152 research outputs found
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
in this context. This extends the results obtained recently in [7],
which are valid only for a restricted range of .Comment: 12 page
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 (also negative values of the multiplicity
function are admitted). Our investigations include maximal operators,
-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
spaces, , and from into weak .Comment: 26 pages. arXiv admin note: text overlap with arXiv:1011.3615 by
other author
Sharp estimates of the spherical heat kernel
We prove sharp two-sided global estimates for the heat kernel associated with
a Euclidean sphere of arbitrary dimension. This solves a long-standing open
problem.Comment: 9 pages, to appear in J. Math. Pures Appl. (9
Genuinely sharp heat kernel estimates on compact rank-one symmetric spaces, for Jacobi expansions, on a ball and on a simplex
We prove genuinely sharp two-sided global estimates for heat kernels on all
compact rank-one symmetric spaces. This generalizes the authors' recent result
obtained for a Euclidean sphere of arbitrary dimension. Furthermore, similar
heat kernel bounds are shown in the context of classical Jacobi expansions, on
a ball and on a simplex. These results are more precise than the qualitatively
sharp Gaussian estimates proved recently by several authors.Comment: 16 page
On Harmonic Analysis Operators in Laguerre-Dunkl and Laguerre-Symmetrized Settings
We study several fundamental harmonic analysis operators in the
multi-dimensional context of the Dunkl harmonic oscillator and the underlying
group of reflections isomorphic to . Noteworthy, we admit
negative values of the multiplicity functions. Our investigations include
maximal operators, -functions, Lusin area integrals, Riesz transforms and
multipliers of Laplace and Laplace-Stieltjes type. By means of the general
Calder\'on-Zygmund theory we prove that these operators are bounded on weighted
spaces, , and from weighted to weighted weak .
We also obtain similar results for analogous set of operators in the closely
related multi-dimensional Laguerre-symmetrized framework. The latter emerges
from a symmetrization procedure proposed recently by the first two authors. As
a by-product of the main developments we get some new results in the
multi-dimensional Laguerre function setting of convolution type
Riesz-Jacobi transforms as principal value integrals
We establish an integral representation for the Riesz transforms naturally
associated with classical Jacobi expansions. We prove that the Riesz-Jacobi
transforms of odd orders express as principal value integrals against kernels
having non-integrable singularities on the diagonal. On the other hand, we show
that the Riesz-Jacobi transforms of even orders are not singular operators. In
fact they are given as usual integrals against integrable kernels plus or
minus, depending on the order, the identity operator. Our analysis indicates
that similar results, existing in the literature and corresponding to several
other settings related to classical discrete and continuous orthogonal
expansions, should be reinvestigated so as to be refined and in some cases also
corrected.Comment: 30 page
Analysis in the multi-dimensional ball
We study the heat semigroup maximal operator associated with a well-known
orthonormal system in the d-dimensional ball. The corresponding heat kernel is
shown to satisfy Gaussian bounds. As a consequence, we can prove weighted
estimates, as well as some weighted inequalities in mixed norm spaces, for this
maximal operator.Comment: 18 page
Some remarks on oscillation inequalities
In this paper we establish uniform oscillation estimates on with
for the polynomial ergodic averages. This result contributes
to a certain problem about uniform oscillation bounds for ergodic averages
formulated by Rosenblatt and Wierdl in the early 1990's. We also give a
slightly different proof of the uniform oscillation inequality of Jones,
Kaufman, Rosenblatt and Wierdl for bounded martingales. Finally, we show that
oscillations, in contrast to jump inequalities, cannot be seen as an endpoint
for -variation inequalities.Comment: 23 pages, no figures, accepted for publication in the Ergodic Theory
& Dynamical System
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