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Fabian Belmonte

Publications and source records attributed to Fabian Belmonte.

6 recordsLinked to original sources
arXiv2025

Smooth Fields of Hilbert Spaces, Hermitian bundles and Riemannian Direct Images

Given a field of Hilbert spaces there are two ways to endow it with a smooth structure: the standard and geometrical notion of Hilbert (or Hermitian) bundle and the analytical notion of smooth field of Hilbert spaces. We study the relationship between these concepts in a general framework. We apply our results in the following interesting example called Riemannian direct images: Let $M,N$ be Riemannian oriented manifolds, $ρ:M\to N$ be a submersion and $π:E\to M$ a finite dimensional vector bundle. Also, let $M_λ=ρ^{-1}(λ)$ and fix a suitable measure $μ_λ$ in $M_λ$. Does the field of Hilbert spaces $\mathcal{H}(λ)=L^2(M_λ,E)$ admits a smooth field of Hilbert space structure? or a Hilbert bundle structure? In order to provide conditions to guarantee a positive answer for these questions, we develop an interesting formula to derivate functions defined on $N$ as a integral over $M_λ$.

math.FA↗
arXiv2023

Dixmier trace and the DOS of perturbed magnetic operators

The main goal of this work is to provide a description of the {trace per unit volume} in terms of the {Dixmier trace} (regularized by the resolvent of the harmonic oscillator) for a large class of two-dimensional \emph{magnetic operators} perturbed by (homogeneous) {potentials}. One of the payoffs of this result is the possibility of reinterpreting the {density of states} (DOS) of these perturbed magnetic systems via the {Dixmier trace}, and taking advantage of the fact that this quantity can be conveniently calculated on the basis of the Laguerrre functions that diagonalize the harmonic oscillator.

math-ph↗
arXiv2021

Dixmier trace and the DOS of magnetic operators

The main goal of this work is to provide two new formulas for the computation of the trace per unit volume, and consequently the integrated density of states (IDOS), for magnetic operators. These formulas also permit the use of the Dixmier trace in the spectral analysis of magnetic operators. The second of these formulas, named energy shell formula, permits to approximate the IDOS by a finite sums of averaged expectation values of the spectral projections.

math-ph↗
arXiv2020

Canonical Quantization of Constants of Motion

We develop a quantization method, that we name decomposable Weyl quantization, which ensures that the constants of motion of a prescribed finite set of Hamiltonians are preserved by the quantization. Our method is based on a structural analogy between the notions of reduction of the classical phase space and diagonalization of selfadjoint operators. We obtain the spectral decomposition of the emerging quantum constants of motion directly from the quantization process. If a specific quantization is given, we expect that it preserves constants of motion exactly when it coincides with decomposable Weyl quantization on the algebra of constants of motion. We obtain a characterization of when such property holds in terms of the Wigner transforms involved. We also explain how our construction can be applied to spectral theory. Moreover, we discuss how our method opens up new perspectives in formal deformation quantization and geometric quantization.

math-ph↗
arXiv2012

Covariant Fields of C*-Algebras under Rieffel Deformation

We show that Rieffel's deformation sends covariant C(T)-algebras into C(T)-algebras. We also treat the lower semi-continuity issue, proving that Rieffel's deformation transforms covariant continuous fields of C*-algebras into continuous fields of C*-algebras. Some examples are indicated, including certain quantum groups.

math.OA↗