Original article at: http://www.math.washington.edu/~ejpecp/ECP/viewarticle.php?id=2245

Localization for (1+1)-dimensional pinning models with (∇ + Δ)-interaction

Francesco Caravenna, Università degli Studi di Padova
Martin Borecki, TU Berlin

Abstract

We study the localization/delocalization phase transition in a class of directed models for a homogeneous linear chain attracted to a defect line. The self-interaction of the chain is of mixed gradient and Laplacian kind, whereas the attraction to the defect line is of δ-pinning type, with strength ε ≥ 0. It is known that, when the self-interaction is purely Laplacian, such models undergo a non-trivial phase transition: to localize the chain at the defect line, the reward ε must be greater than a strictly positive critical threshold εc > 0. On the other hand, when the self-interaction is purely gradient, it is known that the transition is trivial: an arbitrarily small reward ε > 0 is sufficient to localize the chain at the defect line (εc = 0). In this note we show that in the mixed gradient and Laplacian case, under minimal assumptions on the interaction potentials, the transition is always trivial, that is εc = 0.

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Original article at: http://www.math.washington.edu/~ejpecp/ECP/viewarticle.php?id=2245