arXiv subjects

P. R. S. Carvalho

Publications and source records attributed to P. R. S. Carvalho.

At least 19 recordsLinked to original sources

arXiv2025

Exact infrared scaling behavior of Randers-Finsler scalar field theories

We study the scaling behavior of Randers-Finsler massless scalar field theories in the infrared regime. For that, we compute analytically the radiative corrections to the corresponding anomalous dimensions, related to the critical exponents of the theory, first up to next-to-leading loop order and later for all-loop levels. We consider the effect of the Randers-Finsler space-time properties on the critical exponents by considering the parameter characterizing those space-times in its exact form. We employ field-theoretic renormalization group and $ε$-expansion techniques at dimensions $d = 4 - ε$ through three distinct and independent methods. At the end, we furnish the physical interpretation of the obtained results.

hep-th↗

arXiv2025

On the information behavior from quadratically coupled accelerated detectors

In this work, we propose to investigate the information behavior of quantum systems through accelerated detectors quadratically coupled with a massless scalar field. In addition, we made detailed comparisons with the case of linear coupling. The perturbative method was used to evolve the density matrix that describes the interaction of the detector-field system during a finite time. The systems studied were: accelerated single-qubit, quantum interferometric circuit, and the which-path distinguishability circuit. The results on the probability transition rates show that quadratic coupling amplifies the Unruh effect. This is due to the modification of the interaction structure, allowing the simultaneous absorption of multiple quanta. Our findings showed that the information is degraded more quickly in the case of quadratic coupling, when compared to the linear case. Furthermore, this change is mainly given by the coupling constant and by an additional factor that arises in the case of quadratic coupling. Therefore, these results indicate that the nature of the coupling between the detector and the field plays a fundamental role in the behavior of quantum information in high acceleration regimes.

hep-th↗

arXiv2025

Non-ideal quantum electrodynamics

In this Letter we present a field-theoretic formulation for describing non-ideal quantum electrodynamic effects. It generalizes its ideal counterpart and is valid in the non-ideal domain. We compute some non-ideal elementary processes both at leading order as well as up to next-to-leading order. Furthermore, we present some physical effect taken up to next-to-leading order that is not described by earlier similar but non-renormalizable theories defined recently in literature thus characterizing all them, at most, as effective ones. Their effectiveness allows us to obtain such an effect only at leading order. We recover all the corresponding ideal results when we take the limit $a\rightarrow 1$, where $a$ is a parameter that encodes the non-ideal effects. All the results show an interplay between non-ideal properties and fluctuations.

physics.gen-ph↗

arXiv2025

Nonideal Statistical Field Theory at NLO

In this work we introduce a field theory capable of describing the critical properties of nonideal systems undergoing continuous phase transitions beyond the leading order radiative corrections or in the number of loops (effective field theories limited only to leading order were recently defined in literature). These systems present defects, inhomogeneities and impurities as opposed to ideal ones which are perfect, homogeneous and pure. We compute the values of the critical exponents of the theory beyond leading order and compare with their corresponding experimental measured results. The results show some interplay between nonideal effects and fluctuations.

cond-mat.stat-mech↗

arXiv2025

On the completeness of the $δ_{KLS}$-generalized statistical field theory

In this work we introduce a field-theoretic tool that enable us to evaluate the critical exponents of $δ_{KLS}$-generalized systems undergoing continuous phase transitions, namely $δ_{KLS}$-generalized statistical field theory. It generalizes the standard Boltzmann-Gibbs through the introduction of the $δ_{KLS}$ parameter from which Boltzmann-Gibbs statistics is recovered in the limit $δ_{KLS}\rightarrow 0$. From the results for the critical exponents we provide the referred physical interpretation for the $δ_{KLS}$ parameter. Although new generalized universality classes emerge, we show that they are incomplete for describing the behavior of some real materials. This task is fulfilled only for nonextensive statistical field theory, which is related to fractal derivative and multifractal geometries, up to the moment, for our knowledge.

hep-th↗

arXiv2024

Is $γ_{KLS}$-generalized statistical field theory complete?

In this Letter we introduce some field-theoretic approach for computing the critical properties of $γ_{KLS}$-generalized systems undergoing continuous phase transitions, namely $γ_{KLS}$-statistical field theory. From this new approach emerges the new generalized O($N$)$_{γ_{KLS}}$ universality class, which is capable of encompassing nonconventional critical exponents for real imperfect systems known as manganites not described by standard statistical field theory. We compare the generalized results with those obtained from measurements in manganites. The agreement was satisfactory, where the relative errors are $< 5\%$ for the most of manganites used. Although the present approach describes the aforementioned nonconventional critical indices, we show that it is not complete. For example, it does not explain the results for some other manganites, being explained only for nonextensive statistical field theory recently introduced in literature. So, $γ_{KLS}$-statistical field theory has to be discarded for statistical mechanics generalization purposes.

hep-th↗

arXiv2023

Is Kaniadakis $κ$-generalized statistical mechanics general?

In this Letter we introduce some field-theoretic approach for computing the critical properties of systems undergoing continuous phase transitions governed by the $κ$-generalized statistics, namely $κ$-generalized statistical field theory. In particular, we show, by computations through analytic and simulation results, that the $κ$-generalized Ising-like systems are not capable of describing the nonconventional critical properties of real imperfect crystals, \emph{e. g.} of manganites, as some alternative generalized theory is, namely nonextensive statistical field theory, as shown recently in literature. Although $κ$-Ising-like systems do not depend on $κ$, we show that a few distinct systems do. Thus the $κ$-generalized statistical field theory is not general, \emph{i. e.} it fails to generalize Ising-like systems for describing the critical behavior of imperfect crystals, and must be discarded as one generalizing statistical mechanics. For the latter systems we present the physical interpretation of the theory by furnishing the general physical interpretation of the deformation $κ$-parameter.

hep-th↗

arXiv2022

Squeezing as a probe of the universality hypothesis

We compute analytically the radiative quantum corrections, up to next-to-leading loop order, to the universal critical exponents for both massless and massive O($N$) $λϕ^{4}$ scalar squeezed field theories for probing the universality hypothesis. For that, we employ six distinct and independent methods. The outcomes for the universal squeezed critical exponents obtained through these methods are identical among them and reduce to the conventional ones where squeezing is absent. Although the squeezing mechanism modifies the internal properties of the field, the squeezed critical indices are not affected by the squeezing effect, thus implying the validity of the universality hypothesis, at least at the loop level considered. At the end, we present the corresponding physical interpretation for the results in terms of the geometric symmetry properties of the squeezed field.

hep-th↗

arXiv2022

Experimental validation of nonextensive statistical field theory: applications to manganites

In this Letter we validate experimentally the nonextensive statistical field theory, a new general field-theoretic approach introduced recently in the literature. With such an approach, we are capable of computing the critical properties of nonextensive systems undergoing continuous phase transitions, belonging to the new generalized O($N$)$_{q}$ universality class. We compare the nonextensive critical indices values evaluated from the theory with those already obtained in literature through experiments for various distinct manganites presenting nonconventional critical behavior. The agreement is satisfactory, whose relative errors are $< 5\%$ for the most of manganites employed and as better as $|1 - q| < 1$ which is the limit of validity of the theory. We present the physical interpretation of the experimental results and of the theory through the general physical interpretation of the $q$-parameter.

hep-th↗

arXiv2022

Nonextensive percolation and Lee-Yang edge singularity from nonextensive $λϕ^{3}$ scalar field theory

We compute the critical exponents for nonextensive $λϕ^{3}$ scalar field theory for all loop orders and $|q - 1| < 1$. We apply the results for both nonextensive percolation and Lee-Yang edge singularity problems. The corresponding systems are nonextensive generalizations of their extensive counterparts. For that we employ tools from the recently introduced nonextensive statistical field theory. The results for the nonextensive critical exponents computed depend on the nonextensive parameter $q$, which encodes global correlations among the degrees of freedom of the system. The extensive results are recovered in the limit $q\rightarrow 1$. There is an interplay between global correlations and fluctuations, once the nonextensive critical exponents depend on $q$. This dependence is in agreement with the universality hypothesis.

hep-th↗

arXiv2021

Nonextensive statistical field theory

We introduce a field-theoretic approach for describing the critical behavior of nonextensive systems, systems displaying global correlations among their degrees of freedom, encoded by the nonextensive parameter $q$. As some applications, we report, to our knowledge, the first analytical computation of both universal static and dynamic $q$-dependent nonextensive critical exponents for O($N$) vector models, valid for all loop orders and $|q - 1| < 1$. Then emerges the new nonextensive O($N$)$_{q}$ universality class. We employ six independent methods which furnish identical results. Particularly, the results for nonextensive 2d Ising systems, exact within the referred approximation, agree with that obtained from computer simulations, within the margin of error, as better as $q$ is closer to $1$. We argue that the present approach can be applied to all models described by extensive statistical field theory as well. The results show an interplay between global correlations and fluctuations.

hep-th↗

arXiv2021

Parameter estimation in an anisotropic expanding spacetime

In this work, we investigate how the anisotropy affects the cosmological parameters estimation. Here the anisotropy is incorporated as a small gravitational disturbance. We calculate the Fisher information for both cosmological parameters $ε$ (expansion volume) and $ρ$ (expansion rate), and we show that the anisotropy introduces oscillations in the Fisher information spectrum. This implies that the estimation of the cosmological parameters is sensible to the direction of the momentum $k$ of particles. In addition, we observe that for small values of the momentum $k$ there is a substantial difference between the Fisher information spectrum for the minimum and conformal couplings.

gr-qc↗

arXiv2021

Diffeomorphism symmetry effect on the O(N ) universality class

We probe the effect of diffeomorphism symmetry on the critical exponents values for massive O($N$) $λϕ^{4}$ scalar field theories in curved spacetime. We apply field-theoretic renormalization group tools, where we use only momentum coordinates as opposed to the earlier standard procedure with both space and momentum coordinates, for computing analytically the critical exponents up to three-loop order for one of them and up to two-loop level for the remaining ones. We found that the curved spacetime critical exponents are the same as their flat spacetime counterparts, at least up to the level considered. At the conclusions we present the physical interpretation for the results.

hep-th↗

arXiv2020

Influence of conformal symmetry on the amplitude ratios for O($N$) models

In this Letter we compute analytically the effect of conformal symmetry on the radiative corrections to the amplitude ratios for O($N$) $λϕ^{4}$ massless scalar field theories in curved spacetime for probing the two-scale-factor universality hypothesis. For that we employ three distinct and independent field-theoretic renormalization group methods. The amplitude ratios values obtained are identical when computed through the three distinct methods, thus showing their universal character. Furthermore, they are the same as that obtained in flat spacetime, then satisfying the two-scale-factor universality hypothesis.

hep-th↗

arXiv2019

Influence of exact Lorentz-violating mechanism on the critical exponents for massive $q$-deformed $λϕ^{4}$ scalar field theory

We probe the influence of Lorentz-violating mechanism, treated exactly, on the radiative quantum corrections to critical exponents for massive $q$-deformed O($N$) $λϕ^{4}$ scalar field theories. We attain that task by employing three distinct and independent field-theoretic renormalization group methods. Firstly we compute the critical exponents up to the finite next-to-leading order for then generalizing the results for any loop level. We show that the $q$-deformed critical exponents are insensible to the Lorentz symmetry breaking mechanism thus agreeing with the universality hypothesis.

hep-th↗

arXiv2019

Exact Lorentz-violating $q$-deformed O($N$) universality class

We examine the influence of exact Lorentz-violating symmetry mechanism on the radiative quantum corrections to the critical exponents for massless $q$-deformed O($N$) $λϕ^{4}$ scalar field theories. For that, we employ three different and independent field-theoretic renormalization group methods for computing analytically the $q$-deformed critical exponents up to next-to-leading order. Then we generalize the former finite loop level results for any loop order. We show that the Lorentz-violating $q$-deformed critical exponents, obtained through the three methods, turn out to be identical and furthermore the same as their Lorentz-invariant $q$-deformed ones. We argue that this result is in accordance with the universality hypothesis.

hep-th↗

arXiv2019

Universality hypothesis breakdown at one-loop order

We probe the universality hypothesis by analytically computing, at least, the two-loop corrections to the critical exponents for $q$-deformed O($N$) self-interacting $λϕ^{4}$ scalar field theories through six distinct and independent field-theoretic renormalization group methods and $ε$-expansion techniques. We show that the effect of $q$-deformation on the one-loop corrections to the $q$-deformed critical exponents is null, so universality hypothesis is broken down at this loop order. Such effect emerges just, at least, at two-loop level and the validity of universality hypothesis is restored. The $q$-deformed critical exponents obtained through the six methods are the same and, furthermore, reduce to their non-deformed values in the appropriated limit.

hep-th↗

arXiv2019

Exact Lorentz-violating all-loop ultraviolet divergences in scalar field theories

In this work we evaluate analytically the ultraviolet divergences of Lorentz-violating massive O($N$) $λϕ^{4}$ scalar field theories, which are exact in the Lorentz-violating mechanism, firstly explicitly at next-to-leading order and latter at any loop level through an induction procedure based on a theorem following from the exact approach, for computing the corresponding critical exponents. For attaining that goal, we employ three different and independent field-theoretic renormalization group methods. The results found for the critical exponents show that they are identical in the three distinct methods and equal to their Lorentz invariant counterparts. Furthermore, we show that the results obtained here, based on the single concept of loop order of the referred terms of the corresponding $β$-function and anomalous dimensions, reduce to the ones obtained through the earlier non-exact approach based on a joint redefinition of the field and coupling constant of the theory, in the appropriate limit.

hep-th↗