  We construct a phenomenological Z_2 lattice gauge theory to describe the
spin-liquid state of the S=1/2 kagome Heisenberg antiferromagnet in the sector
with zero total spin. The model is a natural generalization of the
Misguich-Serban-Pasquier Hamiltonian with added interactions that are strongly
constrained by lattice symmetries. We are able to reproduce qualitatively many
of the characteristic features observed in recent numerical studies. We also
make connections to the previous works along similar lines.
