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C. F. L. Godinho

Publications and source records attributed to C. F. L. Godinho.

11 recordsLinked to original sources

About Fractional Calculus and its Applications in Physics

Historically the fractional calculus concept works an extended idea based on the question asked by Guillaume de L'Hôpital to Gottfried Wilhelm Leibniz in 1695 about the notation ${d^nf}/{dx^n}$ for the derivative operator "What if $n=\frac{1}{2}$ ?" To which Leibiniz replied : "This is an apparent paradox, from which useful consequences will be established". Our work revisits the unfolds who followed this questions with some classical definitions of fractional derivative operators and fractional integral. We still point out possible applications in areas such as Engineering, Physics, among others. Among these definitions we will focus more on the Riemann-Liouville and Caputo definitions, however other definitions are also briefly commented. In this work we begin with a historical inspection of the birth of the fractional calculus, parallels with the differential calculus and some of its developments are traced. Always focusing on the definitions of Riemann-Liouville and Caputo, more commonly found in the bibliography of the area and more frequent in scientific works. Some examples of its operability are presented, such as the direct calculation of constant function derivatives, polynomial function and exponential function. Derivative operators and fractional integrals are defined as derivatives and noninteger-order integrals. Our work revisits these two classical definitions of derivative operators and fractional integral and points out possible applications in areas such as Engineering, Physics, among others. Our main goal is to address the feasibility of implementing this content in a degree form program in Physics, we strogly believe that this theme will aggregate a lot of content mainly because its multidisciplinary character.

math-ph↗

Fractional Particle with Fractional First Derivatives

In this paper, we introduce a new classical fractional particle model incorporating fractional first derivatives. This model represents a natural extension of the standard classical particle with kinetic energy being quadratic in fractional first derivatives and fractional linear momenta, similarly to classical mechanics. We derive the corresponding equations of motion and explore the symmetries of the model. Also, we present the formulation in terms of fractional potentials. Two important examples are analytically solved: the free particle and the particle subjected to generalized forces characterized by fractional first derivatives.

physics.gen-ph↗

Fractional Mimetic Dark Matter Model in Fractional Action-like Variational Approach

In this paper, we propose a new model of fractional mimetic dark matter based on the fractional action-like variational approach FALVA implementation of fractionality. The model is non-local at classical level and its equations of motion are highly non-linear. We discuss two particular cases of non-fractional and fractional mimetic dark fields and solve completely the equations of motion of these models. In particular, we obtain the metric of the fractional physical space-time. Also, we obtain the basic geometrical objects in the two cases.

gr-qc↗

Variational Procedure for Higher-Derivative Mechanical Models in a Fractional Integral Framework

We present both the Lagrangian and Hamiltonian procedures for treating higher-order equations of motion for mechanical models by adopting the Riemann-Liouville Fractional integral to describe their action. We point out and discuss its efficacy and difficulties. We also present the physical and geometric interpretations for the approach we pursue and present the details of a higher-order harmonic oscillator.

physics.class-ph↗

On the Role of a Torsion-like Field in a Scenario for the Spin Hall Effect

Starting from an action that describes a Dirac fermion, we propose and analyze a model based on a low-relativistic Pauli equation coupled to a torsion-like term to study Spin Hall Effect (SHE). We point out a very particular connection between the modified Pauli equation and the (SHE), where what we refer to torsion as field playing an important rôle in the spin-orbit coupling process. In this scenario, we present a proposal of a spin-type current, considering the tiny contributions of torsion in connection with geometrical properties of the material.

hep-th↗

Aspects of the Coarse-Grained-Based Approach to a Low-Relativistic Fractional Schrödinger Equation

The main goal of this paper is to set up the coarse-grained formulation of a fractional Schrödinger equation that incorporates a higher (spatial) derivative term which accounts for relativistic effects at a lowest order. The corresponding continuity equation is worked out and we also identify the contribution of the relativistic correction the quantum potential in the coarse-grained treatment. As a consequence, in the classical regime, we derive the sort of fractional Newtonian law with the quantum potential included and the fractional conterparts of the De Broglies's energy and momentum relations.

math-ph↗

Fadeev Jackiw Analysis of Constraints on Noncomutative Hall Effect

Constrained systems are fundamental to understanding of several physical realities. Even so the Hall effect is one of more revisited issue we can still find new approaches to obtain old and new important relations. In this paper a semi classical formulation is considered where an Chern-Simons gauge invariant theory is constructed for a Schroedinger field. The main idea is to describe both classical and integer Hall effect. We build up the constraints this model by means of the Fadeev-Jackiw quantization algorithm. In a second step we consider a noncommutative extension to the action. In this extended approach noncommutative constraints relations are obtained and guide us to an interesting adjustment factor on the conductivity expression.

hep-th↗

A Discussion on Supersymmetric Cosmic Strings with Gauge-Field Mixing

In this paper, following a stream of investigation on supersymmetric gauge theories with cosmic string solutions, we contemplate the possibility of building up a D-and-F term cosmic string by means of a gauge-field mixing in connection with a U(1) x U(1)'-symmetry. The spontaneous break of both gauge symmetry and supersymmetry are thoroughly analysed and the fermion zero-modes are worked out. The role of the gauge-field mixing parameter is elucidated in connection with the string configuration that comes out. As an application of the model presented here, we propose the possibility that the supersimetric cosmic string yield production of fermionic charge carriers that may eject, at their late stages, particles that subsequently decay to produce cosmic rays of ultra-high energy. In our work, it turns out that massive supersymmetric fermionic partners may be produced for a susy breaking scale in the range 10^{11} to 10^{13} GeV, which is compatible with the phenomenology of a gravitino mass at the TeV scale. We also determine the range of the gauge-field mixing parameter, α, in connection with the mass scales of the present model.

hep-th↗

The Noncommutative U(N) Kalb-Ramond Theory

We present the noncommutative extention of the U(N) Cremmer-Scherk-Kalb-Ramond theory, displaying its differential form and gauge structures. The Seiberg-Witten map of the model is also constructed up to $0(θ^2)$.

hep-th↗

Dual embedding of the Lorentz-violating electrodinamics and Batalin-Vilkovisky quantization

Modifications of the electromagnetic Maxwell Lagrangian in four dimensions have been considered by some authors. One may include an explicit massive term (Proca) and a topological but not Lorentz-invariant term within certain observational limits. We find the dual-corresponding gauge invariant version of this theory by using the recently suggested gauge embedding method. We enforce this dualisation procedure by showing that, in many cases, this is actually a constructive method to find a sort of parent action, which manifestly establishes duality. We also use the gauge invariant version of this theory to formulate a Batalin-Vilkovisky quantization and present a detailed discussion on the excitation spectrum.

hep-th↗

Triplectic Gauge Fixing for N=1 Super Yang-Mills Theory

The Sp(2)-gauge fixing of N = 1 super-Yang-Mills theory is considered here. We thereby apply the triplectic scheme, where two classes of gauge-fixing bosons are introduced. The first one depends only on the gauge field, whereas the second boson depends on this gauge field and also on a pair of Majorana fermions. In this sense, we build up the BRST extended (BRST plus antiBRST) algebras for the model, for which the nilpotency relations, s^2_1=s^2_2=s_1s_2+s_2s_1=0, hold.

hep-th↗