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

Scattering and bound states of spin-0 particles in a nonminimal vector double-step potential

The problem of spin-0 particles subject to a nonminimal vector double-step potential is explored in the context of the Duffin-Kemmer-Petiau theory. Surprisingly, one can never have an incident wave totally reflected and the transmission amplitude has complex poles corresponding to bound states. The interesting special case of bosons embedded in a sign potential with its unique bound-state solution is analyzed as a limiting case.Comment: 1 figur

Absence of Klein's paradox for massive bosons coupled by nonminimal vector interactions

A few properties of the nonminimal vector interactions in the Duffin-Kemmer-Petiau theory are revised. In particular, it is shown that the space component of the nonminimal vector interaction plays a peremptory role for confining bosons whereas its time component contributes to the leakage. Scattering in a square step potential with proper boundary conditions is used to show that Klein's paradox does not manifest in the case of a nonminimal vector coupling

Relativistic corrections for two- and three-body flux tube model

We generalize the relativistic flux tube model for arbitrary two- or three-body systems. The spin-independent and spin-dependent contributions of the flux tube to the total Hamiltonian are computed in perturbation. In particular, we show that the spin-dependent part exhibits a universal spin-orbit form: It does not depend on the nature of the confined particles. The general equations we present, being well-defined for light particles, can thus be applied to usual as well as exotic hadrons such as hybrid mesons and glueballs.Comment: 10 pages; v2 accepted for publication (minor changes

On the Non-relativistic Limit of Linear Wave Equations for Zero and Unity Spin Particles

The non-relativistic limit of the linear wave equation for zero and unity spin bosons of mass $m$ in the Duffin-Kemmer-Petiau representation is investigated by means of a unitary transformation, analogous to the Foldy-Wouthuysen canonical transformation for a relativistic electron. The interacting case is also analyzed, by considering a power series expansion of the transformed Hamiltonian, thus demonstrating that all features of particle dynamics can be recovered if corrections of order $1/m^{2}$ are taken into account through a recursive iteration procedure.Comment: 10 page

Splitting the Dirac equation: the case of longitudinal potentials

Recently, we have demonstrated that some subsolutions of the free Duffin-Kemmer-Petiau and the Dirac equations obey the same Dirac equation with some built-in projection operators. In the present paper we study the Dirac equation in the interacting case. It is demonstrated that the Dirac equation in longitudinal external fields can be also splitted into two covariant subequations.Comment: LaTeX, 8 pages, two references adde

Exact Solutions of the Duffin Kemmer Petiau Equation for the Deformed Hulthen Potential

Using the Nikiforov Uvarov method, an application of the relativistic Duffin Kemmer Petiau equation in the presence of a deformed Hulthen potential is presented for spin zero particles. We derived the first order coupled differential radial equations which enable the energy eigenvalues as well as the full wavefunctions to be evaluated by using of the Nikiforov Uvarov method that can be written in terms of the hypergeometric polynomials.Comment: 8 pages. submitted to Physica Script

De la découverte des substances psychoactives en milieu festif techno à l’usage maîtrisé

Le milieu festif techno forme un contexte propice à l’usage de substances psychoactives, et en particulier de drogues de synthèse. De la découverte de ces fêtes à un investissement plus large dans l’univers culturel, les parcours de consommation sont multiples et dépendent d’un ensemble complexe de déterminants. Cette étude a porté sur l’évolution des parcours de consommation auprès d’une population professionnalisée, parfois dans le milieu festif techno, ayant commencé sa consommation depuis 6 à 15 ans. Les données ont été analysées par le biais d’une analyse de contenu. Les résultats de cette enquête ont visé à : décrire les spécificités des consommations liées au milieu (usage banalisé, polyconsommation, sociabilité de l’usage), esquisser des parcours de consommation possibles à partir de trois typologies d’usage (festif, récréatif et dopant), analyser la façon dont les modalités de contrôle des consommations s’intègrent dans ces parcours pour parvenir à un usage relativement maîtrisé. Dans une démarche de santé publique, ces résultats permettent d’envisager quelques pistes possibles de sensibilisation à la maîtrise des consommations dans un milieu fortement concerné par l’usage de drogues de synthèse.The techno scene sets up an environment conducive to the use of psychoactive substances, especially synthetic drugs. From the discovery of these parties to a broader investment in the cultural universe, there is a range of consumption careers that depend on a complex set of factors. This study focused on the changing path of consumption in a professionalized population, sometimes in the techno scene, who have been consuming for 6 to 15 years. The data was analyzed through a content analysis. The results of this survey seek to describe specific consumption related to the environment (trite use, poly-consumption, sociability of use), as well as outlining possible careers of consumption based on three types of use (festive, recreational and doping), and analyzing how the mechanisms of control integrate these pathways to achieve a relatively controlled use. In a public health approach, these results allow consideration of possible avenues to raise awareness about the control of consumption in an environment strongly concerned by the use of synthetic drugs.El medio festivo tecno constituye un contexto propicio para el uso de sustancias psicoactivas, en particular para las drogas sintéticas. Desde el descubrimiento de estas fiestas hasta una participación más amplia en el universo cultural, los recorridos de consumo son múltiples y dependen de un conjunto complejo de determinantes. Este estudio se refiere a la evolución de los recorridos de consumo de una población profesionalizada, a veces en el medio festivo tecno, que comenzó su consumo entre 6 a 15 años atrás. Los datos se analizaron por medio de un análisis de contenido. Los resultados de esta investigación apuntaron a lo siguiente: describir las especificidades del consumo relacionado con el medio (uso banalizado, policonsumo, sociabilidad del uso); esbozar los recorridos posibles de consumo a partir de tres tipologías de uso (festivo, recreativo y adictivo) y analizar de qué manera las modalidades de control del consumo se integran en estos recorridos para poder lograr un uso relativamente controlado. En una perspectiva de salud pública, estos resultados permiten considerar algunos caminos posibles para la sensibilización sobre el control del consumo en un medio fuertemente afectado por el uso de drogas sintéticas

Zitterbewegung of Klein-Gordon particles and its simulation by classical systems

The Klein-Gordon equation is used to calculate the Zitterbewegung (ZB, trembling motion) of spin-zero particles in absence of fields and in the presence of an external magnetic field. Both Hamiltonian and wave formalisms are employed to describe ZB and their results are compared. It is demonstrated that, if one uses wave packets to represent particles, the ZB motion has a decaying behavior. It is also shown that the trembling motion is caused by an interference of two sub-packets composed of positive and negative energy states which propagate with different velocities. In the presence of a magnetic field the quantization of energy spectrum results in many interband frequencies contributing to ZB oscillations and the motion follows a collapse-revival pattern. In the limit of non-relativistic velocities the interband ZB components vanish and the motion is reduced to cyclotron oscillations. The exact dynamics of a charged Klein-Gordon particle in the presence of a magnetic field is described on an operator level. The trembling motion of a KG particle in absence of fields is simulated using a classical model proposed by Morse and Feshbach -- it is shown that a variance of a Gaussian wave packet exhibits ZB oscillations.Comment: 16 pages and 7 figure

First Order Actions: a New View

We analyse systems described by first order actions using the Hamilton-Jacobi (HJ) formalism for singular systems. In this study we verify that generalized brackets appear in a natural way in HJ approach, showing us the existence of a symplectic structure in the phase spaces of this formalism