title: Anisotropic isometric fluctuation relations in experiment and theory on a self-propelled rod.
abstract: The isometric fluctuation relation (IFR) [P. I. Hurtado et al., Proc. Natl. Acad. Sci. USA 108, 7704 (2011)10.1073/pnas.1013209108] relates the relative probability of current fluctuations of fixed magnitude in different spatial directions. We test its validity in an experiment on a tapered rod, rendered motile by vertical vibration and immersed in a sea of spherical beads. We analyze the statistics of the velocity vector of the rod and show that they depart significantly from the IFR of Hurtado et al. Aided by a Langevin-equation model we show that our measurements are largely described by an anisotropic generalization of the IFR [R. Villavicencio et al., Europhys. Lett. 105, 30009 (2014)10.1209/0295-5075/105/30009], with no fitting parameters, but with a discrepancy in the prefactor whose origin may lie in the detailed statistics of the microscopic noise. The experimentally determined large-deviation function of the velocity vector has a kink on a curve in the plane.
authors: Department of Physics, Indian Institute of Science, Bangalore 560 012, India.
authors: Nitin
authors: N
authors: Kumar
authors: Department of Physics, Indian Institute of Science, Bangalore 560 012, India.|TIFR Centre for Interdisciplinary Sciences, Tata Institute of Fundamental Research, 21 Brundavan Colony, Osman Sagar Road, Narsingi, Hyderabad 500 075, India.
authors: Harsh
authors: H
authors: Soni
authors: TIFR Centre for Interdisciplinary Sciences, Tata Institute of Fundamental Research, 21 Brundavan Colony, Osman Sagar Road, Narsingi, Hyderabad 500 075, India.
authors: Sriram
authors: S
authors: Ramaswamy
authors: Department of Physics, Indian Institute of Science, Bangalore 560 012, India.
authors: A K
authors: AK
authors: Sood