Centre de Physique Théorique


Mardi 7 mai 2019

Hot topics in Modern Cosmology Spontaneous Workshop XIII

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Spontaneous Workshop (SW) brings together specialists on recent insights in Particle Physics, Astrophysics and Cosmology. The aim is to stimulate debate on common topics in views of providing us with innovating ideas on emerging problems. The workshop’s organization is based on an optimal number of concise presentations and with enough space for discussions in order to favour interactions among participants. Postdocs and PhD students are encouraged to attend.

11h00 – 12h00, Amphi 5 du CPT

Order and symmetry-breaking in the fluctuations of nonequilibrium diffusive systems.

Nicolás Tizón Escamilla

Abstract : Understanding the statistics of macroscopic fluctuations in nonequilibrium systems remains as one of the major challenges of theoretical physics. This interest is rooted in the prominent role that fluctuations play in equilibrium, where their statistics is directly linked to the relevant thermodynamic potentials. Similarly, it is nowadays expected that a deeper understanding of nonequilibrium fluctuations will pave the way to a sound definition of nonequilibrium potentials. In recent years, a macroscopic fluctuation theory (MFT) has been formulated to study dynamic fluctuations in systems far from equilibrium, offering detailed predictions for the large deviation functions associated to the distribution of fluctuations which acts as a marginal of the nonequilibrium analog of thermodynamic potential. MFT also determines the optimal path to a fluctuation shedding light on e.g. the reasons behind the enhanced probability of rare events out of equilibrium, the possibility of dynamic phase transitions and new symmetries.

In this talk, I will focus on the emergence of dynamic phase transitions at a fluctuating level, studying the current statistics of an archetypal two-dimensional (2d) driven diffusive system, the weakly asymmetric simple exclusion process (WASEP), characterizing its properties using MFT. The complex interplay among the external field, anisotropy and currents in 2d leads to a rich phase diagram, with different symmetry-broken fluctuation phases. Order in the form of coherent jammed states emerges, revealing a deep connection between rare events and self-organized structures which enhance their probability, an observation of broad implications.