Browsing by Author "Moreno, Gregorio"

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    Convergence of the Law of the Environment Seen by the Particle for Directed Polymers in Random Media in the L 2 Region
    (2010) Moreno, Gregorio
    We consider the model of directed polymers in an i.i.d. Gaussian or bounded environment (Imbrie and Spencer in J. Stat. Phys. 52(3/4), 609-626, 1988; Carmona and Hu in Probab. Theory Relat. Fields 124(3), 431-457, 2002; Comets et al. in Adv. Stud. Pure Math. 39, 115-142, 2004) in the L (2) region. We prove the convergence of the law of the environment seen by the particle.
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    Directed polymers on hierarchical lattices with site disorder
    (ELSEVIER, 2010) Lacoin, Hubert; Moreno, Gregorio
    We study a polymer model oil hierarchical lattices very close to the one introduced and studied in Derrida and Griffith (1989) [19] and Cook and Derrida (1989) [16]. For this model, we prove the existence of free energy and derive the necessary and Sufficient condition for which very strong disorder holds for all beta, and give some accurate results oil the behavior of the free energy at high temperature. We obtain these results by using a combination of fractional moment method and change of Measure over the environment to obtain all upper bound, and a second moment method to get a lower bound. We also get lower bounds oil the fluctuation exponent of log Z(n), and Study the infinite polymer measure in the weak disorder phase. (C) 2009 Elsevier B.V. All rights reserved.
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    On absolutely continuous spectrum for one-channel unitary operators
    (2024) Bourget, Olivier; Moreno, Gregorio; Sadel, Christian; Taarabt, Amal
    In this paper, we develop the radial transfer matrix formalism for unitary one-channel operators. This generalizes previous formalisms for CMV matrices and scattering zippers. We establish an analog of Carmona's formula and deduce criteria for absolutely continuous spectrum which we apply to random Hilbert Schmidt perturbations of periodic scattering zippers.