Long-Range Nematic Order in Two-Dimensional Active Matter

Abstract

Working in two space dimensions, we show that the orientational order emerging from self-propelled polar particles aligning nematically is quasi-long-ranged beyond ${\ell }_{\mathrm{r}}$, the scale associated to induced velocity reversals, which is typically extremely large and often cannot even be measured. Below ${\ell }_{\mathrm{r}}$, nematic order is long-range. We construct and study a hydrodynamic theory for this de facto phase and show that its structure and symmetries differ from conventional descriptions of active nematics. We check numerically our theoretical predictions, in particular the presence of $\pi$-symmetric propagative sound modes, and provide estimates of all scaling exponents governing long-range space-time correlations.

arXiv comment6 pages, 2 figures, comments welcomed

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Cited by in corpus (5)

• Nematic Torques in Scalar Active Matter: when Fluctuations Favor Polar Order and Persistence
• Reentrant condensation transition in a model of driven scalar active matter with diffusivity edge
• Reentrant phase behavior in binary topological flocks with nonreciprocal alignment
• Phase separation of self-propelled disks with ferromagnetic and nematic alignment
• Individual particle persistence antagonizes global ordering in populations of nematically-aligning self-propelled particles