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arXiv 2104.09470math.AP
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测地双角与本征函数限制的傅里叶系数

Geodesic bi-angles and Fourier coefficients of restrictions of eigenfunctions

Emmett Wyman, Yakun Xi, Steve Zelditch

摘要:

本文研究紧致黎曼流形的Laplace本征函数$ϕ_j$到子流形$H \subset M$的限制的傅里叶系数的联合渐近性.我们固定了一个数$c \in (0,1)$,研究了稀疏和$$ N^{c} _{ε, H }(λ): = \sum_{j, λ_j \leq λ} \sum_{k: |μ_k - c λ_j | < ε} \left| \int_{H} ϕ_j \overline{ψ_k}dV_H \right|^2 $$的渐近性,其中$\{λ_j\}$是$\sqrt{-Δ}_M,$的特征值,$\{(μ_k, ψ_k)\}$是$\sqrt{-Δ}_M,$的特征值.本征函数,$\sqrt{-Δ}_H$。内和表示$ N^{c} _{ε, H }(λ)$的“跳跃”,并反映测地线c-双角的几何形状,其中一条腿在$H$上,第二条腿在$M$上,具有相同的端点和相容的初始切向量$ξ\in S^c_H M, π_H ξ\in B^* H$,其中$π_H ξ$是$ξ$到$H$的正交投影。当$\frac{|π_H ξ|}{|ξ|} = c$。本文还研究了$μ_k$中的光滑和,并给出了跳跃的精确估计。跳跃本身可以跳跃$ε$变化,在某些值的$ε$相关的周期性在c-双角几何。球面的子球面和环面的某些子环面说明了这些跳跃。结果改进了前一篇文章(arXiv:2011.11571)的结果,其中内部和在$k: | \frac{μ_k}{λ_j} - c| \leq ε$上运行,测地线双角不起作用。

英文摘要:

This article concerns joint asymptotics of Fourier coefficients of restrictions of Laplace eigenfunctions $ϕ_j$ of a compact Riemannian manifold to a submanifold $H \subset M$. We fix a number $c \in (0,1)$ and study the asymptotics of the thin sums, $$ N^{c} _{ε, H }(λ): = \sum_{j, λ_j \leq λ} \sum_{k: |μ_k - c λ_j | < ε} \left| \int_{H} ϕ_j \overline{ψ_k}dV_H \right|^2 $$ where $\{λ_j\}$ are the eigenvalues of $\sqrt{-Δ}_M,$ and $\{(μ_k, ψ_k)\}$ are the eigenvalues, resp. eigenfunctions, of $\sqrt{-Δ}_H$. The inner sums represent the `jumps' of $ N^{c} _{ε, H }(λ)$ and reflect the geometry of geodesic c-bi-angles with one leg on $H$ and a second leg on $M$ with the same endpoints and compatible initial tangent vectors $ξ\in S^c_H M, π_H ξ\in B^* H$, where $π_H ξ$ is the orthogonal projection of $ξ$ to $H$. A c-bi-angle occurs when $\frac{|π_H ξ|}{|ξ|} = c$. Smoothed sums in $μ_k$ are also studied, and give sharp estimates on the jumps. The jumps themselves may jump as $ε$ varies, at certain values of $ε$ related to periodicities in the c-bi-angle geometry. Subspheres of spheres and certain subtori of tori illustrate these jumps. The results refine those of the previous article (arXiv:2011.11571) where the inner sums run over $k: | \frac{μ_k}{λ_j} - c| \leq ε$ and where geodesic bi-angles do not play a role.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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