Finite-Time Orientational Relaxation Restructures Collective Motion in Polar Active Matter
Abstract
We introduce a Langevin formulation of Vicsek-like active particles in which orientations evolve through finite-rate relaxation toward the local mean direction, with alignment strength J and rotational diffusivity Dr, thereby combining Vicsek-type local consensus with XY-like orientational dynamics. Using large-scale numerical simulations, we determine the nonequilibrium phase diagram as a function of activity and alignment rate. Increasing the alignment rate drives a sequence of transitions from a homogeneous isotropic state to polar bands, a cross-sea phase of intersecting bands, a homogeneous polar state, and ultimately a micro-clustered regime. The isotropic-to-polar transition is strongly first order, as evidenced by Binder cumulants and bimodal distributions of local polarization and density, indicating coexistence of gas-like and liquid-like regions. Near the onset of collective motion, band size increases with activity but depends non-monotonically on alignment rate. Further increasing the alignment rate drives the system through the cross-sea and homogeneous polar phases before enhanced density fluctuations lead to micro-clustering. Our results demonstrate that finite-time orientational relaxation acts as a control parameter that qualitatively restructures collective behavior in polar active matter.
Versions
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BibTeX
@misc{kumar2026finitetime,
title = {{Finite-Time Orientational Relaxation Restructures Collective Motion in Polar Active Matter}},
author = {Rajneesh Kumar and Subhransu Sekhar Mishra and Debasish Chaudhuri},
howpublished = {arXiv},
year = {2026},
month = jun,
doi = {10.48550/arxiv.2606.10474},
eprint = {2606.10474},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2606.10474},
note = {CC BY 4.0},
}
RIS
TY - UNPB
TI - Finite-Time Orientational Relaxation Restructures Collective Motion in Polar Active Matter
AU - Rajneesh Kumar
AU - Subhransu Sekhar Mishra
AU - Debasish Chaudhuri
PY - 2026
DA - 2026/06/09
PB - arXiv
DO - 10.48550/arxiv.2606.10474
UR - https://arxiv.org/abs/2606.10474
AB - We introduce a Langevin formulation of Vicsek-like active particles in which orientations evolve through finite-rate relaxation toward the local mean direction, with alignment strength J and rotational diffusivity D_r, thereby combining Vicsek-type local consensus with XY-like orientational dynamics. Using large-scale numerical simulations, we determine the nonequilibrium phase diagram as a function of activity and alignment rate. Increasing the alignment rate drives a sequence of transitions from a homogeneous isotropic state to polar bands, a cross-sea phase of intersecting bands, a homogeneous polar state, and ultimately a micro-clustered regime. The isotropic-to-polar transition is strongly first order, as evidenced by Binder cumulants and bimodal distributions of local polarization and density, indicating coexistence of gas-like and liquid-like regions. Near the onset of collective motion, band size increases with activity but depends non-monotonically on alignment rate. Further increasing the alignment rate drives the system through the cross-sea and homogeneous polar phases before enhanced density fluctuations lead to micro-clustering. Our results demonstrate that finite-time orientational relaxation acts as a control parameter that qualitatively restructures collective behavior in polar active matter.
ER -