Séminaire de groupe
|Off-equilibrium scaling driven by time-dependent external fields in O(N) vector models|
|jeudi 13 octobre 2016 , 10h25|
|Salle de séminaire du groupe de Physique Statistique|
This work concerns the study of the off-equilibrium behaviours arising near the critical point in O(N) vector models coupled to time-dependent external fields. The emergence of these off-equilibrium phenomena is related to the divergence of the relaxation times of the system and the consequent impossibility to adapt itself to the external variations, even if these occur very slow. The dynamics can be described in terms of new length and time scales and present universal features: very close to the transition and in the limit of slow time-variations of the external fields, the system exhibits universal scaling behaviours which can be expressed through the equilibrium critical exponents. The analysis of such phenomena is made in the limit of large N which allows analytical computations. The dynamics of the system is chosen such that satisfies a purely dissipative Langevin equation. The external parameters are slowly varied and in such a way that they might drive the system across the critical point.