20 research outputs found
Asymptotic distributions of Periodically Driven Stochastic Systems
We study the large-time behaviour of Brownian particles moving through a
viscous medium in a confined potential, and which are further subjected to
position-dependent driving forces that are periodic in time. We focus on the
case where these driving forces are rapidly oscillating with an amplitude that
is not necessarily small. We develop a perturbative method for the
high-frequency regime to find the large-time behavior of periodically driven
stochastic systems. The asymptotic distribution of Brownian particles is then
determined to second order. To first order, these particles are found to
execute small-amplitude oscillations around an effective static potential which
can have interesting forms.Comment: 8 pages; Included an e.g. in the last section; added references;
final version in two column
Oscillating states of driven Langevin systems in large viscous regime
We employ an appropriate perturbative scheme in the large viscous regime to
study oscillating states in driven Langevin systems. We explicitly determine
oscillating state distribution of under-damped Brownian particle subjected to
thermal, viscous and potential drives to linear order in anharmonic
perturbation. We also evaluate various non-equilibrium observables relevant to
characterize the oscillating states. We find that the effects of viscous drive
on oscillating states are measurable even in the leading order and show that
the thermodynamic properties of the system in these states are immensely
distinct from those in equilibrium.Comment: 14 pages, 2 figure
Critical dynamics of nonconserved -vector model with anisotropic nonequilibrium perturbations
We study dynamic field theories for nonconserving -vector models that are
subject to spatial-anisotropic bias perturbations. We first investigate the
conditions under which these field theories can have a single length scale.
When N=2 or , it turns out that there are no such field theories, and,
hence, the corresponding models are pushed by the bias into the Ising class. We
further construct nontrivial field theories for N=3 case with certain bias
perturbations and analyze the renormalization-group flow equations. We find
that the three-component systems can exhibit rich critical behavior belonging
to two different universality classes.Comment: Included RG analysis and discussion on new universality classe
Phase transitions in periodically driven macroscopic systems
We study the large-time behavior of a class of periodically driven
macroscopic systems. We find, for a certain range of the parameters of either
the system or the driving fields, the time-averaged asymptotic behavior
effectively is that of certain other equilibrium systems. We then illustrate
with a few examples how the conventional knowledge of the equilibrium systems
can be made use in choosing the driving fields to engineer new phases and to
induce new phase transitions.Comment: LaTex, 8 page
The role of initial conditions in the ageing of the long-range spherical model
The kinetics of the long-range spherical model evolving from various initial
states is studied. In particular, the large-time auto-correlation and -response
functions are obtained, for classes of long-range correlated initial states,
and for magnetized initial states. The ageing exponents can depend on certain
qualitative features of initial states. We explicitly find the conditions for
the system to cross over from ageing classes that depend on initial conditions
to those that do not.Comment: 15 pages; corrected some typo
Kinetics of a non-glauberian Ising model: global observables and exact results
We analyse the spin-flip dynamics in kinetic Ising chains with
Kimball-Deker-Haake (KDH) transition rates, and evaluate exactly the evolution
of global quantities like magnetisation and its fluctuations, and the two-time
susceptibilities and correlations of the global spin and the global three-spin.
Information on the ageing behaviour after a quench to zero temperature is
extracted
Kinetics of the long-range spherical model
The kinetic spherical model with long-range interactions is studied after a
quench to or to . For the two-time response and correlation
functions of the order-parameter as well as for composite fields such as the
energy density, the ageing exponents and the corresponding scaling functions
are derived. The results are compared to the predictions which follow from
local scale-invariance.Comment: added "fluctuation-dissipation ratios"; fixed typo