Spectral projection operators of the Sub-Laplacian and Laguerre calculus on non-degenerate nilpotent Lie groups of step two

Fuente: arXiv
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Main Authors: Kang, Qianqian, Chang, Der-Chen, Wang, Wei
Format: Preprint
Published: 2024
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author Kang, Qianqian
Chang, Der-Chen
Wang, Wei
author_facet Kang, Qianqian
Chang, Der-Chen
Wang, Wei
contents In this paper, we introduce the spectral projection operators $\mathbb{P}_m$ on non-degenerate nilpotent Lie groups $\mathcal{N}$ of step two, associated to the joint spectrum of sub-Laplacian and derivatives in step two. We construct their kernels $P_m(\mathbf{y},\mathbf{t})$ by using Laguerre calculus and find a simple integral representation formula for $\mathbf{y}\neq 0$. Then we show the kernels are Lipschitzian homogeneous functions on $\mathcal{N}\setminus \{\mathbf{0}\}$ by analytic continuation. Moreover, they are shown to be Calderón-Zygmund kernels, so that the spectral projection operator $\mathbb{P}_m$ can be extended to a bounded operator from $L^p(\mathcal{N})$ to itself. We also prove a convergence theorem of the Abel sum $\lim _{R \rightarrow 1^-} \sum_{m=0}^{\infty} R^{m}\mathbb{P}_{m}ϕ=ϕ$ by estimating the $L^p(\mathcal{N})$-norms of $\mathbb{P}_m$. Furthermore, $\mathbb{P}_m$ are mutually orthogonal projection operators and $\sum_{m=0}^{\infty} \mathbb{P}_{m}ϕ=ϕ$ for $ϕ\in L^2(\mathcal{N})$.
format Preprint
id arxiv_https___arxiv_org_abs_2404_03378
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle Spectral projection operators of the Sub-Laplacian and Laguerre calculus on non-degenerate nilpotent Lie groups of step two
Kang, Qianqian
Chang, Der-Chen
Wang, Wei
Functional Analysis
In this paper, we introduce the spectral projection operators $\mathbb{P}_m$ on non-degenerate nilpotent Lie groups $\mathcal{N}$ of step two, associated to the joint spectrum of sub-Laplacian and derivatives in step two. We construct their kernels $P_m(\mathbf{y},\mathbf{t})$ by using Laguerre calculus and find a simple integral representation formula for $\mathbf{y}\neq 0$. Then we show the kernels are Lipschitzian homogeneous functions on $\mathcal{N}\setminus \{\mathbf{0}\}$ by analytic continuation. Moreover, they are shown to be Calderón-Zygmund kernels, so that the spectral projection operator $\mathbb{P}_m$ can be extended to a bounded operator from $L^p(\mathcal{N})$ to itself. We also prove a convergence theorem of the Abel sum $\lim _{R \rightarrow 1^-} \sum_{m=0}^{\infty} R^{m}\mathbb{P}_{m}ϕ=ϕ$ by estimating the $L^p(\mathcal{N})$-norms of $\mathbb{P}_m$. Furthermore, $\mathbb{P}_m$ are mutually orthogonal projection operators and $\sum_{m=0}^{\infty} \mathbb{P}_{m}ϕ=ϕ$ for $ϕ\in L^2(\mathcal{N})$.
title Spectral projection operators of the Sub-Laplacian and Laguerre calculus on non-degenerate nilpotent Lie groups of step two
topic Functional Analysis
url https://arxiv.org/abs/2404.03378