title: Topology and phase transitions: paradigmatic evidence
abstract: We report upon the numerical computation of the Euler characteristic chi (a topologic invariant) of the equipotential hypersurfaces Sigma(v) of the configuration space of the two-dimensional lattice varphi(4) model. The pattern chi(Sigma(v)) versus v (potential energy) reveals that a major topology change in the family Sigma(v)(vinR) is at the origin of the phase transition in the model considered. The direct evidence given here-of the relevance of topology for phase transitions-is obtained through a general method that can be applied to any other model.
authors.affiliation: Dipartimento di Fisica, Universita di Firenze, Largo E. Fermi 2, 50125 Firenze, Italy and Istituto Nazionale di Fisica della Materia, Unita di Firenze, Firenze, Italy.
authors.initials: R
authors.lastname: Franzosi
authors.initials: M
authors.lastname: Pettini
authors.initials: L
authors.lastname: Spinelli