Israel-Stewart like theories (IS) describe relativistic viscous fluids that obey first order partial differential equations in its variables, being appealing theories from a numerical-modeling point of view. Furthermore, the IS theory is one of a few theories that has been proven to be causal and stable after small perturbations around equilibrium, both in the linear regime. After the...
In this talk we will discuss color-kinematics duality for higher-derivative Yang-Mills amplitudes. We will show how such amplitudes can be used to construct quadratic-gravity amplitudes from the double copy method. We will also illustrate the use of the generalized unitarity method for loop amplitudes containing resonances with a brief discussion on two specific one-loop examples.
In this talk I will revisit recent studies of brane inflation models and their viability with respect to observational data.
Quantum Field Theory has proven to be a very powerful tool for describing continuous phase transitions. The spontaneous symmetry breaking paradigm, complemented with the Renormalization Group (RG), allows us to classify phase transitions into ``universality classes"\footnote{J. L. Cardy, {\it Scaling and renormalization in statistical physics}, Cambridge lecture notes in physics (1996).}....
We give an overview of quantum fluctuations and dispersive forces, briefly discussing, for example, the van der Waals, Casimir-Polder, Casimir, and dynamical Casimir forces. We make a brief discussion on some main articles on these phenomena, also presenting some contributions to the knowledge of these effects obtained by our research group in UFPA-Brazil.
For instance: our prediction of the...
In this study we analyze the critical dynamics of a real scalar field in 2D near a continuos phase transition. We have computed
and solved Dynamical Renormalization Group (DRG) equations to two loops order. We have found that, different from
the case $ d < 4 $, characterized by a Wilson-Fisher fixed point with $ z = 2 + O(
\epsilon^2) $, the critical dynamics is
dominated by a novel...
In this video, I will talk about a work I did when I was an undergraduate student in physics at Federal Fluminense University (UFF). This work lead to two papers, that are available online on the links:
First: https://dx.doi.org/10.1007/JHEP03%282021%29104
Second: https://arxiv.org/abs/2107.10129v3
We considered the non-relativistic (NR) and the ultra-relativistic (UR) limits of the...
In this contribution, we reassess a supersymmetric model that takes into account the photon-photino sector in presence of a supersymmetric, but Lorentz-symmetry violating (LSV), background. The photon and photino fields appear mixed due to the presence of a constant background Majorana fermion that, as a by-product of supersymmetry, induces the mixing . Two real four-vectors, which represent...
In this work we consider the Einstein-Hilbert action in the first order order formalism coupled to Dirac spinors. From the little group symmetry, we derive the corresponding Bargmann-Wigner current which is conserved but not gauge invariant. Therefore, we construct a gauge invariant version of the Bargmann-Wigner current which is not conserved but potentially observable. Because it is not...
One crucial step to discuss general aspects of the perturbative expansion in quantum field theories is the definition and use of parametric representations of Feynman amplitudes. However, even though the usual zero temperature scenario is well-known and textbook material, a complete discussion of a parametric representation considering finite temperature and finite-size effects is absent in...
In this work, we give a quantitative answer to the question: how sudden or how adiabatic is a frequency change in a quantum harmonic oscillator (HO)? We do that by studying the time evolution of a HO which is initially in its fundamental state and whose time-dependent frequency is controlled by a parameter (denoted by $\epsilon$) that can continuously tune from a totally slow process to a...
In this work, we investigate the combined effects of temperature, external magnetic field and finite size of the system on the properties of neutral mesons in a dense and hot medium, in the context of the Nambu-Jona-Lasinio (NJL) model. In particular, we use the mean-field approximation, Schwinger's proper time method and the Matsubara series treated through the of Jacobi's theta functions, to...
The recently observed doubly charmed state $T_{cc}^+$ belongs to the family
of the multiquark states called exotic hadrons. One of main goals of
modern hadron physics is to determine the strucutre of these exotic hadrons.
Nucleus-nucleus collisions at the LHC offer a possibility to achieve this goal.
The yield of $T_{cc}^+$'s produced at the end of the quark-gluon plasma
phase of...
This work investigates the dynamical symmetry breaking from derivative four-fermion models by calculating the one-loop effective potentials. We demonstrate that they are positively defined and possess a continuous set of minima. We finally calculate the effective action of the corresponding models.
We review our recent work on the new procedure to quantize the Yang-Mills theories in the continuum, which points towards the existence of a Yang-Mills ensemble. In the new approach, the idea is to divide the configuration space into sectors labeled by different topological degrees of freedom and fix the gauge separately on each one of them. To implement this mechanism, the gauge fields are...
We describe the emergence of spontaneous chiral symmetry breaking in holographic QCD via a non-linear extension of the soft wall model with non-minimal couplings. We investigate the behaviour of meson masses and decay constants as a function of the quark mass. In the chiral limit we show the emergence of Nambu-Goldstone bosons in the pseudo-scalar sector and reproduce the...
I use effective field theories to study low energy interactions among hadrons and the consecutive formation of resonant/bound states in hadronic systems. The states formed in such systems are often referred to as dynamically generated or molecular states. In such studies, we consider the hadrons to be the degrees of freedom and the corresponding Lagrangians are constructed by requiring the...
Simulation of quantum field theories by quantum computers
requires not only the discretization of spacetime but also of field space. Naive truncations of field space break symmetries and change the universality class of the theory, complicating the continuum limit. We discuss how one can have finite dimensional Hilbert spaces that “fit” into a quantum computer while, at the same time, ...
The theory of Gravity is classical by its origin while other fundamental forces describing microscopic aspects of nature are quantum mechanical. There are several attempts to unify gravity with forces in the Standard Model. The search to unify gravitation and electromagnetism has a long history. The first studies were carried out by Faraday, Maxwell, Heaviside, Weyl, Kaluza-Klein, among...
The bumblebee field is a self-interacting vector field whose vacuum expectation value (vev) defines
a privileged direction in spacetime. This spontaneous breaking of the Lorentz symmetry has been extensively studied in flat spacetimes, wherein the bumblebee fluctuations give rise to two Nambu-Goldstone transverse mode and one longitudinal massive mode. In flat spacetimes, the NG transverse...
The "puzzling" matter of anomalies at linearly diverging tensors at all even dimensions is being explored with a strategy developed at the end of the '90s, sometimes called implicit regularization. The main focus is not the divergences that are at all avoided but is the role played by the appearance of the epsilon tensor in the traces with the chiral matrix in these amplitudes. Different...
In this work we study kinklike structures, which are localized solutions that appear in models described by real scalar fields. The model to be considered is characterized by two real scalar fields and includes a function of one of the two fields that modifies the kinematics associated to the other field. The investigation brings to light a first order framework that minimizes the energy of...
In the 1970s, heavy mesons like the quarkonia $J/\Psi$ and $\Upsilon$ were discovered, yielding a revolution in hadron physics. Since then, the hadron spectroscopy has gained a lot of attention, with the observation of several states in the charmonium and bottomonium sectors of the spectrum, as well as heavy mesons with open flavors. From the theoretical perspective, we have witnessed the...
We investigate the finite-size effects on the constituent quark masses of a two-flavor four-fermion interaction model with a flavor-mixing in the presence of a magnetic background.
The presence of a magnetic field in a specific direction compromises the isotropy, so that particles subject to this field are no longer described by plane waves. Therefore, the propagator assumes a non-diagonal form, which does not allow us to write it as a Fourier transform. In order to find the propagators of charged particles subject to external magnetic field, onde can use Ritus...
We study the existence of BPS vortices in a Chern-Simons-CP(2) model in the presence of magnetic impurities. The minimization of the energy via the Bogomol’nyi-Prasad-Sommerfield (BPS) formalism allows us to obtain the first-order differential equations (or BPS equations) and the corresponding Bogomol’nyi bound. The magnetic impurity chose for our study is a Gaussian-type, then the numerical...
We investigate the existence of first-order vortices inherent to both the Maxwell-Chern-Simons-Higgs model extended via the inclusion of an extra scalar
sector which plays the role of a source field. For this case, we focus our attention on the time-independent configurations with radial symmetry which can be obtained through the implementation
of the so-called Bogomol’nyi-Prasad-Sommerfield...
In this presentation, we describe the construction of gauged BPS baby skyrmions inherent to a model in which the dynamics of the gauge field is controlled by the usual Maxwell term now multiplied by a nontrivial dielectric function. We introduce the theoretical context in which this investigation is inserted and present the lagrange density which defines the so-called Maxwell baby Skyrme...
We present a dynamical model for describing the pion structure. We based our analysis considering the pion as a bound state of a quark anti-quark pair interacting through a one-gluon exchange. Using the Nakanishi integral representation, we solve the Bethe-Salpeter equation directly in Minkowski space. We obtain the pion weak decay constant, the LF-momentum distributions, the valence...
In this talk we will briefly review the application of QCD effective charges, whose infrared behavior is constrained by a dynamical mass scale, in phenomenology. We illustrate the power of effective charges for studying the effect of higher twist operators of the Wilson operator product expansion in the proton structure function $F_{2}$ at small-$x$
The non-abelian generalization of the gauge symmetry proposed by C. N. Yang and R. Mills in 1954 was done à la Maxwell, i.e., in terms of a set of partial differential equations. However, the integral formulation counterpart of this generalization was not known until quite recently.
The critical problem in constructing the integral Yang-Mills equations is the need for a consistent...
Localized structures usually appear in Field Theory under the action of scalar fields. In 2003, a new class of global defects was introduced by D. Bazeia, J. Menezes and R. Menezes in [Phys. Rev. Lett. 91, 241601 (2003)], where they presented a procedure to circumvent Derrick’s theorem in $(D,1)$ spacetime dimensions. This motivated us to use the scalar field to modify other localized...
Solitary waves or solitons are a special type of solution that emerge due to a perfect balance between the nonlinear and dispersive/diffusive effects of the system. Depending on their form these solutions can be classified as bright, dark, breathers, rogue waves, etc. Various systems are described by the nonlinear Schrödinger (NLS) equation and its generalizations, and the interest includes...
In this talk, I will address the kink-antikink collisions in (1,1)-dimensions. For this, we start to briefly review of the $\phi^4$ and $\phi^6$ models, as well as the standard mechanism of a resonant effect between the vibrational and translational modes. The role of extra vibrational modes in the scattering process will then be discussed, with particular emphasis on the total suppression of...
In this talk, I am going to present the explicit construction of some multi-scalar field theories in
(1 + 1) dimensions supporting BPS solutions. The construction is based on the ideas of the so-called extension method. In particular, I am going to discuss some interesting field theories constructed from non-trivial couplings between several sine-Gordon fields.
We consider a Yang-Mills-Higgs theory with gauge group $G=SU(n)$ broken to $G_{v}= [SU(p) \times SU (n − p) \times U (1)]/Z$ by a Higgs field $\phi$ in the adjoint representation. We obtain monopole solutions whose magnetic field does not lie in the Cartan Subalgebra. And, since their magnetic field vanishes in the direction of the $U(1)_{em}$ electromagnetic group, we call them Dark...
The present work discusses elements of Appleton's model for magnetized plasmas in the context of the Maxwell-Carroll-Field-Jackiw (MCFJ) theory, endowed with a fixed 4-vector of Lorentz symmetry violation. We begin by reviewing the essential aspects of electromagnetic (EM) wave propagation in plasmas, analyzing scattering relations, refractive index, propagation modes, and the birefringence...
In this work we study how CPT-odd Maxwell-Carroll-Field-Jackiw (MCFJ) electrodynamics as well as a dimension-5 extension of it affect the optical activity of continuous media. The starting point is dimension-3 MCFJ electrodynamics in matter whose modified Maxwell equations, permittiv- ity tensor, and dispersion relations are recapitulated. Corresponding refractive indices are achieved in terms...
In this work, we investigate the existence of Anderson localization induced by a specific component of a binary Bose-Einstein condensate. We use a mean-field approach, such that only one type of particle is subject to a disordered quasiperiodic potential, which induces a localization in the partner field. Numerical simulations confirm the existence of Anderson localization in the partner field...
In this contribution, we present a short overview (in portuguese) about magnetic monopoles. We highlight the monopole solutions given by Dirac (1931), 't Hooft-Polyakov (1974) and Cho-Maison (1997). We conclude stating recent results.
In this talk we present an overview of non-local field theories, discussing its mains aspects, motivation and properties: we give some highlights on some application in QFT and also gravitational model.
We use the Zamolodchikov's c function to study the stability of non-Abelian 2+1 dimensional topological phases of matter. We show in the seminar that we can construct an interpolating function that connects UV fixed points with interesting classes of topological spin liquid phases of matter in the IR regime.
Since the final decades of the last century it has become clear that quantum field theory (QFT) represents a major framework for describing fundamental nature phenomena. The generalization of this framework for models containing higher-order derivative terms, however an old subject, still poses itself as a challenging one with many open problems and subtleties. The relevance of...
