title: Two-parameter scaling of correlation functions near continuous phase transitions.
abstract: We discuss the order parameter correlation function in the vicinity of continuous phase transitions using a two-parameter scaling form G(k)=kc(-2)g(kxi,k/kc), where k is the wave vector and xi is the correlation length, and the interaction-dependent nonuniversal momentum scale kc remains finite at the critical fixed point. The correlation function describes the entire critical regime and captures the classical to critical crossover. One-parameter scaling is recovered only in the limit k/kc-->0. We present an approximate calculation of g(x,y) for the Ising universality class using the functional renormalization group.
authors.affiliation: Institut für Theoretische Physik, Universität Frankfurt, Max-von-Laue Strasse 1, 60438 Frankfurt, Germany.
authors.forename: Nils
authors.initials: N
authors.lastname: Hasselmann
authors.forename: Andreas
authors.initials: A
authors.lastname: Sinner
authors.forename: Peter
authors.initials: P
authors.lastname: Kopietz