arXiv subjects

Ronaldo Thibes

Publications and source records attributed to Ronaldo Thibes.

At least 19 recordsLinked to original sources

arXiv2026

Investigating planar Proca metamaterials in nonlinear (2+1)-Electrodynamics

The present work pursues the investigation of the physics of a planar electromagnetic system incorporating nonlinear effects, as well as de Broglie-Proca and Chern-Simons mass terms in vacuum, which can be tuned to describe new planar metamaterials (MTMs) potentially suitable for technological applications. As a result, we observe interesting effects generated by a spatially dispersive profile that emerges from non-linearity. This characterizes the three-dimensional QED vacuum as a nonlocal metamaterial. The constitutive relations are derived, and the dielectric function of the metamaterial (MTM) exhibits spatial dispersion due to the Chern-Simons mass. The dispersion relations are analyzed in terms of applied external electromagnetic fields and both the de Broglie-Proca and Chern-Simons mass parameters. We also notice that, in the special case in which only a background magnetic field is present, this field gives no contribution neither to the dielectric function nor to the spatial dispersion profile, as is the case when both the electric and magnetic fields are present.

physics.optics↗

arXiv2026

Time-dependent Trapped Plasmas: Nonlinear Dynamics, Symmetries and Invariants

We investigate the nonlinear dynamics of a single-component plasma confined in a time-dependent harmonic trap regarding aspects of symmetry and invariant functions. The system is described as a fluid in an isentropic adiabatic regime by a system of partial differential equations. A convenient change of variables, with a Gaussian ansatz for the number density distribution, allows a consistent mathematical description in terms of ordinary differential equations, from which we follow up with an analysis concerning the corresponding differential operators algebraic structure and Noether symmetries in specific physical regimes. For each studied case, proper invariants are identified. The obtained conserved quantities capture an interplay between the internal plasma dynamics and the time modulation of the trap, resulting in a sharp restriction for the system evolution.

physics.plasm-ph↗

arXiv2026

Generalized Entropies and Black Hole Area Quantization from Landauer's Principle

We investigate black hole area quantization by imposing Landauer's principle on the discrete entropy change between consecutive area levels. The elementary transition is identified with the entropy cost of erasing one bit of information, $\Delta S=k_B\ln 2$. For the Bekenstein--Hawking entropy, this gives the standard Bekenstein--Mukhanov value of the area spectrum parameter, which is used as the reference limit. The same discrete construction is then applied to generalized entropy functionals. For Barrow entropy, the parameter $\gamma$ becomes level dependent, while the relative separation between adjacent area levels still vanishes for large $n$. For the modified R\'enyi entropy, the nonsingular branch has vanishing relative spacing at large $n$, whereas the singular branch develops a finite-level pole. For the modified Kaniadakis entropy, the small $\kappa$ expansion shows that a fixed deformation parameter prevents the relative area spacing from vanishing in the large $n$ limit. Overall, the results suggest that Landauer's principle provides a useful way to analyze generalized entropic extensions of the Bekenstein--Mukhanov approach.

gr-qc↗

arXiv2026

Alternative classical Lagrangians for the Standard-Model Extension

The current paper introduces classical, relativistic Lagrangians for point-particle analogs to the field theory description of the Standard-Model Extension (SME) for Lorentz violation. Lagrangians of a form alternative to those derived and studied in previous works are in the spotlight. Interestingly, they have well-defined massless limits, which makes them suitable for describing classical-particle analogs of photons subject to Lorentz violation. We first deal with different types of Dirac fermion coefficients, followed by various configurations of the SME photon sector. The Lagrangians are accompanied by constraints that we treat properly using the techniques due to Dirac. The results encountered may find application in photon propagation through gravitational fields in the presence of spacetime symmetry violation. Connections to Finsler geometry are likely to exist.

hep-ph↗

arXiv2025

On BRST-Related Symmetries in the FLPR Model with Gribov Ambiguities

With a recent revival, novel features of the FLPR model have been reported in the literature. A connection between those features to QCD involving the Gribov problem is explored. We investigate the FLPR model in a recently proposed framework of BRST-related symmetries and perform its full functional quantization as a gauge invariant system taking into account the Gribov ambiguities. We obtain a family of BRST-related transformations generated by the discrete group of symmetries of the action. We show that gauges possessing Gribov ambiguities lead to a violation of the initial discrete group of symmetries of the gauge-fixed action. The obtained results shed light into similar issues in QCD by the corresponding association of variables and fields between the two systems.

hep-th↗

arXiv2025

Forms of BRST symmetry on a Prototypical First-Class System

We obtain the various forms of BRST symmetry by using the Batalin-Fradkin-Vilkovisky formalism in a prototypical first class system. We have shown that the various forms of symmetry can be obtained through canonical transformation in the ghost sector. The so called "dual-BRST" symmetry which is claimed to be an independent symmetry due to its roots in differential geometry is obtained from usual BRST symmetry by making a canonical transformation in the ghost sector.

hep-th↗

arXiv2025

Partition function for position-dependent mass systems from superestatistics

In this work, we show a connection between superstatistics and position-dependent mass (PDM) systems in the context of the canonical ensemble. The key point is to set the fluctuation distribution of the inverse temperature in terms od the system PDM. For PDMs associated to Tsallis and Kaniadakis nonextensive statistics, the pressure and entropy of the ideal gas result lower than the standard case but maintaining monotonic behavior. Gas of non-interacting harmonic oscillators provided with quadratic and exponential PDMs exhibit a behavior of standard ED harmonic oscillator gas and a linear specific heat respectively, the latter being consistent with Nernst's third law of thermodynamics. Thus, a combined PDM-superstatistics scenario offers an alternative way to study the effects of the inhomogeneities of PDM systems in their thermodynamics.

cond-mat.stat-mech↗

arXiv2025

Random walks with homotopic spatial inhomogeneities

In this work we study a generalization of the standard random walk, an homotopic random walk (HRW), using a deformed translation unitary step that arises from a homotopy of the position-dependent masses associated to the Tsallis and Kaniadakis nonexensive statistics. The HRW implies an associated homotopic Fokker-Planck equation (HFPE) provided with a bi-parameterized inhomogeneous diffusion. The trajectories of the HRW exhibit convergence to a position, randomness as well as divergence, according to deformation and homotopic parameters. The HFPE obtained from associated master equation to the HRW presents the features: a) it results an special case of the van Kampen diffusion equation (5) of Ref. [N. G. van Kampen, \emph{Z. Phys. B Condensed Matter} \textbf{68}, 135 (1987)]; b) it exhibits a superdiffusion in function of deformation and homotopic parameters; c) Tsallis and Kaniadakis deformed FPE are recovered as special cases; d) a homotopic mixtured diffusion is observed; and e) it has a stationary entropic density, characterizing a inhomogeneous screening of the medium, obtained from a homotopic version of the H-Theorem.

math-ph↗

arXiv2024

Reduced-order Bopp-Podolsky model on the null-plane

We consider the null-plane dynamics for a reduced-order version of the higher-derivatives Bopp-Podoslky generalized electrodynamics model. By introducing an auxiliary vector field, we achieve a simpler equivalent version with lower derivatives. The massive and massless modes for the Podolsky gauge field get split into two sectors. We describe the model in terms of light-front coordinates and, by choosing $x^+$ as a natural evolution parameter, proceed to its null-plane dynamics analysis obtaining the whole constraints structure and canonical field equations. After a convenient constraints redefinition, we calculate the Dirac brackets corresponding to the second-class sector. Gauge invariance is preserved and, after elimination of second-class constraints, we obtain a consistent Abelian first-class theory for the reduced-order Bopp-Podolsky model.

hep-th↗

arXiv2024

Revisiting the Immirzi parameter: Landauer's principle and alternative entropy frameworks in Loop Quantum Gravity

This paper investigates the implications from area quantization in Loop Quantum Gravity, particularly focusing on the application of the Landauer principle -- a fundamental thermodynamic concept establishing a connection between information theory and thermodynamics. By leveraging the Landauer principle in conjunction with the Bekenstein-Hawking entropy law, we derive the usual value for the Immirzi parameter precisely, $\gamma = \ln2/(\pi \sqrt{3})$, without using the typical procedure that involves the Boltzmann-Gibbs entropy. Furthermore, following an analogous procedure, we derive a modified expression for the Immirzi parameter aligned with Barrow's entropy formulation. Our analysis also yields a new expression for the Immirzi parameter consistent with a corresponding modified Kaniadakis entropy for black hole entropy further illustrating, along with Barrow's entropy, the applicability of Landauer's principle in alternative statistical contexts within black hole physics.

gr-qc↗

arXiv2024

Symplectic Quantization and General Constraint Structure of a Prototypical Second-Class System

We discuss a general prototypical constrained Hamiltonian system with a broad application in quantum field theory and similar contexts where dynamics is defined through a functional action obeying a stationarity principle. The prototypical model amounts to a Dirac-Bergmann singular system, whose constraints restrict the actual dynamics to occur within a differential submanifold, as is the case in the major part of field theoretical models with gauge symmetry. We apply the Dirac-Bergmann algorithm in its full generality unraveling a total of $4m$ second-class constraints and obtain the corresponding Dirac brackets algebra in phase space. We follow with the Faddeev-Jackiw-Barcelos-Wotzasek approach in which the geometric character of the mentioned submanifold is emphasized by means of an internal metric function encoding its symplectic properties. We consider two straightforward examples, applying our general results to constrained motion along a toroidal geometry and to a Lorentz violating toy model in field theory. Since toroidal geometry has been recently used in cosmological models, we suggest how our results could lead to different proposals for the shape of the universe in cosmology.

hep-th↗

arXiv2024

Exploring modified Kaniadakis entropy: MOND-related theory, the Bekenstein bound conjecture, and Hawking evaporation within the Landauer principle

We investigate the description of black-hole thermodynamics in terms of a recently proposed modified version for Kaniadakis entropy. We discuss the role of that proposal within the Modified Newtonian Dynamics (MOND) theory, a generalization of Newton's second law aimed at explaining galaxy rotation curves without resorting to dark matter. We posit a conjecture that the Kaniadakis entropy precisely describes the Bekenstein-Hawking black-hole entropy. Furthermore, we consider the Bekenstein bound conjecture which imposes an upper limit on the entropy of confined quantum systems. We analyze that conjecture in the context of the modified Kaniadakis entropy and find that it holds for typical values of $\kappa$, as evidenced by our numerical investigation. Finally, using the Landauer principle from information theory, we derive an expression for mass loss in black hole evaporation. Our exploration underscores the potential relevance of a modified Kaniadakis statistics in understanding diverse physical phenomena, from gravitational systems to quantum mechanics, offering a promising direction for future research at the intersection among statistical mechanics and a continually increasing number of other important areas of physics.

gr-qc↗

arXiv2024

Note on an extended chiral bosons system contextualized in a modified gauge-unfixing formalism

We analyze the Hamiltonian structure of an extended chiral bosons theory in which the self-dual constraint is introduced via a control $α$-parameter. The system has two second-class constraints in the non-critical regime and an additional one in the critical regime. We use a modified gauge unfixing formalism to derive a first-class system, disclosing hidden symmetries. To this end, we choose one of the second-class constraints to build a corresponding gauge symmetry generator. The worked out procedure converts second-class variables into first-class ones allowing the lifting of gauge symmetry. Any function of these GU variables will also be invariant. We obtain the GU Hamiltonian and Lagrangian densities in a generalized context containing the Srivastava and Floreanini-Jackiw models as particular cases. Additionally, we observe that the resulting GU Lagrangian presents similarities to the Siegel invariant Lagrangian which is known to be suitable for describing chiral bosons theory with classical gauge invariance, however broken at quantum level. The final results signal a possible equivalence between our invariant Lagrangian obtained from the modified GU formalism and the Siegel invariant Lagrangian, with a distinct gauge symmetry.

hep-th↗

arXiv2023

Small mass graviton propagator via finite-field-dependent BRST transformations in the critical dimension Siegel-Zwiebach action from string theory

We discuss the divergent graviton propagator massless limit problem in $D=26$ and show how it can be rigorously approached by interconnecting distinct gauge-fixed Siegel-Zwiebach generating functionals from string theory in the critical dimension through proper finite-field-dependent BRST (FFBRST) transformations. The massive Fierz-Pauli Lagrangian can be obtained from the gauge-invariant Siegel-Zwiebach one in the unitary gauge as a particular case, however suffering from the van Dam-Veltman-Zakharov discontinuity and possessing a ill-defined propagator in the massless limit. Nevertheless, alternatively working in a more suitable generalized Lorenz type gauge, including the transverse-traceless case, the graviton propagator for the Siegel-Zwiebach Lagrangian in the massless limit can be made finite. Gauge attainability and nilpotent BRST symmetries are explicitly worked out. We write down the complete corresponding generating functional, including the ghosts sector, and construct a convenient FFBRST transformation connecting the unitary gauge to a new bi-parametrized class of gauge-fixings containing the transverse traceless case. By taking into account the corresponding change in the Feynman integral Jacobian, a finite massless continuous limit propagator is achieved and fully justified.

hep-th↗

arXiv2023

Modified gauge unfixing formalism and gauge symmetries in the non-commutative chiral bosons theory

We use the gauge unfixing (GU) formalism framework in a two dimensional noncommutative chiral bosons (NCCB) model to disclose new hidden symmetries. That amounts to converting a second-class system to a first-class one without adding any extra degrees of freedom in phase space. The NCCB model has two second-class constraints -- one of them turns out as a gauge symmetry generator while the other one, considered as a gauge-fixing condition, is disregarded in the converted gauge-invariant system. We show that it is possible to apply a conversion technique based on the GU formalism direct to the second-class variables present in the NCCB model, constructing deformed gauge-invariant GU variables, a procedure which we name here as modified GU formalism. For the canonical analysis in noncommutative phase space, we compute the deformed Dirac brackets between all original phase space variables. We obtain two different gauge invariant versions for the NCCB system and, in each case, a GU Hamiltonian is derived satisfying a corresponding first-class algebra. Finally, the phase space partition function is presented for each case allowing for a consistent functional quantization for the obtained gauge-invariant NCCB.

hep-th↗

arXiv2023

Gauge Symmetry of the Chiral Schwinger model from an improved Gauge Unfixing formalism

In this paper, the Hamiltonian structure of the bosonized chiral Schwinger model (BCSM) is analyzed. From the consistency condition of the constraints obtained from the Dirac method, we can observe that this model presents, for certain values of the $α$ parameter, two second-class constraints, which means that this system does not possess gauge invariance. However, we know that it is possible to disclose gauge symmetries in such a system by converting the original second-class system into a first-class one. This procedure can be done through the gauge unfixing (GU) formalism by acting with a projection operator directly on the original second-class Hamiltonian, without adding any extra degrees of freedom in the phase space. One of the constraints becomes the gauge symmetry generator of the theory and the other one is disregarded. At the end, we have a first-class Hamiltonian satisfying a first-class algebra. Here, our goal is to apply a new scheme of embedding second-class constrained systems based on the GU formalism, named improved GU formalism, in the BCSM. The original second-class variables are directly converted into gauge invariant variables, called GU variables. We have verified that the Poisson brackets involving the GU variables are equal to the Dirac brackets between the original second-class variables. Finally, we have found that our improved GU variables coincide with those obtained from an improved BFT method after a particular choice for the Wess-Zumino terms.

hep-th↗

arXiv2022

Improved Gauge-Unfixing Formalism through a Prototypical Second-Class System

We contextualize the improved gauge-unfixing (GU) formalism within a rather general prototypical second-class system, obtaining a corresponding first-class equivalent description enjoying gauge invariance which can be applied to several situations. The prototypical system is chosen to represent a considerable class of relevant models in field theory. By considering the improved version of the GU formalism, we show that any gauge-invariant function can be obtained in terms of a specific deformation in phase space, benefiting thus from the fact that no auxiliary variables are needed in the process. In this way, the resulting converted first-class system is constructed out of the same original canonical variables, preserving the number of degrees of freedom. We illustrate the technique with an application to the nonlinear sigma model.

hep-th↗

arXiv2022

New Forms of BRST Symmetry on a Prototypical First-Class System

We scrutinize the many known forms of BRST symmetries, as well as some new ones, realized within a prototypical first-class system. Similarities and differences among ordinary BRST, anti-BRST, dual-BRST and anti-dual-BRST symmetries are highlighted and discussed. We identify a precise $\mathbb{Z}_4\times\mathbb{Z}_2$ discrete group of symmetries of the ghost sector, responsible for connecting the various forms of BRST transformations. Considering a Hamiltonian approach, those symmetries can be interrelated by canonical transformations among ghost variables. However, the distinguished characteristic role of the dual BRST symmetries can be fully appreciated within a gauge-fixed Lagrangian viewpoint. New forms of BRST symmetries are given, a set generalizing particular ones previously reported in the literature as well as a brand new unprecedented set. The featured gauge invariant prototypical first-class system encompasses an extensive class of physical models and sheds light on previous controversies in the current quantum field theory literature.

hep-th↗