|
|
1995 | 1996 | 1997 | 1998 | 1999 | 2000 | 2001 | 2002 | 2003 | 2004 | 2005 | 2006 | 2007 | 2008
2009 | 2010 | 2011 | 2012
Publications FYMA
Recherchez une publication dans la base de données FYMA en
entrant des mots clés (auteurs, année, titre, ...) dans la case suivante:
21 publications trouvées pour ' 1997'
UCL-IPT-98-08 : ( ps.gz)
|
Auteurs:
|
Jean-Pierre Antoine, P. Vandergheynst
|
|
Titre:
|
Wavelets on the 2-sphere and related manifolds
|
|
Références:
|
Proc. Workshop on geometrical methods in physics (Bialowiecza, July 1997) - Reports on Mathematical Physics 43 (1999) pp. 13-24
|
|
Résumé:
|
We present a group theoretical derivation of the continuous wavelet transform (CWT) on the 2-sphere, based on the construction of coherent states associated to square integrable group representations. The parameter space X is the product of SO(3) X R^+_*, embedded into the Lorentz group SO(3,1) via the Iwasawa decomposition, and X = SO(3,1)/C. The space L^2(S^2) carries a unitary irreducible representation of SO(3,1) which is square integrable over X, and thus yields the wavelets on S^2 and the associated CWT.
|
UCL-IPT-98-02 : ( ps.gz)
|
Auteurs:
|
D. Delepine
|
|
Titre:
|
A Model for a Dynamically Induced Large $CP$-Violating Phase
|
|
Références:
|
Talk given at the 7th workshop on particles and fields (21-27 November 1997, Morelia Mich., Mexico)
hep-ph/9802349
|
|
Résumé:
|
Assuming a new interaction with a $\theta$ term for the third generation of quarks, a value of $\theta$ different from zero dynamically induces the top-bottom mass splitting and a large $CP$-violating phase.
|
UCL-IPT-97-25 : ( pdf)
|
Auteurs:
|
Radelet-de Grave, Patricia
|
|
Titre:
|
Article : Force (Lat. vis, potentia; All. Krafft; Angl. force, strength; It. forza)
|
|
Références:
|
Dictionnaire Européen des Lumières, PUF, Paris (1997) pp. 471-474
|
|
Résumé:
|
|
UCL-IPT-97-12 : ( ps.gz)
|
Auteurs:
|
Philippe Ruelle
|
|
Titre:
|
Modèles de Mécanique Statistique et Théories Conformes.
|
|
Références:
|
Cours donné à Louvain-la-Neuve durant le second semestre 1997.
|
|
Résumé:
|
Ce cours est une introduction élémentaire aux phénomènes critiques et leur description par des théories de champs conformes. L'accent est très nettement mis sur le cas bidimensionnel, qui permet une illustration particulièrement éclairante des relations entre les deux sujets. Les aspects généraux des théories conformes sont présentés : tenseur énergie-moment, algèbre de Virasoro et ses représentations, identités de Ward et calcul des fonctions de corrélations. Leur application aux modèles de mécanique statistique nécessite d'abord de confirmer la présence (attendue) de la symétrie conforme au point critique de modèles spécifiques. La facon d'y parvenir dans le cas de modèles sur réseaux est expliquée, et très largement détaillée pour le modèle de Ising. La fin est consacrée à une brève discussion de problèmes plus avancés : généralisation de modèles sur réseaux critiques et intégrables, invariance modulaire, perturbations (hors point critique) de théories conformes.
|
UCL-IPT-97-10
|
Auteurs:
|
G. Lopez Castro, G. Toledo Sanchez
|
|
Titre:
|
Effects of the magnetic dipole moment of charged vector mesons in their radiative decay distribution
|
|
Références:
|
Phys. Rev. D56 (1997) pp. 4408-4411
|
|
Résumé:
|
We consider the effects of anomalous magnetic dipole moments of vector mesons in the decay distribution of photons emitted in two-pseudoscalar decays of charged vector mesons. By choosing a kinematical configuration appropriate to isolate these effects from model-dependent and dominant bremsstrahlung contributions, we show that this method can provide a valid alternative for a measurement of the unknown magnetic dipole moments of charged vector mesons.
|
UCL-IPT-97-08 : ( ps.gz)
|
Auteurs:
|
S. Focant, Th. Gallay
|
|
Titre:
|
Existence and Stability of Propagating Fronts for an Autocatalytic Reaction-Diffusion System
|
|
Références:
|
|
|
Résumé:
|
We study a one-dimensional reaction-diffusion system describing an isothermal autocatalytic chemical reaction, involving both a quadratic $A+B\to 2B$ and a cubic $A+2B\to 3B$ autocatalysis. The parameters of this system are the ratio $D=D_B/D_A$ of the diffusion constants of the reactant $A$ and the autocatalyst $B$, and the relative activity $k$ of the cubic reaction. First, for all values of $D>0$ and $k\geq 0$, we prove the existence of a one-parameter family of propagating fronts describing the advance of the reaction. According to the usual terminology, these fronts are of ``pushed'' or ``pulled'' type depending on the size of $k$. In particular, in the quadratic case $k=0$, we recover the results of Billingham and Needham [BN]. Then, if $D$ is close to $1$ and $k$ is sufficiently small, we prove using energy functionals that these propagating fronts are stable against small perturbations in appropriate weighted Sobolev spaces. This extends to our system part of the stability results which are known for the scalar Fisher equation.
|
UCL-IPT-97-07 : ( ps.gz)
|
Auteurs:
|
D. Delépine, Jean-Marc Gérard, R. Gonzalez Felipe, Jacques Weyers
|
|
Titre:
|
A Dynamical Scheme for a Large $CP$-Violating Phase
|
|
Références:
|
Phys. Lett. B 411 (1997) pp. 167-172
hep-ph/9705335
|
|
Résumé:
|
A dynamical scheme where the third generation of quarks plays a distinctive role is implemented. New interactions with a $\theta$ term induce the breaking of the electroweak symmetry and the top-bottom mass splitting. A large $CP$-violating phase naturally follows from the latter.
|
UCL-IPT-97-06
|
Auteurs:
|
Jean-Pierre Antoine, A. Inoue, H. Ogi
|
|
Titre:
|
Standard generalized vectors for partial O*-algebras. II
|
|
Références:
|
Annales de l'Institut H. Poincaré 67 (1997) pp. 223-258
|
|
Résumé:
|
We have shown previously that standard generalized vectors on a partial O*-algebra M provide a way of constructing (generalized) KMS states on M, via the Tomita-Takesaki theory of modular automorphisms. Such states would represent equilibrium states if M is the observable set of some physical system. In this paper we investigate the interplay between the automorphism groups generated by two standard generalized vectors $la$ and $mu$ on M. When M is a self-adjoint partial GW *-algebra, we prove the existence of the Connes cocycle $[Dmu:Dla]$ and we establish a Radon-Nikodym theorem, generalizing that obtained by Pedersen and Takesaki for a von Neumann algebra.
|
UCL-IPT-97-04 : ( ps.gz)
|
Auteurs:
|
H. Gonzalez, S. R. Juarez, P. Kielanowski, G. Lopez Castro
|
|
Titre:
|
Quark mixings as a test of a new symmetry of quark Yukawa couplings
|
|
Références:
|
|
|
Résumé:
|
Based on the hierarchy exhibited by quarks masses at low energies, we assume that Yukawa couplings of up and down quarks are related by $Y_u propto Y_d^2$ at grand unification scales. This ansatz gives rise to a symmetrical CKM matrix at the grand unification (GU) scale. Using three specific models as illustrative examples for the evolution down to low energies, we obtain the entries and {em asymmetries} of the CKM matrix which are in very good agreement with their measured values. This indicates that the small asymmetry of the CKM matrix at low energies may be the effect of the renormalization group evolution only.
|
UCL-IPT-97-03 : ( ps.gz)
|
Auteurs:
|
G. Lopez Castro
|
|
Titre:
|
Conventional and S-matrix approaches to hadronic resonances
|
|
Références:
|
To appear in the Proc. of the Semigroup Symposium of the
XXI International Symposium on Group Theoretical Methods in Physics,
15-20 july 1996m Goslar Germany.
|
|
Résumé:
|
We present a comparison of the conventional and S-matrix
formalisms for the description of hadronic resonances in particle
physics. Using the $
ho^0$ meson resonance as an illustrative
example, we argue that the pole of the S-matrix provides a
definition for resonance properties with suitable physical
properties, namely independent of the theoretical model and
background subtraction from experimental data.
|
UCL-IPT-97-02
|
Auteurs:
|
R. Murenzi, Jean-Pierre Antoine
|
|
Titre:
|
Two-dimensional continuous wavelet transform as linear phase space representation of two-dimensional signals
|
|
Références:
|
Proc. Conf. 'Wavelet Applications IV', SPIE 1997 Symposium on Aerospace/Defense Sensing, Simulation, and Controls (Orlando, April 1997), 3078 (1997) pp. 206-217
|
|
Résumé:
|
|
UCL-IPT-97-01 : ( ps.gz)
|
Auteurs:
|
Jean-Pierre Antoine, R. Murenzi, P. Vandergheynst
|
|
Titre:
|
Directional wavelets revisited: Cauchy wavelets and symmetry detection in patterns
|
|
Références:
|
Applied and Computational Harmonic Analysis 6 (1999) pp. 314-345
|
|
Résumé:
|
We introduce a new class of 2-D directional wavelets, called the Cauchy wavelets, strictly supported in a (narrow) convex cone in spatial frequency space. They have excellent angular selectivity, as shown by a standard calibration test and they have minimal uncertainty. As an application, we present a new technique for determining the symmetries of a given pattern with respect to rotations and dilation.
|
UCL-IPT-96-25 : ( ps.gz)
|
Auteurs:
|
M. Beuthe, R. Gonzalez Felipe, G. Lopez Castro, Jean Pestieau
|
|
Titre:
|
Behaviour of the Absorptive Part of the $W^\pm$ Electromagnetic Vertex
|
|
Références:
|
Nucl. Phys. B498 (1997) pp. 55-67
hep-ph/9611434
|
|
Résumé:
|
The absorptive part of the $W W \gamma$ vertex induced by massive fermion loops is considered for different kinematical configurations. We show that the axial part of this vertex is different from zero not only when massive fermions are involved but also for massless fermion loops, if one of the $W$ boson is space-like and the other is time-like. We also discuss in what sense Low's soft photon theorem is satisfied.
|
UCL-IPT-96-22 : ( ps.gz)
|
Auteurs:
|
Zhen Yun Fang, G. Lopez Castro, J.L. Lucio, Jean Pestieau
|
|
Titre:
|
Effective $SU(2)_L \otimes U(1)$ theory and the Higgs boson mass
|
|
Références:
|
Mod. Phys. Lett. A12 (1997) pp. 1531-1535 + fig.
hep-ph/9612430
|
|
Résumé:
|
We assume the stability of vacuum under radiative corrections in the context of the standard electroweak theory. We find that this theory behaves as a good effective model already at cut off energy scales as low as 0.7 TeV. This stability criterion allows to predict $m_H = 318 \pm 13$ GeV for the Higgs boson mass.
|
UCL-IPT-96-18 : ( ps.gz)
|
Auteurs:
|
Jean Bricmont, A. Kupiainen.
|
|
Titre:
|
Renormalization Group for fronts and patterns.
|
|
Références:
|
Proc. of the 2nd European Congress of Mathematics (Budapest, 1996), 1997
|
|
Résumé:
|
We review recent results on the stability of stationary solutions and of moving fronts in several nonlinear parabolic partial differential equations: the Ginzburg-Landau, Swift-Hohenberg and Cahn-Hillard equations, and chemical reaction-diffusion equations. Some of these results are obtained using the Renormalization Group method.
|
UCL-IPT-96-14 : ( ps.gz)
|
Auteurs:
|
Jean-Pierre Antoine, Ph. Antoine et B. Piraux
|
|
Titre:
|
Wavelets in atomic physics
|
|
Références:
|
Workshop on Spline Functions and the Theory of Wavelets (Montréal 1996)AMS, Providence, 1997 (to appear)
|
|
Résumé:
|
|
UCL-IPT-96-11 : ( ps.gz)
|
Auteurs:
|
Jean-Marc Gérard, I. Mahara
|
|
Titre:
|
The attractor mechanism in the minimal tensor-scalar theory of gravity
|
|
Références:
|
Mod. Phys. Lett. A 12 (1997) pp. 631-637
|
|
Résumé:
|
In a previous letter, we proved that the minimal tensor-scalar theory of gravity with a spatially flat Einstein metris does not generically contain an attractor mechanism towards General Relativity. Hereafter we extend our proof to the case of a spatially curved Einstein metric.
|
UCL-IPT-96-08
|
Auteurs:
|
Radelet-de Grave, Patricia
|
|
Titre:
|
Article : Newton
|
|
Références:
|
Dictionnaire du patrimoine littéraire européen, Patrimoine Littéraire Européen vol. 9, De Boeck Université, Louvain-la-Neuve (1997) pp. 40-45
|
|
Résumé:
|
|
UCL-IPT-96-07
|
Auteurs:
|
Radelet-de Grave, Patricia
|
|
Titre:
|
Réversibilité, irréversibilité, un point de vue historique
|
|
Références:
|
Louvain 77 (1997) 25-39
|
|
Résumé:
|
|
UCL-IPT-96-04 : ( ps.gz)
|
Auteurs:
|
M. Bauer, A. Coste, C. Itzykson, Philippe Ruelle
|
|
Titre:
|
Comments on the links between su(3) modular invariants, simple factors in the jacobian of Fermat curves, and rational triangular billiards.
|
|
Références:
|
J. Geom. Phys. 22, pp. 134-189 (1997)
hep-th/9604104
|
|
Résumé:
|
We examine the proposal made recently that the su(3) modular invariant partition functions could be related to the geometry of the complex Fermat curves. Although a number of coincidences and similarities emerge between them and certain algebraic curves related to triangular billiards, their meaning remains obscure. In an attempt to go beyond the su(3) case, we show that any rational conformal field theory determines canonically a Riemann surface.
|
UCL-IPT-95-15 : ( ps.gz)
|
Auteurs:
|
Jean Bricmont, A. Kupiainen
|
|
Titre:
|
Infinite dimensional SRB measures in Proc. of the International Workshop on Lattice Dynamics, Paris, 1995
|
|
Références:
|
Physica D 103 (1997) 18-33
|
|
Résumé:
|
We review the basic steps leading to the construction of a
Sinai-Ruelle-Bowen (S RB) measure for an infinite lattice of
weakly coupled expanding circle maps, and we show tha t this
measure has exponential decay of space-time correlations. First,
using the Perro n-Frobenius operator, one connects the dynamical
system of coupled maps on a d-dimensional lattice to an
equilibrium statistical mechanical model on a lattice of dimension
$d+1$. This lattice model is, for weakly coupled maps, in a
high-temperature phase, and we use a general, but very elementary,
method to prove exponential decay of correlations at high
temperatures.
|
|
