Disorder Induced Depinning Transition
Terence Hwa and Thomas Nattermann
Abstract
       
The competition in the pinning of a directed polymer by a columnar
pin and a background of random point impurities is investigated
systematically using the renormalization group method. With the
aid of the mapping to the noisy-Burgers' equation and the use
of the mode-coupling method, the directed polymer is shown to
be marginally localized to an arbitrary weak columnar pin in 1+1
dimensions. This weak localization effect is attributed to the
existence of large scale, nearly degenerate optimal paths of the
randomly pinned directed polymer. The critical behavior of the
depinning transition above 1 + 1 dimensions is obtained via epsilon-expansion.
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