arXiv subjects

J. F. Assunção

Publications and source records attributed to J. F. Assunção.

8 recordsLinked to original sources

arXiv2026

Dynamical symmetry breaking in a non-polynomial four-fermion model

We present a new four-fermion model with a strongly non-polynomial coupling. To eliminate these non-polynomialities, we introduce two auxiliary vector fields and show that the dynamical Lorentz symmetry breaking is possible in our theory, as revealed by the effective potential generated for these vector fields. We explicitly calculate the low-energy effective action for these fields, which is given by the sum of three Maxwell terms (one for each field and a mixed one) plus a potential term displaying nontrivial minima.

hep-th↗

arXiv2023

One-loop calculations in Lorentz-breaking theories and proper-time method

We discuss applications of the proper-time method in various minimal Lorentz violating modifications of QED and present new results obtained with its use. Explicitly. we calculate the complete one-loop Heisenberg-Euler effective action involving all orders in $F_{mn}$, for two of the most studied minimal Lorentz-violating extensions of QED, the one characterized by the axial vector $b^m$ and the one involving the second-rank constant tensor $c^{mn}$.

hep-th↗

arXiv2022

Relativistic Bose-Einstein condensate in the rainbow gravity

In this paper, we study the effects of a modified theory of gravity - the rainbow gravity - on the relativistic Bose-Einstein condensate (BEC). We initially discuss some formal aspects of the model in order to compute the corrections to the relevant quantities of the condensate. Following, we evaluate the generating functional from which obtain some thermodynamic parameters. Then we calculate the corrected critical temperature $T_c$ that sets the relativistic Bose-Einstein condensate considering the three principal rainbow functions, finding, in addition, a phenomenological upper bound for the parameters involved in the model. Finally, we discuss how harder is for the particles at an arbitrary temperature $T<T_c$ to enter the condensed state compared to the usual scenario, {\it i.e.}, without rainbow gravity.

gr-qc↗

arXiv2021

Bose-Einstein condensation in Hořava-Lifshitz theory

In this paper we study the corrections emergent from a Hořava-Lifshitz extension of the complex scalar sector to the Bose-Einstein condensation and to the thermodynamics parameters. We initially discussed some features of the model to only then compute the corrections to the Bose-Einstein condensation. The calculations were done by computing the generating functional, from which we extract the thermodynamics parameters. We also obtained the Lifshitz scaling correction for the critical temperature $T_c$ that sets the Bose-Einstein Condensation.

hep-th↗

arXiv2021

Nonanalyticity of the nonabelian five-dimensional Chern-Simons term

In this work, we study the behavior of the nonabelian five-dimensional Chern-Simons term at finite temperature regime in order to verify the possible nonanalyticity. We employ two methods, a perturbative and a non-perturbative one. No scheme of regularization is needed, and we verify the nonanalyticity of the self-energy of the photon in the origin of momentum space by two conditions that do not commute, namely, the static limit $(k_0=0,\vec k\rightarrow 0)$ and the long wavelength limit $(k_0\rightarrow 0,\vec k= 0)$, while its tensorial structure holds in both limits.

hep-th↗

arXiv2020

Effects of Lorentz violation in the Bose-Einstein condensation

In this paper we study the corrections emergent from a Lorentz-violating CPT-odd extension of the complex scalar sector to the Bose-Einstein condensation and to the thermodynamics parameters. We initially discussed some features of the model to only then compute the corrections to the Bose-Einstein condensation. The calculations were done by computing the generating functional, from which we extract the thermodynamics parameters. We also obtained a Lorentz-violating correction for the critical temperature $T_c$ that sets the Bose-Einstein Condensation.

hep-th↗

arXiv2020

Lorentz-violating scalar QED renormalization

This paper presents divergent contributions of the radiative corrections for a Lorentz-violating extension of the scalar electrodynamics. We initially discuss some features of the model and extract the Feynman rules. Then we compute the one-loop radiative corrections using Feynman parametrization and dimensional regularization in order to evaluate the integrals. We also discuss Furry's theorem validity and renormalization in the present context.

hep-th↗

arXiv2019

Dynamical Lorentz symmetry breaking in a tensor bumblebee model

In this paper, we formulate a theory of the second-rank antisymmetric (pseudo)tensor field minimally coupled to a spinor, calculate the one-loop effective potential of the (pseudo)tensor field, and, explicitly, demonstrate that it is positively defined and possesses a continuous set of minima, both for tensor and pseudotensor cases. Therefore, our model turns out to display the dynamical Lorentz symmetry breaking. We also argue that, contrarily to the derivative coupling we use here, derivative-free couplings of the antisymmetric tensor field to a spinor do not generate the positively defined potential and thus do not allow for the dynamical Lorentz symmetry breaking.

hep-th↗