סמינר לפיזיקה של מערכות ביולוגיות וחומרים רכים: Exact Results in Stochastic Processes with Division, Death, and Diffusion

Abstract:

We consider a generic class of stochastic particle-based models whose state at an instant in time is described by a set of continuous degrees of freedom (e.g. positions), and the length of this set changes stochastically in time due to birth-death processes. Using a master equation formalism, we write down the dynamics of the corresponding (infinite) set of probability distributions: this takes the form of coupled Fokker-Planck equations with model-dependent source and sink terms. We derive the general expression of entropy production rate for this class of models in terms of path irreversibility. To demonstrate the practical use of this framework, we present a biologically motivated model of division, death, and diffusion which includes spatial correlations through the particle division process. By systematically integrating out excess degrees of freedom, we obtain the marginal probability distribution, enabling exact calculations of key statistical properties such as average density and spatial correlations. Finally, we validate our analytical results through numerical Brownian dynamics simulations, finding excellent agreement between theory and simulation.