Subcritical Fourier uncertainty principles

Fuente: arXiv
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Autori principali: Saucedo, Miquel, Tikhonov, Sergey
Natura: Preprint
Pubblicazione: 2024
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_version_ 1866913420200116224
author Saucedo, Miquel
Tikhonov, Sergey
author_facet Saucedo, Miquel
Tikhonov, Sergey
contents It is well known that if a function $f$ satisfies $$\|f(x) e^{πα|x|^2}\|_p + \| \widehat{f}(ξ) e^{πα|ξ|^2} \|_q<\infty \qquad\qquad\qquad(*)$$ with $α=1$ and $1\le p,q<\infty$, then $f\equiv 0.$ We prove that if $f$ satisfies $(*)$ with some $0<α<1$ and $1\le p,q\leq \infty$, then $$ |f(y)|\le C (1+|y|)^{\frac{d}{p}} e^{- πα|y|^2}, \quad y\in \mathbb{R}^d, $$ with $ C=C(α,d,p,q)$ and this bound is sharp for $p\neq 1$. We also study a related uncertainty principle for functions satisfying $\;\;\displaystyle\|f(x)|x|^m\|_p+ \|\widehat{f}(ξ)|ξ|^n\|_q <\infty.$
format Preprint
id arxiv_https___arxiv_org_abs_2404_07375
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle Subcritical Fourier uncertainty principles
Saucedo, Miquel
Tikhonov, Sergey
Classical Analysis and ODEs
Functional Analysis
42A38, 42B35
It is well known that if a function $f$ satisfies $$\|f(x) e^{πα|x|^2}\|_p + \| \widehat{f}(ξ) e^{πα|ξ|^2} \|_q<\infty \qquad\qquad\qquad(*)$$ with $α=1$ and $1\le p,q<\infty$, then $f\equiv 0.$ We prove that if $f$ satisfies $(*)$ with some $0<α<1$ and $1\le p,q\leq \infty$, then $$ |f(y)|\le C (1+|y|)^{\frac{d}{p}} e^{- πα|y|^2}, \quad y\in \mathbb{R}^d, $$ with $ C=C(α,d,p,q)$ and this bound is sharp for $p\neq 1$. We also study a related uncertainty principle for functions satisfying $\;\;\displaystyle\|f(x)|x|^m\|_p+ \|\widehat{f}(ξ)|ξ|^n\|_q <\infty.$
title Subcritical Fourier uncertainty principles
topic Classical Analysis and ODEs
Functional Analysis
42A38, 42B35
url https://arxiv.org/abs/2404.07375