arXiv subjects

Vitor Oguri

Publications and source records attributed to Vitor Oguri.

At least 19 recordsLinked to original sources

arXiv2025

\`As vezes, solucionar uma crise depende de ampli\'a-la: a contribui\c{c}\~ao de Louis de Broglie \`a F\'isica Qu\^antica

Faz-se uma breve reconstru\c{c}\~ao hist\'orica de alguns pontos que, de algum modo, contribu\'iram para o trabalho seminal de Louis de Broglie. Em particular, enfatiza-se a relev\^ancia de sua tese de doutorado, principalmente por seu valor epistemol\'ogico, ao ampliar a crise que havia sido introduzida na descri\c{c}\~ao da radia\c{c}\~ao pelo \textit{quantum} de Planck, abrindo caminho para sua solu\c{c}\~ao. A brief historical reconstruction of some points that, in some way, contributed to Louis de Broglie's seminal work is made. In particular, the relevance of his doctoral thesis is emphasized, mainly for its epistemological value, in expanding the crisis that had been introduced in the description of radiation by Planck's quantum, paving the way for its solution.

physics.hist-ph↗

arXiv2025

Uma breve hist\'oria do spin

A brief analysis is made of some historical points involved in the consolidation of the theoretical concept of \textit{spin}, originally introduced to explain the structure of atomic spectra in the absence and presence of electromagnetic fields, in 1925, by Dutch physicists Samuel Abraham Goudsmit and George Eugene Uhlenbeck. Its relevance in the context of the quantum description of matter is reiterated.

physics.hist-ph↗

arXiv2024

On the covariance of the d'Alembert equation: the cases of sound and light

The covariance of the d'Alembert equation for acoustic phenomena, described by mechanical waves in one or three spatial dimensions, under Galilean transformations, is demonstrated without the need to abandon the hypothesis that time is absolute in Classical Mechanics. This is true only if and only if the phase velocity of sound depends on the velocity of the observer. On the other hand, it is also shown that the same d'Alembert equation is covariant under Lorentz transformations if and only if the phase velocity of light does not depend on the observer.

physics.class-ph↗

arXiv2023

On the Galilean covariance of the d'Alembert equation for acoustic phenomena

The covariance of the d'Alembert equation for acoustic phenomena -- which is a mechanical wave equation -- under the conventional Galilean transformation is demonstrated without the need to abandon the hypothesis that time is absolute in Classical Mechanics, {what would imply} a modification of Galileo's transformations, as suggested in a paper recently published in this journal.

physics.class-ph↗

arXiv2022

Still learning about space dimensionality: from the description of hydrogen atom by a generalized wave equation for dimensions D$\geq$3

The hydrogen atom is supposed to be described by a generalization of Schrödinger equation, in which the Hamiltonian depends on an iterated Laplacian and a Coulomb-like potential $r^{-β}$. Starting from previously obtained solutions for this equation using the $1/N$ expansion method, it is shown that new light can be shed on the problem of understanding the dimensionality of the world as proposed by Paul Ehrenfest. A surprisingly new result is obtained. Indeed, for the first time, we can understand that not only the sign of energy but also the value of the ground state energy of hydrogen atom is related to the threefold nature of space.

quant-ph↗

arXiv2022

On the influence of Maxwell--Chern--Simons electrodynamics in nuclear fusion involving electronic and muonic molecules

New results recently obtained (\textit{Annals of Physics} (New York) a.n.~168943) established some non-relativistic ground state solutions for three-body molecules interacting through a Chern--Simons model. Within this model, it was argued that Chern--Simons potential should not help improve the fusion rates by replacing electrons with muons, in the case of particular muonic molecules. This achievement motivated us to investigate quantitatively whether or not the Maxwell--Chern--Simons electrodynamics could influence positively, for example, the probability of having a muon-catalyzed fusion; its contribution to electronic molecules is also considered in this letter. The principal factors related to the probability of elementary nuclear fusion are therefore numerically calculated and compared with their analogs admitting other forms of interaction like $-1/ρ$ and $\ln (ρ)$. The analysis carried on here confirms that one should not expect a significant improvement in nuclear fusion rates in the case of muonic molecules, although, surprisingly, the same is not true for electronic molecules, compared with other theoretical predictions. Numerical predictions for the fusion rates for $ppe$, $ppμ$, $dde$ and $ddμ$ molecules are given as well as the predicted value for the tunneling rate for these molecules.

nucl-th↗

arXiv2022

Applications of the Numerov method to simple quantum systems using Python

Numerov's numerical method is developed in a didactic way by using Python in its {\it Jupyter Notebook} version 6.0.3 for three different quantum physical systems: the hydrogen atom, a molecule governed by the Morse potential and for a quantum dot. After a brief introduction to the Numerov method, the complete code to calculate the eigenfunctions and eigenvalues of the hydrogen atom is presented. The necessary code changes to calculate the other two examples are also provided in the sequel.

quant-ph↗

arXiv2021

Non-relativistic solutions for three-body molecules within a Chern-Simons model

The wave functions and the ground state energies for the bound states of four different muonic and electronic molecules, governed by the Chern-Simons potential in two spatial dimensions, are numerically obtained with the Numerov method. The new results are compared with former planar configuration studies that consider the attractive potential as being proportional to $\ln(ρ)$, as well as with the three-dimensional analogs assuming a Coulomb potential.

quant-ph↗

arXiv2021

The Fourth Dimension: From its spatial nature in Euclidean geometry to a time-like component of non-Euclidean manifolds

In this article, the evolution of the ideas about the fourth spatial dimension is presented, starting from those which come out within classical Euclidean geometry and going through those arose in the framework of non-Euclidean geometries, like those of Riemann and Minkowski. Particular attention is given to the moment when real time is effectively considered as a fourth dimension, as introduced by Einstein.

physics.hist-ph↗

arXiv2020

Solving two-dimensional non-relativistic electronic and muonic atoms governed by Chern-Simon potential

Bidimensional muonic and electronic atoms, with nuclei composed of a proton, deuteron, and triton, and governed by Chern-Simons potential, are numerically solved. Their eigenvalues and eigenfunctions are determined with a slightly modified Numerov method. Results are compared with those assuming that the same atoms are governed by the usual $1/r$ potential even in a two-dimensional space, as well as with its three-dimensional analogs.

quant-ph↗

arXiv2019

Numerical solutions for a two dimensional quantum dot model

In this paper, a quantum dot mathematical model based on a two-dimensional Schrödinger equation assuming the 1/r inter-electronic potential is revisited. Generally, it is argued that the solutions of this model obtained by solving a biconfluent Heun equation have some limitations. The known polynomial solutions are confronted with new numerical calculations based on the Numerov method. A good qualitative agreement between them emerges. The numerical method being more general gives rise to new solutions. In particular, we are now able to calculate the quantum dot eigenfunctions for a much larger spectrum of external harmonic frequencies as compared to previous results. Also the existence of bound state for such planar system, in the case l=0, is predicted and its respective eigenvalue is determined.

quant-ph↗

arXiv2019

Two-electron quantum dot model revisited: bound states and other analytical and numerical solutions

The model of a two-electron quantum dot, confined to move in a two dimensional flat space, is revisited. Generally, it is argued that the solutions of this model obtained by solving a biconfluent Heun equation have some limitations. In particular, some corrections are also made in previous theoretical calculations. The corrected polynomial solutions are confronted with numerical calculations based on the Numerov method, in a good agreement between both. Then, new solutions considering the $1/r$ and $\ln r$ Coulombian-like potentials in (1+2)D, not yet obtained, are discussed numerically. In particular, we are able to calculate the quantum dot eigenfunctions for a much larger spectrum of external harmonic frequencies as compared to previous results. Also the existence of bound states for such planar system in the case $l=0$ is predicted and the respective eigenvalues are determined.

quant-ph↗

arXiv2018

How the inter-electronic potential Ansätze affect the bound state solutions of a planar two-electron quantum dot model

The model of a two-electron quantum dot, confined to move in a two dimensional flat space, in the presence of an external harmonic oscillator potential, is revisited for a specific purpose. Indeed, eigenvalues and eigenstates of the bound state solutions are obtained for any oscillation frequency considering both the $1/r$ and $\ln r$ Ansätze for inter-electronic Coulombic-like potentials in 2$D$. Then, it is pointed out that the significative difference between measurable quantities predicted from these two potentials can shed some light on the problem of space dimensionality as well as on the physical nature of the potential itself.

quant-ph↗

arXiv2017

Specific heats of degenerate ideal gases

From arguments based on Heisenberg's uncertainty principle and Pauli's exclusion principle, the molar specific heats of degenerate ideal gases at low temperatures are estimated, giving rise to values consistent with the Nerst-Planck Principle (third law of Thermodynamics). The Bose-Einstein condensation phenomenon based on the behavior of specific heat of massive and non-relativistic boson gases is also presented.

physics.gen-ph↗

arXiv2015

O Átomo

The article is an historical overview of some of the major contributions from different areas of Science with which, for centuries, it has been built up a scientific, sound and consistent vision of the atom. Some experiments that led us to a number of evidence about the composite nature of the atom are highlighted.

physics.hist-ph↗

arXiv2013

Note on the Existence of Hydrogen Atoms in Higher Dimensional Euclidean Spaces

The question of whether hydrogen atoms can exist or not in spaces with a number of dimensions greater than 3 is revisited, considering higher dimensional Euclidean spaces. Previous results which lead to different answers to this question are briefly reviewed. The scenario where not only the kinematical term of Schrödinger equation is generalized to a D-dimensional space but also the electric charge conservation law (expressed here by the Poisson law) should actually remains valid is assumed. In this case, the potential energy in the Schrödinger equation goes like 1/r^{D-2}. The lowest quantum mechanical bound states and the corresponding wave functions are determined by applying the Numerov numerical method to solve Schrödinger's eigenvalue equation. States for different angular momentum quantum number (l = 0; 1) and dimensionality (5 \leq D \leq 10) are considered. One is lead to the result that hydrogen atoms in higher dimensions could actually exist. For the same range of the dimensionality D, the energy eigenvalues and wave functions are determined for l = 1. The most probable distance between the electron and the nucleus are then computed as a function of D showing the possibility of tiny bound states.

quant-ph↗

arXiv2011

Zero-frequency magnetic fluctuations in homogeneous cosmic plasma revisited

Magnetic fluctuations in a non-magnetized gaseous plasma is revisited and calculated without approximations, based on the fluctuation-dissipation theorem. It is argued that the present results are qualitative and quantitative different form previous one based on the same theorem. In particular, it is shown that it is not correct that the spectral intensity does not vary sensitively with $k_{cut}$. Also the simultaneous dependence of this intensity on the plasma and on the collisional frequencies are discussed.

astro-ph.CO↗

arXiv2008

The Cosmic Microwave Background Spectrum and a Determination of Fractal Space Dimensionality

The possibility to constrain fractal space dimensionality from Astrophysics and other areas is briefly reviewed. Assuming such dimensionality to be $3 + ε$, a limit to $ε$ can be inferred from COBE satellite data. The available data for the cosmic microwave background radiation spectrum are fitted by a Planck's radiation distribution generalized to non integer space dimensionality. Our analysis shows that the shape of the CMBR spectrum, which does not depend on the absolute normalization, is correctly described from this distribution provided the absolute temperature is equal to 2.726 $\pm$ $0.003\times 10^{-2}$ K and $ε= - (0.957 \pm 0.006) \times 10^{-5}$. This value for $ε$ is shown to be consistent with what is found on a very different spatial scale based on a quantum field phenomenon. The $|ε|$ is interpreted as an upper limit for how much space dimensionality could have deviated from three. In other words, this is the maximum fluctuation space dimensionality should have experienced in a spatial and temporal scale compared to that of the decoupling era.

astro-ph↗