Browsing by Author "Ikeda, Atsushi"
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Item Open Access Dimensional study of the caging order parameter at the glass transition.(Proc Natl Acad Sci U S A, 2012-08-28) Charbonneau, Patrick; Ikeda, Atsushi; Parisi, Giorgio; Zamponi, FrancescoThe glass problem is notoriously hard and controversial. Even at the mean-field level, little is agreed upon regarding why a fluid becomes sluggish while exhibiting but unremarkable structural changes. It is clear, however, that the process involves self-caging, which provides an order parameter for the transition. It is also broadly assumed that this cage should have a gaussian shape in the mean-field limit. Here we show that this ansatz does not hold. By performing simulations as a function of spatial dimension d, we find the cage to keep a nontrivial form. Quantitative mean-field descriptions of the glass transition, such as mode-coupling theory, density functional theory, and replica theory, all miss this crucial element. Although the mean-field random first-order transition scenario of the glass transition is qualitatively supported here and non-mean-field corrections are found to remain small on decreasing d, reconsideration of its implementation is needed for it to result in a coherent description of experimental observations.Item Open Access Glass transition and random close packing above three dimensions.(Phys Rev Lett, 2011-10-28) Charbonneau, Patrick; Ikeda, Atsushi; Parisi, Giorgio; Zamponi, FrancescoMotivated by a recently identified severe discrepancy between a static and a dynamic theory of glasses, we numerically investigate the behavior of dense hard spheres in spatial dimensions 3 to 12. Our results are consistent with the static replica theory, but disagree with the dynamic mode-coupling theory, indicating that key ingredients of high-dimensional physics are missing from the latter. We also obtain numerical estimates of the random close packing density, which provides new insights into the mathematical problem of packing spheres in large dimensions.