Authors : A. Giuliani and V. Mastropietro

Title: Anomalous critical exponents in the anisotropic Ashkin-Teller model.

Abstract: We perform a rigorous computation of the specific heat of the Ashkin-Teller model in the case of small interaction and we explain how the universality-nonuniversality crossover is realized when the isotropic limit is reached. We prove that, even in the region where universality for the specific heat holds, anomalous critical exponents appear: for instance we predict the existence of a previously unknown anomalous exponent, continuously varying with the strength of the interaction, describing how the difference between the critical temperatures rescales with the anisotropy parameter.

Keywords: Classical spin models, Critical exponents, Universality classes.

Alessandro Giuliani
Dipartimento di Fisica
Universita` di Roma ``La Sapienza"
Piazz.le Aldo Moro 5, 00185 Roma, Italy
e-mail: alessandro.giuliani@roma1.infn.it

Vieri Mastropietro
Dipartimento di Matematica
Universita` di Roma ``Tor Vergata"
Via della Ricerca Scientifica, Roma, Italy
e-mail: mastropi@mat.uniroma2.it