264 research outputs found
Sub-aging in a Domain Growth Model
We study analytically the aging dynamics of the O(n) model in the large-n
limit, with conserved and with non-conserved order parameter. While in the
non-conserved dynamics, the autocorrelation function scales in the usual way
C(t,tw) = C(t/tw), in the case of a conserved order parameter, `multiscaling'
manifests itself in the form C(t,tw) = C (h(t)/h(tw)), with a relaxation time
growing more slowly than the age of the system (sub-aging), and h(t) a function
growing faster than any length scale of the problem. In both cases, the
effective temperature associated to the violation of the fluctuation theorem
tends to infinity in the asymptotic limit of large waiting times
A few bubbles in a glass
I briefly review a recent series of papers putting forward a coarse-grained
theoretical approach to the physics of supercooled liquids approaching their
glass transition. After a suitable coarse-graining, the dynamics of the liquid
is replaced by that of a mobility field, which can then be analytically
treated. The statistical properties of the mobility field then determine those
of the liquid. Thermodynamic, spatial, topographic, dynamic properties of the
liquid can then be quantitatively described within a single framework, and
derive from the existence of an underlying dynamic critical point located at
zero-temperature, where timescales and lengthscales diverge.Comment: Paper presented at "Fluctuations and Noise 2004", May 25-28, 2004,
Maspalomas, Gran Canaria, Spai
Dynamic heterogeneity in amorphous materials
Amorphous solids are mechanically rigid while possessing a disordered
structure similar to that of dense liquids. Recent research indicates that
dynamical heterogeneity, spatio-temporal fluctuations in local dynamical
behavior, might help understanding the statistical mechanics of glassy states.Comment: 7 pages; 5 figures -- "Trends" article published by Physics at
http://physics.aps.org/articles/v4/4
Nonequilibrium glass transitions in driven and active matter
The glass transition, extensively studied in dense fluids, polymers, or
colloids, corresponds to a dramatic evolution of equilibrium transport
coefficients upon a modest change of control parameter, like temperature or
pressure. A similar phenomenology is found in many systems evolving far from
equilibrium, such as driven granular media, active and living matter. While
many theories compete to describe the glass transition at thermal equilibrium,
very little is understood far from equilibrium. Here, we solve the dynamics of
a specific, yet representative, class of glass models in the presence of
nonthermal driving forces and energy dissipation, and show that a dynamic
arrest can take place in these nonequilibrium conditions. While the location of
the transition depends on the specifics of the driving mechanisms, important
features of the glassy dynamics are insensitive to details, suggesting that an
`effective' thermal dynamics generically emerges at long time scales in
nonequilibrium systems close to dynamic arrest.Comment: 7 pages, 2 fig
- …