265 research outputs found
Long-wavelength fluctuations lead to a model of the glass crossover
The effect of long wavelength fluctuations on the Mode-Coupling-Theory (MCT)
dynamical singularity at in the regime is studied by means of the
standard field-theoretical procedure for a genuine second-order phase
transition. The resulting perturbative loop expansion can be resummed leading
to an extension of the MCT equation for the critical correlator with local
random fluctuations of the separation parameter. The corresponding model
explains both qualitatively and quantitatively why the MCT dynamical
singularity is transformed into a crossover from relaxational to activated
dynamics. Dynamical Heterogeneities emerge naturally as the
ergodicity-restoring mechanism instead of {\it ad hoc} hopping processes.Comment: Accepted for publication on EPL, based on talk given at 7 IDMRCS
(arxiv:1307.4303
Ultrametricity Between States at Different Temperatures in Spin-Glasses
We prove the existence of correlations between the equilibrium states at
different temperatures of the multi--spin spherical spin-glass models with
continuous replica symmetry breaking: there is no chaos in temperature in these
models. Furthermore, the overlaps satisfy ultrametric relations. As a
consequence the Parisi tree is essentially the same at all temperatures with
lower branches developing when lowering the temperature. We conjecture that the
reference free energies of the clusters are also fixed at all temperatures as
in the generalized random-energy model.Comment: 18 pages, submitted to EPJ
Chaos in Temperature in Diluted Mean-Field Spin-Glasses
We consider the problem of temperature chaos in mean-field spin-glass models
defined on random lattices with finite connectivity. By means of an expansion
in the order parameter we show that these models display a much stronger chaos
effect than the fully connected Sherrington-Kirkpatrick model with the
exception of the Bethe lattice with bimodal distribution of the couplings.Comment: 9 page
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