642 research outputs found
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
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 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 are taken into
account through a recursive iteration procedure.Comment: 10 page
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
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
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
De la découverte des substances psychoactives en milieu festif techno à l’usage maîtrisé
Le milieu festif techno forme un contexte propice Ă l’usage de substances psychoactives, et en particulier de drogues de synthèse. De la dĂ©couverte de ces fĂŞtes Ă un investissement plus large dans l’univers culturel, les parcours de consommation sont multiples et dĂ©pendent d’un ensemble complexe de dĂ©terminants. Cette Ă©tude a portĂ© sur l’évolution des parcours de consommation auprès d’une population professionnalisĂ©e, parfois dans le milieu festif techno, ayant commencĂ© sa consommation depuis 6 Ă 15 ans. Les donnĂ©es ont Ă©tĂ© analysĂ©es par le biais d’une analyse de contenu. Les rĂ©sultats de cette enquĂŞte ont visĂ© Ă Â : dĂ©crire les spĂ©cificitĂ©s des consommations liĂ©es au milieu (usage banalisĂ©, polyconsommation, sociabilitĂ© de l’usage), esquisser des parcours de consommation possibles Ă partir de trois typologies d’usage (festif, rĂ©crĂ©atif et dopant), analyser la façon dont les modalitĂ©s de contrĂ´le des consommations s’intègrent dans ces parcours pour parvenir Ă un usage relativement maĂ®trisĂ©. Dans une dĂ©marche de santĂ© publique, ces rĂ©sultats permettent d’envisager quelques pistes possibles de sensibilisation Ă la maĂ®trise des consommations dans un milieu fortement concernĂ© 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 sintĂ©ticas. Desde el descubrimiento de estas fiestas hasta una participaciĂłn más amplia en el universo cultural, los recorridos de consumo son mĂşltiples y dependen de un conjunto complejo de determinantes. Este estudio se refiere a la evoluciĂłn de los recorridos de consumo de una poblaciĂłn profesionalizada, a veces en el medio festivo tecno, que comenzĂł su consumo entre 6 a 15 años atrás. Los datos se analizaron por medio de un análisis de contenido. Los resultados de esta investigaciĂłn 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 tipologĂas de uso (festivo, recreativo y adictivo) y analizar de quĂ© manera las modalidades de control del consumo se integran en estos recorridos para poder lograr un uso relativamente controlado. En una perspectiva de salud pĂşblica, estos resultados permiten considerar algunos caminos posibles para la sensibilizaciĂłn sobre el control del consumo en un medio fuertemente afectado por el uso de drogas sintĂ©ticas
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
Technomedia
Le livre Technomedia a reçu le soutien de la Sacem. Ce livre replace la Tecktonik et les danses électro dans l’univers des cultures jeunes et révèle les attentes de la jeunesse dans une société médiatique. L’été 2007, la Tecktonik a provoqué un véritable effet de mode auprès des adolescents et préadolescents. Des jeunes danseurs aux vêtements colorés et aux coiffures stylisées déferlent sur les écrans de télévision, les radios et les magazines, dansent dans les rues, les discothèques et les c..
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