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The definition of a non-trivial space of generalized functions of a complex variable allowing to consider derivatives of continuous functions is a non-obvious task, e.g. because of Morera theorem, because distributional Cauchy-Riemann…

Functional Analysis · Mathematics 2025-10-30 Sekar Nugraheni , Paolo Giordano

Dirac delta function of matrix argument is employed frequently in the development of diverse fields such as Random Matrix Theory, Quantum Information Theory, etc. The purpose of the article is pedagogical, it begins by recalling detailed…

Quantum Physics · Physics 2021-09-07 Lin Zhang

By applying projection operators to state vectors of coordinates we obtain subspaces in which these states are no longer normalized according to Dirac's delta function but normalized according to what we call "incomplete delta functions".…

Quantum Physics · Physics 2007-05-23 A. Gersten

We derive new all-purpose methods that involve the Dirac Delta distribution. Some of the new methods use derivatives in the argument of the Dirac Delta. We highlight potential avenues for applications to quantum field theory and we also…

Mathematical Physics · Physics 2015-06-19 Achim Kempf , David M. Jackson , Alejandro H. Morales

This paper introduces the expanded real numbers as an ordered subring of the hyperreal number field that does not contain any infinitesimals, and defines the set of all integrable functions from the real numbers to the expanded real…

General Mathematics · Mathematics 2021-10-01 Marcoen J. T. F. Cabbolet

In this paper, we describe the line Dirac delta function of a curve in three-dimensional space in terms of the distance function to the curve. Its extension to level set formulation and plane curves are also developed. The main ideas can be…

Metric Geometry · Mathematics 2015-04-14 Zhou Zhang , Xiaoming Zheng

The present work is a brief review of the progressive search of improper delta-functions which are of interest in Quantum Mechanics and in the problem of motion in General Relativity Theory.

Quantum Physics · Physics 2018-08-08 Oscar Rosas-Ortiz

The extension of the Dirac Delta distribution (DD) to the complex field is needed for dealing with the complex-energy solutions of the Schr\"odinger equation, typically when calculating their inner products. In quantum scattering theory the…

Mathematical Physics · Physics 2016-03-18 J. Julve , R. Cepedello , F. J. de Urries

We discuss Donsker's delta function within the framework of White Noise Analysis, in particular its extension to complex arguments. With a view towards applications to quantum physics we also study sums and products of Donsker's delta…

Mathematical Physics · Physics 2007-05-23 Angelika Lascheck , Peter Leukert , Ludwig Streit , Werner Westerkamp

We have shown that in some region where the Euler integral of the first kind diverges, the Euler formula defines a generalized function. The connected of this generalized function with the Dirac delta function is found.

Classical Analysis and ODEs · Mathematics 2017-11-23 Vagner Jikia , Ilia Lomidze

A new classification of real functions and other related real objects defined within a compact interval is proposed. The scope of the classification includes normal real functions and distributions in the sense of Schwartz, referred to…

Mathematical Physics · Physics 2015-07-07 Jorge L. deLyra

A topological description of various generalized function algebras over corresponding basic locally convex algebras is given. The framework consists of algebras of sequences with appropriate ultra(pseudo)metrics defined by sequences of…

Functional Analysis · Mathematics 2019-04-01 Antoine Delcroix , Maximilian F. Hasler , Stevan Pilipović , Vincent Valmorin

Generalizations of classical theta functions are proposed that include any even number of analytic parameters for which conditions of quasi-periodicity are fulfilled and that are representations of extended Heisenberg group. Differential…

Mathematical Physics · Physics 2017-07-13 Yuriy Smilyanets

Mathematical justifications are given for several integral and series representations of the Dirac delta function which appear in the physics literature. These include integrals of products of Airy functions, and of Coulomb wave functions;…

Classical Analysis and ODEs · Mathematics 2013-03-11 Y. T. Li , R. Wong

If $T$ is a (densely defined) self-adjoint operator acting on a complex Hilbert space $\mathcal{H}$ and $I$ stands for the identity operator, we introduce the delta function operator $\lambda \mapsto \delta \left(\lambda I-T\right) $ at…

Functional Analysis · Mathematics 2020-12-08 Juan Carlos Ferrando

A wide class of physical distributions appears to follow the q-Gaussian form, which plays the role of attractor according to a Central Limit Theorem generalized in the presence of specific correlations between the relevant random variables.…

Mathematical Physics · Physics 2015-03-17 M. Jauregui , C. Tsallis

The generalized Fermi-Dirac functions and their derivatives are important in evaluating the thermodynamic quantities of partially degenerate electrons in hot dense stellar plasmas. New recursion relations of the generalized Fermi-Dirac…

Astrophysics · Physics 2009-11-06 Zhigang Gong , Ladislav Zejda , Werner Dappen , Josep M. Aparicio

In this article, we present a new two-dimensional generalization of the gamma function based on the product of the one-dimensional generalized beta function and the one-dimensional generalized gamma function. As will become clear later,…

General Mathematics · Mathematics 2024-03-18 Artem M. Ponomarenko

In the framework of distributionally generalized quantum theory, the object $H\psi$ is defined as a distribution. The mathematical significance is a mild generalization for the theory of para- and pseudo-differential operators (as well as a…

Quantum Physics · Physics 2024-05-08 Michael Maroun

We discuss a generalized representation of the Dirac delta function in $d$ dimensions in terms of $q$-exponential functions. We apply this new representation to the study of the so-called $q$-Fourier transform, proving its invertibility for…

Mathematical Physics · Physics 2017-07-25 Gabriele Sicuro , Constantino Tsallis
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