2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/221244For a much-studied model of random copolymer at a selective interface we prove that the slope of the critical curve in the weak-disorder limit is strictly smaller than 1, which is the value given by the annealed inequality. The proof is based on a coarse-graining procedure, combined with upper bounds on the fractional moments of the partition function.15 pages, 1 figureProbabilitytext