Positive isometric Fourier multipliers on non-commutative $L^p$-spaces

Fuente: arXiv
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Autores principales: Kriegler, Christoph, Merdy, Christian Le, Zadeh, Safoura
Formato: Preprint
Publicado: 2026
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author Kriegler, Christoph
Merdy, Christian Le
Zadeh, Safoura
author_facet Kriegler, Christoph
Merdy, Christian Le
Zadeh, Safoura
contents For a locally compact group \(G\), let \(\mathcal{L}G\) denote its left group von Neumann algebra and let \(L^p(\mathcal{L}G)\), \(1 \le p \le \infty\), be the corresponding non-commutative \(L^p\)-space. Given \(ϕ\in L^\infty(G)\), we study the Fourier multiplier \(M_{ϕ,p}\) acting on \(L^p(\mathcal{L}G)\). We prove that for any \(p \neq 2\), the operator \(M_{ϕ,p}\) is a positive surjective isometry if and only if \(ϕ\) coincides locally almost everywhere with a continuous character of \(G\). This characterization extends results obtained recently (jointly with C.~Arhancet) in the unimodular setting.
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spellingShingle Positive isometric Fourier multipliers on non-commutative $L^p$-spaces
Kriegler, Christoph
Merdy, Christian Le
Zadeh, Safoura
Operator Algebras
For a locally compact group \(G\), let \(\mathcal{L}G\) denote its left group von Neumann algebra and let \(L^p(\mathcal{L}G)\), \(1 \le p \le \infty\), be the corresponding non-commutative \(L^p\)-space. Given \(ϕ\in L^\infty(G)\), we study the Fourier multiplier \(M_{ϕ,p}\) acting on \(L^p(\mathcal{L}G)\). We prove that for any \(p \neq 2\), the operator \(M_{ϕ,p}\) is a positive surjective isometry if and only if \(ϕ\) coincides locally almost everywhere with a continuous character of \(G\). This characterization extends results obtained recently (jointly with C.~Arhancet) in the unimodular setting.
title Positive isometric Fourier multipliers on non-commutative $L^p$-spaces
topic Operator Algebras
url https://arxiv.org/abs/2603.07754