arXiv subjects

F. A. Brito

Publications and source records attributed to F. A. Brito.

At least 109 records · Page 6Linked to original sources

arXiv2013

Noncommutative analogue Aharonov-Bohm effect and superresonance

We consider the idea of modeling a rotating acoustic black hole by an idealized draining bathtub vortex which is a planar circulating flow phenomenon with a sink at the origin. We find the acoustic metric for this phenomenon from a noncommutative Abelian Higgs model. As such the acoustic metric not only describes a rotating acoustic black hole but also inherits the noncommutative characteristic of the spacetime. We address the issues of superresonance and analogue Aharonov-Bohm (AB) effect in this background. We mainly show that the scattering of planar waves by a draining bathtub vortex leads to a modified AB effect and due to spacetime noncommutativity, the phase shift persists even in the limit where the parameters associated with the circulation and draining vanish. Finally, we also find that the analogue AB effect and superresonance are competing phenomena at a noncommutative spacetime.

hep-th↗

arXiv2013

Braneworld solutions from scalar field in bimetric theory

We investigate the presence of braneworld solutions in a bimetric theory, with gravity and the scalar field coupling differently. We consider a non-standard model, with a Cuscuton-like scalar field, and we show how to generate braneworld solutions in this new scenario. In particular, we found no gravitational instabilities for the braneworld solutions.

hep-th↗

arXiv2012

Self-tuning Horava-Lifshitz's Universe

In this paper we show that by considering a slightly modified Horava-Lifshitz gravity one can find self-tuning cosmological scenarios. Since in the proposed model the cosmological constant cancels out, then regardless of its value it cannot produce any gravitational effect. As a consequence this removes the gravitational effect of the vacuum energy on the expansion of the Universe. Accelerating scenarios, however, can be found through the presence of conventional and non-conventional fluids.

hep-th↗

arXiv2012

Analogue Aharonov-Bohm effect in a Lorentz-violating background

In this paper we consider the acoustic black hole metrics obtained from a relativistic fluid under the influence of constant background that violates the Lorentz symmetry to study the analogue of the Aharonov-Bohm (AB) effect. We show that the scattering of planar waves by a draining bathtub vortex leads to a modified AB effect and due to the Lorentz symmetry breaking, the phase shift persists even in the limit where the parameters associated with the circulation and draining vanish. In this limit, the Lorentz-violating background forms a conical defect, which is also responsible for the appearance of the analogue AB effect.

hep-th↗

arXiv2012

The 4D-2D projection of Lorentz-violating Myers-Pospelov QED

We consider the four-dimensional quantum electrodynamics extended with Myers-Pospelov Lorentz-violating dimension-5 operators to investigate 4D-2D projection. In projecting out the 4D theory down to a 2D theory we get analogs of these operators. Namely, we obtain a new two-dimensional theory with corresponding scalar and fermionic 2D Myers-Pospelov Lorentz-violating dimension-3 operators. New defect structures can also be found from this new projected out 2D scalar sector. Furthermore, we also show that this 2D scalar sector can be also radiatively induced through the new 2D fermionic sector.

hep-th↗

arXiv2012

Spectral dimension of Horava-Snyder spacetime and the $AdS_2\times S^2$ momentum space

We show that the UV-regime at the Lifshitz point $z=3$ is equivalent to work with a momenta manifold whose topology is the same as that of an $AdS_2\times S^2$ space. According to Snyder's theory, curved momentum space is related to non-commutative quantized spacetime. In this sense, our analysis suggests an equivalence between Horava-Lifshitz and Snyder's theory.

hep-th↗

arXiv2012

Thermal properties of a solid through q-deformed algebra

We address the study of the thermodynamics of a crystalline solid by applying q-deformed algebras. We based part of our study by considering both Einstein and Debye models. We have mainly explored the q-deformed thermal and electric conductivities as a function of the Debye specific heat. The results led to the interpretation of the q-deformation acting as a factor of disorder or impurity modifying the characteristics of a crystalline structure as, for example, in the case of semiconductors.

cond-mat.stat-mech↗

arXiv2011

Superluminal neutrinos from Lorentz-violating dimension-5 operators

We consider Lorentz- and CPT-violating dimension-5 operators to address the issue of superluminal neutrinos recently pointed out in OPERA experiments. We assume these operators in the photon and neutrino sectors coupled to Lorentz-violating backgrounds in a preferred frame defined by a time-like direction. We show that such operators can produce a curve with OPERA's slope that fits OPERA, MINOS and supernova SN1987a data.

hep-ph↗

arXiv2011

4D gravity on a non-BPS bent dilatonic brane

We investigate the localization of metastable four-dimensional gravity around a bent dilatonic brane, embedded into a five-dimensional space, that exists only up to distances sufficiently small compared to a crossover scale. Far from such scale, five-dimensional effects strongly deviate the Newtonian potential. We study this effect by considering localization of massive gravity on a non-BPS bent dilatonic 3-brane solution of a five-dimensional supergravity. Our results show that the cosmological constant on the bent brane controls the size of the crossover scale. For sufficiently small positive cosmological constant, that is in accord with the present observations, the crossover scale becomes very large.

hep-th↗

arXiv2011

Inflationary Cosmology and Superluminal Neutrinos

We show that in the presence of a distance dependent Lorentz-violating time-like background one may find superluminal neutrinos at some high energy such as OPERA's scale. The similar behavior but approaching the subluminal branch is found to appear for inflaton field in the low energy scale. Thus this scenario seems to be suitable to acomplish both superluminal neutrinos and dark energy.

hep-ph↗

arXiv2011

Supersonic Velocities in Noncommutative Acoustic Black Holes

In this paper we derive Schwarzschild and Kerr - like noncommutative acoustic black hole metrics in the (3+1)-dimensional noncommutative Abelian Higgs model. We have found that the changing in the Hawking temperature T_H due to spacetime noncommutativity account for supersonic velocities and analogously may also account for superluminal particles in the general form (v-c)/c=ΔT_H/8T_H. Assuming this form is also valid for gravitational black holes and particle physics, we have found that for ΔT_H about the heaviest muon neutrino mass and T_H about proton mass gives 2.12\times 10-5 which agrees with the recent OPERA experiments. We also consider the Hawking temperature in terms of surface gravity to address the issue of background influence in the neutrino superluminality to show that our investigations also agree with supernova SN1987A measurements.

hep-th↗

arXiv2011

3D black holes on a 2-brane in 4D Minkowski space

We investigate three-dimensional black hole solutions in the realm of pure and new massive gravity in 2+1 dimensions induced on a 2-brane embedded in a flat four-dimensional spacetime. There is no cosmological constant neither on the brane nor on the four-dimensional bulk. Only gravitational fields are turned on and we indeed find vacuum solutions as black holes in 2+1 dimensions even in the absence of any cosmological solution. There is a crossover scale that controls how far the three- or four-dimensional gravity manifests on the 2-brane. Our solutions also indicate that local BTZ and SdS_3 solutions can flow to local four-dimensional Schwarzschild like black holes, as one probes from small to large distances, which is clearly a higher dimensional manifestation on the 2-brane. This is similar to the DGP scenario where the effects of extra dimensions for large probed distances along the brane manifest.

hep-th↗

arXiv2011

Superresonance effect from a rotating acoustic black hole and Lorentz symmetry breaking

We investigate the possibility of the acoustic superresonance phenomenon (analog to the superradiance in black hole physics), i.e., the amplification of a sound wave by reflection from the ergoregion of a rotating acoustic black hole with Lorentz symmetry breaking. For rotating black holes the effect of superradiance corresponds to the situation where the incident waves has reflection coefficient greater than one, and energy is extracted from them. For an acoustic Kerr-like black hole its rate of loss of mass is affected by the Lorentz symmetry breaking. We also have shown that for suitable values of the Lorentz violating parameter a wider spectrum of particle wave function can be scattered with increased amplitude by the acoustic black hole.

hep-th↗

arXiv2011

On the effective action of the vacuum photon splitting in Lorentz-violating QED

We consider one-loop radiative corrections from Lorentz- and CPT- violating extended QED to address the specific problem of finding explicitly an effective action describing amplitude of photon triple splitting. We show that it is not possible to find a nonzero photon triple splitting effective action, at least by using the derivative expansion method (at zero external momenta), up to leading order in the Lorentz- and CPT- violating parameter.

hep-th↗

arXiv2011

q-Deformed Landau diamagnetism problem embedded in D-dimensions

We address the issue of generalizing the thermodynamic quantities via $q$-deformation, i.e., via the $q$-algebra that describes $q$-bosons and $q$-fermions. In this study with the application of $q$-deformation to the Landau diamagnetism problem in two dimensions, embedded in a $D$-dimensional space, we will attempt to get a better understanding of the $q$-deformation. We obtain new results for q-deformed internal energy, number of particles, magnetization and magnetic susceptibility, which recover the values already known in the literature in the limit $q\to1$.

cond-mat.stat-mech↗

arXiv2011

4D gravity on a BPS brane in 5D AdS-Minkowski space

We calculate small correction terms to gravitational potential near an asymmetric BPS brane embedded in a 5D AdS-Minkowski space in the context of supergravity. The normalizable wave functions of gravity fluctuations around the brane describe only massive modes. We compute such wave functions analytically in the thin wall limit. We estimate the correction to gravitational potential for small and long distances, and show that there is an intermediate range of distances in which we can identify 4D gravity on the brane below a crossover scale. The 4D gravity is metastable and for distances much larger than the crossover scale the 5D gravity is recovered.

hep-th↗

arXiv2010

Glueballs Mass Spectrum in an Inflationary Braneworld Scenario

We address the issue of glueball masses in a holographic dual field theory on the boundary of an AdS space deformed by a four-dimensional cosmological constant. These glueballs are related to scalar and tensorial fluctuations of the bulk fields on this space. In the Euclidean AdS4 case the allowed masses are discretized and are related to distinct inflaton masses on a 3-brane with several states of inflation. We then obtain the e-folds number in terms of the glueball masses. In the last part we focus on the Lorentzian dS4 case to focus on the QCD equation of state in dual field theory.

hep-th↗

arXiv2010

Brane resolution in heterotic theory through BF term

We have studied the resolution of a naked singularity of a conifold in heterotic theory by a BF topological defect living in a 5-brane. The singularity is removed due to Chern-Simons action that changes the Bianchi identity for the H3 3-form. Following the previous analysis of Cvetic, Lu and Pope where they have studied the resolution through an instanton defect, we have taken a conifold over an Eguchi-Hanson manifold and a harmonic self-dual 2-form related with F2 to solve the differential equation for the warp factor. Since the H3 field is related to torsion in the extra manifold, we can interpret this conifold as one with torsion. Using the so called BF term we have found a solution with the same properties of the instanton such that the conifold is smoothed out and has a torsion that diverges in IR regime and vanish in UV regime.

hep-th↗