Mixed symmetries in active non-reciprocal systems

Yuv Agarwal; Ylann Rouzaire; Daniel J. G. Pearce

Home/Archive/arXiv

arXiv · 2610.36817

Mixed symmetries in active non-reciprocal systems

Yuv Agarwal·Ylann Rouzaire·Daniel J. G. Pearce

View original source ↗Read source document ↗Export metadata ↓

Abstract

Active materials are driven out of equilibrium at the microscopic scale and display diverse phenomenology; non-reciprocity is a subclass of activity in which action-reaction symmetry is also broken. These models are often grouped by the order of symmetry of their components, such as polar bird flocks or hexatic cellular tissues. However, many biological examples exist in which the components appear to have two or more symmetries simultaneously. To study this effect we introduce two independently controllable symmetries to the non-reciprocal XY model. This lattice model demonstrates wide ranging behavior dictated by the chosen symmetries. We derive a full hydrodynamic description of our lattice model that highlights the mechanisms driving its behavior. Each combination of symmetries can lead to a different hydrodynamic model with one or two simultaneous order parameters with different levels of orientational order that can appear active or not.

Explore related subjects

cond-mat.soft

Keep this discovery

Explore connections, maps & timelines

BibTeX RIS

Yuv Agarwal, Ylann Rouzaire, Daniel J. G. Pearce. 2026-10-27. Mixed symmetries in active non-reciprocal systems. https://arxiv.org/abs/2610.36817

Cite the original work for its findings. Save a collection to share your selection of sources.

KEEP EXPLORING

Related papers

arXiv2026

Active tissue mechanics drives a diversity of collective flows in uniaxially compressed 3D spheroids

Compression can enhance or suppress cell motion and induce coherent rotation in tissue spheroids, but the physical factors governing these responses remain unclear. Using a minimal three-dimensional active vertex model, we examine how tissue mechanics, active driving, and directional alignment shape the response to uniaxial compression. Without alignment, compression enhances transverse motion in solid-like spheroids throughout the tested activity range, whereas fluid-like spheroids switch from acceleration at low activity to slowing at high activity. Changes in contact persistence connect these responses to neighbor exchange. Passive five-cell calculations show that compression reshapes local rearrangement barriers depending on geometry and loading direction; a high-strain increase in the fluid-like mean coexists with many low-barrier paths. With strong alignment, compression induces coherent rotation in solid-like spheroids, while fluid-like spheroids show no comparable rotation. Rotating solids retain more persistent cell contacts than fluids and develop tangential organization of peripheral cells. Controlled perturbations reveal that compression softens a differential-twist mode and activity slows its relaxation. Together, these results link activity-dependent reversal of the speed response and compression-induced coherent rotation to contact dynamics, local rearrangement costs, and active driving. Our findings demonstrate that one minimal model, with parameters representing effective mechanical and active tissue properties, captures diverse collective responses to compression and provides a framework for predicting how different tissues respond to mechanical loading.

cond-mat.soft↗

arXiv2026

Tribocharging of Granular Materials Dictated by Geometric and Thermoelectric Effects

Tribocharging of granular materials is a widespread phenomenon ranging from volcanic eruptions and dust storms to pharmaceutical processing, yet its underlying mechanism remains elusive. Recent thermoelectric models have provided a quantitative framework for triboelectric charge transfer, but they have difficulty accounting for charging between identical materials. In this Letter, we propose a theory of granular tribocharging based on the interplay between particle geometry and thermoelectric response. Collision-induced frictional heating produces a size-dependent temperature asymmetry between particles, generating a thermoelectric voltage that drives charge transfer. The sign of the Seebeck coefficient determines the charging polarity, while particle size and thermal properties set its magnitude. Our multi-collision theory explains the experimentally observed size- and material-dependent reversal of charging polarity, as in quartz and nylon.

cond-mat.soft↗

arXiv2026

Multiscale dynamics in yield stress fluids during homogeneous and shear-banded yielding

Whether homogeneous and shear-banded yielding involve distinct microscopic mechanisms remains unresolved. We combine oscillatory rheology with gradient-resolved particle tracking to compare a ductile Carbopol microgel that yields homogeneously with a more brittle dense emulsion that develops stationary shear bands. In both systems, we separate long-range correlated ballistic flow from local Fickian diffusion and find that the two act on the same tracers, rather than on distinct persistent populations. This finding challenges the distinct-population interpretation of earlier experiments, which could access only dynamics averaged over particles and along the velocity-gradient direction. We distinguish these contributions in Carbopol by varying the tracer radius $a$ and the observation-window size $L$ independently. The ballistic velocity is independent of $a$ but increases with $L$, indicating correlations beyond the field of view; the diffusion coefficient $D$ scales as $1/a$ and is independent of $L$. At fixed driving frequency and tracer size, emulsion measurements collapse onto a single $D(γ_L)$ curve, whether taken across the banded profile or at fixed height under varying applied amplitude. Local strain amplitude, rather than stress, therefore governs the mean diffusive mobility within our resolution. The increase of $D$ with $γ_L$ is steeper than in Carbopol, consistent with the emulsion's greater brittility. Diffusive displacements are nearly Gaussian in Carbopol, with no measurable cooperativity, while in the emulsion they are strongly non-Gaussian and cooperative. There, the four-point susceptibility is largest at the strain characterising the interband region. Homogeneous and shear-banded yielding therefore share the same dynamical ingredients, while differing in the statistics and spatial organisation of the residual diffusive motion.

cond-mat.soft↗