title: Universal frozen spectra after time-dependent symmetry restoring phase transitions.
abstract: For a general O(N) model, we study the time-dependent phase transition from a state with broken symmetry <φ> ≠ 0 to the symmetric phase <φ> = 0. During this non-equilibrium process, the primordial quantum (or thermal) fluctuations of the initial Goldstone modes are frozen and result in a deviation from the final ground (or thermal) state. For very slow transitions, we find that these fluctuations display a universal scaling behaviour. Their spectra are universal functions of a single parameter, which combines the initial frequency of the Goldstone modes and the sweep rate. As a result, the final two-point function [φa(r)φb(r')] is not exponentially suppressed at large distances Δr = r - r' (as it would be in the ground state) but decays polynomially in 1/|Δr|. Finally, we exemplify this universal behaviour for the transition from the super-fluid phase to the Mott state in the Bose-Hubbard model.
authors.affiliation: Fakultät für Physik, Universität Duisburg-Essen, D-47057 Duisburg, Germany.
authors.forename: Friedemann
authors.initials: F
authors.lastname: Queisser
authors.forename: Patrick
authors.initials: P
authors.lastname: Navez
authors.forename: Ralf
authors.initials: R
authors.lastname: Schützhold
mesh_terms: D000465:Algorithms; D003198:Computer Simulation; D005615:Freezing; D008956:Models, Chemical; D008958:Models, Molecular; D044367:Phase Transition; D013816:Thermodynamics