Bulletin of the American Physical Society
APS March Meeting 2021
Volume 66, Number 1
Monday–Friday, March 15–19, 2021; Virtual; Time Zone: Central Daylight Time, USA
Session E09: Universal Properties at the Jamming Transition: Mean Field Approaches to Glasses and Granular MaterialsInvited Live
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Sponsoring Units: DSOFT Chair: James Sethna, Cornell University; Danilo Liarte, Cornell University |
Tuesday, March 16, 2021 8:00AM - 8:36AM Live |
E09.00001: Jamming with Tunable Roughness Invited Speaker: Carolina Brito The jamming transition is a key property of granular materials, including sand and dense suspensions. Although this transition has been extensively studied, there are still open questions in the generic situation of nonspherical particles or in presence of friction. In this talk I will present some advances in the understanding of the scaling properties of the non-spherical particles at the jamming point and a model where friction can be explored by tunning particles roughness. |
Tuesday, March 16, 2021 8:36AM - 9:12AM Live |
E09.00002: Critical jammed phase of linear soft spheres Invited Speaker: Silvio Franz Soft spheres interacting with a linear ramp potential, appear as a class of finite dimensional systems that self-organize into a new, critical, marginally stable state. When overcompressed beyond the jamming point, fall in an amorphous solid phase which is critical, mechanically marginally stable and share many features with the jamming point itself. In the whole phase, the relevant local minima of the potential energy landscape display an isostatic contact network of perfectly touching spheres whose statistics is controlled by an infinite length scale. Excitations around such energy minima are non-linear, system spanning, and characterized by a set of non-trivial critical exponents. We perform numerical simulations to measure their values and show that, while they coincide, within numerical precision, with the critical exponents appearing at jamming. |
Tuesday, March 16, 2021 9:12AM - 9:48AM Live |
E09.00003: Emergence of elasticity In amorphous solids: a gauge theory Invited Speaker: Bulbul Chakraborty Amorphous solids that appear in strongly non-equilibrium processes that do not allow thermalization include gels, jammed grains, and even biological tissues. The mechanical response of such disordered solids are not described by the conventional paradigm of broken symmetry that defines crystalline elasticity. In contrast, the response of such athermal solids are governed by local conditions of mechanical equilibrium, i.e., force and torque balance of its constituents. In a recent paper [1], we showed that these constraints have the mathematical structure of a generalized electromagnetism. In particular, the electrostatic limit of this theory successfully captures the anisotropic elasticity of amorphous solids and provides a natural explanation for the presence of stress heterogeneities visulaized as "force chains" in granular media. The emergence of elasticity from local mechanical constraints offers a new paradigm for systems with no broken symmetry, analogous to emergent gauge theories of quantum spin liquids. Specifically, our U(1) rank-2 symmetric tensor gauge theory of elasticity translates to the electromagnetism of fractonic phases of matter with the stress mapped to electric displacement and forces to vector charges. I will present results from experiments and numerical simulations that corroborate our theoretical results broadly, present experimental evidence indicating that force chains in granular media are sub-dimensional excitations of amorphous elasticity similar to fractons, and address the long-standing problem of stress transmission in "sandpiles" using the gauge-theory framework. |
Tuesday, March 16, 2021 9:48AM - 10:24AM Live |
E09.00004: Elasticity of disordered elastic networks: Jamming, rigidity percolation and beyond Invited Speaker: Danilo Liarte Elastic networks provide a simple and reliable framework to study rigidity transitions in a variety of disordered systems, from amorphous solids and confluent cell tissues to traditional rigidity percolation and jamming [1]. Here I will present results of a new theory [2] of the jamming transition that is both analytically tractable and that clarifies the relation between jamming and rigidity percolation. Our theory yields a faithful description of jamming, including spatial and temporal dependences in the elastic and fluid phases and crossover behavior. I will then derive scaling forms for singular dynamical responses and extract diverging length scales, critical exponents, invariant scaling combinations and explicit formulas for universal scaling functions. Finally, I will make contact with microscopy experiments of colloidal suspensions of silica particles in glycerin/water, and published measurements featuring the unusual charge response of strange metals [3]. |
Tuesday, March 16, 2021 10:24AM - 11:00AM Live |
E09.00005: Criticality and Scaling around the Jamming Transition Invited Speaker: Carl Goodrich The jamming transition of athermal soft spheres provides a starting point for understanding the mechanical and thermal properties of disordered solids. Despite being a highly idealized model, this non-equilibrium critical point exhibits very rich physics, including power-law scaling, multiple diverging length scales, and finite size effects. I will show how our understanding of these behaviors can be unified through a Widow-like scaling ansatz. In addition to predicting novel scaling behaviors, this ansatz provides a framework for connecting the physics of the jamming transition to more realistic systems by, for example, including temperature, friction, or long-ranged attractions. I will also outline some new techniques for probing both the critical and non-critical behavior in these more generalized frameworks. |
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