Further, we obtain upper bounds for the average number of lattice points near more general spheres described with respect to radial, Heisenberg homogeneous norms as considered in \cite{GNT}.
title Counting Lattice Points near Korányi Spheres via Generalized Radon Transforms
topic Number Theory
Classical Analysis and ODEs
11P21, 42B20, 42B25, 22E25, 22E40
url https://arxiv.org/abs/2502.05900