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arXiv · 1502.02066

The Helmholtz equation with $L^p$ data and Bochner-Riesz multipliers

Michael Goldberg
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Abstract

We prove the existence of $L^2$ solutions to the Helmholtz equation $(-\Delta - 1)u = f$ in ${\mathbb R}^n$ assuming the given data $f$ belongs to $L^{(2n+2)/(n+5)}({\mathbb R}^n)$ and satisfies the "Fredholm condition" that $\hat{f}$ vanishes on the unit sphere. This problem, and similar results for the perturbed Helmholtz equation $(-\Delta -1)u = -Vu + f$, are connected to the Limiting Absorption Principle for Schr\"odinger operators. The same techniques are then used to prove that a wide range of $L^p \mapsto L^q$ bounds for Bochner-Riesz multipliers are improved if one considers their action on the closed subspace of functions whose Fourier transform vanishes on the unit sphere.

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BibTeXRIS

Michael Goldberg. 2015-02-06. The Helmholtz equation with $L^p$ data and Bochner-Riesz multipliers. https://doi.org/10.4310/mrl.2016.v23.n6.a5

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