We present a certain class of two-dimensional frustrated quantum Heisenberg
spin systems with multiple ring exchange interactions which are rigorously
demonstrated to have quantum disordered ground states without magnetic
long-range order. The systems considered in this paper are s=1/2
antiferromagnets on a honeycomb and square lattices, and an s=1 antiferromagnet
on a triangular lattice. We find that for a particular set of parameter values,
the ground state is a short-range resonating valence bond state or a valence
bond crystal state. It is shown that these systems are closely related to the
quantum dimer model introduced by Rokhsar and Kivelson as an effective
low-energy theory for valence bond states.Comment: 6 pages, 4 figure