FisMat2017 - Submission - View

Abstract's title: Nonperturbative RG treatment of amplitude fluctuations in Berezinskii-Kosterlitz-Thouless phase transitions
Submitting author: Andrea Trombettoni
Affiliation: CNR-IOM DEMOCRITOS and SISSA
Affiliation Address: Via Bonomea, 265 - 34136 Italy
Country: Italy
Oral presentation/Poster (Author's request): Oral presentation
Other authors and affiliations: Nicolo' Defenu (Institut fur Theoretische Physik, Universitat Heidelberg, D-69120 Heidelberg, Germany), Istvan Nandori (University of Debrecen, P.O.Box 105, H-4010 Debrecen, Hungary), Tilmann Enss (Institut fur Theoretische Physik, Universitat Heidelberg, D-69120 Heidelberg, Germany)
Abstract

The study of the Berezinskii-Kosterlitz-Thouless (BKT) transition in two-dimensional |φ|^4 models can be performed in several representations, and the amplitude-phase (AP) Madelung parametrization is a natural way to study the contribution of density fluctuations to non-universal quantities. We show how one can obtain a consistent phase diagram in the AP representation using the functional renormalization group scheme. Constructing the mapping between |φ|^4 and the XY models allows us to treat these models on equal footing. We estimate universal and non-universal quantities of the two models and find good agreement with available Monte Carlo results. The presented approach is flexible enough to treat parameter ranges of experimental relevance.