On the origin of mixed inhomogeneous phase in vortical gluon plasma

Recently, lattice simulations of SU(3) Yang-Mills theory revealed that rotating hot gluon matter in thermal equilibrium possesses a novel inhomogeneous phase consisting of the deconfinement phase located in the center region, which is spatially separated from the confinement phase in the periphery. This inhomogeneous two-phase structure is also expected to be produced by vorticity in quark-gluon plasma formed in non-central relativistic heavy-ion collisions. We show that its vortical properties are determined by two types of couplings of the angular velocity to the gluon fields: a linear coupling to the mechanical angular momentum of gluons and a quadratic ``magnetovortical'' coupling to a chromomagnetic component. We demonstrate numerically that the distinctive inhomogeneous structure of the vortical (quark-)gluon plasma is determined by the latter, while the former plays only a subleading role. We argue that the anisotropy of the gluonic action in the curved co-rotating background can quantitatively explain the remarkable property that the spatial structure of this inhomogeneous phase disobeys the picture based on a straightforward implementation of the Tolman-Ehrenfest law. We also support our findings with Monte Carlo simulations of Yang-Mills plasma at the real-valued angular frequency, which take into account only the magnetic part of the action.