title: Directed polymer in random media with a defect.
abstract: We investigate a directed polymer in random media with an attractive defect at the center of the one-dimensional substrate. Without the defect, the end to end distance Deltax of the polymer follows Deltax approximately t;{1/z} , with z=3/2 and t is the polymer length. When the defect strength is weak, its contribution to Deltax is negligible. If > or =_{c} , then Deltax approaches a finite value Deltax_{sat}() in large t limit, and we find Deltax_{sat} approximately (-_{c});{-delta} , with delta approximately 3.0 . Such transition is related to the queuing phenomena of the asymmetric simple exclusion process. The polymer energy fluctuation is also discussed.
authors.affiliation: Department of Physics, Soongsil University, Seoul 156-743, Korea.
authors.forename: Jae Hwan
authors.initials: JH
authors.lastname: Lee
authors.forename: Jin Min
authors.initials: JM
authors.lastname: Kim