An approach is presented for coupled chaotic systems, estimating an inferior bound value for the absolute phase difference, in order to say that phase synchronization is present. This approach shows that synchronicity in phase implies synchronicity in the time of events. This is used to derive an equation to detect phase synchronization, based on the absolute difference between the time of these events. A phase based on the vector field is also introduced. It can be used to calculate the frequency of attractors with non-coherent phase dynamics.

M. S. Baptista T. Pereira J. Kurths

Concepts from the Ergodic Theory are used to describe the existence of non-transitive maps in attractors of phase synchronous chaotic systems. It is shown that for a class of phase-coherent systems, e.g. the sinusoidally forced Chua's circuit and two coupled R{\"o}ssler oscillators, phase synchronization implies that such maps exist. These ideas are also extended to other coupled chaotic systems. In addition, a phase for a chaotic attractor is defined from the tangent vector of the flow. Finally, it is discussed how these maps can be used to real time detection of phase synchronization in experimental systems.

M. S. Baptista T. Pereira I. L. Caldas J. C. Sartorelli

We analyze the properties of impurities immersed in a vortex lattice formed by ultracold bosons in the mean field quantum Hall regime. In addition to the effects of a periodic lattice potential, the impurity is dressed by collective modes with parabolic dispersion (Tkachenko modes). We derive the effective polaron model, which contains a marginal impurity-phonon interaction. The polaron spectral function exhibits a Lorentzian broadening for arbitrarily small wave vectors even at zero temperature, in contrast with the result for optical or acoustic phonons. The anomalous damping of Tkachenko polarons could be detected experimentally using momentum-resolved spectroscopy.

M. A. Caracanhas V. S. Bagnato R. G. Pereira

In this paper we present exact solutions to the so-called Elko spinors for three models of expanding universe, namely the de Sitter, linear and the radiation type evolution. The study was restrict to flat, homogeneous and isotropic Friedmann-Robertson-Walker backgrounds. Starting with an Elko spinor we present the solutions for these cases and compared to the case of Dirac spinors. Besides, an attempt to use Elko spinors as a dark energy candidate in the cosmological context is investigated.

J. M. Hoff da Silva S. H. Pereira

The Casimir effect for {mass dimension one fermion fields (sometimes called Elko)} in $3+1$ dimension is obtained using Dirichlet boundary conditions. It is shown the existence of a repulsive force four times greater than the case of the scalar field. The precise reason for such differences are highlighted and interpreted, as well as the right parallel of the Casimir effect due to scalar and fermionic fields.

S. H. Pereira J. M. Hoff da Silva Rubia dos Santos

The Refined Gribov-Zwanziger framework takes into account the existence of equivalent gauge field configurations in the gauge-fixing quantization procedure of Euclidean Yang-Mills theories. Recently, this setup was extended to the family of linear covariant gauges giving rise to a local and BRST-invariant action. In this paper, we give an algebraic proof of the renormalizability of the resulting action to all orders in perturbation theory.

M. A. L. Capri D. Fiorentini A. D. Pereira S. P. Sorella

We present an approach which enables to state about the existence of phase synchronization in coupled chaotic oscillators without having to measure the phase. This is done by observing the oscillators at special times, and analyzing whether this set of points is localized. In particular, we show that this approach is fruitful to analyze the onset of phase synchronization in chaotic attractors whose phases are not well defined, as well as, in networks of non-identical spiking/bursting neurons connected by chemical synapses.

T. Pereira M. S. Baptista J. Kurths

We present a complex field formulation of the quantum Fisher estimation theory that works natively with complex statistics on the dependence of complex parameters. This states new complex versions of the main quantities and results of the estimation theory depending on complex parameters, such as Fisher information matrices and Cram\'er-Rao bounds. This can be useful in contexts where the quantum states are described through complex parameters, as coherent states or squeezed states. We show an application of our theory in quantum communication with coherent states.

M. Muñoz L. Pereira S. Niklitschek A. Delgado

It is presented a microscopic interpretation for the temperature within Tsallis thermostatistics, generalizing the classical derivation based on the Boltzmann-Gibbs statistics. It is shown that with this definition the zeroth law and the equipartition theorem are valid in their classical form. Moreover, it is observed that the equation of state for an ideal gas within generalized thermostatistics preserves the classical Boyle's law form $PV=NkT$.

M. P. Almeida F. Q. Potiguar U. M. S. Costa

We have synthesized Fe$_{1+y}$Te thin films by means of molecular beam epitaxy (MBE) under Te-limited growth conditions. We found that epitaxial layer-by-layer growth is possible for a wide range of excess Fe values, wider than expected from what is known on the bulk material. Using x-ray magnetic circular dichroism spectroscopy at the Fe L$_{2,3}$ and Te M$_{4,5}$ edges, we observed that films with high excess Fe contain ferromagnetic clusters while films with lower excess Fe remain nonmagnetic. Moreover, x-ray absorption spectroscopy showed that it is possible to obtain films with very similar electronic structure as that of a high quality bulk single crystal Fe$_{1.14}$Te. Our results suggest that MBE with Te-limited growth may provide an opportunity to synthesize FeTe films with smaller amounts of excess Fe as to come closer to a possible superconducting phase.

V. M. Pereira C. N. Wu C. E. Liu S. -S. Liao C. F. Chang C. -Y. Kuo C. Koz U. Schwarz H. -J. Lin C. T. Chen. L. H. Tjeng S. G. Altendorf