## Van der Waals-Zeeman Colloquium

Tuesday, 14 Oct 2008, 16:00h

**The Saga of of 3D Critical Wetting with Short-Ranged Forces**

**Prof. Andrew O. Parry**

Dept. Mathematics,
Imperial College of Science, Technology and Medicine, London

A long standing problem in Soft-Matter Physics is the nature of the wetting transition in three dimensional systems with short-ranged forces. Some 25 yrs ago, renormalization group studies, by Brezin, Halperin and Leibler, based on the standard interfacial model of wetting, famously predicted non--universal critical exponents for the transition. However these exotic predictions have never been seen in Ising model simulation studies and also experiments, which have only ever revealed simple mean-field-like exponents. This problem was further compounded by theoretical work from Fisher and Jin who tried to improve on the original calculations and concluded paradoxically that the critical wetting transition couldnt not exist at all!

We show how these and other problems in wetting can be consistently resoloved using a Non-Local interfacial Hamiltonian. This has an elegant diagrammatic formulation and contains new physics that was missing in the original analyses of Brezin et al and Fisher. In particular we show how an additional diverging coherence length, arises from two-body interfacial interactions, and serves to dampen interacial fluctuations. This avoids the Fisher-Jin paradox and leads to a smaller effective value of the wetting parameter controlling the non-universality, in quantitative agreement with the Ising model simulations.