Depinning of a polymer in a multi-interface medium

Abstract

In this paper we consider a model which describes a polymer chain interacting with an infinity of equi-spaced linear interfaces. The distance between two consecutive interfaces is denoted by $T = T_N$ and is allowed to grow with the size $N$ of the polymer. When the polymer receives a positive reward for touching the interfaces, its asymptotic behavior has been derived in Caravenna and Petrelis (2009), showing that a transition occurs when $T_N \approx \log N$. In the present paper, we deal with the so-called depinning case, i.e., the polymer is repelled rather than attracted by the interfaces. Using techniques from renewal theory, we determine the scaling behavior of the model for large $N$ as a function of $\{T_N\}_{N}$, showing that two transitions occur, when $T_N \approx N^{1/3}$ and when $T_N \approx \sqrt{N}$ respectively.