  We report a theoretical study of electron spin resonance in bulk topological
insulators, such as Bi2Se3, Bi2Te3 and Sb2Te3. Using the effective four-band
model, we find the electron energy spectrum in a static magnetic field and
determine the response to electric and magnetic dipole perturbations,
represented by oscillating electric and magnetic fields perpendicular to the
static field. We determine the associated selection rules and calculate the
absorption spectra. This enables us to separate the effective orbital and spin
degrees of freedom and to determine the effective g-factors for electrons and
holes.
