Mathematical Physics Seminar

I will present results on the critical behavior of directed polymer models interacting with a defect line, in presence of quenched disorder. These models show a localization-delocalization phase transition. Our main result is that the transition in presence of disorder is always smooth, while in the pure case it can be of first order. This change in the nature of the transition is in agreement with prediction based on the Harris criterion. We also obtain finite-size estimates on the order parameter in a "critical window" around the critical point.