LPTMS Publications


Archives :

    Publications de l'année 2003 :

  • Alternative solutions to diluted p-spin models and XORSAT problems

    Marc Mézard 1, Federico Ricci-Tersenghi 2, Riccardo Zecchina 3

    Journal of Statistical Physics 111 (2003) 505-533

    We derive analytical solutions for p-spin models with finite connectivity at zero temperature. These models are the statistical mechanics equivalent of p-XORSAT problems in theoretical computer science. We give a full characterization of the phase diagram: location of the phase transitions (static and dynamic), together with a description of the clustering phenomenon taking place in configurational space. We use two alternative methods: the cavity approach and a rigorous derivation.

    • 1. Laboratoire de Physique Théorique et Modèles Statistiques (LPTMS), CNRS : UMR8626 – Université Paris XI - Paris Sud
    • 2. Dipartimento di Fisica and INFM, Università degli studi di Roma I - La Sapienza
    • 3. International Center for Theoretical Physics, International Center for Theoretical Physics

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  • Asymptotic behaviour of multiple scattering on infinite number of parallel half-plane

    Bogomolny, E., Schmit, C.

    Nonlinearity 16 (2003) 2035-2059

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  • Brownian Motion in wedges, last passage time and the second arc-sine law

    Alain Comtet 1, 2, Jean Desbois 1

    Journal of Physics A 36 (2003) L255-L262

    We consider a planar Brownian motion starting from $O$ at time $t=0$ and stopped at $t=1$ and a set $F= \{OI_i ; i=1,2,..., n\}$ of $n$ semi-infinite straight lines emanating from $O$. Denoting by $g$ the last time when $F$ is reached by the Brownian motion, we compute the probability law of $g$. In particular, we show that, for a symmetric $F$ and even $n$ values, this law can be expressed as a sum of $\arcsin $ or $(\arcsin)^2 $ functions. The original result of Levy is recovered as the special case $n=2$. A relation with the problem of reaction-diffusion of a set of three particles in one dimension is discussed.

    • 1. Laboratoire de Physique Théorique et Modèles Statistiques (LPTMS), CNRS : UMR8626 – Université Paris XI - Paris Sud
    • 2. IHP, Institut Henri Poincaré

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  • Charge and current distribution in graphs

    Christophe Texier 1, 2, Pascal Degiovanni 3

    Journal of Physics A 36 (2003) 12425-12452

    We consider graphs made of one-dimensional wires connected at vertices, and on which may live a scalar potential. We are interested in a scattering situation where such a network is connected to infinite leads. We study the correlations of the charge in such graphs out of equilibrium, as well as the distribution of the currents in the wires, inside the graph. These quantities are related to the scattering matrix of the graph. We discuss the case where the graph is weakly connected to the wires.

    • 1. Laboratoire de Physique Théorique et Modèles Statistiques (LPTMS), CNRS : UMR8626 – Université Paris XI - Paris Sud
    • 2. Laboratoire de Physique des Solides (LPS), CNRS : UMR8502 – Université Paris XI - Paris Sud
    • 3. Laboratoire de Physique de l'ENS Lyon (Phys-ENS), CNRS : UMR5672 – École Normale Supérieure - Lyon

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  • Clustering and thermodynamics in the lattice-gas model

    Campi, X., Krivine, H., Krivine, J.

    Physica A 320 (2003) 41-50

  • Dense loops, supersymmetry, and Goldstone phases in two dimensions

    Jesper-Lykke Jacobsen 1, Nicholas Read 2, Hubert Saleur 3

    Physical Review Letters 90 (2003) 090601

    Loop models in two dimensions can be related to O(N) models. The low-temperature dense-loops phase of such a model, or of its reformulation using a supergroup as symmetry, can have a Goldstone broken-symmetry phase for N<2. We argue that this phase is generic for -2< N <2 when crossings of loops are allowed, and distinct from the model of non-crossing dense loops first studied by Nienhuis [Phys. Rev. Lett. 49, 1062 (1982)]. Our arguments are supported by our numerical results, and by a lattice model solved exactly by Martins et al. [Phys. Rev. Lett. 81, 504 (1998)].

    • 1. Laboratoire de Physique Théorique et Modèles Statistiques (LPTMS), CNRS : UMR8626 – Université Paris XI - Paris Sud
    • 2. Department of Physics, Yale University
    • 3. Department of Physics and Astronomy, University of Southern California

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  • Dynamique vitreuse de l’espace des phases à l’espace réel

    Bertin, E.

    . Thèse-CEA Saclay (2003)

  • Electron’s selftrapping at the field-effet junction of a molecular crystal

    Kirova, N., Bussac, M.-N.

    Physical Review B 68 (2003) 235312

  • Energy exponents and corrections to scaling in Ising spin glasses

    Jean-Philippe Bouchaud 1, Florent Krzakala 2, 3, Olivier C. Martin 1, 2

    Physical Review B 68 (2003) 224404

    We study the probability distribution P(E) of the ground state energy E in various Ising spin glasses. In most models, P(E) seems to become Gaussian with a variance growing as the system's volume V. Exceptions include the Sherrington-Kirkpatrick model (where the variance grows more slowly, perhaps as the square root of the volume), and mean field diluted spin glasses having +/-J couplings. We also find that the corrections to the extensive part of the disorder averaged energy grow as a power of the system size; for finite dimensional lattices, this exponent is equal, within numerical precision, to the domain-wall exponent theta_DW. We also show how a systematic expansion of theta_DW in powers of exp(-d) can be obtained for Migdal-Kadanoff lattices. Some physical arguments are given to rationalize our findings.

    • 1. Service de physique de l'état condensé (SPEC), CNRS : URA2464 – CEA : DSM/IRAMIS
    • 2. Laboratoire de Physique Théorique et Modèles Statistiques (LPTMS), CNRS : UMR8626 – Université Paris XI - Paris Sud
    • 3. Dipartimento di Fisica, INFM – SMC – Università degli studi di Roma I - La Sapienza

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  • Exercices de mathématiques pour physiciens

    Krivine, H.

    Ed. Cassini (2003)

  • Ferroelectric Mott-Hubbard phase in organic conductors

    Serguei Brazovskii 1, Pierre Monceau 2, F. Ya Nad 3

    Synthetic Metals 137 (2003) 1331-1333

    We present key issues of related phenomenons of the Ferroelectricity and the Charge Disproportionation in organic metals. In (TMTTF_2X the dielectric susceptibility demonstrates clear cases of the ferroelectric and anti-ferroelectric phase transitions. Both the susceptibility and the conductivity prove independence and occasional coexistence of 'structurless' ferroelectric transitions and usual 'anionic' ones. Their sequence gives access to physics of three types of solitons emerging upon cooling via several steps of symmetry breaking. The theory invokes a concept of the Combined Mott-Hubbard State which focuses upon weak processes of electronic Umklapp scattering coming from both the build-in nonequivalence of bonds and the spontaneous one of sites. We propose that the charge ordering in its form of the ferroelectricity exists hiddenly even in the Se subfamily (TMTSF)_2X, giving rise to the unexplained yet low frequency optical peak and the enhanced pseudogap.

    • 1. Laboratoire de Physique Théorique et Modèles Statistiques (LPTMS), CNRS : UMR8626 – Université Paris XI - Paris Sud
    • 2. Centre de Recherches sur les Très Basses Températures (CRTBT), CNRS : UPR5001 – Université Joseph Fourier - Grenoble I – Institut National Polytechnique de Grenoble (INPG)
    • 3. Institute of Radioelectronics, Russian Academy of Sciences

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  • Interlayer tunneling spectroscopy of the charge density wave (CDW) state in NbSe3

    Latyshev, Yu-I., Monceau, P., Sinchenko, A.-A., Bulaevskii, L.-N., Brazovskii, S., Kawae, T., Yamashitz, T.

    Journal of Physics A: Math. Gen. 36 (2003) 9323

  • Large geometric phases and non-elementary monopoles

    Leboeuf, P., Mouchet, A.

    Journal of Physics A: Math. Gen. 36 (2003) 2847-2856

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  • Local excitations of a spin glass in a magnetic field

    Julien Lamarcq 1, Jean-Philippe Bouchaud 1, Olivier C. Martin 2

    Physical Review B 68 (2003) 012404

    We study the minimum energy clusters (MEC) above the ground state for the 3-d Edwards-Anderson Ising spin glass in a magnetic field. For fields B below 0.4, we find that the field has almost no effect on the excitations that we can probe, of volume V <= 64. As found previously for B=0, their energies decrease with V, and their magnetization remains very small (even slightly negative). For larger fields, both the MEC energy and magnetization grow with V, as expected in a paramagnetic phase. However, all results appear to scale as BV (instead of the B sqrt(V) expected from droplet arguments), suggesting that the spin glass phase is destroyed by any small field. Finally, the geometry of the MEC is completely insensitive to the field, giving further credence that they are lattice animals, in the presence or the absence of a field.

    • 1. Service de physique de l'état condensé (SPEC), CNRS : URA2464 – CEA : DSM/IRAMIS
    • 2. Laboratoire de Physique Théorique et Modèles Statistiques (LPTMS), CNRS : UMR8626 – Université Paris XI - Paris Sud

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  • Local Friedel sum rule on graphs

    Christophe Texier 1, 2, Markus Buttiker 3

    Physical Review B 67 (2003) 245410

    We consider graphs made of one-dimensional wires connected at vertices and on which may live a scalar potential. We are interested in a scattering situation where the graph is connected to infinite leads. We investigate relations between the scattering matrix and the continuous part of the local density of states, the injectivities, emissivities and partial local density of states. Those latter quantities can be obtained by attaching an extra lead at the point of interest and by investigating the transport in the limit of zero transmission into the additional lead. In addition to the continuous part related to the scattering states, the spectrum of graphs may present a discrete part related to states that remain uncoupled to the external leads. The theory is illustrated with the help of a few simple examples.

    • 1. Laboratoire de Physique Théorique et Modèles Statistiques (LPTMS), CNRS : UMR8626 – Université Paris XI - Paris Sud
    • 2. Laboratoire de Physique des Solides (LPS), CNRS : UMR8502 – Université Paris XI - Paris Sud
    • 3. Département de Physique Théorique, University of Geneva

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  • Loop models from Coulomb gases and supersymmetry: Goldstone phases in two-dimensional polymers. Dans Gazeau J-P. et al (eds), Physical and mathematical aspects of symmetries: proceedings of the 24th international colloquium on group theoretical methods in physics

    Jacobsen, J.L.

    Institute of Physics Conference Series 173 (2003) 323-326

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