Grupo de Análisis Matemático Aplicado (GAMA)
http://hdl.handle.net/10016/5857
2014-04-17T21:46:04ZDemixing behavior in two-dimensional mixtures of anisotropic hard bodies
http://hdl.handle.net/10016/7012
Demixing behavior in two-dimensional mixtures of anisotropic hard bodies
Martínez-Ratón, Yuri; Velasco, Enrique; Mederos, Luis
Scaled particle theory for a binary mixture of hard discorectangles and for a binary mixture of hard rectangles is used to predict possible liquid-crystal demixing scenarios in two dimensions. Through a bifurcation analysis from the isotropic phase, it is shown that isotropic-nematic demixing is possible in two-dimensional liquid-crystal mixtures composed of hard convex bodies. This bifurcation analysis is tested against exact calculations of the phase diagrams in the framework of the restricted-orientation two-dimensional model (Zwanzig model). Phase diagrams of a binary mixture of hard discorectangles are calculated through the parametrization of the orientational distribution functions. The results show not only isotropic-nematic, but also nematic-nematic demixing ending in a critical point, as well as an isotropic-nematic-nematic triple point for a mixture of hard disks and hard discorectangles.
11 pages, 9 figures.-- PACS nrs.: 64.70.Md, 64.75.+g, 61.20.Gy.-- ArXiv pre-print available at: http://arxiv.org/abs/cond-mat/0509213
2005-09-01T00:00:00ZRecent trends in orthogonal polynomials and their applications
http://hdl.handle.net/10016/6935
Recent trends in orthogonal polynomials and their applications
Marcellán, Francisco; Arvesú, Jorge
In this contribution we summarize some new directions in the theory of orthogonal polynomials. In particular, we emphasize three kinds of orthogonality conditions which
have attracted the interest of researchers from the last decade to the present time. The
connection with operator theory, potential theory and numerical analysis will be shown.
29 pages, 1 figure.-- MSC2000 codes: 42C05, 33C45.-- Contributed to: XVII CEDYA: Congress on differential equations and applications/VII CMA: Congress on applied mathematics (Salamanca, Spain, Sep 24-28, 2001).; MR#: MR1873645 (2002i:42031); Zbl#: Zbl 1026.42025
2001-01-01T00:00:00ZOn free nets over Minkowski space
http://hdl.handle.net/10016/6853
On free nets over Minkowski space
Baumgärtel, Hellmut; Jurke, Matthias; Lledó, Fernando
Using standard results on CAR- and CCR-theory and on representation theory of the Poincaré group a direct way to construct nets of local C*-algebras satisfying Haag-Kastler's axioms is given. No explicite use of any field operator or of any concrete representation of the algebra is made. The nets are associated to models of mass m ≥ 0 and arbitrary spin or helicity. Finally, Fock states satisfying the spectrality condition are specified.
27 pages, no figures.-- MSC2000 codes: 46L60, 81T05.; MR#: MR1369988 (96m:81132); Zbl#: Zbl 0883.46040
1995-02-01T00:00:00ZSuperselection structures for C*-algebras with nontrivial center
http://hdl.handle.net/10016/6852
Superselection structures for C*-algebras with nontrivial center
Baumgärtel, Hellmut; Lledó, Fernando
We present and prove some results within the framework of Hilbert C*-systems $\{{\cal F},{\cal G}\}$ with a compact group ${\cal G}$. We assume that the fixed point algebra ${\cal A}\subset{\cal F}$ of ${\cal G}$ has a nontrivial center ${\cal Z}$ and its relative commutant w.r.t. ${\cal F}$ coincides with ${\cal Z}$, i.e., we have ${\cal A}'\cap{\cal F}= {\cal Z}\supset\bbfC\text{\bf 1}$. In this context, we propose a generalization of the notion of an irreducible endomorphism and study the behaviour of such irreducibles w.r.t. ${\cal Z}$. Finally, we give several characterizations of the stabilizer of ${\cal A}$.
35 pages, no figures.-- MSC2000 codes: 46L05, 46L60.; MR#: MR1475657 (99g:46097); Zbl#: Zbl 0893.46046
1997-01-01T00:00:00Z