R. Friedberg et Yk. Yu, REPLICA MODEL AT LOW INTEGER-N FOR DIRECTED POLYMERS IN (1+1) DIMENSIONS, Physical review. E, Statistical physics, plasmas, fluids, and related interdisciplinary topics, 49(5), 1994, pp. 4157-4166
We study directed polymers in a (1 + 1)-dimensional disordered environ
ment with discrete space and time. For fixed L (polymer length) and r
(disorder parameter) the quantity (Z(n)) has two crossovers in n, one
related to the radius of convergence of the cumulant expansion for lnZ
and one related to the discreteness of the lattice. The existence of
the first crossover [at n1(L)-->0 as L --> infinity] weakens the custo
mary argument relating the behavior of the cumulants of lnZ to the n d
ependence of E(n) = -lim(L-->infinity)ln[Z(n)]/L. The second crossover
[at n2(r)--> infinity as r --> 0] is explored here by computing E2 an
alytically and E3 numerically to high accuracy for several values of r
in two models.