Auxiliary fields and the flux tube model

It is possible to eliminate exactly all the auxiliary fields (einbein fields) appearing in the rotating string Hamiltonian to obtain the classical equations of motion of the relativistic flux tube model. A clear interpretation can then be done for the characteristic variables of the rotating string model.Comment: No table, No figur

Covariant oscillator quark model for glueballs and baryons

An analytic resolution of the covariant oscillator quark model for a three-body system is presented. Our harmonic potential is a general quadratic potential which can simulate both a $\delta$-shape configuration or a simplified Y-configuration where the junction is located at the center of mass. The mass formulas obtained are used to compute glueball and baryon spectra. We show that the agreement with lattice and experimental data is correct if the Casimir scaling hypothesis is assumed. It is also argued that our model is compatible with pomeron and odderon approaches.Comment: 2 figures; content changed and enlarge

Lagrange mesh, relativistic flux tube, and rotating string

The Lagrange mesh method is a very accurate and simple procedure to compute eigenvalues and eigenfunctions of nonrelativistic and semirelativistic Hamiltonians. We show here that it can be used successfully to solve the equations of both the relativistic flux tube model and the rotating string model, in the symmetric case. Verifications of the convergence of the method are given.Comment: 2 figure

Philosophie et efficience du droit civil

Le thème « La loi du plus fort, les droits du plus faible », appliqué au droit civil, appelle quatre tempéraments. Premièrement, la division de la société contemporaine en forts et en faibles n'est pas évidente. Deuxièmement, le Code civil du Québec de 1991 n'a pas été fait par les forts contre les faibles. Troisièmement, le droit civil n'a pas pour mission essentielle de protéger les faibles contre les forts. Quatrièmement, enfin, pour déterminer si le droit civil protège « suffisamment » les faibles contre les forts, il est nécessaire de réfléchir sur sa philosophie et sur son efficience. La philosophie du droit civil consiste à créer un équilibre socialement acceptable entre les intérêts légitimes en conflit d'une pluralité de personnes dont il doit régir les rapports. Cet équilibre doit être révisé périodiquement pour tenir compte de l'évolution sociale. Le défi a été relevé avec succès par ceux et celles qui ont contribué à l'élaboration du Code civil du Québec de 1991. L'efficience du droit civil laisse à désirer. Le coût et les délais de la justice engendrent un déséquilibre. La partie économiquement faible est désavantagée lorsqu’elle cherche à obtenir la sanction de son droit par voie judiciaire contre une partie qui a les moyens de payer et intérêt à prolonger indûment le procès. Les correctifs qui s'imposent font appel à la volonté et à la créativité de tous les intervenants.In Civil Law, the notion of « might is right vs. the rights of weaker parties » calls for four distinctions. First, any division of society along lines of force and frailty is far from obvious. Secondly, the Civil Code of Québec of 1991 was not crafted by strong parties over weaker ones. Third, the essentiel mission of Civil Law is not to protect the weak from the strong. Fourth and finally, to determine if Civil Law adequately protects weaker parties from strong ones, some thought must be devoted to its philosophy and effectiveness. The philosophy underpinning Civil Law consists in creating a socially acceptable equilibrium between conflicting legitimate interests among a plurality of persons whose relations it must govern. This equilibrium must be reviewed periodically to take social evolution into account. This challenge has been successfully met by those who contributed to the Civil Code of Québec of 1991. The effectiveness of Civil Law is incomplete. The costs and delays inherent in the legal system create imbalance. Hence economically weaker parties are put at a disadvantage when seeking justice through the courts and faced with opponents who are less limited by resources and time to pursue their interests. Remedies to such situations largely depend upon the will and creativity of all involved

Charm and bottom baryon masses in the combined 1/Nc1/N_c and 1/mQ1/m_Q expansion versus quark model

A good agreement between a flux tube-based quark model of light baryons (strange and nonstrange) and the $1/N_c$ expansion mass formula has been found in previous studies. In the present work a larger connection is established between the quark model and the $1/N_c$ and $1/m_Q$ expansion method by extending the previous procedure to baryons made of one heavy and two light quarks. The compatibility between both approaches is shown to hold in this sector too

Dynamic modeling of Terahertz Quantum cascade lasers

In this paper, the influence of the simplifications made in the four-equation-based set of rate equations describing the dynamic behavior of a Quantum Cascade Laser (QCL) is studied. Numerical simulations based on the set of four rate equations has been developed, enabling the theoretical study of the influence of different parameters on the direct modulation response of the laser. These equations have been then linearized in order to deduce a set of state system equations, which was written in a matrix formalism. Finally, an approximate second order transfer function has been derived with the linearized dependence of its times constant

On the effect of rotation on magnetohydrodynamic turbulence at high magnetic Reynolds number

This article is focused on the dynamics of a rotating electrically conducting fluid in a turbulent state. As inside the Earth's core or in various industrial processes, a flow is altered by the presence of both background rotation and a large scale magnetic field. In this context, we present a set of 3D direct numerical simulations of incompressible decaying turbulence. We focus on parameters similar to the ones encountered in geophysical and astrophysical flows, so that the Rossby number is small, the interaction parameter is large, but the Elsasser number, defining the ratio between Coriolis and Lorentz forces, is about unity. These simulations allow to quantify the effect of rotation and thus inertial waves on the growth of magnetic fluctuations due to Alfv\'en waves. Rotation prevents the occurrence of equipartition between kinetic and magnetic energies, with a reduction of magnetic energy at decreasing Elsasser number {\Lambda}. It also causes a decrease of energy transfer mediated by cubic correlations. In terms of flow structure, a decrease of {\Lambda} corresponds to an increase in the misalignment of velocity and magnetic field.Comment: 18 pages, 12 figure

Light baryon masses in different large-NcN_c limits

We investigate the behavior of light baryon masses in three inequivalent large-$N_c$ limits: 't~Hooft, QCD$_{{\rm AS}}$ and Corrigan-Ramond. Our framework is a constituent quark model with relativistic-type kinetic energy, stringlike confinement and one-gluon-exchange term, thus leading to well-defined results even for massless quarks. We analytically prove that the light baryon masses scale as $N_c$, $N_c^2$ and $1$ in the 't~Hooft, QCD$_{{\rm AS}}$ and Corrigan-Ramond limits respectively. Those results confirm previous ones obtained by using either diagrammatic methods or constituent approaches, mostly valid for heavy quarks.Comment: Final version to appear in Phys. Rev.