Excitons in Mott insulators -: art. no. 035111

Motivated by recent Raman and resonant inelastic x-ray scattering experiments performed for Mott insulators we present a theory of exciton formation in the upper Hubbard band. The analysis based on the spin-polaron approach is performed in the framework of an effective model. Our results confirm existence of excitons and bear resemblance to experimental data despite simplicity of our approach. They prove that the basic underlying mechanism of exciton formation is similar to that which gives rise to binding of holes in weakly doped antiferromagnets but differs from the latter in some crucial aspects.