Stieltjes transforms defined by C0-semigroups

AbstractIn this paper we use the resolvent semigroup associated to a C0-semigroup to introduce the vector-valued Stieltjes transform defined by a C0-semigroup. We give new results which extend known ones in the case of a scalar generalized Stieltjes transform. We work with the vector-valued Weyl fractional calculus to present a deep connection between both concepts

Fine scales of decay of operator semigroups

Motivated by potential applications to partial differential equations, we develop a theory of fine scales of decay rates for operator semigroups. The theory contains, unifies, and extends several notable results in the literature on decay of operator semigroups and yields a number of new ones. Its core is a new operator-theoretical method of deriving rates of decay combining ingredients from functional calculus, and complex, real and harmonic analysis. It also leads to several results of independent interest.Comment: Version 2 includes numerous minor corrections, and is the authors' final version. The pape will be published in the Journal of the European Mathematical Society in April 201

Calder\'on-Zygmund operators in the Bessel setting for all possible type indices

In this paper we adapt the technique developed in [17] to show that many harmonic analysis operators in the Bessel setting, including maximal operators, Littlewood-Paley-Stein type square functions, multipliers of Laplace or Laplace-Stieltjes transform type and Riesz transforms are, or can be viewed as, Calder\'on-Zygmund operators for all possible values of type parameter $\lambda$ in this context. This extends the results obtained recently in [7], which are valid only for a restricted range of $\lambda$.Comment: 12 page

Product formulas in functional calculi for sectorial operators

We study the product formula $(fg)(A) = f(A)g(A)$ in the framework of (unbounded) functional calculus of sectorial operators $A$. We give an abstract result, and, as corollaries, we obtain new product formulas for the holomorphic functional calculus, an extended Stieltjes functional calculus and an extended Hille-Phillips functional calculus. Our results generalise previous work of Hirsch, Martinez and Sanz, and Schilling.Comment: This is the authors accepted manuscript for a paper being published in Mathematische Zeitschrift. The final publication is available at Springer via http://dx.doi.org/10.1007/s00209-014-1378-

On fundamental harmonic analysis operators in certain Dunkl and Bessel settings

We consider several harmonic analysis operators in the multi-dimensional context of the Dunkl Laplacian with the underlying group of reflections isomorphic to $\mathbb{Z}_2^n$ (also negative values of the multiplicity function are admitted). Our investigations include maximal operators, $g$-functions, Lusin area integrals, Riesz transforms and multipliers of Laplace and Laplace-Stieltjes transform type. Using the general Calder\'on-Zygmund theory we prove that these objects are bounded in weighted $L^p$ spaces, $1<p<\infty$, and from $L^1$ into weak $L^{1}$.Comment: 26 pages. arXiv admin note: text overlap with arXiv:1011.3615 by other author