Director structure around a colloid particle suspended in a nematic liquid crystal.

We analyze the director field around a spherical colloid particle with radial ~homeotropic! anchoring on its surface. Depending on the relative strength of anchoring W, controlled by the parameter WR/K with K the Frank constant andR the particle radius, the director distribution may possess a singular ring of a 21/2 disclination in the equatorial plane. The equilibrium radius of this ring, at rigid radial anchoring, is a*'1.25R and only weakly depends on the disclination core energy. At small anchoring the director field is regular and weakly disturbed by the particle, there is a characteristic crossover W* between the two regimes. We obtain the analytical expression for n~ r !, which decays as rsin2u away from the particle, and compare it with the exact numerical solution in the highly distorted nonlinear regime. @S1063-651X~96!04511-4#