Angular forces between disclinations in elastically anisotropic nematic liquid crystals

In elastically anisotropic nematic liquid crystals one finds a new type of interaction between disclinations. It is shown that energy is needed for one defect to move round another resulting in angular forces. To a first order in elastic anisotropy this force can easily be computed. When extended to long pitch cholesterics the theory brings out some interesting features observed experimentally. In particular, the observation that disclination pairs are always helical appears to follow naturally from the theory