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UID:0-847@lptms.universite-paris-saclay.fr
DTSTART;TZID=Europe/Paris:20221206T110000
DTEND;TZID=Europe/Paris:20221206T120000
DTSTAMP:20221201T084738Z
URL:http://www.lptms.universite-paris-saclay.fr/seminars/seminaire-du-lptm
 s-elisabeth-agoritsas-epfl/
SUMMARY:Séminaire du LPTMS : Elisabeth Agoritsas (EPFL and University of G
 eneva) - Salle des séminaires du FAST et du LPTMS\, bâtiment Pascal n°5
 30 - 6 Déc 22 11:00
DESCRIPTION:Towards a unifying (mean-field) picture of driven disordered sy
 stems\n Elisabeth Agoritsas (EPFL and University of Geneva)\n\nHybrid: ons
 ite seminar + zoom.\n\nRegister in advance for this meeting:\nhttps://cnrs
 .zoom.us/meeting/register/tJcrd-yvrjgsH9NhSH2WxoMgM-npghTmncWx \nAfter reg
 istering\, you will receive a confirmation email containing information ab
 out joining the meeting.\n\nDisorder is ubiquitous in physical systems\, a
 nd can radically alter their physical properties compared to their ‘pure
 ’ counterparts. For instance\, amorphous materials such as emulsions\, f
 oams\, metallic glasses or biological tissues are all structurally disorde
 red\, and this has key implications for their rheological\, mechanical or 
 transport properties. Nevertheless\, theoretical descriptions of such ‘d
 riven' amorphous materials remain challenging\, despite decades of extensi
 ve analytical and computational studies. The difficulties pertain to the i
 nterplay of competing sources of stochasticity\, and to the resulting out-
 of-equilibrium nature of these systems.\nA standard model for amorphous ma
 terials\, which allows one to focus on the key role of their structural (p
 ositional) disorder\, is provided by dense many-body systems of pairwise i
 nteracting particles. Here I will introduce an exact Dynamical Mean-Field 
 Theory (DMFT) for these many-body systems\, derived in the limit of infini
 te spatial dimension. In this framework\, the many-body Langevin dynamics 
 of the whole problem can be exactly reduced to a single scalar effective s
 tochastic process\, and dynamical observables such as pressure or shear st
 ress can be computed for arbitrary driving protocols. Using this DMFT\, we
  were in particular able to establish a direct equivalence between a globa
 l forcing (external shear) and a random local forcing (reminiscent of acti
 ve matter)\, upon a simple rescaling of the control parameter (the accumul
 ated strain). In this framework\, global shear is thus simply a special ca
 se of a much broader family of local forcing that can be explored by tunin
 g its spatial correlations. Our predictions were moreover found to be in r
 emarkably good agreement with two-dimensional numerical simulations. These
  results hint at a unifying framework for establishing rigorous analogies\
 , at the mean-field level\, between different families of driven disordere
 d systems\, such as sheared granular materials and active matter\, or mach
 ine-learning algorithms.
CATEGORIES:seminars
LOCATION:Salle des séminaires du FAST et du LPTMS\, bâtiment Pascal n°53
 0\, rue André Riviere\, Orsay\, 91405\, France
X-APPLE-STRUCTURED-LOCATION;VALUE=URI;X-ADDRESS=rue André Riviere\, Orsay\
 , 91405\, France;X-APPLE-RADIUS=100;X-TITLE=Salle des séminaires du FAST 
 et du LPTMS\, bâtiment Pascal n°530:geo:0,0
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DTSTART:20221030T020000
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