  Ground state cooling of massive mechanical objects remains a difficult task
restricted by the unresolved mechanical sidebands. We propose an
optomechanically-induced-transparency cooling scheme to achieve ground state
cooling of mechanical motion without the resolved sideband condition in a pure
optomechanical system with two mechanical modes coupled to the same optical
cavity mode. We show that ground state cooling is achievable for sideband
resolution $\omega_{m}/\kappa$ as low as 0.003. This provides a new route for
quantum manipulation of massive macroscopic devices and high-precision
measurements.
