Year: 2025
Type: preprint
Abstract: We prove that any measurable set in the Heisenberg group, $\mathbb{H}^n$, of positive upper density has the property that all sufficiently large real numbers are realised as the Korányi distance between points in that set. The result can be seen as a Heisenberg group analogue to a corresponding Euclidean large distance set result in the $1986$ paper of Bourgain, \cite{1986Bourgain}. Along the way, to prove our main theorem, we give the ``decay" of the coefficients $R_{k}(λ, σ)$, appearing in the spectral decomposition of the group Fourier transform, $\hatσ(λ)$ $= \sum_{k=0}^{\infty} R_{k}(λ, σ) \mathcal{P}_{k}(λ)$, of the surface measure $σ$ on the Korányi sphere in $\mathbb{H}^n$, in a certain ``high frequency" region, that is, when $2(2k+n) |λ| \gg 1$; which seems to be new in the literature. We also show that the positive upper density cannot be qualitatively improved further.
Source: arXiv (Cornell University)
Authors: Raani, K S Senthil, Singh, Rajesh K.
Language: English
Subfield: Applied Mathematics
Field: Mathematics
Domain: Physical Sciences
Open Access status: green
OpenAlex ID: W4417434174
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