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E. Passos

Publications and source records attributed to E. Passos.

At least 73 records · Page 4Linked to original sources
arXiv2014

The entropy of the noncommutative acoustic black hole based on generalized uncertainty principle

In this paper we investigate statistical entropy of a 3-dimensional rotating acoustic black hole based on generalized uncertainty principle. In our results we obtain an area entropy and a correction term associated with the noncommutative acoustic black hole when $λ$ introduced in the generalized uncertainty principle takes a specific value. However, in this method, it is not needed to introduce the ultraviolet cut-off and divergences are eliminated. Moreover, the small mass approximation is not necessary in the original brick-wall model.

hep-th↗
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↗
arXiv2012

A new CPT-even and Lorentz-Violating nonminimal coupling in the Dirac equation

In this work, we propose a CPT-even and Lorentz-violating dimension-five nonminimal coupling between fermionic and gauge fields, involving the CTP-even and Lorentz-violating gauge tensor of the SME. This nonminimal coupling modifies the Dirac equation, whose nonrelativistic regime is governed by a Hamiltonian which induces new effects, such as an electric-Zeeman-like spectrum splitting and an anomalous-like contribution to the electron magnetic moment, between others. Some of these new effects allows to constrain the magnitude of this nonminimal coupling in 1 part in 10^16.

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

An Analogy of the Quantum Hall Condutivity in a Lorentz-symmetry Violation Setup

We investigated some influences of unconventional physics, such Lorentz-symmetry violation, for quantum mechanical systems. In this context, we calculated a important contribution for Standard Model Extension. In the non-relativistic limit, we obtained a analogy of the Landau levels and the quantum Hall conductivity related to this contribution for low energy systems.

hep-th↗
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

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

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↗
arXiv2010

Acoustic Black Holes from Abelian Higgs Model with Lorentz Symmetry Breaking

In this paper we derive acoustic black hole metrics in the (3+1) and (2+1)-dimensional Abelian Higgs model with Lorentz symmetry breaking. In this set up the sound waves lose the Lorentz boost invariance and suffer a 'birefringence' effect. We have found acoustic black holes and respective Hawking temperatures depending on the Lorentz violating parameter. Furthermore, we obtain an acoustic Kerr-like black hole metric with the Lorentz violating term affecting its rate of loss of mass. 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↗
arXiv2009

Lorentz-violating Chern-Simons action under high temperature in massless QED

Lorentz and CPT violating QED with massless fermions at finite temperature is studied. We show that there is no ambiguity in the induced coefficient of the Chern-Simons-like term that defines the so-called Carroll-Field-Jackiw model at high temperature. We also show that this system constitutes an example where the breaking of CPT and Lorentz symmetries is more severe at high temperature than in the zero temperature case thus precluding any naive expectations of Lorentz symmetry restoration.

hep-th↗
arXiv2008

Induced Chern-Simons-like action in Lorentz-violating massless QED

In the present work, we study different aspects of Lorentz and CPT symmetry violation in extended massless QED. By following the observation that the 2+1 dimensional Maxwell-Chern-Simons theory can be originated from the 3+1 dimensional Chern-Simons-like action, we also focus on the fermion sector to relate the 3+1 dimensional extended massless QED to 2+1 dimensional massive QED. We take advantage of this to state that the Chern-Simons-like action in extended massless QED can be induced with its coefficient being well defined and finite just as its 2+1 counterpart. We make use of three different regularization schemes by inducting the Chern-Simons-like in 3+1 dimensions to support this conjecture.

hep-th↗
arXiv2008

Lorentz symmetry violation and an Analog of Landau levels

Within the context of Lorentz violating extended electrodynamics, we study an analog of Landau quantization for a system where a neutral particle moves in the presence of an electromagnetic field and a constant four-vector that breaks Lorentz symmetry. The nonrelativistic Hamiltonian associated to this system is obtained using the Foldy-Wouthuysen transformation for a Dirac spinor. The degenerated energy spectrum is obtained for a time-like and a space-like parameter Lorentz-breaking vector. The energy dependence of the cyclotron rotation direction in terms of supersymmetric quantum mechanics is analyzed.

hep-th↗
arXiv2008

Two-dimensional Lorentz-violating Chern-Simons-like action

We demonstrate generation of the two-dimensional Chern-Simons-like Lorentz-breaking action via an appropriate Lorentz-breaking coupling of scalar and spinor fields at zero as well as at the finite temperature and via the noncommutative fields method and study the dispersion relations corresponding to this action.

hep-th↗