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arXiv · 2507.20376

Optimal decay of semi-uniformly stable operator semigroups with empty spectrum

Morgan Callewaert·Lenny Neyt·Jasson Vindas
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Abstract

We show that it is impossible to quantify the decay rate of a semi-uniformly stable operator semigroup based on sole knowledge of the spectrum of its infinitesimal generator. More precisely, given an arbitrary positive function $r$ vanishing at $\infty$, we construct a Banach space $X$ and a bounded semigroup $ (T(t))_{t \geq 0}$ of operators on it whose infinitesimal generator $A$ has empty spectrum $\sigma(A)=\varnothing$, but for which, for some $x \in X$, $$ \limsup_{t\to\infty} \frac{\|T(t)A^{-1}x\|_{X}}{r(t)}=\infty. $$

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Morgan Callewaert, Lenny Neyt, Jasson Vindas. 2025-07-27. Optimal decay of semi-uniformly stable operator semigroups with empty spectrum. https://doi.org/10.1090/proc%2F17466

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