Abstract
| Original language | English |
|---|---|
| Article number | 073039 |
| Pages (from-to) | 1-14 |
| Number of pages | 14 |
| Journal | New Journal of Physics |
| Volume | 18 |
| DOIs | |
| Publication status | Published - 20 Jul 2016 |
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Keywords
- active matter
- flocking
- response theory
- emergent behavior
- renormalization group
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Leading birds by their beaks : the response of flocks to external perturbations. / Kyriakopoulos, Nikos; Ginelli, Francesco; Toner, John.
In: New Journal of Physics, Vol. 18, 073039, 20.07.2016, p. 1-14.Research output: Contribution to journal › Article
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TY - JOUR
T1 - Leading birds by their beaks
T2 - the response of flocks to external perturbations
AU - Kyriakopoulos, Nikos
AU - Ginelli, Francesco
AU - Toner, John
N1 - Acknowledgments We have benefited from discussions with H Chaté and A Cavagna. We acknowledge support from the Marie Curie Career Integration Grant (CIG) PCIG13-GA-2013-618399. JT also acknowledges support from the SUPA distinguished visitor program and from the National Science Foundation through awards # EF-1137815 and 1006171, and thanks the University of Aberdeen for their hospitality while this work was underway. FG acknowledges support from EPSRC First Grant EP/K018450/1.
PY - 2016/7/20
Y1 - 2016/7/20
N2 - We study the asymptotic response of polar ordered active fluids ("flocks") to small external aligning fields h. The longitudinal susceptibility χ∥ diverges, in the thermodynamic limit, like h−ν as h→0. In finite systems of linear size L, χ∥ saturates to a value ∼Lγ. The universal exponents ν and γ depend only on the spatial dimensionality d, and are related to the dynamical exponent z and the "roughness exponent" α characterizing the unperturbed flock dynamics. Using a well supported conjecture for the values of these two exponents, we obtain ν=2/3, γ=4/5 in d=2 and ν=1/4, γ=2/5 in d=3. These values are confirmed by our simulations.
AB - We study the asymptotic response of polar ordered active fluids ("flocks") to small external aligning fields h. The longitudinal susceptibility χ∥ diverges, in the thermodynamic limit, like h−ν as h→0. In finite systems of linear size L, χ∥ saturates to a value ∼Lγ. The universal exponents ν and γ depend only on the spatial dimensionality d, and are related to the dynamical exponent z and the "roughness exponent" α characterizing the unperturbed flock dynamics. Using a well supported conjecture for the values of these two exponents, we obtain ν=2/3, γ=4/5 in d=2 and ν=1/4, γ=2/5 in d=3. These values are confirmed by our simulations.
KW - active matter
KW - flocking
KW - response theory
KW - emergent behavior
KW - renormalization group
U2 - 10.1088/1367-2630/18/7/073039
DO - 10.1088/1367-2630/18/7/073039
M3 - Article
VL - 18
SP - 1
EP - 14
JO - New Journal of Physics
JF - New Journal of Physics
SN - 1367-2630
M1 - 073039
ER -