Issue Europhys. Lett. Volume 62, Number 2, April 2003 Page(s) 196 - 202 Section General DOI 10.1209/epl/i2003-00346-7

DOI: 10.1209/epl/i2003-00346-7
Europhys. Lett., 62 (2) , pp. 196-202 (2003)

Active nematics on a substrate: Giant number fluctuations and long-time tails

S. Ramaswamy¹, R. Aditi Simha¹ and J. Toner<sup>2

1</sup>  Centre for Condensed-Matter Theory, Department of Physics Indian Institute of Science - Bangalore 560 012, India
²  Department of Physics, University of Oregon - Eugene, OR 94703, USA

sriram@physics.iisc.ernet.in
aditi@mpipks-dresden.mpg.de
jjt@darkwing.uoregon.edu

(Received 27 August 2002; accepted in final form 18 February 2003)

Abstract
We construct the equations of motion for the coupled dynamics of order parameter and concentration for the nematic phase of driven particles on a solid surface, and show that they imply i) giant number fluctuations, with a standard deviation proportional to the mean in dimension d = 2 of primary relevance to experiment, and ii) long-time tails in the autocorrelation of the particle velocities despite the absence of a hydrodynamic velocity field. Our predictions can be tested in experiments on aggregates of amoeboid cells as well as on layers of agitated granular matter.

PACS
05.70.Ln - Nonequilibrium and irreversible thermodynamics.
87.18.Ed - Aggregation and other collective behavior of motile cells.
45.70.-n - Granular systems.

© EDP Sciences 2003

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