arXiv subjects

A. Soto

Publications and source records attributed to A. Soto.

9 recordsLinked to original sources

arXiv2025

Cosmic Backgrounds in the Gravitational Standard-Model Extension

We consider background fields within the gravitational sector of the Standard-Model Extension (SME) in a cosmological setting. Our analysis is divided into two parts. The first part addresses the consistency of nondynamical backgrounds in scenarios where diffeomorphism invariance is explicitly broken. Focusing on gravitational systems that admit Killing vector fields and possess a priori symmetries, we demonstrate that potential discrepancies between Riemannian geometry and dynamical equations can be avoided. The second part presents a direct application of various techniques developed by decomposing the modified Einstein equations along normal and tangential directions of the (3+1) decomposition. We show that nondynamical backgrounds can lead to accelerated cosmological expansion without requiring a cosmological constant, thereby opening new avenues for interpreting dark energy.

gr-qc↗

arXiv2024

On the photon mass generation in Rarita-Schwinger QED

This work examines the dynamical mass generation for the photon in Rarita-Schwinger QED. We focus our attention on the cases of $\omega=2,3$ dimensional spacetime. In these frameworks, it is well known that in the usual QED, the photon field (dynamically) acquires a gauge invariant mass (the Schwinger and Chern-Simons mass, respectively). We wish to scrutinize this phenomenon in terms of the Rarita-Schwinger fields. The presence of higher-derivative terms is shown as the leading contributions to the $1$PI function $\langle AA \rangle$ at one-loop order. We study the pole structure of the photon's complete propagator to unveil the main effects of the Rarita-Schwinger fields on the photon's mass. In addition, we present some remarks about the renormalizability of this model (in different dimensions) due to the presence of higher-derivative corrections at one-loop.

hep-th↗

arXiv2023

Induced CP-violation in the Euler-Heisenberg Lagrangian

In this paper, we examine the behaviour of the Euler-Heisenberg effective action in the presence of a novel axial coupling among the gauge field and the fermionic matter. This axial coupling is responsible to induce a CP-violating term in the extended form of the Euler-Heisenberg effective action, which is generated naturally through the analysis of the box diagram. However, this anomalous model is not a viable extension of QED, and we explicitly show that the induced CP-violating term in the Euler-Heisenberg effective Lagrangian is obtained only by adding an axial coupling to the ordinary QED Lagrangian. In order to perform our analysis, we use a parametrization of the vector and axial coupling constants, $g_{v}$ and $g_{a}$, in terms of a new coupling $β$. Interestingly, this parametrization allows us to explore a hidden symmetry under the change of $g_{v}\leftrightarrow g_{a}$ in some diagrams. This symmetry is explicitly observed in the analysis of the box diagram, where we determine the $λ_i$ coefficients of $\cal{L}_{\rm ext.}^{\rm \small EH}=λ_{1}\cal{F}^{2}+λ_{2}\cal{G}^{2}+λ_{3}\cal{F}\cal{G}$, specially the coefficient $λ_3$ related with the CP-violating term due to the axial coupling. As a phenomenological application of the results, we compute the relevant cross section for the light by light scattering through the extended Euler-Heisenberg effective action.

hep-th↗

arXiv2022

Schwinger-Dyson equations and mass generation for an axion theory with a PT symmetric Yukawa fermion interaction

A nonperturbative Schwinger-Dyson analysis of mass generation is presented for a non-Hermitian PT-symmetric field theory in four dimensions of an axion coupled to a Dirac fermion.The model is motivated by phenomenological considerations.The axion has a quartic self-coupling $λ$ and a Yukawa coupling $g$ to the fermion. The Schwinger-Dyson equations are derived for the model with generic couplings. In the non-Hermitian case there is an additional nonperturbative contribution to the scalar mass. In a simplified rainbow analysis the solutions for the SD equations, are given for different regimes of the couplings $g$ and $λ$.

hep-ph↗

arXiv2022

Induced non-Abelian Chern-Simons effective action in very special relativity

In this paper, we study the one-loop induced effective action for a non-abelian gauge field in the very special relativity (VSR) framework in a $(2+1)$-dimensional spacetime. We show that there are new graphs contributing to the amplitudes of gluon $n$-point functions, e.g. $\langle GG\rangle$, $\langle GGG \rangle$ and $\langle GGGG \rangle$, originating from the non-local couplings generated in VSR. Using the one-loop analysis of the relevant graphs, we evaluate the VSR corrections to the induced kinetic term of the non-abelian gauge field action in three dimensions. Next, by applying the Ward identity, we determine the general tensorial structure for the amplitude of $\langle GG\rangle$ in VSR, which is valid at any order of the loop analysis. Moreover, we discuss the leading VSR corrections to the non-abelian Chern-Simons and Yang-Mills action through the analysis of $\langle GG\rangle$, $\langle GGG \rangle$ and $\langle GGGG \rangle$. In order to highlight the VSR effects, we present the VSR modification of non-abelian Chern-Simons effective action and then obtain the equation of motion for the non-abelian gauge field. As a result, we observe that the well-known pure gauge solution does not hold in the presence of VSR effects.

hep-th↗

arXiv2022

PT symmetric fermionic field theories with axions: Renormalization and dynamical mass generation

We consider the renormalisation properties of non-Hermitian Yukawa theories involving a pseudoscalar (axion) field at or near $4$ dimensions. The non-Hermiticity is \cPT-symmetric where $\mathcal P$ is a linear idempotent operator (such as parity) and $\mathcal T$ is an anti-linear idempotent operator (such as time-reversal). The coupling constants of the Yukawa and quartic scalar coupling terms reflect this non-Hermiticity. The path integral representing the field theory is used to discuss the Feynman rules associated with the field theory. The fixed point structure associated with the renormalisation group has \cPT- symmetric and Hermitian fixed points. At two loops in the massless theory, we demonstrate the flow from Hermitian to non-Hermitian fixed points. From the one-loop renormalisation of a massive Yukawa theory, a self-consistent Nambu-Jona Lasinio gap equation is established and its real solutions are discussed.

hep-th↗

arXiv2022

Impossibility of obtaining a CP-violating Euler-Heisenberg effective theory from a viable modification of QED

In this paper, we examine the CP-violating term of the Euler-Heisenberg action. We focus in the aspects related with the generation of such a term from a QED-like model in terms of the effective action approach. In particular, we show that the generation of the CP-violating term is closely related with both of vector and axial fermionic bilinears. Although, these anomalous models are not a "viable" extension of QED, we argue that the CP-violating term in the photon sector is obtained only from this class of models, and not from any fundamental field theory.

hep-ph↗

arXiv2021

Adler-Bell-Jackiw anomaly in VSR electrodynamics

In this paper, we examine the problem of anomalies of the fermionic currents in the context of the very special relativity (VSR). We consider the VSR contributions to the triangle amplitude $\left\langle J_{5}^λ J^μ J^ν \right\rangle $, which allows the evaluation of the vector and axial Ward identities. Actually, we observe that the VSR nonlocal effects respect the vector Ward identity, and it also contributes in a very interesting and unique way for the Adler-Bell-Jackiw anomaly.

hep-th↗

arXiv2020

Induced Maxwell-Chern-Simons Effective Action in Very Special Relativity

In this paper, we study the one-loop induced photon's effective action in the very special relativity electrodynamics in $(2+1)$ spacetime (VSR-QED$_{3}$). Due to the presence of new nonlocal couplings resulting from the VSR gauge symmetry, we have additional graphs contributing to the $\langle AA\rangle$ and $\langle AAA \rangle$ amplitudes. From these contributions, we discuss the VSR generalization of the Abelian Maxwell-Chern-Simons Lagrangian, consisting in the dynamical part and the Chern-Simons-like self-couplings, respectively. We use the VSR-Chern-Simons electrodynamics to discuss some non-Ohmic behavior on topological materials, in particular VSR effects on Hall's conductivity. In the dynamical part of the effective action, we observe the presence of a UV/IR mixing, due to the entanglement of the VSR nonlocal effects to the quantum higher-derivative terms. Furthermore, in the self-coupling aspect, we verify the validity of the Furry's theorem in the VSR-QED$_{3}$ explicitly.

hep-th↗