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M. A. Marques

Publications and source records attributed to M. A. Marques.

At least 37 records · Page 2Linked to original sources
arXiv2023

Flat and bent branes in Born-Infeld-like scalar field models

In this work, we investigate the presence of thick branes modeled by a single scalar field with Born-Infeld-like dynamics. We consider the 4-dimensional metric being Minkowski, de Sitter or anti-de Sitter. We obtain the field equations and the conditions to get a first order formalism compatible with them. To illustrate our procedure, some specific models are presented. They support localized warp factor and have their properties controlled by the 4-dimensional cosmological constant. In particular, a hybrid brane may arise, with a thick or thin profile depending on the extra dimension being inside or outside a compact space.

hep-th↗
arXiv2023

Impurity-doped scalar fields in arbitrary dimensions

We investigate the presence of localized structures for relativistic scalar fields coupled to impurities in arbitrary spatial dimensions. Such systems present spatial inhomogeneity, realized through the inclusion of explicit coordinate dependence in the Lagrangian. It is shown that, in stark contrast to the impurity-free scenario, Derrick's argument does not present a strong hindrance to the existence of stable solutions in this case. Bogomol'nyi equations giving rise to global minima of the energy are found, and some of the ensuing BPS configurations are presented.

hep-th↗
arXiv2023

Maxwell-scalar system and scalar field with impurity: novel approach to find nontrivial solutions

In this work, we investigate a Maxwell-scalar model that couples the scalar and gauge fields through the electric permittivity and another model, in which the scalar field lives in the presence of impurity. By considering a single spatial dimension, we determine the conditions under which the model with impurity can be seen as an effective model for the Maxwell-scalar system, having similar solutions. This correspondence shows that the impurity can be used to describe the presence of a charge density, and we use it to verify that the impurity-free case, which supports minimum energy configurations, is related to the case of point charges. We also investigate a class of impurities which modifies the core of the scalar field, and find the corresponding nontrivial charge densities and electric fields. In particular, the asymptotic behavior in terms of the impurity is also studied, leading to solutions exhibiting long-range or quasi-compact profile.

hep-th↗
arXiv2023

Geometrically constrained kinklike configurations engendering long range, double exponential, half-compact and compact behavior

We describe a procedure that contributes to modify the asymptotic behavior of kinks in a model described by two real scalar fields. The investigation takes advantage of a first order formalism based on energy minimization to unveil how to modify the asymptotic profile of kinklike configurations. In particular, we show that the exponential tails of standard kinklike configurations can be smoothly modified to engender long range, double exponential, half-compact or compact behavior.

hep-th↗
arXiv2023

Vortices in Maxwell-Higgs models with a global factor

This paper deals with planar vortices in a generalized model that presents a global factor which depends on the scalar field in the Nielsen-Olesen Lagrange density. We show that the system supports a first order framework. Contrary to what occurs with kinks in the line, planar vortices require the presence of constraints that brings modifications into the first order equations. Novel features are unveiled, such as finite energy configurations with infinite energy density at the origin and the presence of parameters that modifies the energy, keeping the solutions unchanged.

hep-th↗
arXiv2023

Cuscuta-Galileon Braneworlds

We investigate braneworlds modeled by topological solutions that arise from the so-called Cuscuta-Galileon model. We develop a first order framework and illustrate our procedure with the scalar field having the well-known hyperbolic tangent profile. We find conditions that must be imposed to the parameters of the model in order to have solutions connecting minima of the potential, with the brane constrained to interpolate Minkowski and anti de Sitter geometries. We also find solutions where the brane only interpolates anti de Sitter geometry. In both cases, the gravity sector of the brane is stable against small fluctuations of the metric.

hep-th↗
arXiv2023

Mechanism to induce geometric constriction on kinks and domain walls

We investigate scalar field theories in the multifield scenario, focusing mainly on the possibility to smoothly build internal structure and asymmetry for kinks and domain walls. The procedure requires the inclusion of an extra field which is associated to a function that modifies the dynamics of the other fields. We investigate minimum energy configurations, which support first order equations compatible with the equations of motion. The extra field allows a transition which is guided by a parameter that connects the standard solution to another one, geometrically constrained, mimicking the effects of geometrical constrictions in magnetic materials.

hep-th↗
arXiv2022

Manipulating the internal structure of Bloch walls

In this work, we describe a procedure to manipulate the internal structure of localized configurations of the Bloch wall type. We consider a three-field model and develop a first order formalism based on the minimization of the energy of the static fields. The results show that the third field may be decoupled and used to change the geometric arrangement of the Bloch wall, giving rise to a diversity of modifications of its internal structure. The procedure captures effects that goes beyond the standard situation and can be used in several applications of practical interest, in particular, for the study of the magnetization of magnetic materials at the nanometric scale.

hep-th↗
arXiv2022

Electrically charged multi-field configurations

In this work we investigate the presence of electrically charged structures that are localized in two and three spatial dimensions. We use the Maxwell-scalar Lagrangian to describe several systems with distinct interactions for the scalar fields. The procedure relies on finding first order differential equations that solve the equations of motion and ensure stability of the corresponding minimum energy solutions. We illustrate the many possibilities in two and in three spatial dimensions, examining different examples of electrically charged solutions that engender internal structure

hep-th↗
arXiv2022

Generalized Maxwell-Higgs vortices in models with enhanced symmetry

Topological vortices in relativistic gauge theories in flat three-dimensional spacetime are investigated. We consider the symmetry $\rm{U(1)}\times...\times \rm{U(1)}$, and for each $\rm{U(1)}$ subgroup, a complex scalar field transforming under its action is introduced, as well as generalized permeabilities through which the subsystems are coupled. We investigate in detail the features of static, finite energy solutions within this class of generalized Maxwell-Higgs models, and study the effect of the winding numbers in the magnetic properties of each subsystem. A BPS bound and the related first order equations are introduced for a large class of models. Finally, we present some specific models and solve their equations of motion to find solutions engendering many distinct features in relation to each other and to the standard Nielsen-Olesen vortex.

hep-th↗
arXiv2021

Maxwell-scalar device based on the electric dipole

In this work we study the electric field of a dipole immersed in a medium with permittivity controlled by a real scalar field which is non-minimally coupled to the Maxwell field. We model the system with an interesting function, which allows the presence of exact solutions, describing the possibility of the permittivity to encapsulate the charges at very high values, giving rise to an effect that is not present in the standard situation. The results are of direct interest to applications for emission and absorption of radiation, and may motivate new studies concerning binary stars and black holes in gravity scenarios of current interest.

hep-th↗
arXiv2021

Impurity-like solutions in vortex systems coupled to a neutral field

In this work, a Maxwell-Higgs system is coupled to a neutral scalar field that engenders $Z_2$ symmetry. At critical coupling, the resulting field equations may be identified with those of a Maxwell-Higgs model doped with an impurity whose form changes according to properties of the neutral scalar field, such as the topological sector and position of its zeros. This allows for an interpretation of parameters appearing in impurity models in terms of properties of the kink-like defect, and provides a convenient way to understand and generate impurities. By solving the first order equations, we found vortices with a novel internal structure in relation to standard solutions. The procedure was also adapted to generate impurities for Chern-Simons-Higgs theory.

hep-th↗
arXiv2021

Novel way to construct spatially localized finite energy structures

In this work we introduce a procedure to find localized structures with finite energy. We start dealing with global monopoles, and add a new contribution to the potential of the scalar fields, to balance the contribution of the angular gradients of the fields which lead to a slow falloff in the energy density. Within the first order formalism, first order equations that are compatible with the equations of motion are obtained and the stability under small fluctuations is investigated. We then include another set of scalar fields and study how it contributes to change the profile of the localized structure. We also study how these configurations modify the electric properties of a system with a single point charge, with generalized electric permittivity controlled by scalar fields. In this new model, in particular, we show that, depending on the specific modification of the electric properties of the medium, the electric field may engender the unusual behavior of pointing towards a positive charge.

hep-th↗
arXiv2021

Internal structure of cuscuton Bloch brane

This work deals with thick branes in bulk with a single extra dimension modeled by a two-field configuration. We first consider the inclusion of the cuscuton to also control the dynamics of one of the fields and investigate how it contributes to change the internal structure of the configuration in two distinct situations, with the standard and the asymmetric Bloch brane. The results show that the branes get a rich internal structure, with the geometry presenting a novel behavior which is also governed by the parameter that controls the strength of the cuscuton term. We also study the case where the dynamics of one of the two fields is only described by the cuscuton. All the models support analytical solutions which are stable against fluctuations in the metric, and the main results unveil significant modifications in the warp factor and energy density of the branes.

hep-th↗
arXiv2021

Multimagnetic Monopoles

In this work we investigate the presence of magnetic monopoles that engender multimagnetic structures, which arise from an appropriate extension of the $\rm{SU(2)}$ gauge group. The investigation is based on a modified relativistic theory that contain several gauge and matter fields, leading to a Bogomol'nyi bound and thus to a first order framework, from which stable multimagnetic solutions can be constructed. We illustrate our findings with several examples of stable magnetic monopoles with multimagnetic properties.

hep-th↗
arXiv2020

Electrically charged localized structures

This work deals with an Abelian gauge field in the presence of an electric charge immersed in a medium controlled by neutral scalar fields, which interact with the gauge field through a generalized dielectric function. We develop an interesting procedure to solve the equations of motion, which is based on the minimization of the energy, leading us to a first order framework where minimum energy solutions of first order differential equations solve the equations of motion. We investigate two distinct models in two and three spatial dimensions and illustrate the general results with some examples of current interest, implementing a simple way to solve the problem with analytical solutions that engender internal structure.

physics.gen-ph↗
arXiv2020

New twinlike models for scalar fields

This work investigates twinlike scalar field models that support kinks with the same energy density and stability. We find the first order equations compatible with the equations of motion. We use them to calculate the conditions under which they attain the twinlike character. The linear stability is also investigated, and there we show that the addition of extra requirements may lead to the same stability under small fluctuations.

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