Universal scaling of segment fluctuations in polymer and chromatin dynamics

TL;DR

This paper uncovers how center-of-mass motion affects polymer and chromatin segment fluctuations, revealing a universal $1/s$ scaling law that clarifies the relationship between structure and dynamics across different systems.

Contribution

It introduces a universal scaling law for segment fluctuations influenced by COM motion, validated through theory, simulations, and chromatin imaging data.

Findings

COM diffusivity scales as 1/s regardless of system details

Dynamic exponent reveals topological constraints in chromatin

Resolves discrepancy between chromatin structure and dynamics

Abstract

We demonstrate how center-of-mass (COM) motion influences polymer segment fluctuations. Cancellation of internal forces, together with spatially uncorrelated external noise, generally yields COM diffusivity scaling as $1/s$ with segment length $s$, regardless of fractal dimension, viscoelasticity, or activity. This introduces distinct dynamic scaling corrections to two-point fluctuations and quenched-induced tangential correlations, validated by theory, simulations, and chromatin imaging data. In the latter, the extracted dynamic exponent reveals topological constraints, thereby resolving the discrepancy between chromatin's crumpled structure and its Rouse-like dynamics.