Equilibrium of a charged spinning test particle in Reissner-Nordstrom backgrounds with a nonzero cosmological constant - art. no. 104016

The equilibrium of a charged test particle with spin located in the Reissne r-Nordstrom background with a nonzero cosmological constant is investigated . The stationary equilibrium conditions resulting from the equations of mot ion and the equations of spin dynamics have to be satisfied simultaneously. It is shown that equilibrium conditions are independent of the spin of the test particle. For uncharged particles, they are satisfied at the so-calle d static radius, where gravitational attraction is exactly compensated for by cosmological repulsion. For charged particles, there is a variety of pos sible equilibria due to the electromagnetic interaction of the particle and the background. Any charged particle can be in an unstable equilibrium sta te between the black-hole and cosmological horizons of asymptotically de Si tter spacetimes, while sufficiently repulsed particles can be in an inner u nstable equilibrium state and an outer stable equilibrium state above the h orizon of asymptotically anti-de Sitter spacetimes. The separation-independ ent equilibrium is possible in extreme Reissner-Nordstrom(c)spacetimes only .