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

Writing a Children Story Book: Rosaline the Beautiful Rose

This project brings up an issue about beauty concept in a form of children's story book with fantasy genre for children at the ages of 12 to 15. The story shows some beauty concepts in the world through the main character's fantastical adventure. The main character of this story is a beautiful little girl who always wants to be the most beautiful girl wherever she is. The main character thinks that beauty will help her to gain attention from everybody, and she loves to be the center of attention. The beauty concept obsesses her very much because of the beauty hegemony that appears in her society. Then through the magical journey in the four countries, the main character learns that beauty is not something as simple as the way she knows about it before. The main character experiences the false consciousness of beauty concepts from the society conditioning. In the end of the story, the main character then realizes that inner beauty is far more important than physical beauty

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

Analisa Pengaruh Brand Identity Terhadap Pembentukan Brand Image Dengan Promotion Mix Dan Brand Awareness Sebagai Variabel Intervening Pada Merek Speedo

Penelitian ini dilakukan untuk mengetahui seberapa dampak variabel brand identity terhadap pembentukan brand image pada merek Speedo. Penelitian menggunakan variabel penghubung promotion mix dan brand awareness. Bahasan utama dari penelitian adalah seberapa signifikan dampak dari brand identity terhadap brand image secara langsung maupun melalui variabel intervening promotion mix dan brand awareness pada merek Speedo. Penelitian berjenis kuantitatif dengan penyebaran kuisioner kepada 150 pelau olahraga renang di Surabaya menggunakan format kuisioner skala likert. Penelitian dilakukan dengan teknik analisa partial least square (PLS)

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

Conformal invariance of massless Duffin-Kemmer-Petiau theory in Riemannian space-times

We investigate the conformal invariance of massless Duffin-Kemmer-Petiau theory coupled to riemannian space-times. We show that, as usual, in the minimal coupling procedure only the spin 1 sector of the theory -which corresponds to the electromagnetic field- is conformally invariant. We show also that the conformal invariance of the spin 0 sector can be naturally achieved by introducing a compensating term in the lagrangian. Such a procedure -besides not modifying the spin 1 sector- leads to the well-known conformal coupling between the scalar curvature and the massless Klein-Gordon-Fock field. Going beyond the riemannian spacetimes, we briefly discuss the effects of a nonvanishing torsion in the scalar case.Comment: 8 pages, no figures. Major changes in contend and results. To appear in Class.Quant.Gra

Relativistic Tunneling Through Two Successive Barriers

We study the relativistic quantum mechanical problem of a Dirac particle tunneling through two successive electrostatic barriers. Our aim is to study the emergence of the so-called \emph{Generalized Hartman Effect}, an effect observed in the context of nonrelativistic tunneling as well as in its electromagnetic counterparts, and which is often associated with the possibility of superluminal velocities in the tunneling process. We discuss the behavior of both the phase (or group) tunneling time and the dwell time, and show that in the limit of opaque barriers the relativistic theory also allows the emergence of the Generalized Hartman Effect. We compare our results with the nonrelativistic ones and discuss their interpretation.Comment: 7 pages, 3 figures. Revised version, with a new appendix added. Slightly changes in the styles and captions of Figures 1 and 2. To appear in Physical Review