Monday, December 12

• 08:30 - 08:50   Coffee & Croissants
• 08:50 - 09:00   Welcome Speech
• 09:00 - 10:00 P. Harrowell

  The origin of persistent stress shear in supercooled liquids
  
  The rapid growth of the shear viscosity of a liquid as it is cooled is a direct consequence of the increasing persistence of shear stress fluctuations. Using simulations, we show that the slow relaxation of stress is directly attributable to long wavelength stress trapped in the inherent structures. This picture provides an explicit approach to understanding the coupling between local particle movements and the associated stress fluctuations and also the connection between viscous response and the continuous analogue of the jamming transition in the inherent structures of the model liquids.
  

• 10:00 - 10:30 C. Brun

  Nonlinear susceptibility in glassy glycerol: an ebreaknce for the increase of the range of spatial correlations with the age of the system.
  
  C. Brun^a, D. L'Hôte^a, F. Ladieu^a, G. Biroli^b, J.-P. Bouchaud^c
  
  a SPEC (CNRS URA 2464), DSM/IRAMIS CEA Saclay, Bat.772, F-91191 Gif-sur-Yvette, France
  b Institut de Physique Théorique, CEA, (CNRS URA 2306), 91191 Gif-sur-Yvette, France
  c Science & Finance, Capital Fund Management, 6, Bd. Haussmann, 75009 Paris, France
  
  Below its glass transition temperature Tg, a supercooled liquid falls, by definition, out of equilibrium. Its dynamics becomes non stationary and exhibits aging, which means that its effective relaxation time ?? depends on the age of the system ta, i.e. on the time elapsed since Tg was crossed. As a result most of its properties evolve with time, which is of paramount importance for many materials applications. However, the lack of equilibrium makes this aging regime very difficult to handle from a fundamental point of view, and a full understanding of aging is still lacking.
  We have carried out the first-of-the-kind measurements of the nonlinear susceptibility ?3 in the aging regime. This was motivated by the prediction of Bouchaud and Biroli stating that ?3 is directly proportional to the number Ncorr of dynamically correlated molecules [1]. Above Tg, this prediction has been successfully tested in recent experiments [2,3,4], allowing to draw the temperature dependence of Ncorr in the supercooled glycerol. Below Tg, we have measured the ta dependence of ?3 for several frequencies?for glycerol. A scaling analysis, where the ??(ta) dependence is drawn from the aging of the linear susceptibility ?1, shows that a unique Ncorr(ta) dependence rationalizes the aging behavior of ?3 at all the measured frequencies. At a temperature T=0.96Tg where the aging lasts 100ks before reaching equilibrium, we find that Ncorr increases by typically 10% when ta increases from 1ks to 100ks. This corresponds to an increase of Ncorr by typically a few molecules during the observable aging regime -- note that most of the increase is expected to take place before 1ks.
  
  [1] J.-P. Bouchaud, G. Biroli, Phys. Rev. B 72, 064204 (2005).
  [2] C. Crauste-Thibierge, C. Brun, F. Ladieu, D. L'Hôte, G. Biroli, and J.-P.Bouchaud, Phys. Rev. Lett. 104, 165703 (2010).
  [3] C. Brun, F. Ladieu, D. L'Hôte, M. Tarzia, G. Biroli, and J.-P.Bouchaud, Phys. Rev. B. 84, 104204 (2011).
  [4] C. Thibierge, D. L'Hote, F. Ladieu, R. Tourbot, Rev. Scient. Instrum.79, 103905 (2008).
  

• 10:30 - 11:00   Coffee break

• 11:00 - 12:00 A. Montanari

  Sharp Thresholds in Statistical Learning
  
  Sharp thresholds are ubiquitous high-dimensional combinatorial structures. The oldest example is probably the sudden emergence of the giant component in random graphs, first discovered by Erdos an Renyi. More recently, threshold phenomena have started to play an important role in some statistical learning and statistical signal processing problems, in part because of the interest in 'compressed sensing'. The basic setting is one in which a large number of noisy observations of a high-dimensional object are made. As the ratio of the number of observations to the number of `hidden dimensions' crosses a threshold, our ability to reconstruct the object increases dramatically. I will discuss several examples of this phenomenon, and some algorithmic and mathematical ideas that allow to characterize these threshold phenomena. [based on joint work with Mohsen Bayati, David Donoho, Iain Johnstone, Arian Maleki]
  

• 12:00 - 12:30 F. Krzakala

  Many properties associated in the present literature with the dynamics of structural glass formers (faster than exponential growth of the relaxation time, dynamical heterogeneities, point-to-set correlations, mode-coupling versus Vogel-Fulcher relaxation etc.) are already present in a much simpler situation, namely the melting of an ordered phase beyond a ?rst order phase transition point. This suggest that the melting problem has many common feature with the dynamics in liquids when the temperature is lowered. Interstingly, one can show that the correspondence between the two problems holds exactly for models on the Nishimori line, and in any dimensions. In fact, the glassy dynamics can be exactly mapped to a rst-order melting behavior where the dynamical or mode-coupling transition corresponds to the spinodal point, while the Kauzmann transition corresponds to the first order ferromagnetic phase transition point. This suggests a new approach towards a theory of the glass transition as a "stationary" melting process.
  

• 12:30 - 13:00 F. Zamponi

  Glass transition and random close packing in 3+ dimensions Glass transition and random close packing in 3+ dimensions
  
  Authors: Patrick Charbonneau, Atsushi Ikeda, Giorgio Parisi, Francesco Zamponi
  
  Abstract: Motivated by a recently identified severe discrepancy between a static (replica theory) and a dynamic (mode-coupling theory) mean-field theory of glasses, we numerically investigate the behavior of dense hard spheres in spatial dimensions 3 to 12. The trend upon increasing dimension is consistent with replica theory, but disagree with mode-coupling theory, indicating that some important ingredients are missing from the latter. Identifying the problem should lead to a consistent formulation of Random First Order Transition theory for hard spheres in the large dimension mean field limit. As a byproduct, we obtain numerical estimates of the random close packing density in dimension up to 12, which provides new insights into the mathematical problem of packing spheres in large dimension.
  

• 13:30 - 14:30   Lunch
• 14:30 - 15:30 S. Glotzer

  Hard particle fluids and their crystals and glasses
  
  The hard sphere model is among the simplest systems exhibiting crystallization and vitrification due solely to entropic forces. Hard particles of non-spherical shape also form crystals and glasses, and a rich diversity of structures - including rotator (plastic) crystals, network glasses, complex crystals and quasicrystals - are now predicted to form in Monte Carlo simulations. We present our new findings based on the simulation of nearly 200 hard particle shapes, and show how the "directionality" of entropic forces can be used to rationalize what types of structures, if any, form via thermodynamic self assembly, and under what conditions glasses form instead. We also compare structures formed via self-assembly with densest packings.
  

• 15:30 - 16:00 P. Royall

  Sticky spheres have a continuous glass transition and a discontinuous gel transition Sticky spheres have a continuous glass transition and a discontinuous gel transition
  
  We identify dynamic and structural signatures which distinguish gels and glasses in a colloidal model system of hard and sticky spheres. Since gels are identified with arrested spinodal decomposition, this presents a thermodynamic basis upon which to identify gelation, and distinguish it from vitrification. We base our findings on confocal microscopy experiments of and confirm these with molecular dynamics simulations.
  
  In the gel transition, upon crossing the spinodal line at a packing fraction 0.35, we find a sharp change in the structural relaxation time, and enter an ageing regime. Simultaneously, our novel structural analysis shows a large and sudden change in local structure. This is confirmed in simulation where the pressure turns negative upon gelation. Thus gelation is ?first-order-like?. By contrast, the approach to the glass is continuous, and not associated with any phase transition. We show this in hard spheres, where both relaxation time and the local structural change.
  
  In ?sticky spheres?, since gelation occurs at the spinodal line, it appears ?first-order-like?, while on the timescales we access, the glass transition is continuous. Arrested states lying in the metastable gas-liquid regime gels and those outside glasses. Significantly, the gel extends to packing fractions of at least 0.59.
  

• 16:00 - 16:30   Coffee break

• 16:30 - 17:00 S. Ciliberto

  Heat flux fluctautions during the sol-gel transition. Heat flux fluctautions during the sol-gel transition.
  
  We measure the energy fluctuations of a Brownian particle confined by an optical trap in an aging gelatin after a very fast quench (less than 1 ms). The strong nonequilibrium fluctuations due to the assemblage of the gel are interpreted, within the framework of fluctuation theorem, as a heat flux from the particle towards the bath.We derive an analytical expression of the heat probability distribution, which fits the experimental data and satisfies a fluctuation relation similar to that of a system in contact with two baths at different temperatures.
  
  PRL 106, 200602 (2011)
  

• 17:00 - 17:30 H. Tanaka

  Recently it has been revealed that when approaching the glass transition temperature Tg, liquid dynamics not only drastically slow, but also become progressively more heterogeneous. We recently found that the heterogeneous dynamics is a result of critical-like fluctuations of static structural order. However, this structural ordering accompanies little density change over a long range, which explains why it has not been detected by the static structure factor so far. Static structural order is associated with the lower free energy configuration and in some cases characterized by bond orienational order, whose symmetry is linked to that of the equilibrium crystal. We also confirmed that the growing lengthscale of structural order is essential for the slowing down of dynamics and the nonlocal cooperativity in particle motion. The roles of such glassy structure order in crystal nucleation, the dynamics of a spatially confined supercooled liquid, and the ageing dynamics of glass will also be discussed.
  
  Related references:
  H. Tanaka et al., Nature Mater. 9, 324 (2010).
  K. Watanabe, T. Kawasaki and H. Tanaka, Nature Mater. 10, 512 (2011).
  

Tuesday, December 13

• 09:00 - 10:00 G. Parisi

   

• 12:00 - 12:30 R. Jack

  We have previously shown that methods based on large deviations of the dynamical activity in model supercooled fluids can be used to prepare inactive dynamical phases where structural relaxation is completely arrested [1]. Here we examine the properties of these inactive phases in more detail, illustrating their relation to metastable glassy states. In the inactive states, the `fast' vibrational degrees of freedom in the liquid are maintained at thermal equilibrium by contact with a heat bath, while the `slow' structural degrees of freedom are located in deep valleys of the energy landscape. The glassy states that we prepare are very stable to thermal fluctuations and their vibrational fluctuations indicate that they are also more mechanically rigid than low-temperature equilibrated configurations. If time permits, we will also show preliminary results for the degree of amorphous ordering in these states.
  
  Relevant preprint: arXiv:1109.2715
  
  [1] See eg, Hedges et al, Science 323, 1309 (2009).
  

• 10:30 - 11:00   Coffee break

• 11:00 - 12:00 R. Zecchina

   

• 12:00 - 12:30 C. Cammarota

  Ideal Glass Transitions by Random Pinning We study the effect of freezing the positions of a fraction $c$ of particles from an equilibrium configuration of a supercooled liquid at a temperature $T$. We show that within the Random First-Order Transition theory pinning particles leads to an ideal glass transition for a critical fraction $c=c_{K}(T)$ even for moderate super-cooling, e.g. close to the Mode-Coupling transition temperature. We first derive the phase diagram in the $T-c$ plane by mean field approximations. Then, by applying a real-space renormalization group method, we obtain the critical properties for $|c-c_{K}(T)|\rightarrow 0$, in particular the divergence of length and time scales. These are dominated by two zero-temperature fixed points. We also show that for $c=c_{K}(T)$ the typical distance between frozen particles is related to the static point-to-set lengthscale of the unconstrained liquid. We discuss what are the main differences when particles are frozen in other geometries and not from an equilibrium configuration. Finally, we explain why the glass transition induced by freezing particles provides a new and very promising avenue of research to probe the glassy state and ascertain, or disprove, the validity of the theories of the glass transition.
  

• 12:30 - 13:00 C. Fullerton

    We present a binary disk model in which phase separation and crystallisation are prevented and it is possible to study the glass transition as an equilibrium problem. Analysis of this model suggests it is consistent with mapping the structural glass to an Ising spin glass in a field. This implies that there is no ideal glass transition at finite temperature. A growing correlation length and structural relaxation time is predicted as the packing fraction approaches a critical value. Extensions to three dimensions and soft potentials will be discussed.
  

• 13:00 - 14:30   Lunch
• 14:30 - 15:30 H. Nishimori

  Ensemble inequivalence in disordered spin systems
  
  Canonical and microcanonical ensembles generally give equivalent results when applied to the same physical system. A prominent counterexample is the gravitational system, where specific heat, which is always positive in the canonical ensemble, becomes negative in the microcanonical ensemble due to the long-range nature of interactions. In the present talk, I will report on our results on disordered spin systems where ensemble inequivalence is observed. I will discuss through numerous examples when and how such anomalous phenomena might take place.
  
  [1] Z. Bertalan, T. Kuma, Y. Matsuda and H. Nishimori, J. Stat. Mech. (2011) P01016
  [2] H. Nishimori, J. Phys. Soc. Jpn. 80 (2011) 023002
  [3] Z. Bertalan and H. Nishimori, Phil. Mag. (2011) doi:10.1080/14786435.2011.568018
  [4] K. Takahashi, H. Nishimori and V. Martin-Mayor, J. Stat. Mech. (2011) P08024
  [5] Z. Bertalan and K. Takahashi, arXiv:1109.6366
  [6] Z. Bertalan and K. Takahashi, arXiv:1107.1929
  

• 15:30 - 16:00 L. Leuzzi

  How to compute mode-coupling theory decay exponents An important prediction of Mode-Coupling-Theory is the relationship between the decay exponents in the $\alpha$ and $\beta$ regimes and the so-called $\lambda$ parameter. In the original structural glass context these relationship follow from the MCT equations that are obtained making rather uncontrolled approximation. As a consequence, it is usually assumed that the relationship between the exponents is correct while the parameter $\lambda$ has to be treated like a tunable parameter. On the other hand, it is known that in some mean-field spin-glass models the dynamics is precisely described by MCT. In that context $\lambda$ can be computed exactly, though moving to more realistic models, e.g., finite-dimensional, it becomes difficult to estimate it. By means of an effective theory of dynamics we can show that it is possible to link $\lambda$ to physical observables and, consequently, provide a general procedure to compute it in any system. The connection can, further, be extended to theories predicting a continuous phase transition, e.g., across the dAT line in spin-glasses. The procedure has been applied to Ising p-spin, Potts and Random Orthogonal models, as well as to the Sherrington-Kirkpatrick model in magnetic field, both in fully connected and dilute systems. Comparison to existing numerical data is presented and discussed.
  

• 16:00 - 16:30 G. Szamel

  Beyond the mode-coupling theory: a perturbative diagrammatic approach Grzegorz Szamel, Hisao Hayakawa and Elijah Flenner
  
  We analyze corrections to the mode-coupling theory of the glass transition, focusing on the self-consistent equation for the non-ergodicity parameter. We use a previously derived diagrammatic formulation of the dynamics of interacting Brownian particles [1]. Our approach builds upon an earlier identification of a divergent contribution to a four-point correlation function [2]. We find that diagrams similar to those generating the divergence of the four-point function lead to divergent corrections to the mode-coupling theory's prediction for the long time limit of the irreducible memory function. We obtain an integral equation for a vertex function that re-sums a whole class of such divergent corrections. We show that the resulting additional contribution to the long time limit of the irreducible memory function cancels the mode-coupling contribution. We discuss consequences of this cancellation for the dynamic glass transition scenario predicted by the mode-coupling theory.
  
  [1] G. Szamel, J. Chem. Phys. 127, 084515 (2007).
  [2] G. Szamel, Phys. Rev. Lett. 101, 205701 (2008).
  

• 16:30 - 18:00   Posters (with coffee break from 4.30 to 5)

Wednesday, December 14

• 09:00 - 10:00 A. Liu

  Jamming and glasses
  
  The jamming transition of frictionless soft spheres coincides with the threshold for mechanical stability. This lends the marginally-jammed solid just above the transition special properties, including a diverging length scale and excess low-frequency modes that extend all the way down to zero frequency at the transition. Ellipsoids represent a singular perturbation to this picture because their packings lie below the threshold for mechanical stability at the jamming transition; there are an extensive number of zero frequency modes associated with rotations of the ellipsoids. Despite this, we find that the nature of the jamming transition appears to be the same for ellipsoids as it is for spheres, and argue that the transition is associated with a diverging length scale. Moreover, marginally-jammed ellipsoid packings can have three distinct classes of excess low-frequency modes. I will argue that the excess modes of the boson peak in real glasses result from the proximity of these systems to a jamming transition.
  

• 10:00 - 10:30 Mosayebi

  Correlations in non affine displacements of inherent structures
  
  Majid Mosayebi, Emanuela Del Gado, Patrick Ilg, and Hans Christian Öttinger
  
  Deformation of inherent structures can be a powerful tool for detecting structural changes and the onset of cooperativity in supercooled liquids. We use small static deformations to perturb inherent structures and to extract non-affine displacements by comparing them before and after deformation. This idea arises from a non-equilibrium thermodynamic model of glasses in which non-affine convection is assumed for the reversible part of dynamics [1]. Extended numerical simulations show that these non-affine displacements becomes very sensitive to temperature changes upon approaching glass transition [2] and allow to detect a growing static correlation length, with features strongly reminiscent of critical phenomena [3]. We now characterize distributions of displacement intensity and correlation patterns in the non-affine displacement field to discuss deeper the connections with the cooperative dynamics of supercooled liquids.
  
  [1] H. C. Öttinger, Phys. Rev. E 74, 095501 (2006).
  [2] E. Del Gado, P. Ilg, M. Kröger and H. C. Öttinger, Phys. Rev. Lett. 101, 095501 (2008).
  [3] M. Mosayebi, E. Del Gado, P. Ilg and H. C. Öttinger, Phys. Rev. Lett. 104, 205704 (2010).
  

• 10:30 - 11:00   Coffee break

• 11:00 - 12:00 E. Bouchaud

  STRESS CORROSION FRACTURE OF GLASS
  
  F. Lechenault^1,4, C. Rountree², F. Cousin³, L. Ponson⁵, J.-P. Bouchaud⁶ and E. Bouchaud^1,7
  
  1-3 CEA-Saclay, 91191 Gif-sur-Yvette Cedex, France
  1 Service de Physique de l’Etat Condensé (SPEC)
  2 Service de Physique et Chimie des Surfaces et Interfaces (SPCSI)
  3 Laboratoire Léon Brillouin (LLB)
  4 ENS, LPS, 24 rue Lhomond, 75231 Paris Cedex 05, France
  5 Institut Jean Le Rond d'Alembert, Case 162, 4 Place Jussieu, 75252 Paris Cedex 05, France
  6 CFM, 6 Boulevard Haussmann, 75009 Paris, France
  7ESPCI, UMR Gulliver, EC2M, Bât. H, 10 rue Vauquelin, 75231 Pris Cedex 05, France
  
  Although amorphous silica has a liquid-like homogeneous structure at length scales as short as ~10 Å, it seems to behave as a disordered material when fractured. Controversial Atomic Force Microscopy experiments have indeed suggested that a stress corrosion crack – which progresses very slowly under the combined action of an external load and of a chemical reaction with the water present in the surrounding atmosphere – propagates through the nucleation, growth and coalescence of nanometric cracks forming ahead of its tip. This “quasi-brittle” fracture mechanism is typical of highly disordered solids such as wood, concrete, or mortars.
  Because the presence of water leads to the rupture of Si-O bonds under very moderate external loads, we have probed the quantity of water entered into the glass during the fracture process. For this purpose, we have grown subcritical cracks in a controlled stable way within a saturated heavy water atmosphere. The resulting fracture surfaces were probed with neutron reflection and it was shown that heavy water had actually penetrated into the bulk of the material around the crack tip by ~100 Å. Furthermore, the high water concentrations stored within the first ~50 Å under the fracture surfaces suggest the presence of a highly damaged zone around the main crack tip.
  
  

• 12:00 - 12:30 J. R. Gomez-Solano

  We experimentally measure the spontaneous fluctuations of the position of a Brownian particle confined by an optical trap in an aging gelatin droplet after a fast quench and its linear response to an external perturbation. We compute the heat flux from the particle to the bath due tothe assemblage of the gel. We show that the heat fluctuations satisfy the asymmetry relation imposed by the fluctuation theorem and the mean heat flux is quantitatively related to the violation of the equilibrium fluctuation-dissipation theorem as a measure of the broken detailed balance during the aging process.
  
  References
  J. R. Gomez-Solano, A. Petrosyan, and S. Ciliberto, Phys. Rev. Lett. 106, 200602 (2011).
  

• 12:30 - 13:00 H. Yoshino

  Rigidity of structural glasses at finite temperatures - a first principle computation of the shear-modulus Microscopic understanding of the elasticity of structural glasses from the molecular level is an important problem both from scientific and practical point of views. We developed a first principle scheme to compute the elastic moduli of structural glasses at finite temperatures using the cloned liquid approach which combines the liquid theory and the replica method. We tested the scheme by applying it to the binary mixture of soft-spheres and obtained the shear-modulus which compares quite well with the earlier result of the molecular dynamic simulation by Barrat et. al. on the same system. The shear-modulus is significantly smaller than the instantaneous one and strongly depends on the temperature due to stress relaxations inside cages. By increasing the temperature the shear modulus crosses zero at a temperature Tc up to which the cage size remains small. Presumably Tc corresponds to the mode coupling critical temperature. The continuous vanishing of the shear-modulus is reminiscent of superheated crystals approaching the spinodal temperature, suggesting that the Born's criteria of melting - mechanical catastrophe - is relevant for amorphous solids as well as crystals.
  

• 13:00 - 14:30   Lunch
• 14:30 - 15:30 T. Voigtmann

  On the Yielding of Colloidal (and Other) Glass Formers
  
  I will discuss recent results of the mode-coupling theory for the nonlinear response of glass-forming suspensions under strong shear flow. In the steady state, these systems flow at the expense of a given shear stress that, in the limit of vanishing shear rate, defines a dynamical yield stress. Several predictions for the behavior of the yield stress close to the dynamical glass transition are contrasted with each other. I will also discuss other measures for the yield strength of glasses, in particular the point where plastic deformation sets in after the start-up of shear flow, and the slow creep deformation under fixed external load. The similarities and dis-similarities between colloidal glass formers, molecular glass formers, and some granular model materials will be addressed throughout the talk.
  

• 15:30 - 16:00 P. Chaudhuri

  Confined flow of amorphous materials
  
  Amorphous materials flow only when the applied external stress exceeds a critical yielding value. Flow of such materials in thin films or small channels is not only of industrial significance, it also provides much insight into their complex properties. Using simulations, we study such confined flows, for athermal and thermal systems, imposing different stress maps, viz. Couette (constant stress) and Poiseuille (heterogeneous stress). Our first observation is that, under confinement, the onset of flow in the Poiseuille setup requires stresses which are much higher than the measured bulk yield stress value. This is in contrast with Couette flow of similarly confined systems. Secondly, the yielding threshold for Poiseuille flow strongly depends on the channel-width : thinner the film, larger is the threshold. To account for the rheology of such jammed systems, a non-local flow model has been recently introduced, based on the idea that the flow is built via the occurrence of plastic events, triggered self-consistently by other events in the neighbourhood. Solving this model for the confined flows, we show that the heterogeneous stress map of the Poiseuille setup coupled with the correlations necessary for fluidization result in the dependence on confinement which we observe. Our finding thus suggests that generically the confined flow of amorphous materials in complex geometries could lead to nontrivial yielding scenarios.
  

• 16:00 - 16:30   Coffee break

• 16:30 - 17:00 G. Diezemann

  Nonlinear response theory for Markov processes In recent years, there has been an increasing number of investigations of the nonlinear response of glassy systems, partly because it gives access to the length scale associated with glassy dynamics.
  While most theoretical investigations focussed on the relevant four-point correlation functions, only a few model calculations of a nonlinear response have been performed.
  For Hamiltonian and stochastic Langevin dynamics a general nonlinear response theory has been developed some time ago.
  In the present contribution I will concentrate on the more general case of a Markovian dynamics described by a master equation.
  In this case, the formalism is somewhat more involved because the coupling to an external field is not restricted to be linear as for Langevin dynamics.
  This implies a more complex behavior of nonlinear response functions, which I will discuss for some specific examples.
  I will present explicit results for the method of nonresonant holeburning (NHB) and for the third order susceptibility for simple models.
  For example, in NHB even the sign of the spectral modification changes for different ways of couplings to the field showing that care has to be taken in the interpretation of experimental results.
  

• 17:00 - 17:30 S. Bhatatcharyya

    Analysis of the time series of particle displacement obtained from simulations have shown a decoupling between persistence and exchange time thus predicting a hierarchy of events [1]. The persistence time has been identified with the activated motion and the exchange time with the diffusive motion. The unified theory did predict hopping induced diffusion [2] but it failed to incorporate in the formulation the hierarchy of the events. The extended mode coupling theory [3] and the unified theory, [2] consider that diffusive and activated motions take place simultaneously and independently. A modified version of the continuous time random walk (CTRW) model incorporated this hierarchy, considering that the first jump is different from the subsequent jumps (4). Here we present a model where the dynamics is formulated using the concepts of a further modified CTRW and the continuous and activated motions are calculated using the concepts of the unified theory (2). As in the case of the unified theory the present formulation also predicts an interplay between the diffusive and the activated motion. At low temperatures, a regime usually not accessible to simulations, where kinetically constrained model shows the disappearance of fast processes (5), the dynamics is primarily activated. The present theory goes beyond the CTRW formulation (4) and shows that in this regime the activated motion is not only responsible for structural relaxation but it even gives rise to diffusion. We further show, that in this regime, the contribution of the activated motion to the structural relaxation and diffusive motion are different and this gives rise to the breakdown of the Stokes-Einstein relation (6).
  
  1.L. O. Hedges, L. Maibaum, D. Chandler and J. P. Garrahan, J. Chem. Phys. 127, 211101 (2007).
  2.S. M. Bhattacharyya, B. Bagchi, P. G. Wolynes, Proc. Natl. Acad. Sci. 105, 16077 (2008).
  3.W. Gotze and L. Sjogren, Z. Phys. B: Condens. Matter. 65, 415 (1987);
  S-H Chong, Phys. Rev. E 78, 041501 (2008).
  4.P. Chaudhuri, L. Bertheir, and W. Kob, Phys. Rev. Lett. 99, 060604 (2007) : P. Chaudhuri et. al. J. Phys. Condensed Mat. 20, 244126 (2008).
  5. L. Bertheir and J. P. Garrahan, Phys. Rev. E 68, 041201 (2003)
  6. S. M. Bhatatcharyya (manuscript under preparation)
  

•   Conference dinner

Thursday, December 15

• 09:00 - 10:00 P. G. Wolynes

  Glasses, Supercooled Liquids and their Ultimate Fate
  
  Peter G. Wolynes, Rice University, Houston, Texas US
  
  Supercooled liquids and glasses can be viewed as aperiodic crystals. Pursuing this view leads to the random first order transition theory of glasses. A liquid in this picture can be thought of as a mosaic of local energy landscapes. The theory explains quantitatively, without adjustable parameters, the super-Arrhenius slowing of dynamics and emergence of non-exponential relaxation in the supercooled liquid regime. The aging and rejuvenation upon heating of glasses can be quantitatively treated. The ultimate fate of glasses, at low temperature and in the fullness of time, is to become periodic crystals. The new length scales associated with the mosaic lead to new mechanisms of nanocrystallite formation and growth near and below the conventional laboratory glass transition.
  

• 10:00 - 10:30 T. Rizzo

  Field Theory of Fluctuations in Glasses We develop a field-theoretical description of dynamical heterogeneities and fluctuations in supercooled liquids close to the (avoided) MCT singularity. We eliminate time from the description and we characterize fluctuations in the beta regime. We argue that heterogeneities can be described through a replicated cubic field theory. The critical behaviour of such a theory turns out to be equivalent perturbatively to a cubic stochastic equation. A remarkable consequence is that that the most relevant sources of fluctuations are associated to variations of "self-induced disorder" in the initial condition of the dynamics. The phenomenon of perturbative dimensional reduction ensues, well known in random field problems, which implies an upper critical dimension of the theory equal to 8. We apply our theory to finite size scaling for mean-field systems and we test its prediction against numerical simulations. (S. Franz, G. Parisi, F. Ricci-Tersenghi and T. Rizzo, Eur. Phys. J. E. (2011) 34: 102)
  

• 10:30 - 11:00   Coffee break

• 11:00 - 12:00 M. Mézard

  Statistical physics-based reconstruction in compressed sensing
  
  Compressed sensing is triggering a major evolution in signal acquisition. It consists in sampling a sparse signal at low rate and later using computational power for its exact reconstruction, so that only the necessary information is measured. The talk will give an introduction to this topic from a statistical physics perspective. It will also describe some recent advances, based on the joint use of three essential ingredients: a probabilistic approach to signal reconstruction, a message-passing algorithm adapted from belief propagation, and a careful design of the measurement matrix inspired from the theory of crystal nucleation.
  Based on joint work with Florent Krzakala, François Sausset, Yifan Sun and Lenka Zdeborov
  

• 12:00 - 13:00 S.-I. Sasa

  Constructive approach to glass in finite dimensions
  
  Toward understanding the nature of glass in finite dimensions, I take a rather different approach from previous and current studies on glass physics. First, I construct lattice models with an infinite series of irregular-ground states generated by a deterministic rule, where the irregularity is defined as the absence of long range positional order. Second, I study the existence of a thermodynamic transition associated with these irregular ground states. Finally, by characterizing the ordered phase below the transition temperature, I consider whether this phase is glass-like or not The analysis on the basis of traditional ideas including a replica symmetry breaking is also discussed. Demonstrating the analysis of a few examples, I wish to provide a fresh view of glass.
  

• 13:00 - 13:30   Sandwich

• 13:30 - 14:30   Posters session

• 14:30 - 15:30 M. Van Hecke

  Extreme Physics and Rearrangements near Jamming
  
  Disordered packings of soft particles lose their mechanical rigidity at the jamming point. In recent years, much focus has been on scaling of linear response quantities with distance to the jamming point. Here I argue that the most important consequence of the jamming point is that it spawns a whole sector of intrinsically nonlinear, 'extreme physics'. I give some examples of this idea, and focus in particular on the nature of flow and rearrangements near jamming.
  

• 15:30 - 16:00 P. Charbonneau

    Identifying a relevant amorphous order parameter for the glass transition and jamming remains an open challenge, as several theoretical descriptions emphasize the role of a growing static length associated with the dynamical slowdown. The static ordering scenario based on the geometrical frustration of icosahedra has had a marked impact on the structural analysis of dense ?uids, but its dynamical predictions remain largely untested. Here, we examine this glass formation scenario in simple hard sphere models. We find that the suggested dual picture in terms of defects brings little insight and no theoretical simplification to the understanding of the dynamical slowdown, because of the strong frustration characterizing these systems. The possibility of a growing static length is furthermore found to be physically irrelevant in the regime that is accessible to computer simulations.
  
  Benoit Charbonneau, Patrick Charbonneau, Gilles Tarjus, "Geometrical Frustration and Static Correlations in a Simple Glass Former", arXiv:1108.2494v1.
  

• 16:00 - 16:30   Coffee break

• 16:30 - 17:00 D. Coslovich

  Many-body static correlations and fragility of viscous liquids We discuss the relationship between many-body static correlations and fragility in model viscous liquids. To probe static correlations beyond the pair level we analyze the spatial extension of clusters of interconnected locally preferred structures [1]. We also extract the point-to-set correlation lengths by randomly pinning the positions of finite fractions of particles. As a general rule, we find that many-body static correlations of LJ mixtures starts growing markedly upon cooling below the onset temperature T_O. Deep in the slow dynamics regime, the thermal rate of growth of static correlations is higher the more fragile the liquid. These two observations allow us to rationalize the large discrepancies of dynamic behavior between LJ and WCA liquids reported in [2]. Eventually, we compare our results for close-packed liquids to those for a model of strong, tetrahedral liquid. In this latter case, the growth of point-to-set correlation lengths by decreasing temperature appears weaker than in the LJ liquids. Our results thus indicate that inclusion of many-body static correlations in theories of the glass transition should be most crucial for the description of fragile glass-formers.
  
  [1] D. Coslovich, PRE 83, 051505 (2011)
  [2] L. Berthier and G. Tarjus PRL 103, 170601 (2009)
  

• 17:00 - 17:30 T. Schroeder

  Beyond power-law density scaling: Theory of isomorphs in dense liquids. Both experiments [1,2] and computer simulations [3,4] have shown that a large number of viscous liquids to a good approximation obey power-law density scaling, according to which the relaxation time is a function of a single variable $\rho^\gamma/T$. Here we show that power-law density scaling is an approximation to a more general form of scaling which we derive from the theory of isomorphs in dense liquids [5,6]. According to this, relaxation time is a function of $g(\rho)/T$, as originally proposed by Alba-Simionesco et al.[7] For liquids interacting via generalized LJ potentials we derive an explicit expression for $g(\rho)$ parameterized by a single parameter which can be determined independently. We show that the new scaling provides excellent results for the Kob-Andersen binary LJ mixture in a density range where power-law density scaling clearly fails.
  
  [1] C.M.Roland et al., Rep.Prog.Phys. v68, 1405 (2005).
  [2] D.Gundermann et al., NaturePhysics (2011).
  [3] D.Coslovich and C.M.Roland, J.Phys.Chem.B v112, 1329 (2008).
  [4] T.B.Schroeder et al., Phys.Rev.E (2009).
  [5] N.Gnan et al., J.Chem.Phys. v131, 234504 (2009).
  [6] T.B.Schroeder et al., J.Chem.Phys. v134, 164505 (2011).
  [7] C.Alba-Simionesco et al., Europhys.Lett. v68, 58 (2004).
  

Friday, December 16

• 09:00 - 10:00 J. Kurchan

  Glassy dynamics with selection: a different form of glassiness.
  
  We study the problem of a set of systems evolving in the same landscape, with relatively fast drift plus a weak rate of cloning and death depending on the position in the landscape. The time to fall into an attractor is assumed to be much shorter than the characteristic timescale of population change due to cloning/death.
  
  This problem may be relevant for example to the case of the dynamics of the transcriptional state of a (monoclonal) system of cells, under the influence of a selection pressure favoring certain transcriptional states.
  

• 10:00 - 10:30 L Foini

  Dynamic relaxation of a liquid cavity under amorphous boundary conditions The growth of cooperatively rearranging regions was invoked long ago by Adam and Gibbs to explain the slowing down of glass-forming liquids. The lack of knowledge about the nature of the growing order, though, complicates the definition of an appropriate correlation function. One option is the point-to-set correlation function, which measures the spatial span of the influence of amorphous boundary conditions on a confined system. By using a swap Monte Carlo algorithm we measure the equilibration time of a liquid droplet bounded by amorphous boundary conditions in a model glass-former at low temperature, and we show that the cavity relaxation time increases with the size of the droplet, saturating to the bulk value when the droplet outgrows the point-to-set correlation length. This fact supports the idea that the point-to-set correlation length is the natural size of the cooperatively rearranging regions. On the other hand, the cavity relaxation time computed by a standard, nonswap dynamics, has the opposite behavior, showing a very steep increase when the cavity size is decreased. We try to reconcile this difference by discussing the possible hybridization between MCT and activated processes, and by introducing a new kind of amorphous boundary conditions, inspired by the concept of frozen external state as an alternative to the commonly used frozen external configuration. arXiv:1006.3746v3
  

• 10:30 - 11:00   Coffee break

• 11:00 - 12:00 M. Mueller

  Quantum glasses and localization
  
  Classical glasses break ergodicity and localize in phase space due to frustration and the emergence of high barriers. Similar ergodicity breaking phenomena occur in strongly disordered quantum systems, but rather due to Anderson localization. The interplay of these two different causes of non-ergodicity will be discussed for two representative cases:
  
  (i) We present the solution of the quantum glass phase the field Ising spin glasses in a transverse field at T=0 and discuss the nature of its low energy collective excitations.
  (ii) The interplay between glassy freezing and localization is studied in a model of bosonic glasses, which can be simultaneously superfluid. Most interestingly, the model exhibits a disordered superfluid-to-insulator transition, which can be exactly solved. The latter elucidates many aspects of the non-trivial relation between Anderson delocalization and the onset of superfluidity.
  

• 12:00 - 12:30 A. Amir

  Lessons on Aging from Electron Glasses
  
  Among the key properties of glasses are slow relaxations to equilibrium without a typical timescale and aging. Understanding these phenomena is a long-standing problem in physics. In this talk I will show that the particular example of electron glasses is useful as a test-case to understand the generic mechanisms involved, leading to aging. I will describe our approach to the problem, and show that it generally leads to a particular form of aging, which we found to agree well with data on electron glasses, as well as various other systems such as disordered semiconductors and structural glasses. I will also show results on the expected deviations from the universal form, and what we think can be learnt from them.
  

• 12:30 - 13:00 P. Strack

  Tunable quantum glasses and phase transitions of atoms and photons: first testable predictions for glassy physics with many-body cavity QED
  
  Recent studies of strongly interacting atoms and photons in optical cavities have rekindled interest in the Dicke model of atomic qubits coupled to discrete photon cavity modes. In this talk, we argue that realizations of the Dicke model with variable atom-photon couplings can give rise to a ground state phase diagram exhibiting quantum phase transitions between paramagnetic, ferromagnetic, and a spin glass phase. These quantum optics realizations of quantum glasses are distinctive to condensed matter systems and provide new opportunities for glassy physics with many-body cavity QED. The photon-mediated random couplings between the atomic qubits (Ising spins) are truly long-ranged and the theory for these systems remains analytically tractable. We compute atomic and photon spectral response functions across this phase diagram, and outline how our predictions can be observed in experiments.
  

• 13:00 - 14:30   Lunch
• 14:30 - 15:30 V. Vitelli

   

• 15:30 - 16:00 H. Hayakawa

  Jamming transition at finite temperature
  
  We discuss a jamming transition of soft spheres after a quench from a high temperature to a low temperature in terms of the molecular dynamics simulation. We find that (i) the pressure and the plateau height of mean square displacement of a tracer particle exhibit critical scaling laws as functions of the quenched temperature and the excess volume fraction, (ii) a set of approximate scaling exponents is obtained from a mean field theory, (iii) some exponents agree with those from the replica theory, (iv) numerical estimated exponents are a little deviated from the theoretical values, and (v) the exponents depend on the initial temperature. The initial temperature dependence of the exponents may be related to the emergence of inherent structure in many valley systems, in which the temperature may be identical to the mode-coupling theory. This work is based on the collaboration with Michio Otsuki.
  

• 16:00 - 16:30   Coffee break

• 16:30 - 17:00 P. Keim

  Elastic properties of 2D amorphous solids
  
  In this contribution, we present experimental results on the elastic properties of a two-dimensional colloidal glass former. Given that glasses are solids, one expects a finite zero frequency shear modulus ? distinguishing them from the fluid phase. Using positional data from video microscopy [1] we study the displacement field and connect it to the dynamical matrix D(q) via the equipartition theorem, a method well established for crystalline solids [2]. In the long wavelength limit this data is used to derive the Lame coefficients and the corresponding moduli from thermally excited modes using continuum elasticity theory [3]. We consider finite size and time effects and find the expected frequency dependence of the shear modulus ?. By cooling the system, the onset of a zero frequency shear modulus ? allows us to determine the transition temperature from fluid to amorphous solid [4]. Following the method described in [5,6], we compute the short wavelength excitations in our system and analyse the density of states as well as the structure of normal modes in a two-dimensional colloidal system.
  
  [1] F. Ebert, P. Dillmann, G. Maret, and P. Keim, Rev. Sci. Instr. 80, 083902 (2009)
  [2] P. Keim, G. Maret, U. Herz, and H. H. von Gr¨unberg, Phys. Rev. Lett. 92, 215504 (2004)
  [3] H. H. Von Gr¨unberg, P. Keim, and G. Maret, Phys. Rev. Lett. 93, 255703 (2004)
  [4] C. Klix, E. Ebert, G. Maret, P. Keim, arXiv:1108.2636v1
  [5] A. Gosh, V. K. Chikkadi, P. Schall, J. Kurchan, and D. Bonn, Phys. Rev. Lett. 104, 248305 (2010)
  [6] D. Kaya, N. L. Green, C. E. Maloney, and M. F. Islam, Science 329, 656 (2010)
  

• 17:00 - 17:30 I. Procaccia

  Universality in the Mechanical Response and Plastic Failure of AmorphousSolids.
  
  On the basis of extensive simulations of metallic glasses and LenardJones glasses,we discover universal exponents in the elasto-plastic response of the systemto external strains.We will argue that this universality stems from the genericity of thesaddle-node bifurcationcharacterizing the plastic failure in such systems.