  A symmetry based analysis (Projective Symmetry Group) is used to study spin
liquid phases on the triangular and Kagom\'e lattices in the Schwinger boson
framework. A maximum of eight distinct $Z_2$ spin liquid states are found for
each lattice, which preserve all symmetries. Out of these only a few have
nonvanishing nearest neighbor amplitudes which are studied in greater detail.
On the triangular lattice, only two such states are present - the first
(zero-flux state) is the well known state introduced by Sachdev, which on
condensation of spinons leads to the 120 degree ordered state. The other
solution which we call the $\pi$-flux state has not previously been discussed.
Spinon condensation leads to an ordering wavevector at the Brillouin zone edge
centers, in contrast to the 120 degree state. While the zero-flux state is more
stable with just nearest-neighbor exchange, we find that the introduction of
either next-neighbor antiferromagnetic exchange or four spin ring-exchange (of
the sign obtained from a Hubbard model) tends to favor the $\pi$-flux state. On
the Kagom\'e lattice four solutions are obtained - two have been previously
discussed by Sachdev, which on spinon condensation give rise to the $q=0$ and
$\sqrt{3}\times\sqrt{3}$ spin ordered states. In addition we find two new
states with significantly larger values of the quantum parameter at which
magnetic ordering occurs. For one of them this even exceeds unity,
$\kappa_c\approx 2.0$ in a nearest neighbor model, indicating that if
stabilized, could remain spin disordered for physical values of the spin. This
state is also stabilized by ring exchange interactions with signs as derived
from the Hubbard model.
