arXiv subjects

P. Pitanga

Publications and source records attributed to P. Pitanga.

5 recordsLinked to original sources

arXiv2012

The boundary of Gödel's spacetime and the chronology protection conjecture

We present a homogenous anisotropic conformal spacetime manifold that provide an example of Hawking's chronology protection conjecture in three-dimensional gravity theory. The solution is based upon the fact that the seven-dimensional group of the automorphism of the Heisenberg motion group H1{\times}U(1), modulo discrete sub-group Γ, is the symmetry group of the sub-Riemannian (SR)- manifold, boundary of the Cauchy-Riemann (CR)-manifold, allowing the existence of positive mass, momentum, angular-momentum and timelike-translation. It is shown that many mirror symmetric self-similar Gödel's surfaces are hidden behind a Cauchy spacelike surface so that causality violation is not visible from outside.

gr-qc↗

arXiv2011

Gödel's universe and the chronology protection conjecture

We present a solution for the geodesic motion in Gödel's universe that provides a particular proof of Hawking's chronology protection conjecture in three-dimensional gravity theory. The solution is based upon the fact that the group of the automorphisms of the Heisenberg motion group H1\timesU(1), modulo discrete sub-group Z, act isometrically on the boundary of the hyperbolic three-dimensional manifold. Closed timelike curves do not exist due to the presence of a closed Cauchy-Riemann surface for chronology protection, with two mirror symmetric sets of helicoidal self-similar modules inside. The present solution is isometrically equivalent to a cylindrical gravitational monochromatic wave front.

gr-qc↗

arXiv2000

The Heavy Dirac Monopole

We present a model for the Dirac magnetic monopole, suitable for the strong coupling regime. The magnetic monopole is static, has charge g and mass M, occupying a volume of radius R ~ O (g^2/M). It is shown that inside each n-monopole there exist infinite multipoles. It is given an analytical proof of the existence of monopole-antimonopole bound state. Theses bound-states might give additional strong light to light scattering in the proton-antiproton collision process at FermiLab TEVATRON.

hep-th↗

arXiv2000

Time of arrival in the presence of interactions

We introduce a formalism for the calculation of the time of arrival t at a space point for particles traveling through interacting media. We develop a general formulation that employs quantum canonical transformations from the free to the interacting cases to construct t in the context of the Positive Operator Valued Measures. We then compute the probability distribution in the times of arrival at a point for particles that have undergone reflection, transmission or tunneling off finite potential barriers. For narrow Gaussian initial wave packets we obtain multimodal time distributions of the reflected packets and a combination of the Hartman effect with unexpected retardation in tunneling. We also employ explicitly our formalism to deal with arrivals in the interaction region for the step and linear potentials.

quant-ph↗

arXiv1999

Time of arrival through a quantum barrier

We introduce a formalism for the calculation of the time of arrival t at a detector of particles traveling through interacting environments. We develop a general formulation that employs quantum canonical transformations from the free to the interacting cases to compute t. We interpret our results in terms of a Positive Operator Valued Measure. We then compute the probability distribution in times of arrival at a detector of those particles that, after their initial preparation, have undergone quantum tunneling or reflection due to the presence of potential barriers. We obtain the expected retardation or advancement for transmitted wave packets, and non-foreseen double bump structures for some cases of reflection.

quant-ph↗