We investigate the phase transition properties of the polymer-Potts model, a chain composed of monomers with magnetic degrees of freedom, with the motivation to study the conformation and mark switching dynamics of chromatin. By the mean-field approximation, we find that the phase transition between the swollen-disordered state and the compact-ordered state is discrete; it is first-order as in the long-range Potts model, but with a significantly larger jump in magnetization (i.e., mark coherence) upon the ordering transition. The results imply how small changes in epigenetic writer concentrations can lead to a macroscopic switching of the chromatin state, suggesting a simple mechanism of discrete switching observed, for instance, in cell differentiation.
@article{arxiv.1907.10533,
title = {Chromatin state switching in a polymer model with mark-conformation coupling},
author = {Kyosuke Adachi and Kyogo Kawaguchi},
journal= {arXiv preprint arXiv:1907.10533},
year = {2019}
}