Semi-flexible polymers with attractive interactions

The delocalization and unbinding transitions of two semi-flexible polymers which experience attractive interactions are studied by a variety of theoretical methods. In two-dimensional systems, one has to distinguish four different universality classes for the interaction potentials. In particular, the delocalization transitions from a potential well and the unbinding transitions from such a well in the presence of a hard wall exhibit distinct critical behavior governed by different critical exponents. In three-dimensional systems! we predict first-order transitions with a jump in the energy density but with critical or self-similar fluctuations leading to distribution functions with poser law tails. The predicted critical behavior is confirmed numerically by transfer matrix calculations in two dimensions and by Monte Carlo simulations in three dimensions. This behavior should be accessible to experiments on biopolymers such as actin filaments or microtubuli.