Before revision:  We theoretically analyze the dynamical effects of histone modifications on gene switching by using the Doi-Peliti operator formalism of chemical reaction kinetics . The calculated probability flux in self-regulating genes shows a distinct circular flow  around basins in the landscape of the gene state distribution, giving rise to hysteresis in gene switching.
After revision:  We theoretically analyze the dynamical effects of histone modifications on gene switching by using the Doi-Peliti operator formalism of reaction kinetics to the problem of coupled molecular processes. The spin-1 and spin-1/2 coherent state representations are introduced to describe stochastic reactions of histones and binding/unbinding of TF in a unified way, which provides a concise view of the effects of timescale difference among these molecular processes; even in the case that binding/unbinding of TF to/from DNA are adiabatically fast, the slow nonadiabatic histone dynamics give rise to a distinct circular flow around basins in the landscape of the gene state distribution, giving rise to hysteresis in gene switching.