  In spatial dimensions d >= 2, Kondo lattice models of conduction and local
moment electrons can exhibit a fractionalized, non-magnetic state (FL*) with a
Fermi surface of sharp electron-like quasiparticles, enclosing a volume
quantized by (\rho_a-1)(mod 2), with \rho_a the mean number of all electrons
per unit cell of the ground state. Such states have fractionalized excitations
linked to the deconfined phase of a gauge theory. Confinement leads to a
conventional Fermi liquid state, with a Fermi volume quantized by \rho_a (mod
2), and an intermediate superconducting state for the Z_2 gauge case. The FL*
state permits a second order metamagnetic transition in an applied magnetic
field.
