Remarks on Bessel beams, signals and superluminality

We address the question about the velocity of signals carried by Bessel beams wave packets propagating in vacuum and having well defined wavefronts in time. We find that this problem is analogous to that of propagation of usual plane wave packets within dispersive media and conclude that the signal velocity can not be superluminal.Comment: LaTeX, 16 pages, no figures. Completely revised version, accepted for publication in Physics Letters

A note on Duffin-Kemmer-Petiau equation in (1+1) space-time dimensions

In the last years several papers addressed the supposed spin-1 sector of the massive Duffin-Kemmer-Petiau (DKP) equation restricted to (1+1) space-time dimensions. In this note we show explicitly that this is a misleading approach, since the DKP algebra in (1+1) dimensions admits only a spin-0 representation. Our result also is useful to understand why several recent papers found coincident results for both spin-0 and spin-1 sectors of the DKP theory in (3+1) dimensions when the dynamics is restricted to one space dimension.Comment: 3 pages, no figure

Interacting spin 0 fields with torsion via Duffin-Kemmer-Petiau theory

Here we study the behaviour of spin 0 sector of the DKP field in spaces with torsion. First we show that in a Riemann-Cartan manifold the DKP field presents an interaction with torsion when minimal coupling is performed, contrary to the behaviour of the KG field, a result that breaks the usual equivalence between the DKP and the KG fields. Next we analyse the case of Teleparallel Equivalent of General Relativity Weitzenbock manifold, showing that in this case there is a perfect agreement between KG and DKP fields. The origins of both results are also discussed.Comment: 10 pages, no figures, uses REVTEX. Changes in the presentation, minor misprints and one equation corrected. References updated. To appear in General Relativity and Gravitatio

Distributional approach to point interactions in one-dimensional quantum mechanics

We consider the one-dimensional quantum mechanical problem of defining interactions concentrated at a single point in the framework of the theory of distributions. The often ill-defined product which describes the interaction term in the Schr\"odinger and Dirac equations is replaced by a well-defined distribution satisfying some simple mathematical conditions and, in addition, the physical requirement of probability current conservation is imposed. A four-parameter family of interactions thus emerges as the most general point interaction both in the non-relativistic and in the relativistic theories (in agreement with results obtained by self-adjoint extensions). Since the interaction is given explicitly, the distributional method allows one to carry out symmetry investigations in a simple way, and it proves to be useful to clarify some ambiguities related to the so-called $\delta^\prime$ interaction.Comment: Open Access link: http://journal.frontiersin.org/Journal/10.3389/fphy.2014.00023/abstrac

Gauged Thirring Model in the Heisenberg Picture

We consider the (2+1)-dimensional gauged Thirring model in the Heisenberg picture. In this context we evaluate the vacuum polarization tensor as well as the corrected gauge boson propagator and address the issues of generation of mass and dynamics for the gauge boson (in the limits of QED$_3$ and Thirring model as a gauge theory, respectively) due to the radiative corrections.Comment: 14 pages, LaTex, no figure

Spin 1 fields in Riemann-Cartan space-times "via" Duffin-Kemmer-Petiau theory

We consider massive spin 1 fields, in Riemann-Cartan space-times, described by Duffin-Kemmer-Petiau theory. We show that this approach induces a coupling between the spin 1 field and the space-time torsion which breaks the usual equivalence with the Proca theory, but that such equivalence is preserved in the context of the Teleparallel Equivalent of General Relativity.Comment: 8 pages, no figures, revtex. Dedicated to Professor Gerhard Wilhelm Bund on the occasion of his 70th birthday. To appear in Gen. Rel. Grav. Equations numbering corrected. References update