Quadratic estimates for the $H^\infty$-functional calculus of bisectorial Clifford operators

Fuente: arXiv
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Autori principali: Colombo, Fabrizio, Mantovani, Francesco, Schlosser, Peter
Natura: Preprint
Pubblicazione: 2025
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author Colombo, Fabrizio
Mantovani, Francesco
Schlosser, Peter
author_facet Colombo, Fabrizio
Mantovani, Francesco
Schlosser, Peter
contents The $H^\infty$-functional calculus is a two-step procedure, introduced by A. McIntosh, that allows the definition of functions of sectorial operators in Banach spaces. It plays a crucial role in the spectral theory of differential operators, as well as in their applications to evolution equations and various other fields of science. An extension of the $H^\infty$-functional calculus also exists in the hypercomplex setting, where it is based on the notion of $S$-spectrum. Originally this was done for sectorial quaternionic operators, but then also generalized all the way to bisectorial fully Clifford operators. In the latter setting and in Hilbert spaces, this paper now characterizes the boundedness of the $H^\infty$-functional calculus through certain quadratic estimates. Due to substantial differences in the definitions of the $S$-spectrum and the $S$-resolvent operators, the proofs of quadratic estimates in this setting face additional challenges compared to the classical theory of complex operators.
format Preprint
id arxiv_https___arxiv_org_abs_2506_16783
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Quadratic estimates for the $H^\infty$-functional calculus of bisectorial Clifford operators
Colombo, Fabrizio
Mantovani, Francesco
Schlosser, Peter
Spectral Theory
The $H^\infty$-functional calculus is a two-step procedure, introduced by A. McIntosh, that allows the definition of functions of sectorial operators in Banach spaces. It plays a crucial role in the spectral theory of differential operators, as well as in their applications to evolution equations and various other fields of science. An extension of the $H^\infty$-functional calculus also exists in the hypercomplex setting, where it is based on the notion of $S$-spectrum. Originally this was done for sectorial quaternionic operators, but then also generalized all the way to bisectorial fully Clifford operators. In the latter setting and in Hilbert spaces, this paper now characterizes the boundedness of the $H^\infty$-functional calculus through certain quadratic estimates. Due to substantial differences in the definitions of the $S$-spectrum and the $S$-resolvent operators, the proofs of quadratic estimates in this setting face additional challenges compared to the classical theory of complex operators.
title Quadratic estimates for the $H^\infty$-functional calculus of bisectorial Clifford operators
topic Spectral Theory
url https://arxiv.org/abs/2506.16783