2026
3.
Andriy Goychuk
Gaussian closure and dynamical mean-field theory for self-avoiding heteropolymers Miscellaneous
2026, (Version Number: 1).
Abstract | Links | BibTeX | Tags: Mean Field Theory, Polymers, Soft Condensed Matter
@misc{goychuk_gaussian_2026,
title = {Gaussian closure and dynamical mean-field theory for self-avoiding heteropolymers},
author = {Andriy Goychuk},
url = {https://arxiv.org/abs/2604.02085},
doi = {10.48550/ARXIV.2604.02085},
year = {2026},
date = {2026-01-01},
urldate = {2026-05-29},
publisher = {arXiv},
abstract = {Analytical treatments of polymer dynamics have mostly been restricted to linear response theory around some steady state obtained via perturbative field theory. Here, I derive an analytical framework that yields unified access to the evolution of conformations, contact probabilities, and fluctuations within a dynamical mean-field theory. Starting with the Langevin equation of a hydrodynamically coupled and self-avoiding heteropolymer, the key idea is to focus on the two-point correlator as the lowest-order relevant observable. Truncating higher-order correlations via a Gaussian closure leads to a self-consistent diffusion equation for the chain correlations. The theory is validated by contrasting coiled, globular, and self-avoiding polymers within a single dynamical framework, and predicts hyper-compacted fractal states in hydrodynamically coupled active polymers such as chromatin.},
note = {Version Number: 1},
keywords = {Mean Field Theory, Polymers, Soft Condensed Matter},
pubstate = {published},
tppubtype = {misc}
}
Analytical treatments of polymer dynamics have mostly been restricted to linear response theory around some steady state obtained via perturbative field theory. Here, I derive an analytical framework that yields unified access to the evolution of conformations, contact probabilities, and fluctuations within a dynamical mean-field theory. Starting with the Langevin equation of a hydrodynamically coupled and self-avoiding heteropolymer, the key idea is to focus on the two-point correlator as the lowest-order relevant observable. Truncating higher-order correlations via a Gaussian closure leads to a self-consistent diffusion equation for the chain correlations. The theory is validated by contrasting coiled, globular, and self-avoiding polymers within a single dynamical framework, and predicts hyper-compacted fractal states in hydrodynamically coupled active polymers such as chromatin.
2.
Matteo Ciarchi; Andriy Goychuk; Erwin Frey
Active fluctuations induce buckling of living surfaces Miscellaneous
2026, (Version Number: 1).
Abstract | Links | BibTeX | Tags: Active Matter, Soft Condensed Matter, Statistical Mechanics
@misc{ciarchi_active_2026,
title = {Active fluctuations induce buckling of living surfaces},
author = {Matteo Ciarchi and Andriy Goychuk and Erwin Frey},
url = {https://arxiv.org/abs/2602.24272},
doi = {10.48550/ARXIV.2602.24272},
year = {2026},
date = {2026-01-01},
urldate = {2026-05-29},
publisher = {arXiv},
abstract = {Active tissues exhibit tension fluctuations that are correlated in space and time. We study a minimal overdamped surface model in which such fluctuations enter as a zero-mean, multiplicative modulation of the local surface tension. Although the deterministic elastic dynamics (tension plus bending) stabilizes the flat state for all nonzero wave numbers, we find that sufficiently persistent active fluctuations generate positive ensemble growth rates for a finite band of Fourier modes, leading to stochastic buckling with wavelength selection. A non-Markovian theory based on the Novikov–Furutsu theorem captures the instability threshold and unstable band observed in simulations.},
note = {Version Number: 1},
keywords = {Active Matter, Soft Condensed Matter, Statistical Mechanics},
pubstate = {published},
tppubtype = {misc}
}
Active tissues exhibit tension fluctuations that are correlated in space and time. We study a minimal overdamped surface model in which such fluctuations enter as a zero-mean, multiplicative modulation of the local surface tension. Although the deterministic elastic dynamics (tension plus bending) stabilizes the flat state for all nonzero wave numbers, we find that sufficiently persistent active fluctuations generate positive ensemble growth rates for a finite band of Fourier modes, leading to stochastic buckling with wavelength selection. A non-Markovian theory based on the Novikov–Furutsu theorem captures the instability threshold and unstable band observed in simulations.
2024
1.
Matthew Du; Andriy Goychuk; Suriyanarayanan Vaikuntanathan
Hidden nonreciprocity as a stabilizing effective potential in active matter Miscellaneous
2024, (Version Number: 3).
Abstract | Links | BibTeX | Tags: Nonreciprocal Systems, Soft Condensed Matter, Statistical Mechanics
@misc{du_hidden_2024,
title = {Hidden nonreciprocity as a stabilizing effective potential in active matter},
author = {Matthew Du and Andriy Goychuk and Suriyanarayanan Vaikuntanathan},
url = {https://arxiv.org/abs/2401.14690},
doi = {10.48550/ARXIV.2401.14690},
year = {2024},
date = {2024-01-01},
urldate = {2026-05-29},
publisher = {arXiv},
abstract = {Nonreciprocal interactions are known to produce distinctive dynamics in active matter. To shed light on how the stationary state of such systems is affected by breaking reciprocity, we consider active Ornstein-Uhlenbeck particles coupled nonreciprocally by a transverse force, which is perpendicular to the gradient of the interaction energy. Focusing on the steady-state distribution of positions, we show that the nonreciprocal coupling helps keep the system at its stable configurations, including not only energy minima but also nonequilibrium configurations stabilized by the persistent noise which propels the particles. In contrast, the transverse force would not change the stationary distribution at all if the noise were thermal. For a variety of active systems, we demonstrate the stabilizing role of the nonreciprocity, finding that it stiffens springs, aligns spins, improves associative memory, and enhances motility-induced phase separation.},
note = {Version Number: 3},
keywords = {Nonreciprocal Systems, Soft Condensed Matter, Statistical Mechanics},
pubstate = {published},
tppubtype = {misc}
}
Nonreciprocal interactions are known to produce distinctive dynamics in active matter. To shed light on how the stationary state of such systems is affected by breaking reciprocity, we consider active Ornstein-Uhlenbeck particles coupled nonreciprocally by a transverse force, which is perpendicular to the gradient of the interaction energy. Focusing on the steady-state distribution of positions, we show that the nonreciprocal coupling helps keep the system at its stable configurations, including not only energy minima but also nonequilibrium configurations stabilized by the persistent noise which propels the particles. In contrast, the transverse force would not change the stationary distribution at all if the noise were thermal. For a variety of active systems, we demonstrate the stabilizing role of the nonreciprocity, finding that it stiffens springs, aligns spins, improves associative memory, and enhances motility-induced phase separation.