An optimal multiplier theorem for Grushin operators in the plane, II
| Autor: | Alessio Martini, Gian Maria Dall'Ara |
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| Jazyk: | angličtina |
| Rok vydání: | 2021 |
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| Popis: | In a previous work we proved a spectral multiplier theorem of Mihlin--H\"ormander type for two-dimensional Grushin operators $-\partial_x^2 - V(x) \partial_y^2$, where $V$ is a doubling single-well potential, yielding the surprising result that the optimal smoothness requirement on the multiplier is independent of $V$. Here we refine this result, by replacing the $L^\infty$ Sobolev condition on the multiplier with a sharper $L^2$ condition. As a consequence, we obtain the sharp range of $L^1$ boundedness for the associated Bochner--Riesz means. The key new ingredient of the proof is a precise pointwise estimate in the transition region for eigenfunctions of one-dimensional Schr\"odinger operators with doubling single-well potentials. Comment: 21 pages. This work refines the multiplier theorem proved in arXiv:2107.12015 |
| Databáze: | OpenAIRE |
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