Statut  Confirmé 
Série  FORUMENS 
Domaines  condmat.statmech 
Date  Mercredi 23 Mars 2022 
Heure  14:30 
Institut  LPENS 
Salle  Salle Djebar (29 rue d'Ulm) 
Nom de l'orateur  Agoritsas 
Prenom de l'orateur  Elisabeth 
Addresse email de l'orateur  
Institution de l'orateur  EPFL 
Titre  Role of structural disorder in dense particle systems: from amorphous materials to active matter 
Résumé  Amorphous materials are ubiquitous around us: emulsions as mayonnaise, foams, sandpiles or biological tissues are all structurally disordered, and this has key implications for their response to an external deformation. Nevertheless, theoretical descriptions of such ‘driven' amorphous materials remain challenging, despite of decades of extensive analytical and computational studies. The difficulties pertain to the interplay of competing sources of stochasticity, and to the resulting outofequilibrium nature of these systems. A standard model for amorphous materials, which allows to focus on the key role of their structural (positional) disorder, is provided by dense manybody systems of pairwise interacting particles. In infinite dimension, these systems even provide exact analytical benchmarks for quasistatic features of amorphous materials, such as their response under quasistatic shear. Furthermore, there has been recently many attempts to relate the important corpus of known results for such ‘passive' amorphous materials, and their counterparts in active matter such as confluent biological tissues. One strong motivation is that the interplay between activity and structural disorder might in turn be related to biological functionalities. Here I will discuss recent results on the exact meanfield dynamics of these manybody systems, that we have derived in the limit of infinite spatial dimension, for different driving protocols. We were in particular able to establish a direct equivalence between a global forcing (external shear) and a random local forcing (reminiscent of active matter), upon a simple rescaling of the control parameter (the accumulated strain). In this framework, global shear is thus simply a special case of a much broader family of local forcing, that can be explored by tuning its spatial correlations. Our predictions were moreover found to be in remarkably good agreement with twodimensional numerical simulations. These results hint at a unifying framework for establishing rigorous analogies, at the meanfield level, between different families driven disordered systems, such as sheared granular materials and active matter. [1] "Outofequilibrium dynamical equations of infinitedimensional particle systems I. The isotropic case", E. Agoritsas, T. Maimbourg and F. Zamponi, J. Phys. A: Math. and Theor. 52, 144002 (2019). [2] "Outofequilibrium dynamical equations of infinitedimensional particle systems. II. The anisotropic case under shear strain", E. Agoritsas, T. Maimbourg and F. Zamponi, J. Phys. A: Math. and Theor. 52, 334001 (2019). [3] "A direct link between active matter and sheared granular systems », P. Morse*, S. Roy*, E. Agoritsas*, E. Stanifer, E. I. Corwin, and M. L. Manning, PNAS 118, e2019909118 (2021). [4] "Meanfield dynamics of infinitedimensional particle systems: global shear versus random local forcing », E. Agoritsas, J. Stat. Mech. 2021, 033501 (2021) 
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Commentaires  for the zoom link, please write to misaki.ozawa@phys.ens.fr 
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